peptidoglycan structure
sugar backbone with peptide side chains cross linked with transpeptidase
lipoteichoic acid in what organisms and activity
Gram positives, induces TNG and IL-1
Lipopolysaccharide in what and does what
Endotoxin of gram negatives. Induces TNF and IL-1. O polysaccharide is the antigen.
Space between cytoplasmic membrane and outer membrane in gram negatives
Periplasm: contains hydrolytic enzymes including Beta-lactamases
what is a capsule made of
polysccharide
exception to polysaccharide capsule
Bacillus anthracis, contains D-glutamate
sex pilus for what process
conjugation
pilus and fimbria made of
glycoprotein
spore made of
keratin-like coat; dipicolinic acid; peptidoglycan
dipicolinic acid??
????
glycocalyx structure and function
polysaccharide, adheres to surfaces (biofilms)
capsules in what organisms
both gram positives and negatives
Name the gram + cocci
staph and strep
gram - cocci
neisseria (gram - diplococci)
What are the branching filamentous bacteria
actinomyces and nocardia (weakly acid fast) Gram positives!!!
What are the pleomorphic bacteria
Rickettsiae (Giemsa) and Chlamydiae (Giemsa) Gram negatives!!!!
What are the spiral bacteria
Spirochetes (gram negatives): Borrelia (Giemsa), Leptospira, Treponema
No cell wall bacteria
Mycoplasma (does not Gram stain)
Mycoplasma cell membrane
Contain sterols and have no cell wall
Mycobacteria cell wall
Contains mycolic acid with high lipid content.
Name the gram positive rods
Clostridium, corynebacterium, bacillus, listeria, mycobacterium (acid fast), gardnerella (gram variable)
The gram-negative rods
There are a ton.
Make a table of the different kinds of bacteria, at least be able to recognize what each one is.
…………………….If you know all the gram-positives (there are only a few), you can know what all the gram negatives are!!!!!
Everything is gram negative except for
Staph, strep, clostridium, corynebacterium, bacillus, listeria, gardnerella, actinomyces, nocardia, (not sure about nocardia)
Is mycoplasma gram +?
??????????????
What is in acid fast stain
Carbolfuchsin to stain the high lipid content of mycobacteria
Legionella is found where
Priarmily intracellular
Legionella staining
silver stain
Rickettsia gram stain?
Intracellular parasite (doesn’t gram stain)
Chlamydia stain?
IC parasite; lacks muramic acid in cell wall
Muramic acid?
???
What is Giemsa stain?
?????
What bugs stain with Giemsa???
Chlamydia, Borrelia, Rickettsia, Trypanosomes, Plasmodium (these sound intracellular, but are all of them?….nope..fuck)
What is PAS stain
Periodic acid-Schiff: stains glycogen!!!!, mucopolysaccharides. PASs the sugar.
PAS stain for what
Tropheryma whipplei (Whipple disease)
Ziehl-Neelsen stain
Carbolfuchsin (Acid fast: nocardia, mycobacterium)
India ink stain
Cryptococcus
Other way of staining cryptococcus
Mucicarmine to stain thick polysaccharide capsule red
Silver stain for what
Fungi (pneumocystis), legionella, helicobacter
Special culture requirements….Know them???
?????????
Growing neisseria gonorrheae or meningitidis
Thayer-Martin or VPN media (Vancomycin, Polymyxin, and Nystatin.
Growing Bordetella pertussis
Bordert-Gengou (potato) agar (Bordet for Bordertella)
Growing E. coli
Eosin-Methylene blue (EMB) agar as colonies with green metallic sheen
Growing Fungi
Sabouraud agar. “Sab’s a fun guy!”
What are the obligate aerobes
Pseudomonas, Mycobacterium tuberculosis, and Nocardia! All lung infections
What part of lung has the highest PO2
Apices of lung, where M. tuberculosis goes after reactivation from immune compromise or TNF-alpha inhibitor.
Bacteria in burn wounds
P. aeruginosa
Where do you see P. aeruginosa
Burn wounds, complications of diabetes, nosocomial PNA, and pneumonias in cystic fibrosis patients.
