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Flashcards in Microbiology Deck (70)
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1
Q

Give 3 symptoms of influenza

A
  • General malaise
  • Myalgia Headache
  • Dry cough
  • Prostration - extreme fatigue and weakness
  • Fever
2
Q

What are potential causes of classical flu?

A
  • Influenza type A or B viruses
  • Influenza type C virus can also cause a form of influenza yet it is less common
3
Q

How is flu spread?

A
  1. Droplets/formites
  2. Direct contact with respiratory secretions from an infected individual
4
Q

How can influenza be treated?

A

Treatment can be:

  1. Symptomatic - bed rest, maintain fluids etc.
  2. Curative - antivirals such as oseltamivir and zanamivir
5
Q

What allows influenza to cause frequent epidemics?

A

Antigenic drift - minor surface protein changes (usually)

6
Q

Pandemics are potentially very dangerous when involving influenza - why?

A

Influenza A viruses only are involved. Antigenic shift occurs in a animal reservoir or mixing vessel This means a “hybrid” virus can be formed that humans will have little if no immunity to

7
Q

Which laboratory techniques can be used to determine the presence of the flu virus?

A
  • PCR - using nasopharyngeal swabs, throat swabs or other respiratory samples
  • Immunofluorescence for antigen detection
  • Viral cultures
  • Antibody detection
8
Q

Influenza is prevented though vaccines, what is a “killed vaccine”?

A

The virus is grown in culture, inactivated and combined with an adjuvant - a substance to enhance immune reaction. This can be given annually to patients at risk of contraction, healthcare workers, the very young/old

9
Q

Influenza is prevented though vaccines, what is an attenuated vaccine”?

A

This is a more effective vaccine vs a killed vaccine The real pathogen is used, but with reduced virulence. This vaccine is given to all children aged between 2 and 5

10
Q

What is the most common cause of community acquired pneumonia?

A

Streptococcus pneumoniae

11
Q

What are the three causes of atypical pneumonia?

A
  • Mycoplasma pneumonia
  • Legionella pneumonia
  • Chlamydophilia pneumoniae
12
Q

Coxiella burnetii is associated with which two main conditions?

A
  1. Q fever
  2. Pneumonia
13
Q

A complication, involving Q fever and the heart is likely to be what?

A

Infective endocarditis

(caused by Coxiella burnetii)

14
Q

Chlamydophila psittaci causes which condition?

A

Psittacosis

This is an uncommon sporadic zoonosis (pet birds) and will normally present as pneumonia

15
Q

What is a sporadic zoonosis?

A

An infectious disease from animals that can spready to humans

16
Q

What is bronchiolitis?

A

A common lower respiratory tract infection causing inflammation of the bronchioles

It normally affects people in the first or second year of life

Grunting will occur - difficulty in breathing, reduced partial pressure of oxygen and sternal indrawing

17
Q

What is most likely to cause bronchiolitis?

A

Respiratory synctial virus (RSV)

18
Q

What is metapneumovirus?

A

The second most common cause (after RSV) of lower respiratory infection in young children

The virus has highest incidence in winter

19
Q

How is metapneumovirus diagnosed?

A

Throat swabs and PCR

20
Q

What is chlamydia trachomatis?

A

An STI caused by bacteria

The bacteria can present in one of three ways:

  1. Genitourinary
  2. Pulmonary
  3. Ocular

It can cause pneumonia in infants

Diagnosed by PCR on urine of mother, or pernasal/throat swabs of child

21
Q

Coxiella burnetii is a becteria mostly spread from what to humans?

A

Animals such as sheep or goats

22
Q

When was metapneumovirus discovered?

A

2001

23
Q

Name an alpha-haemolytic streptocooci that can cause respiratory tract infection

A

Strep pnemoniae

24
Q

Name a beta haemolytic streptococci that can cause respiratory tract infection

A

Strep pyogenes

25
Q

Name two key gram negative bacteria that can cause respiratory tract infection

A
  1. Haemophilus influenzae
  2. Moraxella catharalis
26
Q

What pathogen will cause acute epiglottitis?

A

Haemophilus influenza type B

27
Q

What is used to test for the presence of haemophilus influenzae in epiglottitis?

A

Blood cultures

(not throat swabs)

28
Q

What is the treatment for epiglottitis?

A

Ceftriaxone

29
Q

Haemophilus influenzae will only grow on what?

A

Lysed blood agar

30
Q

Exacerabtions of COPD can be caused by which pathogens?

A
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Streptococcus pneumoniae
  • Gram negatives
31
Q

What is Moraxella catarrhalis?

A

A gram-negative coccus bacteria commonly found in respiratory tract infection

32
Q

How can the cause of a COPD exacerbation be tested for?

A
  1. Sputum culture
  2. Sputum purulence
  3. CXR
33
Q

When will a COPD exacerbation be treated for infection?

A
  • When sputum is purulent
  • When CXR changes
  • In the presence of pneumonia
34
Q

What is the first line treatment for infection during a COPD exacerbation?

A

Amoxicillin (500mg) for 5 days

(aims to treat H.influenzae, M.catarrhalis, S.pneumoniae)

35
Q

What is the second line treatment for infection during a COPD exacerbation?

A

Doxycycline 200mg on day 1 which drops down to 100mg between days 2 and 5

36
Q

By what other name is acute laryngotracheobronchitis known?

A

Croup

37
Q

Croup is characterised mainly by what?

