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Flashcards in Organisms Deck (121)
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1
Q

Streptococcuspyogenes (Group A)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram + cocci
β-hemolytic
extracellular
——————
- human reservoir
(colonize throat and skin)
- transmission by aerosolized fomites & direct contact
——————
1) M protein: complexes with LTA to bind fibronectin and adhere; complexes with factor H to coat bacteria (molecular mimicry) and avoid alternate complement pathway and phagocytosis; induces autoantibodies with react with cardiac tissue
2) lipoteichoic acid (LTA): attaches to fibronectin on oropharyngeal cells; promotes inflammation
3) hyaluronic acid capsule: inhibits phagocytosis; molecular mimicry (identical to human ground substance)
4) C5a peptidase: cleaves C5a
5A) Streptolysin O (SLO): β-hemolysis
5B) Streptolysin S (SLS): β-hemolysis
6)Streptokinase (SKA): clot dissolution
7) Streptodornase (DNAse B): digests DNA
8) Hyaluronidase: digests hyaluronic acid in capsule and tissue
9) Erythrogenic toxin: superantigen that diffusely activates T cells and damages small blood vessels; associated with scarlet fever & TSS
10) protein G: binds Ig Fc portion

---------------------
mucosal infections
- local spread from pharyngeal colonization
pyogenic infections
- local spread or bacteremia
- multiple target organs
toxigenic infections
- local infection acts as a site for toxin secretion to host (e.g. erythrogenic toxin)
immunologic
- rheumatic fever caused by GAS proteins which target host organs
- post-streptococcal glomerulonephritis caused by deposition of antibody-antigen complexes
----------------------
mucosal infections
- pharyngitis
pyogenic infections
- necrotizing fasciitis
toxigenic infections
- scarlet fever
- toxic shock syndrome
immunologic
- rheumatic fever
-post-streptococcal glomerulonephritis
  • can be classified by M protein type
  • all antibacterial medications EXCEPT
    1) Ceftazidime
    2) Monobactams
    3) Tetracyclines
    4) TMP/SMX
    5) Rifampin (not as monotherapy)
    6) Metronidazole
    7) Polymyxins
2
Q

Mycobacterium tuberculosis

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
atypical rod with waxy coating
slow-growing
primarily intracellular
aerobic
-----------------------
- inhalation of aerosolized bacteria
- only people with active disease are contagious
  • Kat G: catylase/peroxidase that prevents death from ROS
  • mycolic acid: long chain fatty acid that is a major component of cell walls; required for cell viability
  • lipoarabinomannan (LAM): mycobacterial version of LPS; signals host molecules
  • other lipids: survival, immunomodulatory
  • persistence genes
  • macrophage survival genes
  • ESX loci (e.g. ESAT-6/CFP-10): secretion systems; also immunostimulatory
  • inhibit phagosome-lysosome fusion
  • resistant to lysosomal enzymes due to cell wall
  • down-regulate MHCII presentation to avoid detection by CD4 cells

1) enter alveolar macrophages via phagocytosis (complement receptor and mannose receptor can enhance this process)
2) inflammatory signals from infected cells
3) recruitment of monocytes (which become macrophages) and lymphocytes to lungs
4) caseous granuloma formation (necrotic center)
5) active TB: bacteria escape and form more granulomas
6) latent TB: bacteria is contained by granuloma; becomes fibrotic and may become calcified
7) reactivation: bacteria escape TB due to age or immunosuppression
8) can spread to other organs through blood
- host immune response contributes to pathology

pulmonary TB
- lung destruction
- pulmonary hemorrhage and hemoptysis
- fever
- wasting
- sepsis
extrapulmonary TB
- spread through blood to other organs after pulmonary infection
- Pott’s disease: disease of the spine; usually occurs in children
- meningitis, usually in children
- TB of GI tract
- TB of lymph nodes
miliary TB
- spreads throughout lungs or throughout body
- typically occurs in children or immunocompromised people
50% fatality if untreated
primary TB = active TB within 1-2 years of initial infection
- latent TB = infection without clinical disease
- reactivation TB = reactivation of latent infection that results in active TB; can occur in the lungs or elsewhere

  • PPD test: antigen mixture is injected under skin of forearm; T cell-mediated delayed type hypersensitivity reaction occurs if the person is infected
  • IGRA (IFN-γ release assay): measures IFN-γ production by ELISA following stimulation of blood with ESAT-6 + CFP-10; used to distinguish Mtb infection from BCG vaccination or non-tuberculous mycobacteria sensitization
  • CXR: lesion or cavity indicates infection and disease
  • acid-fast stain of sputum
  • culture (takes a long time)
  • PCR-based detection that also indicates drug resistance
-----------------------
use all 4 of these for the first 2 months:
- Rifampin
- Isoniazid
- Ethambutol
- Pyrazinamide
use both of these for the next 4 months:
- Rifampin
- Isoniazid
add this if the bacteria is resistant to the drugs listed above:
- Moxifloxacin
airborne precautions
3
Q

Mycobacterium leprae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
atypical rod with waxy coating
obligate intracellular
cannot culture
-----------------------
- respiratory
- can infect armadillos
  • waxy coating provides resistance to desiccation and phagocytosis
  • capsule containing phenolic glycolipid (PGL-1)
  • lives in macrophages & Schwann cells
    lepromatous leprosy
  • type 2 immune response
  • CD8 >CD4
  • IL-4, IL-10
  • antibodies
  • nerve damage is the result of bacteria replicating in Schwann cells
  • erythema nodosum leprosum most likely immune complex-mediated
    tuberculoid leprosy
  • CD4 > CD8
  • IFN-γ, IL-2
  • macrophage activation
  • cell-mediated response
  • ## nerve damage is the result of inflammation in tuberculoid leprosy
- lesions are flat, depigmented, and anesthetic
lepromatous leprosy
- skin lesions, sensory deficits, enlarged peripheral nerves, dermal edema, disfigurement of nose and face
tuberculoid leprosy
- skin lesions & peripheral nerve damage
- erythema nodosum leprosum: painful nodules and neuritis; occurs most often after antibiotic treatment 
-----------------------
- diagnose by skin biopsy stained with hematoxylin and eosin and acid-fast stain
lepromatous leprosy
- high bacterial load
- few lymphocytes
- foamy macrophages
- lack of granulomas
- negative DTH (response to leprosy antigen lepromin) due to anergy
tuberculoid leprosy
- low bacterial load
- numerous lymphocytes in lesions
- granulomas
- positive DTH test	
-----------------------
- Rifampin
- Dapsone
4
Q

Mycobacterium avium complex
(MAC)
(includes M. avium and M. intracellulare)

Morphology
Transmission and Reservoir
Virulence Factors

Diseases
Diagnosis
Treatment and Prevention

A

atypical rod with waxy coating

  • environmental
  • waxy coating provides resistance to desiccation and phagocytosis

-AIDS patients
- fever
- wasting
- may be disseminated to blood and bone marrow
- pulmonary disease (rare)
Children
- cervical lymphadenitis
———————–
- acid-fast stain
———————–
- macrolides

5
Q

Mycobacterium marinum

Morphology
Transmission and Reservoir
Virulence Factors

Diseases
Diagnosis

A

atypical rod with waxy coating

- marine organism - ----------------------	
- waxy coating provides resistance to desiccation and phagocytosis - ----------------------	
  • swimmer’s granuloma / fish tank
    granuloma
    ———————–
  • ## acid-fast stain
6
Q

Mycobacterium kansaii

Morphology
Transmission and Reservoir
Virulence Factors

Diagnosis

A

atypical rod with waxy coating

  • environmental
  • waxy coating provides resistance to desiccation and phagocytosis

acid-fast stain
———————–

7
Q

Mycobacterium ulcerans

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
A

atypical rod with waxy coating

  • environmental
  • endemic in parts of Africa and Australia
  • transmitted by water bugs?
  • waxy coating provides resistance to desiccation and phagocytosis
  • extracellular, unlike others
  • toxin necrotizes skin
  • Buruli ulcer
  • acid-fast stain
8
Q

Mycobacterium fortuitum

Morphology
Transmission and Reservoir
Virulence Factors
Diagnosis

A

atypical rod with waxy coating

  • environmental
  • usually causes disease in immunocompromised people
  • waxy coating provides resistance to desiccation and phagocytosis
  • acid-fast stain
9
Q

Rickettsia rickettsii

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

atypical; Gram- structure; pleomorphic

obligate intracellular

  • ability to direct actin reorganization resulting in the formation of filopodia that enhance spread between cells
  • ## phospholipases, proteases, and membrane peroxidation result in host cell damage1) enters through tick bite
    2) spread via lymph and blood
    2) grows inside vascular endothelial cells and causes lysis and rash
  • ## escapes phagosome to live in cytoplasmRocky Mountain spotted fever
    1) spotted rash 2-4 days after onset (not always seen)
    2) fever, malaise, headache, myalgias, vomiting, abdominal pain, diarrhea, conjunctivitis, mental confusion, meningitis, respiratory difficulties, renal dysfunction, myocarditis
    3) 25% fatality if untreated; 4% fatality if treated
    ———————–
  • ## can be non-specifically detected by Weil-Felix test (not currently used clinically)
  • Doxycycline
10
Q