What are the obligate anaerobes
Clostrium, bacteroides, and actinomyces (actinomyces and nocardia are at opposite ends)
What do obligate anaerobes lack
Catalase and/or superoxide dismutase
Characteristics of obligate anaerobes
Smell bad (short-chain fatty acids), difficult to culture, and produce gas in tissue (CO2 and H2).
What ABx can’t be used against anaerobes
Aminoglycosides because they require O2 to enter.
Obligate intracellular bugs
Rickettsia, Chlamydia (can’t make own ATP)
Facultative intracellular bugs
Salmonella, neisseria, brucella, mycobacterium, listeria, francisella, legionella, yersinia pestis
Mnemonic for facultative intracellular bugs
Some Nasty Bugs May Live FacultativeLY
Encapsulated Bacteria
SHiNE SKiS: Strep pneumo, HiB, N. meningitidis, E. coli, Salmonella, Kleb, group B Strep
How to kill encapsulated bacteria
Opsonized and cleared by spleen
What vaccines to give aplenics
S. pneumo, H. flu, and N. meningitidis
Catalase-positive organisms
Pseudomonas, Listeria, Aspergillus, Candida, E.coli, S. aureus, Serratia (You need PLACESS for your CATs)
What kind of vaccine activates T-cells
Conjugated vaccine (to protein), polysaccharide antigen cannot be presented to T cells.
Pneumovax kind of vaccine
Pneumococcal Polysaccharide Vaccine (PPSV) with no conujugated protein
Prevnar is what kind of vaccine
Pneumococcal Conjugate Vaccine (PCV)
HiB vaccine
Conjugate
Meningococcal vaccine
Conjugate vaccine
Urease-positive bugs
Cryptococcus, H. pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus
Pigment-producing bacteria
Actinomyces israelii (Yellow), S. aureus (Yellow), Pseudomonas aeruginosa (blue-green), Serratia marcescens (red)
What does Protein A do?
Binds Fc region of IgG. Prevents opsonization and phagocytosis. Expressed by S. aureus.
What does IgA protease do?
Cleaves IgA. Secreted by S. pneumo, HiB, and Neisseria (SHiN)
What does M protein do?
Helps prevent phagocytosis. Expressed by group A strep.
Compare exotoxin and endotoxin..
………….
Basics of endotoxin
Outer cell membrane of most gram-negative bacteria, is not secreted, is made out of LPS (released when lysed), made by bacterial chromosome, low toxicity, creates fever, chock (hypotension), and DIC, induces TNF,IL-1, and IL-6, poorly antigenic, no toxoids formed and no vaccine avaialble, stable at 100 degrees celsius for 1 hr. Found in meningococcemia, sepsis by gram negative rods
What is a toxoid?
Toxoid is the toxin that has been inactivated chemically or with heat but still has its immunogenicity and is used as vaccine.
Basics of exotoxin
Certain species of gram + and gram - bacteria, secreted from cell, polypetide, from plasmid or bacteriophage, high toxicity, induces hihg-titer antibodies called antitoxins, toxoids used as vaccines, destroyed rapidly at 06 degrees celsius (except staph enterotoxin), causes tetanus, botulism, and diphtheria.
Write out a table of bugs with exotins
……..
Dysentery from what bacteria
Shigella
ETEC toxins mnemonic
Labile int he Air, Stable on the Ground (cAMP and cGMP)
ENDOTOXIN mnemonic
Edema, nitrix oxide, DIC/Death, Outer membrane, TNF-alpha, O-antigen, eXtremely heat stable, IL-1, Neutrophil chemotaxis
What are endotoxins
A LPS in outer membrane of gram negatives
What does Lipid A do
It is an endotoxin, activates macrophages, complement, and tissue factor.
What activated macrophages do
IL-1, TNF, and NO
What activated complement does
C3a and C5a
What activated tissue factor does
Coagulation cascade and subsequent DIC
What is competence
The ability to take up naked DNA from environment for Transformation
What bacteria are known for transformation
SHiN: S. pneumo, HiB, and Neisseria
What is optochin
Optochin is used to distinuish alpha-hemolytic strep. Strep pneumo is optochin sensitive but strep viridans is resistant.