A

Harsh cough and stridor

38
Q

How is croup treated?

A

Steroids

Humidification

39
Q

Coryza can be caused by which pathogens?

A

Rhinovirus - mainly

Coronavirus

40
Q

What is cystic fibrosis?

A

An inherited disease causing abnormally thick mucous blocking many tubular structures in the body (mostly lungs and digestive system)

This will lead to repeated chest infections and chronic infection because microbes become trapped

41
Q

What will often precede an episode of acute bronchitis?

A

UTI

(whooping cough can cause the condition)

42
Q

What is the clinical presentation of acute bronchitis?

A
  • Infection an inflammation of bronchi
  • Productive cough
  • Wheeze
  • Fever
  • Normal CXR
43
Q

What causes whooping cough?

A

Bordetella pertussis

44
Q

How does whooping cough present clinically?

A
  • Acute tracheobronchitis
  • Cold-like symptoms
  • Paroxysmal coughing (sudden recurrence/worsening)
  • Repeated violent exhalations
  • Potentially vomiting
45
Q

How is Bordetella pertussis diagnosed?

A
  • Bacterial culture - pernasal swabbing and charcoal-blood agar
  • PCR - pernasal swab
  • Serology
46
Q

How does the treatment of whooping cough vary based on age?

A
  • Age <1 - clarithromycin
  • Age>1 - clarithromycin and azithromycin
  • Pregnancy - erythromycin
47
Q

Community acquired pneumonia is caused most frequently bvy which pathogen?

A

Step pneumoniae

48
Q

How is pneumonia diagnosed?

A
  • Culturing sputum
  • Undergoing viral PCR
49
Q

How is pneumonia treated?

A

Amoxicillin (5 days)

or

Co-amoxiclav and doxycycline (100mg)

Very severe:

Co-amoxiclav and IV clarithromycin

50
Q

How is pneumonia tested for?

A

Bloods

  • Erythrocyte sedimentation rate
  • C-reactive protein
  • Cultures

Sputum

  • Microscopy
  • Culture
  • Cytology

CXR and potentially CT

51
Q

Legionella pneumonia is known by which other name?

A

Legionnaire’s disease

52
Q

Legionella pneumonia is a form of _________ pneumonia

A

Atypical

53
Q

Where does the pathogen legionella pneumonia normally reside and how is it acquired?

A

Resides in water (stagnant) with water amoeba which provide nutrients and protection

Often acquired by coming into contact with this water (inhalation) or from direct person to person contact

Often acquired on holiday abroad

54
Q

What are some risk factors for Legionella pneumonia?

A
  • Coming into contact with contaminated water
  • Impaired immunity
  • Altered immunity
  • Diabetes
  • Smoking
  • Having a malignancy
55
Q

What is the treatment for legionella pneumonia?

A

Clarithromycin and erythromycin

or

Quinolones such as levofloxacin

56
Q

What are the commonest causes for hospital acquired pneumonia?

A

Gram negative bacteri such as:

  • Klebsiella spp
  • Pseudomonas spp
  • E.coli

Clostridia (gram postive bacteria)

Staph aureus

57
Q

What is pneumocystis pneumonia and what causes it?

A

Pneumocystis jirovecii

58
Q

What is pneumocystis jirovecii and how is it acquired?

A

A fugus acquired through inhalation of spores

(usually only affected severly immonocompromised - HIV etc)

59
Q

How does pneumcystis jirovecii present clinically?

A
  • Dry cough
  • Fever
  • Breathlessness
  • Fatigue
60
Q

How is pneumcystis jirovecii diagnosed?

A
  • Bronchoalveolar lavage
  • Sputum sample or gargle
  • Immunofluorescence (antibody techniques)
61
Q

What can used as treatment for pneumcystis jirovecii?

A

Co-trimoxazole and prophylaxis

62
Q

What is aspergillus?

A

Aspergillus fumigatus is a fungus that can cause severe pneumonia and invasive disease when inhaled in immunocompromised individuals

In normal patients localised pulmonary infection and potentially a aspergilloma (fungus ball) will develop

63
Q

How can aspergillus be diagnosed?

A

Bronchoalveolar lavage to obtain specimens for fungal culture and PCR

(tissue can also be examined)

64
Q

How is aspergillus fumigatus treated?

A

Amphotericin B

Voriconazole

Surgery

65
Q

Tb is detected by which methods?

A
  • Culturing (most sensitive)
  • PCR
  • Ziehl-Neelsen stain (least sensitive)
66
Q

Describe how a Ziehl-Neelsen stain is performed

A
  • A red dye (carbol fuchsin) is added to a sample of Tb
  • The sample is heated slighly to melt the waxy coat of Tb
  • Alcohol and acid are then added and in mycobacteria the colour of the dye is still retained
  • A blue dye is then added (methylene blue)
  • If red dye is still visible under the microscope then Tb is present
67
Q

What are the pros and cons of a Ziehl-Neelsen stain?

A

Pros

  • Cheap
  • Fast

Cons

  • Does not distinguish between species
  • Gives no information on drug sensitivity
68
Q

What are the pros and cons of PCR for Tb detection?

A

Pros

  • Inexpensive
  • Fast

Cons

  • Little information on species
  • Little infomation on drug sensitivity
69
Q

What are the pros and cons of culturing as a detection method for Tb?

A

Pros

  • Highly sensitive and specific
  • Allows for information on drug sensitivity

Cons

  • Slow
70
Q
A