Chlamydia trachomatis

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A

atypical; Gram- structure w/o peptidoglycan; pleomorphic

elementary & reticulate bodies

obligate intracellular

STD, perinatal transmission
———————–
1) grows within epithelial cells of ocular & genital mucosa
2) results in chronic inflammatory response & scarring
3) adaptive immune response cannot prevent re-infection
4) L serovars (which cause LGV) infect macrophages and lymph nodes
———————–
- often asymptomatic
- men: Urethritis → epididymitis, arthritis, Reiter’s syndrome (arthritis + Urethritis + conjunctivitis)
- women: Urethritis, cervicitis → endometritis, salpingitis, PID → infertility, ectopic pregnancy
- babies: conjunctivitis, pneumonia
- LGV: primary lesion → fever, headache, myalgias → lymph node inflammation → lymph node rupture, elephantiasis, proctitis, rectal damage

11
Q

Chlamydia pneumoniae

Morphology
Diseases
Treatment and Prevention

A
atypical; Gram- structure w/o peptidoglycan; pleomorphic
elementary & reticulate bodies
obligate intracellular
energy parasite	
-----------------------
community-acquired pneumonia	
-----------------------
- tetracyclines
- fluoroquinolones
- macrolides
12
Q

Chlamydia psittaci

Morphology
Transmission and Reservoir

Diseases

A

atypical; Gram- structure w/o peptidoglycan; pleomorphic

elementary & reticulate bodies

obligate intracellular

energy parasite	
-----------------------
birds	
-----------------------
psittacosis (pneumonia)
13
Q

Treponema pallidum
(Spirochete)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

atypical; Gram - structure; spiral-shaped; endoflagellum

  • STD
  • ## can cross the placentano LPS on outer membrane,
    GAGs in outer sheath (molecular mimicry)
    ———————–
    1) infection through skin abrasions & mucous membranes
    2) spreads throughout blood
    3) colonizes spleen and lymph nodes in latent phase
    4) reactivates
    ———————–
  • primary syphilis: chancre
  • secondary syphilis: rash (entire body including palms and soles of feet), lymphadenopathy, condyloma lata
  • tertiary syphilis: gummas, neurosyphilis, heart problems
  • congenital syphilis: stillbirth or premature; enlarged liver & spleen, skeletal involvement, pneumonia, skin lesions
  • ## congenital syphilis after 2 years: bone, tooth, & skin malformations, pathologic changes in CNS
  • visualize by dark field microscopy
  • ## serologic tests (treponemal & non-treponemal)
  • penicillin
  • aminopenicillin
14
Q
Borrelia burgdorferi
(Spirochete)
Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

  • reservoir: rodents (white-footed mouse)
  • transmission: deer tick bite (nymph or adult stage); transmission requires at least 36 hours
  • ## found in northeast, northern midwest, and northwest (Washington)Osps: surface lipoproteins that are differentially expressed in
    tick and human hosts; important for tissue attachment and for activation of growth; attaches to proteoglycans receptors at site where it grows
    ———————–
    1) bacteria is injected during tick bite
    2) local replication in skin (days)
    3) widespread dissemination to other organs (days-weeks)
    local inflammatory reaction (lymphocytes & plasma cells)
    ———————–
    Lyme disease
  • early stage (2-30 days): erythema migrans rash (not always present), malaise, fatigue, headache, fever, chills, myalgias
  • early disseminated (2 weeks - 6 months): neurological, ocular, and/or cardiac symptoms
  • late (2 months - 7 years): oligoarthritis, chronic dermatologic syndromes, neurologic symptoms
  • ## post-treatment Lyme disease syndromes: similar to chronic fatigue, fibromyalgia; likely autoimmune, not chronic infection
  • visualize by dark field microscopy
  • ## diagnose with ELISA and Western blot
  • Doxycycline
  • Amoxicillin
  • Ceftriaxone
15
Q

Leptospira
(Spirochete)

Morphology
Diseases

A

atypical; Gram - structure; spiral-shaped

leptospirosis

16
Q

Mycoplasma pneumoniae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases

Treatment and Prevention

A

atypical; no cell wall; sterols in plasma membrane

  • human reservoir
  • inhalation of respiratory droplets
  • adhesins
  • CARDS toxin: ADP-ribosylating and vacuolating cytotoxin
  • peroxides damage epithelium
  • 1) inhalation
    2) nasopharyngeal colonization
    3) aspiration
    4) bronchopneumonia (does not enter alveoli)
    5) inflammatory response damages respiratory epithelium
  • often asymptomatic
  • persistent cough (“walking pneumonia”)
  • erythema multiforme rash
  • anemia
  • tetracyclines
  • fluoroquinolones
  • macrolides
17
Q

Candida albicans

Morphology
Transmission and Reservoir

Diseases

Treatment and Prevention

A
yeast	
-----------------------
- mouth, skin, GI tract, vagina
- occurs when there is a breach in the host immune defense
- usually endogenous infection
- can be passed between people in some instances
-----------------------
- oral thrush
- esophagitis
- vaginitis
- bloodstream infection
- abscesses
- catheter-associated UTI
- can disseminate to multiple organs
-----------------------
mucocutaneous:
- Nystatin
- oral or topical azoles
systemic:
- azoles
- Echinocandins
- Amphotericin B
18
Q

Candida glabrata

Morphology
Transmission and Reservoir

Diseases

Treatment and Prevention

A

yeast

  • mouth, skin, GI tract, vagina
  • occurs when there is a breach in the host immune defense
  • seen when C. albicans is decreased by fluconazole treatment
  • oral thrush
  • esophagitis
  • vaginitis
  • bloodstream infection
  • abscesses
  • same as Candida albicans
19
Q

Cryptococcus neoformans

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
yeast	
-----------------------
- soil contaminated by bird droppings
- inhalation
- immunocompromised hosts	
-----------------------
- polysaccharide capsule
-  melanin to protect against oxidative stress
-----------------------
1) inhaled
2) travels to CNS and other organs	
-----------------------
pneumonia
meningoencephalitis
- occurs in up to 10% of people with AIDS
- persistent, dull headache, malaise, fever, night sweats, meningeal signs may or may not be present
skin & bloodstream infections	
-----------------------
- India ink stain of CSF
- Cryptococcal antigen test on blood or CSF: measuring polysaccharide antigen by ELISA or latex agglutination
- CSF culture	
-----------------------
- Amphotericin B + 5-flucytosine, followed by fluconazole
20
Q

Cryptococcus gattii

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
yeast	
-----------------------
-inhalation
- tropical areas	
-----------------------
- polysaccharide capsule
- melanin to protect against oxidative stress
-----------------------
1) inhaled
2) travels to CNS and other organs	
-----------------------
pneumonia
meningoencephalitis
skin & bloodstream infections	
-----------------------
- stain w/ India ink
-----------------------
- same as Cryptococcus neoformans
21
Q

Pneumocystis jiroveci (Pneumocystis carinii)

Morphology
Transmission and Reservoir

Diseases
Diagnosis
Treatment and Prevention

A

yeast

lacks ergosterol
-----------------------
- inhalation of cyst in childhood
- reactivation when immunocompromised
-----------------------
Pneumocystis jiroveci Pneumonia (PJP)
- gradual onset of fever, dyspnea, and non-productive cough	
-----------------------
- CXR with bilateral interstitial infiltrates, rarely focal or cavitary	
-----------------------
- TMP/SMX
22
Q

Aspergillus flavus

Morphology
Transmission and Reservoir
Virulence Factors

Diseases
Diagnosis
Treatment and Prevention

A
mold
-----------------------
- rotting plants
- inhalation	
-----------------------
aflatoxin B1 is a powerful carcinogen	
-----------------------
-----------------------
hepatocellular carcinoma	
-----------------------
- branching, septate hyphae	
-----------------------
- Amphotericin
- Voriconazole
- Posaconazole
- Itraconazole
- Echinocandins
23
Q

Aspergillus perasiticus

Morphology
Transmission and Reservoir
Virulence Factors

Diseases
Diagnosis
Treatment and Prevention

A
mold
-----------------------
- rotting plants
- inhalation	
-----------------------
aflatoxin B1 is a powerful carcinogen	
-----------------------
-----------------------
hepatocellular carcinoma	
-----------------------
- branching, septate hyphae	
-----------------------
same as A. flavus:
- Amphotericin
- Voriconazole
- Posaconazole
- Itraconazole
- Echinocandins
24
Q

Aspergillus fumigates

Morphology
Transmission and Reservoir

Pathogenesis
Diseases
Diagnosis
Treatment and Prevention

A

mold

  • rotting plants
  • inhalation
  • 1) inhalation of spores
    2) evasion of pulmonary macrophages or neutrophils
    3) local infection in the lung
    4) entry into blood vessels
    5) dissemination to other sites (e.g. brain)
  • airway colonization
  • allergic bronchopulmonary aspergillosis (ABPA)
  • treacheobronchitis
  • sinusitis
  • aspergilloma (fungus ball)
  • invasive pulmonary aspergillosis
  • disseminated aspergillosis
  • branching, septate hyphae
  • same as A. flavus
25
Q