Example of Viridans strep
S. mutans
F+ conjugation
From a F+ plasmid which contains genes for sex pilus and conjugation. no chromosomal genes. The entire plasmid is shuttled through sex pilus.
Hfr conjugation
Incorporated into bacterial chromosome. Transfers plasmid and chromosome genes.
Transposition in bacteria
Transposons between plasmid and chromosome. Abx resistance genes on R plasmid.
Generalized transduction
Lytic phage gets DNA incorporated into the virion.
Specialized transduction
Lysogenic phage gets flanking DNA from bacteria
5 bacterial toxins encoded in a lysogenic phage
ABCDE: ShigA-like toxin, Botulinum, Cholera, Diphtheria, Erythrogenic of Strep pyogenes.
Do strep have catalase?
No, all strep lack catalase, staph has catalase
Is staph aureus hemolytic?
Yes, beta-hemolytic
Is listeria hemolytic
Yes
Listeria describtion
Tumbling motion, newborn meningitis, unpasteurized milk
Where to find Staph aureus
The nose.
What is protein A
Virulence factor of staph aureus binding Fc-IgG, inhibits complement activation and phagocytosis.
Bacterial superinfection after flu
Staph aureus
Staph aureus toxins
TSST-1 (toxic shock syndrome), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (enterotoxins)
MRSA (methicillin-resistant S. aureus infection) MOA of resistance
Altered penicillin binding protein
What is TSST and what does it do
Superantigen activating a huge percentage of T-cells with MHCII. Presents with fever, vomiting, rash, desquamation, shock, end-organ failuire, use of vaginal or nasal tampons predisposes to toxic shock syndrome.
Incubation period of s. aureus food poisoning
2-6 hrs. Enterotoxin is heat stable, not destroyed by cooking
What does coagulase do
Forms fibrin clot around self to lead to an abscess
Staph epidermidis blurb
Biofilms on prosthetics and catheters. Contaminates blood cultures. Novobiocin sensitive.
Staph saprophyticus blurb
Second MCC of uncomplicated UTI in young women (1. is E. coli). Novobiocin resistant
Strep pneumo MCC of what diseases
MOPS: meningitis, otitis media (children), pneumonia, and sinusitis.
Morphology of strep pneumo
Lancet-shaped, gram-positive diplococci, encapsulated. IgA protease
Pneumococcus sputum
Rusty sputum
Pneumocccus causes sepsis in what
Sickle cell and splenectomy
What happens if you remove pneumococcus capsule
No virulence without it!
Pneumococcus and optochin
Sensitive
Name the viridans group strep and description
S. mutans in mouth (caries), cause subacute bacterial endocarditis at damaged valves (S. sanguinis). Resistant to optochin. Alpha-hemolytic.
Strep pyogenes infections
Scarlet fever is toxin induced (rheumatic fever is immunologic), can cause cellulitis, impetigo, necrotizing fasciitis.
Strep pneumo description
Group A beta-hemolytic strep. Bacitracin sensitive. Antibodies to M protein enhance host defense but give rise to rheumatic fever. .
Recent strep pyo infection dx
ASO titer (anti-streptolysin O antibodies)
JONES criteria for rheumatic fever
Joints (polyarthralgias), carditis, nodules (subQ), Erythema marginatum, sydenham chorea.
What strep pyo infections can cause rheumatic fever and glomerulonephritis
Pharyngitis can do both. Impetigo more commonly precedes glomerulonephritis than pharyngitis.
Scarlet fever sxs
Scarlet rash with sandpaper-like texture, strawberry tongue, circumoral pallor.
What does erythema marginatum look like
it looks like pink rings
Strep agalactiae description
beta-hemolytic (Group B strep), in vagina. Bacitracin resistant. Causes PNA, meningitis, sepsis in babies.
What is CAMP factor
Made by strap agalactiae, enlarges the area of hemolysis formed by S. aureus
What to diagnose strap agalactiae with
CAMP test (named after authors). It turns hippurate test positive.
Screening and management for strep agalactiae
Screen pregnant women at 35-37 weeks. patients with positive culture receive intrapartum penicillin ppx.
Enterococci cause what infections
UTI, biliary tract infections, and subacute endocarditis after GI/GU procedures.
Enterococci tx
Resistant to penicillin G
Nonenterococcal group D strep
Can’t grow in 6.5% NaCl and bile (enterococci can)
Where to find strep bovis
In the gut, can cause bacteremia and subacute endocarditis in colon cancer patients.
What kind of strep is strep bovis
gamma-hemolytic group D strep
What is pseudomembranous mean?
For diphtheria, it is gray-white exudative layer of necrotic epithelium and debris, fibrin, bacteria, and neutrophils. Removing it causes hemorrhage.
Diphtheria presentatin
Pseudomembranous pharyngitis, bull neck lymphadenopathy, myocarditis, and arrythmias.
Diphtheriae dx
Gram-positive rods with metachromatic (blue and red) granules and Elek test for toxin.
What does diphtheria look like on agar
Black colonies on cystine-tellurite agar.
Diphtheriae mnemonic
ADP-ribosylation, beta-prophage, corynebacterium, diphtheriae, elongation factor 2, granules
Diphtheriae path
Exotoxin encoded on Beta-prophage. Potent exotoxin hibits protein synthesis via ADP-ribosylation of EF-2
What do spores have??
Dipicolinic acid in their core with nometabolic activity.
What bacteria form spores
Bacillus anthracis, clostridium perfringens, C. tetani. SPORE FORMING GRAM POSITIVES IN SOIL.
other spore formers are B. cereus, C. botulinum, and Coxiella botulinum
Full name for B. cereus
Bacillus cereus
What is a bacteroides species?
Bacteroides fragilis
What are the clostridia
Gram-positive, spore-forming, obligate anaerobic bacilli.
What does tetanospasmin do
Blocks glycine and GABA release from REnshaw cells in spinal cord.
What is floppy baby syndrome?
Caused by Botulinum toxin.
What does C. perfringens make?
Alpha toxin (“lecithinase” a phospholipase) that causes myonecrosis (gas gangrene) and hemolysis.
C. difficile toxins
Toxin A, enterotoxin, binds to the brush border of the gut. Toxin B, cytotoxin, causes cytoskeletal disruption via actin depolymerization leading to pseudomembranous colitis and diarrhea.
C. diff most commonly due to what Abx
clindamycin and ampicillin.
What is bacillus anthracis
Gram-positive, spore forming rod that produces anthrax toxin. The ONLY bacterium with a polypeptide capsule (contains D-glutamate)
Cutaneous anthrax presentation
Painless, necrotic black eschar that starts out as a boil-like lesion. Does not lead to bacteremia and death.
Pulmonary anthrax presentation
Inhalation of spores causes flu-like sxs that progresses to fever, pulm. hemorrhage, mediastinitis, and shock.
What is woolsorters’ disease
Pulm. anthrax from breathing in spores from contaminated wool.
What causes Reheated Rice Syndrome
Bacillus cereus
How can Bacillus cereus cause disease in boiled rice?
Spores!!!
Types of bacillus cereus infections
Emetic type: rice and pasta. n/V within 1-5 hrs. Caused by cereulide, a preformed toxin.
Diarrheal type: Water, nonbloody diarrhea and GI pain within 8-18 hr
Listeria monocytogenes description
Facultative intracellular microbe, from unpasteurized dairy products and deli meats, via transplacental transmission, or from vagina during birth.
How does listeria get around
Rocket tails from actin polymerization. Characteristic tumbling motility; is only gram positive organism to produce LPS
The only gram positive to produce LPS
Listeria
What can listeria cause
Amnionitis, septicemia, and spontaneous abortion in pregnant women; granulomatosis infantiseptica; neonatal meningitis; meningitis in immunocompromised patients; mild gastroenteritis in healthy individuals.
Treating listeria
Gastroenteritis is self-limited. Ampicillin in infants, immunocompromised patients, and elderly in empirical treatment of meningitis
Distinguish actinomyces from nocardia
Make a table to compare……
Nocardia infections
Pulm. infections in immunocompromised and cutaneous infections after trauma in immunocompetent
Actinomyces infections
oral/facial abscesses that drain through sinus tracts, forms yellow “sulfur granules”
What to treat Nocardia with
Sulfonamides
What to treat Actinomyces with
Penicillin
What is primary tuberculosis
The Ghon complex (hilar lymph nodes and Ghon focus in mid-lung field). Occurs in infection naive people, usually children. Can proceed to several endpoints like death or heals.