Aspergillus niger

Morphology
Transmission and Reservoir 
Diseases
Diagnosis
Treatment and Prevention
A
mold
-----------------------
- rotting plants
- inhalation
-----------------------
chronic otitis externa	
-----------------------
- branching, septate hyphae	
-----------------------
- same as A. flavus
26
Q

Zoophilic Dermatophyte:
Microsporum canis

Morphology
Transmission and Reservoir

Pathogenesis
Diseases
Diagnosis
Treatment and Prevention

A
mold	
-----------------------
- animals
- contact	
-----------------------
 infect keratinized layer of skin	
-----------------------
tinea corpis (ring worm), tinea capitis (scalp infection)	
-----------------------
- skin scrapings or nail clippings can be examined microscopically or cultured
- fluoresces green under UV light	
-----------------------
- Imidazoles
- Terbinafine
- Azoles
27
Q

Anthropophilic Dermatophyte:
Trichophyton rubrum

Morphology
Transmission and Reservoir

Pathogenesis
Diseases
Diagnosis
Treatment and Prevention

A
mold	
-----------------------
- humans
- contact	
-----------------------
 infect keratinized layer of skin	
-----------------------
tinea pedis (athlete’s foot), tinea cruris (jock itch)
-----------------------
- skin scrapings or nail clippings can be examined microscopically or cultured
  • Imidazoles
  • Terbinafine
  • Azoles
28
Q
Zygomycetes:
Mucor
Absidia
Rhizopus
Rhizomucor
Morphology
Transmission and Reservoir 
Diseases
Diagnosis
Treatment and Prevention
A
mold	
-----------------------
- inhalation
- risk factors: immune deficiency, diabetes, hemochromatosis
-----------------------
pneumonia
sinusitis
brain abscess
thrombosis
infarction	
-----------------------
- non-septate hyphae that branch at right angles
-----------------------
- Amphotericin B
- Posaconazole
29
Q

Sporothrix schenckii

Morphology
Transmission and Reservoir
Diseases

A

dimorphic fungi
(mold at ambient temperature, yeast at 37C)
———————–
soil, infected plant products, wood, roses
- puncture wound
———————–
cutaneous disease with local lymphatic spread

30
Q

Histoplasma capsulatum

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
dimorphic fungi	
-----------------------
- soil in Mississippi & Ohio River Valleys
- inhalation	
-----------------------
-disseminated from respiratory tract	
-----------------------
histoplasmosis
pulmonary infection; can be disseminated
31
Q

Coccidioides spp.

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
dimorphic fungi	 
-----------------------
-soil in SW US
- inhalation
- no person-to-person transmission	
-----------------------
1) mycelia (infectious) form in soil
2) spores within humans convert to spherules
3) spherules rupture and release endospores, which form more spherules
- disseminated from respiratory tract	
-----------------------
valley fever:
- can be asymptomatic
- primary disease usually resolves spontaneously
- immunocompromised patients are more susceptible to chronic or disseminated infection
- complications:
1) cavity formation
2) dissemination to skin
3) meningitis
4) pneumonia
32
Q

Blastomyces dermatitidis

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
dimorphic fungi	
-----------------------
- soil in Mississippi & Ohio River Valleys
- inhalation	-	
-----------------------
disseminated from respiratory tract
-----------------------
blastomycosis:
pulmonary infection that spreads to skin and bone
33
Q

Dermatiaceous molds

Morphology
Diseases

A

mold

cutaneous & subcutaneous infection,
fungal meningitis

34
Q

Penicillium marneffei

Transmission and Reservoir

A
  • SE Asia

- immunocompromised hosts

35
Q

Fusarium

Transmission and Reservoir

A
  • patients with hematological malignancies and bone marrow transplantation
36
Q

Scedosporium

Transmission and Reservoir

A
  • post-traumatic infection in immunocompetent

- disseminated infection in immunocompromised

37
Q

Entamoeba histolytica

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases

Treatment and Prevention

A
protazoa	
-----------------------
- fecal-oral
- contaminated food or water
- rarely found in US	
-----------------------
- cysts	
-----------------------
1) cyst is excreted by a person
2) fecally contaminated food or water is ingested
3) becomes a trophozoites in the gut and attaches to colonic mucosa
4) may penetrate mucosa and travel to the liver via the portal circulation, forming liver abscesses
5) more cysts are formed in the gut and shed
-----------------------
bloody diarrhea
liver abscess
incubation time of 2-4 weeks	
-----------------------
Metronidazole
38
Q

Acanthamoeba

Morphology
Transmission and Reservoir
Diseases

A
protozoa	
-----------------------
- contaminated water
- contact lenses
-----------------------
lens opacity;
can lead to blindness
39
Q

Naegleria fowleri

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

protazoa

  • warm freshwater & soil
  • southern US
  • enters the nose when swimming
  • brain infection
  • fatal
40
Q

Giardia

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

protazoa

  • reservoir: wild animals, farm animals, pets
  • fecal-oral
  • contaminated water or food
  • occurs in US
  • IgA deficiency is pre-disposing factor
  • cysts
  • 1) trophozoites multiply in duodenum
    2) cysts form in colon and are excreted
    3) intestinal inflammation and malabsorption of fats and carbohydrates
  • explosive diarrhea involving foul-smelling, greasy stool
  • significant weight loss in children
  • chronic diarrhea in adults
  • relapses are common
  • incubation time: 1-4 weeks
  • trophozoites or cysts in stool
  • Metronidazole
41
Q

Cryptosporidium parvum

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

protazoa

  • reservoir: farm animals, pets
  • fecal-oral
  • contaminated water
  • occurs in US
  • oocysts
  • 1) sporozoites penetrate enterocytes and develop into trophozoites
    2) oocytes form and are shed in stool
    3) inflammation and malabsorption
  • ranges from mild diarrhea to severe dysentery in immunocopromised
  • relapses can occur
  • 5-10 day incubation
  • oocysts in stool
  • modified acid-fast stain
  • Nitazoxanide
42
Q

Microsporidia

Morphology
Transmission and Reservoir
Diseases

A
protazoa	
-----------------------
- affects immunocompromised
- occurs in US
-----------------------
diarrhea
43
Q

Trichomonas vaginalis

Morphology
Transmission and Reservoir 
Diseases
Diagnosis
Treatment and Prevention
A
protazoa	
-----------------------
- STD
- occurs in US	
-----------------------
asymptomatic in men; vaginal discharge with fish-like odor in women	
-----------------------
- pear-shaped, flagellated organisms with characteristic twitching motility	
-----------------------
- Metronidazole
44
Q

Plasmodium
(vivax, ovale, and falciparum)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

  • mosquito bites
  • occurs outside of US
  • vivax & ovale found in temperate zones (mosquitoes during warmer months)
  • falciparum found in tropical regions (mosquitoes year round)
  • sickle cell anemia is protective
  • ## unexposed people are most susceptible-PfEMP in falciparum: variable protein that can cause binding of RBC to many different host proteins; causes RBC sequestration and obstruction to tissue perfusion; avoids clearance by the spleen
    ———————–
    1) sporozoites from mosquito infect humans
    2) travel to liver and invade hepatocytes
    3) differentiate into tissue schizonts and multiply
    4) live in the liver as latent hypnozoites (only occurs in vivax & ovale)
    5) differentiate into merozoites and exit hepatocytes
    6) merozoites invade RBCs (falciparum can invade RBCs of any age, but vivax & ovale only invade reticulocytes)
    7) RBCs lyse and release merozoites
    8) some differentiate into gametocytes and are taken up by mosquitoes to complete the cycle
  • ## cyclic fevers occur b/c RBCs lyse to release merozoites every 48 hoursmalaria - vivax & ovale
  • cyclic fevers
    severe malaria - falciparum
  • 7-90 day incubation
  • cyclic or non-cyclic fevers
  • microvascular disease
  • hypoglycemia
  • cerebral malaria
  • renal failure
  • pulmonary edema
  • anemia
  • multiorgan failure
  • ## coma
  • blood smear
  • ## rings only seen with falciparum
  • Chloroquine: usually ineffective due to resistance
  • Quinine
  • Primaquine: only drug active against hypnozoites
  • Artemisinin derivatives: use for resistant strains as combination therapy
  • Mefloquine (Lariam): prophylaxis & treatment
  • Atovaquone/ proguanil (Malarone): prophylaxis & treatment
45
Q

Babesia

Morphology
Transmission and Reservoir

Pathogenesis
Diseases
Diagnosis

A

protazoa

  • reservoir: deer & white-footed mice
  • vector: ticks
  • asplenia is a risk factor
  • NE US, Nantucket Island, Martha’s Vineyard, Cape Cod
  • infects erythrocytes Babesiosis (malaria-like disease)
  • Maltezer cross
46
Q

Leishmania

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
protazoa	
-----------------------
- vector: sandflies
- found in Central and South America, Middle East, and Africa		
-----------------------
- invade macrophages in humans	
-----------------------
cutaneous leishmaniasis
visceral leishmaniasis (kala azar):
- fevers
- hepatosplenomegaly
47
Q

Trypansoma cruzi

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
protazoa	
-----------------------
- kissing bugs
- contaminated fruit juice
- blood transfusions
- mother-to-child transmission
- Central and South America	
-----------------------
- does not undergo antigenic shift
- evades complement
- escapes phagosome to live in cytoplasm	
-----------------------
- blood stage and intracellular stage (in phagosomes)	
-----------------------
Chagas disease
- esophageal and colon dysmotility
- cardiomyopathy
48
Q

Trypansoma brucei

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

protazoa

flagellated	
-----------------------
- tsetse fly
- Africa	
-----------------------
- variable surface glycoprotein (VSG): covers surface; antigenic shift through gene conversion	
-----------------------
- extracellular parasite
- spreads systemically	
-----------------------
African sleeping 
sickness
- stage 1: 
lymphadenopathy, fever, anemia, edema, 
rash
- stage 2:
meningoencephalitis, CNS symptoms including sleeping during the day, coma, death
49
Q

Toxoplasma gondii

Morphology
Transmission and Reservoir

Pathogenesis
Diseases
Diagnosis
Treatment and Prevention

A

protazoa

obligate intracellular

  • found in cat feces & undercooked meat
  • can cross the placenta
  • reactivation in T-cell immunocompromised patients -
  • 1) infected rodents are eaten by cats
    2) parasites undergo sexual cycle in cats
    3) sporozoites in cat feces are ingested by humans
    4) sporozoites penetrate the intestinal wall
    5) tachyzoites (replicative form) infect macrophages)
    6) disseminate via hematogenous spread
    7) can cross the placenta
    8) can form cysts with bradyzoites (latent form) in brain
    9) if immunocompromised, cysts can release tachyzoites into brain and induce inflammation
  • common latent infection in many countries
  • congenital toxoplasmosis - acute infection during pregnancy can lead to retinitis & CNS disease in babies
  • Toxoplasma encephalitis or ocular toxoplasmosis in immunocompromised (e.g. AIDS patients)
  • head CT shows ring-like structure in brain
  • TMP/SMX
50
Q

Enterobius vermicularis
(Pinworm)
Morphology
Transmission and Reservoir

Diseases

Treatment and Prevention

A
intestinal nematode
-----------------------
- ingestion of infective eggs
- not associated with any specific socioeconomic level	
-----------------------
perianal itch	
-----------------------
- Albendazole / Mebendazole
- Pyrantel
51
Q

Necator americanis
(Hookworm

Morphology
Transmission and Reservoir

Diseases

A
intestinal nematode	
-----------------------
- penetration of skin by larval forms
- impoverished rural areas	
-----------------------
itchy feet with rash
anemia
52
Q

Ancylostoma duodenale
(Hookworm)

Morphology
Transmission and Reservoir

Diseases

A
intestinal nematode	
-----------------------
- penetration of skin by larval forms
- impoverished rural areas	
-----------------------
itchy feet with rash
anemia
53
Q

Trichuris trichiura

Whipworm

A

intestinal nematode - ingestion of infective eggs

  • impoverished rural areas - - non-specific abdominal discomfort and/or anemia - - Albendazole / Mebendazole
  • Ivermectin
54
Q

Ascaris lumbricoides

Morphology
Transmission and Reservoir
Diseases

Treatment and Prevention

A
intestinal nematode
-----------------------
- ingestion of infective eggs
- impoverished rural areas	
-----------------------
non-specific abdominal discomfort and/or anemia

Albendazole / Mebendazole
Ivermectin

55
Q

Onchocerca

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

Treatment and Prevention

A
tissue nematode (filaria)	
-----------------------
- mosquito/ insect bite
- non-US	
-----------------------
infection of lymphatics	
-----------------------
river blindness	
-----------------------
Ivermectin
56
Q

Wucheria

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
tissue nematode (filaria)	
-----------------------
mosquito/ insect bite
- non-US	-	
-----------------------
infection of lymphatics	
-----------------------
elephantiasis
57
Q

Brugia

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
tissue nematode (filaria)	
-----------------------
mosquito/ insect bite
- non-US	-	
-----------------------
infection of lymphatics	
-----------------------
elephantiasis
58
Q

Trichinella

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

A
tissue nematode (filaria)	
-----------------------
- contaminated food (undercooked pig, boar, or bear meat)
- occurs in US		
-----------------------
1) ingestion
2) migrate through intestine
3) migrate to muscles
4) immune-mediated inflammatory reaction	
-----------------------
fever, myalgias, edema
3-30 day incubation
59
Q

Schistosoma spp.

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

Treatment and Prevention

A

  • grow in snails
  • skin contact with contaminated water
  • ## occurs everywhere except North America, Europe, & Australiasnail → fresh water → human skin → lungs & liver → GI tract or bladder
    ———————–
    acute schistosomiasis: Katayama fever
    chronic schistosomiasis:
    liver disease, hematuria, bladder cancer, neurologic disease
    ———————–
    eggs in urine (S. hematobium) or feces (S. japonicum or mansoni)
60
Q

Taenia solium

Morphology
Transmission and Reservoir

Diseases

Treatment and Prevention

A
tapeworm (cestode)	
-----------------------
- reservoir: pigs
- ingestion of T. solium eggs or undercooked pork	
-----------------------
cysticercosis
neurocysticercosis (seizures)
-----------------------
Albendazole/ Mebendazole
61
Q

Taenia saginata

Morphology
Transmission and Reservoir

Diseases

A
tapeworm (cestode)	
-----------------------
- reservoir: cows
- ingestion of undercooked beef	-
-----------------------
abdominal symptoms	-	-
62
Q

Echinococcus

Morphology
Transmission and Reservoir

Pathogenesis
Diseases

Treatment and Prevention

A
tapeworm (cestode)	
-----------------------
- reservoir: dogs
- dog fecal-oral	
-----------------------
1) ingestion of eggs
2) eggs hatch to form oncospheres that penetrate the intestinal mucosa and enter the circulation
3) cysts formin organs, particularly the liver	
-----------------------
Hydatid disease - liver cysts
-----------------------
Albendazole / Mebendazole
63
Q

Lice

Morphology

Diseases

Treatment and Prevention

A
ectoparasite	
-----------------------
nits - scalp hair infestation
body lice - body hair infestation
crabs - pubic hair infestation	
-----------------------
 Ivermectin
- Permethrin
- Malathion
64
Q

Sarcoptes scabei

Morphology

Diseases

Treatment and Prevention

A
ectoparasite	
-----------------------
scabies - itchy rash between fingers	
-----------------------
Ivermectin
- Permethrin
65
Q

maggots

Morphology
Diseases

A

myiasis (maggots under the skin)

66
Q

new variant Creutzfeldt-Jakob disease (vCJD)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
prion	
-----------------------
- consumption of BSE meat contaminated with brain tissue or the consumption of brain tissue itself	
-----------------------
- PrPsc	
-----------------------
PrPsc (abnormal prion protein) accumulates in the brain	
-----------------------
CNS degeneration, death
67
Q

kuru

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
prion	
-----------------------
- tribe members in New Guinea eating human brains	
-----------------------
- PrPsc	
-----------------------
PrPsc (abnormal prion protein) accumulates in the brain	
-----------------------
CNS degeneration, death
68
Q

bovine spongiform encephalopathy (BSE) (mad cow disease)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
prion	
-----------------------
- consumption of bone meal made from diseased cows
- occurs in cows	
-----------------------
- PrPsc	
-----------------------
PrPsc (abnormal prion protein) accumulates in the brain	CNS degeneration, death
69
Q

scrapie

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
prion
-----------------------
- occurs in sheep	
-----------------------
- PrPsc	
-----------------------
PrPsc (abnormal prion protein) accumulates in the brain	
-----------------------
CNS degeneration, death
70
Q

chronic wasting disease

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A
prion	
-----------------------
- occurs in deer & elk	
-----------------------
- PrPsc	
-----------------------
PrPsc (abnormal prion protein) accumulates in the brain	
-----------------------
CNS degeneration, death
71
Q

Streptococcus agalactiae
(Group B)

Morphology
Transmission and Reservoir
Virulence Factors
Diseases

A

Gram+ cocci
β-hemolytic

  • ## human reservoir (colonize female genital tract)
  • ## capsule: binds factor H and makes C5a-degrading enzymeneonatal sepsis & meningitis
72
Q

Streptococcus pneumoniae
(pneumococcus)
(no Lancefield group)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram + cocci

alpha-hemolytic

extracellular
-----------------------
- human reservoir (colonize upper respiratory tract)
- transmission by respiratory droplets & close contact
-----------------------
1) polysaccharide capsule: prevents phagocytosis; doesn’t bind factor B, so the alternative complement pathway isn’t activated
2) IgA protease
3) pneumolysin O: causes plasma membrane lysis; damages bronchi, ciliated cells, and alveoli, promoting inflammation and spread
4) neuraminidase: cleaves sialic acid to open site for attachment
5) lipoteichoic acid (LTA): promotes IL-1 and TNF- release
6) altered PBP: leads to -lactam resistance, but can usually be overcome by increasing drug dose
-----------------------
1) colonize
2) move to lower airway by aspiration
3) enter bloodstream from pharynx or lung
-----------------------
respiratory tract 
- sinusitis
- otitis media
- conjunctivitis
- bronchitis
- CA-pneumonia
disseminated
- bacteremia
- endocarditis
- meningitis
- peritonitis
- septic arthritis
- osteomyelitis
-----------------------
1) Macrolides
2) Tetracyclines
3) Moxifloxacin
4) Levofloxacin
73
Q