What can happen to primary tuberculosis
- Heal by fibrosis with hypersensitivity and immunity and tuberculin +
- Progressive lung disease and death (malnutrition, HIV)
- Severe bacteremia, miliary tuberculosis leading to death.
- Preallergic lymphatic or hematogenous dissemination leading to dormant tubercle bacilli in several organs and reactivation in adult life.
How does secondary tuberculosis happen?
Partially immune hypersensitized host gets reinfected or patient with latent TB gets reactivation.
How does secondary tuberculosis present?
Fibrocaseous cavitary lesion (usually upper lobes)
Examples of extrapulmonary tuberculosis
CNS (parenchymal tuberculoma or menigitis), vertebral body in Pott’s disease), lymphadenitis, Renal, GI, and adrenal infection.
BCG + on PPD?
Yes
When is PPD negative?
steroids, malnutrition, immunocompromise leading to anergy AND SARCOIDOSIS
What does a caseating granuloma have?
Central necrosis with multinucleated Langhans giant cells.
More specific test than PPD?
Interferon-gamma release assay IGRA is more specific. Fewer false positives than BCG.
TB symptoms
Fever, night sweats, weight loss, and hemoptysis.
Mycobacterium kansasii presentation
Pulmonary TB like symptoms
Mycobacterium avium-intracellulare presentation
Disseminated, non-TB dsiease in AIDS; often resistant to multiple drugs. Prophylactic treatment with azithromycin.
Which mycobacterium is not acid fast?
All are acid fast
What is cord factor
For M. tuberculosis that inhibits macrophage maturation and induces release of TNF-alpha. Sulfatides (surface glycolipids) inhibit phagolysosomal fusion.
Other name for leprosy
Hansen disease
Agar media for Mycobacterium leprae
Cannot be grown in vitro. Reservoir is armadillos.
M. leprae does what path
Likes cool temps (skin and superficial nerves, glove and stocking loss of sensation)
Forms of leprosy
Lepromatous and Tuberculoid
Lepromatous leprosy presentation
Presnts diffusely over the skin with leonine facies, communicable, characterized by low cell-mediated immunity with a humoral TH2 response.
Tuberculoid leprosy presentation
Limited to a few hypoesthetic, hairless skin plaques; characterized by high cell-mediated immunity with a largely Th1-type immune response.
Treating leprosy
Multidrug therapy with dapsone and rifampin for 6 months for tuberculoid form; and dapsone, rifampin, and clofazimine for 2-5 years for lepromatous form.
Is lepromatous leprosy lethal?
It can be!
Know the gram-negative lab algorithm
What are the gram negative diplococci
What grows pink colonies on MacConkey agar
Lactose fermenting enteric bacteria. Citrobacter, Klebsiella, E. coli, Entergoacter, and Serratia (weak fermenter).
What enzyme does E. coli produce
Beta-galactosidase which breaks down lactose into glucose and lactose
EMB agar grows what
Lactose fermenters grow as purple/black colonies. E. coli is purple colonies with a green sheen.
Penicillin and gram-negative bugs.
Gram negative bacilli are resistant to penicillin G but may be susceptible to ampicillin and amox. Gram neg. outer lmembrane inhibits penicillin G and vancomycin entry.
Neisseria general description
Gram-negative diplococci.
Both ferment glucose and produce IgA proteases. N. gonorrhoeae is often intracellular (within neutrophils)
Neisseria mnemonics
MeninGococci ferment Maltose and Glucose.
Gonococci ferment Glucose.
Compare gonococci to meningococci in a table
….
Mnemonic for Haemophiluis
HaEMOPhilus (epiglottitis, meningitis, otitis media, and PNA.
H. flu tx
mucosal infection with augmentin.
Meningitis with ceftriaxone.
Rifampin ppx in close contacts.
H flu characteristics
small gram-negative coccobacillary rod. Aerosol transmission.