Viridans streptococci spp.
(usually no Lancefield group)

Morphology
Transmission and Reservoir
Diseases

A

Gram+ cocci

alpha-hemolytic or γ-hemolytic

extracellular

  • human reservoir (colonize upper respiratory tract, colon, and female genital tract)
  • dental caries
  • endocarditis
  • abscesses
74
Q

Enterococcus
faecalis
(Group D)

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

Gram+ cocci

alpha- or γ-hemolytic

extracellular
-----------------------
- human reservoir
(GI tract, skin of hospitalized patients)
- spread by contact
-----------------------
- alteration in cell wall leads to Ampicillin & Vancomycin resistance
-----------------------
- bacteremia
- endocarditis
- UTI
-  surgical site infections
- abscesses
-----------------------
“Learn VRE Drugs for Test Now.”
1) Linezolid
2) Daptomycin
3) Tigecycline
4) Nitrofurantoin
- contact precautions for VRE
75
Q

Enterococcus faecium

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

Gram+ cocci

extracellular

  • same as E. faecalis
  • same as E. faecalis
  • more likely than faecalis to be Vancomycin-resistant
  • same as E. faecalis
  • same as E. faecalis
76
Q

Staphylococcus aureus
(USA300 is a common cause of CA-MRSA)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram+ cocci

β-hemolytic

  • human reservoir (colonize warm, moist areas)
  • ## transmission through fomites, contact, and eating contaminated foodExotoxins
    1) hemolysin -γ (includes  toxin)
    2) enterotoxins A-J: act as superantigens and cause diffuse immune activation
    3) heat-stable enterotoxin - superantigen involved in food poisoning
    4) exfoliative epidermolytic toxin A/B: superantigens that cause skin to slough off
    5) toxic shock syndrome toxin (TSST-1): superantigen that stimulates 20% of T cells and causes secretion of IL-2 and TNF-
    6) Panton-Valentine Leukocidin: cytotoxin associated with CA-MRSA; probably just a genetic marker for other virulence factors
    Adherence - MSCRAMMs
    1) protein A: binds Ig via Fc portion, coating membrane without causing phagocytosis
    2) clumping factor A/B: bind fibrinogen
    3) collagen binding protein
    4) fibronectin binding protein A/B
    5) plasmin-sensitive protein: promotes binding to nasal epithelial cells
    Cell Wall Components
    1) polysaccharide capsule: inhibits phagocytosis
    2) peptidoglycan: provides anchor for MSCRAMMs; triggers cytokine release
    3) LTA: pro-inflammatory; stimulates cytokine release
    4) β-lactamases
    5) MecA: altered PBP that causes MRSA; gene found on Staphylococcal Chromosomal
    Cassette (SCC); SCCMecIV IV associated with CA-MRSA
    Biofilms
    Quorum-Sensing and Two-Component Regulatory Systems
  • AIP (auto-inducer)  AgrC (membrane sensor)  AgrA (transcriptional regulator)  transcription of toxin genes
  • ## AIP from one strain can competitively inhibit AgrC from another strain
  • ## bacterial intoxication in TSS and food poisoningskin and soft tissue disease
  • abscess
  • cellulitis
  • myositis
  • osteomyelitis
  • septic arthritis
  • necrotizing fasciitis
    disseminated disease
  • bacteremia
  • endocarditis
  • toxic shock syndrome: fever, rash, hypotension, confusion, renal failure, vomiting, diarrhea
    device infections
  • central venous catheters
    food poisoning
  • 1-6 hour incubation time
  • ## vomiting“Drugs to Confidently Treat Very Lethal Commensals”
    1) Daptomycin
    2) TMP/SMX
    3) Ceftaroline
    4) Tetracycline/ Tigecycline
    5) Vancomycin
    6) Linezolid
    7) Clindamycin
  • contact precautions for MRSA
77
Q

coagulase- staphylococcus
(e.g. S. saprophyticus)

Morphology
Diseases

A

Gram + cocci

extracellular

  • vascular line-associated bacteremia
  • cystitis in women (S. saprophyticus)
78
Q

coagulase- staphylococcus
(e.g. S. saprophyticus)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

Gram+ spore-forming rod

extracellular

aerobic
-----------------------
- fecal-oral
- contaminated food
-----------------------
- heat-stable emetic enterotoxin
-----------------------
bacterial intoxication
-----------------------
food poisoning
- 1-6 hours incubation time
- vomiting
79
Q

Bacillus cereus (non-emetic form)

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

Gram+ spore-forming rod

extracellular

aerobic
-----------------------
- fecal-oral
- contaminated food
-----------------------
- heat-labile diarrheal enterotoxin
-----------------------
production of enterotoxin in vivo
-----------------------
food poisoning
- 12 hour incubation time
- diarrhea, cramps
80
Q

Bacillus anthracis

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram+ spore-forming rod

extracellular

aerobic

  • cattle, sheep, goats
  • no person-to-person transmission
    cutaneous
  • spores enter cutaneous abrasion
    inhalation
  • inhalation of spores
    GI
  • ## ingestion of uncooked meat
  • poly-D glutamic acid capsule: anti-phagocytic
  • protective antigen (PA): binds to host cell receptors and LF and EF
  • lethal factor (LF): toxin that is a protease
  • edema factor (EF): toxin that activates adenylate cyclase to increase cAMP in host cells
  • capsule encoded by pXO2 plasmid
  • ## exotoxins (LF and EF) encoded by pXO1 plasmid1) germination of the spore
    2) multiplication and toxin production
    3) may stay contained in the skin or spread through the
    bloodstream and lymphatics
    3) causes inflammation of lymph nodes
    ———————–
    cutaneous anthrax:
  • 1-7 day incubation
  • pruritic papule  vesicle  black eschar
  • enlarged lymph nodes
    inhalation anthrax (Woolsorter’s Disease):
  • 4-6 day incubation
  • flu symptoms w/o runny nose
  • bloody pleural effusions
  • mediastinal widening due to enlarged lymph nodes
  • hemorrhagic meningitis
  • 45% fatality if recognized and treated early
    GI anthrax:
  • 1-5 day incubation
  • GI symptoms
  • ## 40% mortality
  • medusa’s head/comet tail colonies on blood agar
  • box car appearance on Gram stain
  • Doxycycline
  • Ciprofloxacin
  • Raxibacumab
81
Q

Clostridium botulinum

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram + spore-forming rod

anaerobic

tennis racket appearance of Gram stain

  • ingestion of contaminated food (e.g. honey, home-cooked food)
  • colonization of GI tract or wound
  • ## no person-to-person transmission
  • botulinum toxin: prevents release of ACh by cleaving neuronal proteins involved in synaptic vesicle docking; acts at neuromuscular junction
  • serotype A is most serious because it persists longest in the neuron
  • ## serotype E also causes vomiting
  • usually a bacterial intoxication
  • infant botulism and adult infant botulism are caused by C. botulinum that colonizes the GI tract and produces toxins in vivo
  • wound botulism: C. botulinum enters wound and produces toxin in vivo
  • ## toxin spreads to CNSbotulism
  • 12-72 hour incubation
  • double vision
  • swallowing difficulties
  • descending flaccid paralysis
  • breathing problems
  • infants first present with constipation
  • ## 70% fatality if untreated; 10% fatality if treated
  • anti-toxin
82
Q

Clostridium perfringens

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

Gram + spore-forming rod

anaerobic

extracellular
-----------------------
- found in soil, GI tract, & contaminated food
- puncture wound or ingestion of contaminated food
-----------------------
- alpha toxin: phospholipase C that disrupts plasma membranes
- β toxin: forms pores
- heat-labile enterotoxin: damages membranes
-----------------------
- toxin production in vivo
-----------------------
gas gangrene,
anaerobic cellulitis
wound infections
organ infections
bacteremia
food poisoning
- 12 hour incubation
- diarrhea, cramps
83
Q

Clostridium septicum

Morphology
Transmission and Reservoir
Diseases

A

Gram + spore-forming rod

anaerobic

extracellular
-----------------------
- found in GI tract
-----------------------
infections in patients with cancer of the GI tract
84
Q

Clostridium difficile

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram + spore-forming rod

anaerobic

  • GI tract
  • ## ingestion
  • toxin A: monoglucosyltransferase; interferes with actin cytoskeleton to make intestinal epithelial cells leaky; attracts neutrophils and stimulates the release of cytokines; causes inflammation
  • toxin B: same mechanism as toxin A; also induces cytopathic effect in tissue culture cells
  • ## binary toxin: disrupts actin cytoskeleton; only found in some isolates; more frequent in patients w/ more severe disease1) use of antibiotics disrupts the gut flora
    2) ingestion
    3) colonization in gut
    4) toxin production leads to diarrhea
    5) pseudomembranous inflammation
    ———————–
    diarrhea in hospitalized patients; spectrum from asymptomatic carriage to toxic megacolon and death; relapse may occur
    ———————–
  • ## detection of toxins is gold standard for diagnosis“Very Fun Medications”
    1) Vancomycin
    2) Fidaxomicin
    3) Metronidazole
  • use soap and water, not alcohol, to remove spores
85
Q

Clostridium tetani

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram+ spore-forming rod

anaerobic

extracellular
-----------------------
- soil
- puncture wound or contaminated umbilical stump
-----------------------
- tetanus neurotoxin/tetanospasmin: inhibits release of inhibitory neurotransmitter glycine by cleaving neuronal proteins involved in synaptic vesicle docking; works on CNS in spinal cord
-----------------------
toxin migrates 
along motor neurons into CNS
-----------------------
tetanus
- incubation time up to months
- spastic paralysis
- death by respiratory failure
neonatal tetanus
-----------------------
- tetanus antitoxin
86
Q

Corynebacterium diphtheriae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram+ rod

  • human reservoir
  • aerosol droplets
  • inhalation leads to nasopharyngeal diphtheria
  • ## infection of a wound leads to cutaneous diphtheria
  • diphtheria toxin: ADP-ribosylates elongation factor 2 (EF-2), causing inhibition of host protein synthesis and cell death
  • tox gene encodes diphtheria toxin and is carried by the β phage which lysogenically infects C. diptheriae
  • expression of diphtheria toxin only occurs under low-iron conditions
  • high iron: diphtheria toxin repressor (DtxR) binds iron, forms dimer, and inhibits transcription of the tox gene
  • low iron: DtxR cannot bind iron and dimerize, so the tox gene is expressed
  • DtxR is encoded by the bacterial chromosome
  • ## adhesins: necessary for colonization1) colonizes nasopharynx or skin
    2) produces diphtheria toxin
    3) necrosis and formation of a pseudomembrane
    4) toxin can travel through the blood and damage organs
    ———————–
    diphtheria
  • 1-7 day incubation
  • malaise, sore throat, enlarged cervical lymph nodes
  • gray pseudomembrane over tonsils and throat
  • pseudomembrane can lead to suffocation
  • ## dissemination of diphtheria toxin can lead to damage of internal organs (e.g. the heart) and death
  • microscopy: club-shaped rods that are arranged in palisades or Chinese character formations; polyphosphate granules
  • isolate on media containing tellurite salts
  • ## toxin testing to differentiate from non-toxigenic strains
  • antitoxin + antimicrobials
87
Q

Listeria monocytogenes

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram+ rod

intracellular

β-hemolytic

optimal growth at 30C-37C, but can grow at 4C

  • soil, decaying vegetation
  • intestinal tract of many animals, including cattle
  • processed foods that are not re-heated
  • Listeriolysin O (gene hlyA): breaks open the phagosome and allows the bacterium to enter the cytoplasm
  • actA gene: allows Listeria to nucleate host actin to form a tail, which can propel it into neighboring cells
  • 1) enters GI tract through ingestion
    2) multiplies in liver
    3) spreads to brain and/or placenta via bloodstream
  • invades cells through zipper mechanism
  • induces inflammation
  • incubation time of several days
  • influenza-like disease
  • neonatal meningitis
  • meningoencephalitis or bacteremia in immunocompromised
  • infection during pregnancy can result in spontaneous abortion, stillbirth, premature labor, or newborn with high bacterial load
  • monocytes/ macrophages in CSF
  • Ampicillin +/- Sulbactam
  • Amoxycillin +/- Clavulanate
88
Q

Nocardia

Morphology
Treatment and Prevention

A

Gram+ rod
branching filaments
———————–
- TMP/SMX

89
Q

Moraxella catarrhalis

Morphology
Diseases
Treatment and Prevention

A
Gram- diplococci
-----------------------
community-acquired pneumonia
-----------------------
- macrolides
- tetracyclines
90
Q

Neisseria gonorrhoeae

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A
Gram- diplococci inside of neutrophils
-----------------------
- human reservoir
- STD
-----------------------
- pili: attachment to urogenital tract (phase variation and antigenic shift due to gene conversion)
- Opa proteins: increase adherence (phase and antigenic variation)
- LOS (phase and antigenic variation)
 - IgA protease
-----------------------
males
- urethritis with purulent discharge
female
- may be asymptomatic
- cervicitis
- urethritis
female complications
- PID
- infertility
- conjunctivitis in babies
-----------------------
- macrolides
- tetracyclines
91
Q

Neisseria meningitidis

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram- diplococci inside of neutrophils

  • human reservoir
  • meningococcal belt in Africa during Dec-June
  • polysaccharide capsule: avoidance of immune response; many serotypes
  • serotype B capsule: identical to human neuronal sialic acid
  • outer membrane proteins: attachment to CD24 and fibronectin; antigenic variation
  • pili: attachment, invasion, passage through blood-brain barrier; antigenic variation
  • LOS: pro-inflammatory
  • IgA protease: cleaves IgA
  • fHbp: binds factor H
  • 1) attach to the epithelium of the pharynx via pili and outer membrane proteins
    2) invade epithelial cells
    3) enter vascular space, rapidly multiply, and release LOS
    4) circulate to distant sites
    5) cause meningitis in the brain
    6) cause purpura in the skin
  • many carriers
  • meningitis (fever, headache, neck stiffness)
  • purpura or petechiae
  • Rifampin
92
Q

Commensal Neisseria

Morphology
Virulence Factors
Diseases

A

Gram- diplococci

  • no capsule or pili
  • colonize oral and GI tract, but do not cause disease
93
Q

Enterotoxigenic E. coli (ETEC)
(O148:H28)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

  • human reservoir
  • ## contaminated food or water
  • common/type 1 pilli: attach to mannose receptors on host surfaces; phase variation
  • siderophores: have high affinity for iron
  • LPS: endotoxin
  • CFAI/II/III: unique pilli used for colonizing the intestine
  • heat stable enterotoxin
    (STa): increases
    intestinal cGMP to stimulate fluid & electrolyte secretion
  • heat labile enterotoxin (LT): increases intestinal cAMP
  • ## CFA and enterotoxin genes are on a single plasmid
  • colonize small intestine
  • multiply and produce enterotoxins in vivo
  • ## toxins increase intestinal fluid secretion
  • watery diarrhea in infants and travelers to regions with poor sanitation
  • ## 16-72 hour incubation time
  • Ampicillin +/- Sulbactam
  • Amoxycillin +/- Clavulanate
  • 1st and 2nd generation cephalosporins
  • Nitrofurantoin
94
Q

Enteropathogenic E. coli (EPEC)
(O26:H11)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram- enteric rod

  • human reservoir
  • contaminated food or water
  • common/type 1 pilli
  • siderophores
  • LPS
  • bfp
  • TIR
  • intimin
  • EPEC adheres to enterocytes using bundle-forming pillus (bfp)
  • delivery of effectors (TIR intimin receptor) via type III secretion system
  • TIR inserts into host membrane
  • bacterial intimin binds to TIR
  • actin polymerization occurs in the host cell, creating a pedestal
  • infant diarrhea in developing countries
  • attaching and effacing lesions visible on biopsy
  • same as ETEC
95
Q

Enteroaggregative E. coli (EAEC)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram- enteric rod

  • human reservoir
  • contaminated food or water
  • common/type 1 pilli
  • siderophores
  • LPS
  • EAST
  • shiga toxin (recent outbreak)
  • biofilms
  • adherence to enterocytes as aggregates composed of many bacterial cells
  • increase mucus production, resulting in trapping of bacteria in biofilm
  • make EAST (enteroaggregative-like stable toxin)
  • cause watery discharge and subtle inflammation
  • in a recent outbreak, a strain produced shiga toxin
  • chronic diarrhea in HIV+ individuals in developing countries
  • infant diarrhea in US
  • acute traveler’s diarrhea
  • low grade fever may occur
  • HUS in adults if it produces shiga toxin
  • same as ETEC
96
Q

Enteroinvasive
E. coli (EIEC)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram- enteric rod

  • human reservoir
  • contaminated food or water
  • common/type 1 pilli
  • siderophores
  • LPS
  • afimbrial adhesions
  • type III secretion system
  • invade enterocytes
  • lyse endocytic vesicles and escape into the cytoplasm
  • multiply and cause cell destruction
  • watery diarrhea, sometimes with blood and fecal leukocytes
  • same as ETEC
97
Q

Enterohemorrhagic E. coli (EHEC)
(O157:H7)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A
Gram- enteric rod
-----------------------
- human reservoir
- contaminated food
- infected animals
- swimming pools w/ inadequate chlorination
-----------------------
- common/type 1 pilli
- siderophores
- LPS
- bfp
- TIR
- intimin
- shiga toxin: inactivates 60S ribosomal subunit, causing inhibition of protein synthesis; kidney cells are sensitive
(essentially EPEC + shiga toxin)
-----------------------
- close adherence via intimin
- production of shiga toxin in vivo
- shiga toxin causes colonic damage and can be absorbed into the circulation and affect the kidneys
-----------------------
- 15-48 hour incubation time
- hemorrhagic colitis
- hemolytic uremic syndrome (HUS): kidney failure, usually in children
-----------------------
- same as ETEC
- antibiotics contra-indicated in HUS
98
Q

Uropathogenic
E. coli (UPEC)
(O4:H5)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A
Gram- enteric rod
-----------------------
- human GI tract
- spread from rectum
-----------------------
- common/type 1 pilli
- siderophores
- LPS
- P pilli/pap pilli: able to bind to P blood group / Forssman antigen on renal epithelium; phase variation
- hemolysin: forms pores; damages kidney cells
-----------------------
- can be invasive
-----------------------
UTI
- cystitis
- pyelonephritis
-----------------------
- same as ETEC
99
Q