Nontypeable strains cause what
Mucosal infections (otitis media, conjunctivitis, bronchitis)
What does Hib vaccine contain
Type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein. Given between 2-18 months of age.
Legionella description
Gram negative rod stained with silver stain.
Legionella growth
Charcoal yeast extract culture with iron and cysteine.
legionella dx
Urine antigen
Legionella transmission
Aerosol around water sources. No person to person transmission
Legionella tx
Macrolide or quinolone
Legionnaires’ disease presentation
Severe PNA, fever, GI and CNS sxs
Pontiac fever presentation
Mild flu-like syndrome
Legionella bloodwork
Hyponatremia.
Pseudomonas description
Aerobic gram-negative rod. non-lactose fermenting, oxidase positive. Produces pyocyanin (blue green); grade like odor. Water source. Produces endotoxin (fever, shock) and exotoxin A (inactivates EF-2).
Pseudomonas mnemonic
PSEUDOmonas: associated with wound and burn infections, PNA (cystic fibrosis), Sepsis, External otitis (swimmer’s ear), UTI, Drug use and Diabetic Osteomyelitis, and hot tub folliculitis. Malignant otitis externa in diabetics
Ecthyma gangrenosum
Rapidly progressive, necrotic cutaneous lesions caused by Pseudomonas bacteremia. Typically seen in immunocompromised patients.
Ecthyma tx
Aminoglycoside plus extended-spectrum penicillin (e.g. piperacillin, ticarcillin, cefepime, imipenem, meropenem.
E. coli virulence factors
Fimbriae: cystitis and pyelonephritis
K capsule: PNA, neonatal meningitis
LPS endotoxin: septic shock
4 A’s of Klebsiella
Aspiration PNA, Abscess in Lungs and Liver, Alcoholics, di-A-betics
Typhoid fever presentation
Only in humans. Rose spots on the abdomen, fever, headache, and diarrhea. Can remain in gallbladder and cause a carrier state.
Campylobacter jejuni
Major cause of bloody diarrhea, especially in children.
Campylo transmission
Fecal-oral through poultry, meat, unpasteurized miolk.
Campylo morph.
s-shaped, oxidase +, grows at 42 degrees (campylobacter likes the hot CAMPfire)
Extraintestinal findings of Campylobacter
Guillain-Barre and reactive arthritis
Vibrio cholerae morph.
comma shaped, oxidase +, grows in alkaline media. Endemic to developing countries.
Yersinia enterocolitica transmission
From puppy feces, contaminated milk, or pork. Causes mesenteric adenitis that can mimic Crohn disease or appendicitis.
What does H. pylori increase the risk of
Peptic ulcer, gastric adenocarcinoma, and lymphoma
H. pylori morph
Catalase, oxidase, and urease + (can use urea breath test or fecal antigen test for diagnosis).
H. pylori tx
Triple therapy: Proton pump inhibitor + clarithromycin + either amoxicillin or flagyl
Name the spirochetes
Borrelial (big size), Leptospira, Treponema (BLT).
Imaging spirochetes
Only Borrelia can be visualized with aniline dyes (Write or Giemsa stain) in light microscopy. Treponema is dark-field microscopy.
Leptospira disease
Leptospira interrogans causes leptospirosis from water contaminated with animal urine: flu-like sxs, jaundice, photophobia with conjunctival suffusion (erythema without exudate). Prevalent among surfers and in tropics (i.e. Hawaii)
What is Weil disease
Icterohemorrhagic leptospirosis: severe form with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage, and anemia
Lyme disease mnemonic
FAKE a Key Lyme pie: Facial nerve palsy (bilateral), Arthritis, Kardiac block, Erythema migrans
VDRL false positives
VDRL: viruses (mono, hepatitis), drugs, rheumatic fever, lupus and leprosy
Treatment for all Rickettsial diseases and vector-borne illness
Doxycycline!!!!
Where do you seen rash on palms and soles
CARS: Coxsackievirus A (hand food mouth), RMSF, and Secondary Syphilis
Difference in rash between Typhus and RMSF
Typhus starts centrally, RMSF starts peripherally
Cause of Q fever
Coxiella burnetii