E. coli
(K1)
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram- enteric rod

  • human reservoir
  • common/type 1 pilli
  • siderophores
  • LPS
  • sialic acid capsule: inhibits phagocytosis and complement activation; molecular mimicry
  • endotoxin induces symptoms (fever, shock, etc.)
  • neonatal / childhood meningitis
  • same as ETEC
100
Q

Non-Typhoid Salmonella
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
A

  • reservoir: nearly all common food animals, pets including turtles
  • contaminated food
  • contaminated water
  • person-to-person spread by fecal-oral route
  • ## some human carriers
  • Inv/Spa type III secretion system: promotes entry into intestinal epithelial cells
  • Spi/Ssa type III secretion system: contributes to survival inside macrophages
  • Sip: transferred to host cell surface; induces membrane ruffling
  • invasion genes are chromosomal
  • LPS: inflammation
  • two component regulatory system
  • PhoQ: membrane sensor; activated by low Mg+2 inside of phagocytes
  • PhoP: transcriptional regulator
  • pag genes: intracellular survival & resistance to antimicrobial peptides(through activation of PrmA/PrmB system and production of protective membrane proteins)
  • prg genes: extracellular survival & early steps in pathogenesis
  • PrmA/PrmB: second two-component regulator that causes production of enzymes that modify LPS so that it no longer binds antimicrobial peptides
  • PagC and other outer membrane proteins: allow Salmonella to resist some antimicrobial peptides
  • Adhesins: adhesion to intestinal cells
  • Enterotoxin: found in some strains; not necessary for virulence, or an important part of pathogenesis
  • ## Flagella: allows movement through intestinal mucus; phase variation1) ingestion
    2) exposure to body temperature triggers expression of genes
    encoding invasive factors
    3) Sip is transferred to host cell membrane
    4) membrane ruffling
    5) enters M cells & enterocytes via macropinocytosis
    6) replicate in endosomes
    7) released into lamina propria
    8) phagocytosed by macrophages; live inside of macrophages
    9) strong inflammatory response
    10) can disseminate if immunocompromised
    ———————–
  • 12-48 hour incubation time
  • fever and diarrhea
  • septicemia and death in AIDS patients
  • ## osteomyelitis and septicemia in sickle cell patients
  • stool cultures
101
Q

Salmonella typhi
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

  • reservoir: human carriers (often with gallstones)
  • transmission: fecal-oral contamination
  • ## India subcontinent, Central & South America, Asia, Africa
  • same virulence factors as non-typhoid Salmonella
  • ## polysaccharide capsule containing Vi antigen1) similar to non-typhoid Salmonella, except it disseminates quickly once it reaches the lamina propria
    2) moves through the blood and/or lymph to reticuloendothelial tissue (liver, spleen, bone marrow)
    3) multiplies in those tissues
    4) suddenly emerge 1-2 weeks later in the blood and bile
    ———————–
    typhoid fever
    initial symptoms:
  • low grade fever
  • constipation
    after 1-2 weeks:
  • septic shock
  • high fever
  • diarrhea
  • hemorrhaging and perforation of the intestine, which can lead to peritonitis
  • abdominal rose spots
  • ## 10-20% mortality w/o treatment
  • ## blood cultures
  • Ciprofloxacin
  • Ceftriaxone
102
Q

Shigella spp.
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

  • human reservoir
  • fecal-oral
  • ingestion of contaminated food or water
  • extremely virulent
  • ## person-to-person transmission
  • resistant to gastric acid
  • LPS: endotoxin
  • Mxi-Spa proteins (translocon): needle of type III secretion system (TTSS)
  • Ipa: transferred to host cell surface; induces membrane ruffling
  • IcsA: causes reorganization of host cell cytoskeleton, allowing for motility
  • IcsB: allows escape from vesicles when moving between adjacent colonocytes
  • Shiga toxin: inactivates 60S ribosomal subunit, causing inhibition of protein synthesis; found in S. dysenteriae
  • ## genes are plasmid-encoded1) ingestion
    2) exposure to body temperature triggers expression of genes
    encoding invasive factors
    3) Ipa is transferred to host cell membrane
    4) membrane ruffling
    5) enters M cells via macropinocytosis
    6) exit basal surface of M cells
    7) use Ipas to invade basal surface of colonocytes
    8) escape from endosome and multiply in the cytoplasm
    9) use IcsA to move in cytoplasm
    10) move directly between colonocytes via vesicles; IcsB is required for escape from vesicles
    11) induce inflammation through interactions with macrophages and attracting neutrophils
    12) GI symptoms and fever caused by colonic inflammation and sometimes Shiga toxin
  • ## restricted to epitheliumdiarrhea/dysentery with fecal leukocytes and fever
    16-72 hour incubation time
103
Q

Yersinia enterocolitica
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

Gram- enteric rod

  • fecal-oral, or ingestion of contaminated food or water
  • Yersinia outer proteins (YOPs): resist phagocytosis
  • invasin: binds 1 integrin on M cells; bacterium is then pulled into host cell by zipper mechanism
  • LPS: causes fever
  • heat-stable enterotoxin: increases intestinal cGMP
  • 1) invasin is made
    2) ingestion
    3) invasion of M cells
    4) released into underlying subepithelial tissue of Peyer’s patches
    5) spread to mesenteric lymph nodes
  • fever & diarrhea
  • 72 hour incubation time
104
Q

Yersinia pestis
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

Gram- enteric rod

safety pin morphology
-----------------------
- rodent reservoir
- flea vector
- contagious
- SW US
-----------------------
- plasminogen activator - causes fleas to regurgitate it
- Yersinia outer protein (YOP): inhibits phagocytosis & lymphocyte proliferation
- LPS: endotoxic
- polypeptide capsule
-----------------------
acute febrile lymphadenitis (bubonic plague)
 - most common form
- fevers, chills, weakness, headache, pain and swelling in lymph nodes
pneumonic
- 2-4 day incubation
-  pneumonia w/ bloody sputum
- 50% mortality
septicemic 
- bacteremia after escape from lymph nodes
-----------------------
- Streptomycin or Gentamicin
- Doxycycline or ciprofloxacin for PEP
- contact isolation
- droplet precautions for 72 hours after starting antibiotics
105
Q

Klebsiella pneumoniae
Enterobacteriaceae

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

  • human reservoir (lower GI tract, skin colonization)
  • ## contact
  • mucoid polysaccharide capsule: resistant to phagocytosis
  • adept at acquiring antibiotic resistance genes
  • chromosomally- encoded β-lactamase: inactivates penicillin
  • extended spectrum beta lactamase (ESBL): resistance to all β-lactams except
    carbapenems
  • carbapenemase:
    resistant to all -lactams including carbapenems
    ———————–
  • bacteremia
  • nosocomial pneumonia
  • ## UTI
  • Ampicillin + Sulbactam
  • Amoxycillin + Clavulanate
  • 1st and 2nd generation cephalosporins
  • Nitrofurantoin
  • contact precautions when multi-drug resistant
106
Q

Proteus mirabilis
Enterobacteriaceae

Morphology
Diseases
Treatment and Prevention

A
Gram- enteric rod
-----------------------
catheter-associated UTI
-----------------------
- Aminopenicillins +/- B-lactamase inhibitors
107
Q

Enterobacter cloacae
Enterobacteriaceae

Morphology
Diseases
Treatment and Prevention

A
Gram- enteric rod
-----------------------
hospital-acquired pneumonia
-----------------------
- Nitrofurantoin
108
Q

Vibrio cholerae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram- enteric rod

  • reservoir: estuary waters and asymptomatically colonized people
  • ingestion of contaminated food or water
  • stool contains a very high number of infectious bacteria
  • ## vomit can also contain infectious bacteria
  • toxin-coregulated pilus (TCP): required for colonization of small intestine epithelium; receptor for phage
  • cholera toxin: causes ADP-ribosylation of Gs, causing activation of adenylate cyclase and accumulation of intestinal cAMP
  • accessory enterotoxins
  • biofilm production: protects bacteria from acidic environment of the stomach
  • flagella: involved in movement through intestinal mucus to reach epithelium
  • CTXf phage carries genes that encode cholera toxin and accessory enterotoxins
  • TCP and cholera toxin are coordinately expressed
  • ## TcpP and ToxR regulatory proteins  transcription of ToxT  ToxT protein  transcription of cholera toxin (from ctxAB gene) and TCP (from tcp operon)1) ingested
    2) colonizes small intestine
    3) produces cholera toxin
    ———————–
    cholera
  • incubation period of several hours to several days
  • moderate to severe diarrhea
  • “rice water stool”
  • vomiting
  • severe dehydration
  • ## cardiac problems, shock, death
  • microscopy: comma-shaped and flagellated
  • isolate on TCBS agar
  • classify by Serotyping (O1 and O139 are associated with epidemic/ pandemic spread)
  • ## no fecal leucocytes
  • IV fluids in severe cases
  • oral rehydration solution containing salts and glucose
  • antibiotics to lessen disease severity and duration and limit spread
109
Q

Campylobacter jejuni

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Treatment and Prevention
A

Gram- enteric
rod

curved

motile
microaerophilic

  • reservoir: animals, including pets
  • ingestion of contaminated food (poultry) or water
  • ## contact with sick pets
  • adhesins
  • LPS
  • enterotoxin: causes ADP-ribosylation of Gs, resulting in activation of adenylate cyclase and accumulation of intestinal cAMP; not required for pathogenesis
  • ## gangliosides sugars mimic neuronal tissue and are associated with Guillain-Barre syndromeinvades lower small intestine or upper large intestine and induces inflammation
    ———————–
  • 3-5 day incubation
  • cramps, diarrhea (sometimes with fecal leucocytes), fever
  • ## Guillain-Barre syndrome
  • macrolides
  • tetracyclines
110
Q

Helicobacter pylori

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A

Gram- enteric rod

curved

motile

microaerophilic

grows best at 37C

  • human reservoir
  • fecal-oral
  • oral-oral
  • urease: produces ammonia and bicarbonate from urea; raises local pH
  • flagella: used to move into the mucus membrane where pH is higher
  • LPS: weak endotoxin
  • vacuolating cytotoxin (VacA): damages stomach epithelial cells
  • CagA: induces inflammation
  • type IV secretion system
  • CagA and secretion system are on cag pathogenicity island
  • ingested
  • protects itself from stomach acid using urease and by moving into mucus layer
  • induces inflammation via VacA, CagA, and ammonia (produced by urease)
  • mild GI disease
  • chronic gastritis
  • duodenal or gastric ulcers
  • gastric cancer or gastric lymphoma
  • endoscopy
  • breath tests using radioactive urea
  • serologic tests
  • macrolides
  • metronidazole
111
Q

Pseudomonas aeruginosa

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

Gram- enteric rod

aerobic

motile

blue-green pigment
-----------------------
- contaminated water
- can’t penetrate the epithelium, so mainly causes diseases through wounds, surgical incisions, and burns
- infects people with CF
-----------------------
- polysaccharide capsule: anti-phagocytic; important for making biofilms
- protease and elastase: cause tissue damage
- exotoxin A: ADP-ribosylates EF-2 causing inhibition of host cell protein synthesis; causes necrosis
- leucocidin: inhibits/kills WBCs
- phospholipase C: hemolysin, affects WBCs
- endotoxin: promotes shock; relatively weak compared to other endotoxins
- pili: adhesion
- quorum sensing system
- PAI-1  LASR  transcription of Exotoxin A and PAI-2
- PAI2  RhIR  transcription of additional virulence factors
-----------------------
- hospital-acquired pneumonia
- CF infections
- burn infections
- catheter-associated UTI
- IV line-associated bacteremia
- disseminated infection can lead to cellulitis
- high mortality rate
-----------------------
“Get MIC and PD to TACCL PA”
- Gentamicin
- Meropenem
- Imipenem
- Ciprofloxacin
- Polymyxins
- Doripenem
- Tobramycin
- Amikacin
- Cefepime
- Ceftazidime
- Levofloxacin
- Piperacillin
- Aztreonam
112
Q

Bacteroides fragilis

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A

Gram- enteric rod

anaerobic
-----------------------
- found in colon
 -endogenous infection
-----------------------
- capsule
- enterotoxin (some species)
- proteases & enzymes
- LPS (not endotoxic)
-----------------------
intra-abdominal infections (peritonitis followed by abscess formation) & bacteremia
-----------------------
These Many Medications Can Confidently Cover Bacteroides
1) Tigecycline
2) Metronidazole
3) Moxifloxacin
4) Clindamycin
5) Cefoxitin
6) Carbapenems
7) B-lactams + B-lactamase inhibitors
113
Q

Porphyromonas gingivalis

Morphology
Transmission and Reservoir
Virulence Factors
Diseases

A

Gram- rod

anaerobic

bile-sensitive
-----------------------
- found in mouth
- endogenous infection
-----------------------
- endotoxic LPS
- proteases and other enzymes
-----------------------
respiratory tract infections
114
Q

Prevotella melaninogenica

Morphology
Transmission and Reservoir
Virulence Factors
Diseases

A

Gram- rod

anaerobic

bile-sensitive
-----------------------
- found in mouth
- endogenous infection
-----------------------
- capsule
- endotoxic LPS
- proteases and other enzymes
-----------------------
respiratory tract infections
115
Q

Prevotella bivia

Morphology
Transmission and Reservoir
Virulence Factors
Diseases

A

Gram- rod

anaerobic

bile-sensitive
-----------------------
- found in female genital tract
- endogenous infection
-----------------------
- endotoxic LPS
- proteases and other enzymes
-----------------------
pelvic inflammatory disease; infertility
116
Q

Haemophilus influenzae

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
Gram- rod (pleomorphic coccobacilli)
-----------------------
- human reservoir
- inhalation of droplets
-----------------------
- PRP capsule in typeable strains; no capsule in non-typeable strains (capsule not required for virulence)
- endotoxic LOS
- IgA protease
- adhesins
- ability to obtain iron from heme and transferrin
-----------------------
1) transmission
2) absence of protective antibody
3) colonization
4) viral infection or humoral deficiency
5) infection
-----------------------
non-typeable
- otitis media
- sinusitis
-  lower respiratory tract infection in adults
type b
- epiglottitis
- pneumonia
- meningitis (particularly neonatal)
- bacteremia
-----------------------
- requires lysed RBCs for growth
-----------------------
- Aminopenicillins +/- B-lactamase inhibitors
- 2nd generation cephalosporins
- macrolides
- tetracyclines
117
Q

Legionella pneumophila

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
Diagnosis
Treatment and Prevention
A
Gram- rod
-----------------------
- bodies of water
- grows as a biofilm in water sources, since it can survive chlorination
- normally lives in protazoa
- inhalation
- not transmitted between people
-----------------------
- prevents phago-lysosome fusion by remodeling phagosome to look like RER
- type IV secretion system (dot/icm genes): may allow rapid secretion of effector molecules to modulate phagosome and prevent fusion with lysosomes
- two mutually exclusive sets of genes for virulence: those involved in replication phase and those involved in transmission
- flagellum
- multiple fimbriae
-----------------------
- lives in macrophages
-----------------------
Legionnaires’ disease
- pneumonia
- cough, fever, diarrhea
- 2-10 day incubation
Pontiac fever
- acute febrile illness without pneumonia
-----------------------
- LPS antigen in urine
-----------------------
- tetracyclines
- macrolides
- fluoroquinolones
118
Q

Bordetella pertussis

Morphology
Transmission and Reservoir 
Virulence Factors
Pathogenesis
Diseases
A

Gram- rod

  • highly communicable
  • ## reservoir: asymptomatic adults
  • pertussis toxin: ADP-ribosylates Gi protein, resulting in activation of mammalian adenylate cyclase and increasing cAMP levels
  • bacterial adenylate cyclase
  • tracheal cytotoxin: specifically kills ciliated cells and induces local damage
  • heat-labile (dermonecrotic) toxin: local damage
  • regulated by two component regulatory system
  • bvgS: surface receptor
  • ## bvgA: transcriptional regulator
  • accumulation of mucus, cells, and bacteria in the airways
  • mucociliary elevator is impaired
  • ## cough is easily triggered because of sensitization of cough receptors by a toxin produced by the bacteriawhooping cough
  • intense coughing that can lead to hemorrhage or vomiting
    complications
  • secondary infections including pneumonia
  • CNS abnormalities
  • can be life-threatening
119
Q

Francisella tularensis

Morphology
Transmission and Reservoir 
Virulence Factors
Diseases
Treatment and Prevention
A
Gram- rod
-----------------------
reservoir: 
- various animals
infectious material:
- tick saliva or 
feces
- contaminated 
animal products
- water
- dust
- hay
transmission
- tick bite
- inoculation into wound
- contact
- inhalation
- ingestion
- not transmissible between people
very virulent
found in Martha’s vineyard
-----------------------
- capsule
- FPI pathogenicity island: cluster of genes that are responsible for intracellular survival
-----------------------
tularemia
- 3-5 day incubation
- fever, chills, headache, malaise, anorexia, fatigue
- ulceroglandular (lesion + lymphadenopathy)
- oculoglandular
- pharyngeal
- glandular
- pneumonic
- typhoidal: disseminated infection that does not fall into other categories
- 4% fatality
-----------------------
- Streptomycin or Gentamicin
- Doxycycline or Ciprofloxacin for PEP
- alert microbiology lab, b/c very virulent
120
Q

Acinetobacter spp.

Morphology
Transmission and Reservoir
Virulence Factors
Diseases

A
Gram- rod
-----------------------
- soil (e.g. Afghanistan)
- contact, wounds
-----------------------
- endotoxin
- resistant to desiccation
- readily acquires antibiotic resistance genes
-----------------------
hospital-acquired pneumonia (e.g. ventilator-associated)
121
Q

Enterobacteriaceae general

A
  • Gram negative
  • Faculative anaerobe: oxidase negative
  • isolated from feces, urine, blood and CSF
  • Cultivated on media containing bile (MacConkey)
  • Motile or non motile

speciation relies on lactose utilization