Microbiology 12: Respiratory Tract Infections Flashcards

1
Q

Blood culture from a young women isolates a gram +ve diplococcus, alpha-haemolytic bacteria which is optochin sensitive.

What is the most likely causative organism of her pneumonia?

A

Streptococcus. Pneumoniae

  • NB since gram +ve, this would stian purple
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2
Q

Blood culture finding if strept pneumoniae

A
  • purple stain (gram +ve)
  • a-haemolytic and optochin-sensitive
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3
Q

List the 3 most common causative organisms of pneumonia in neonates 0-1 months old ?

A

E.coli
Group B streptococcus (GBS)
Listeria monocytogenes

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4
Q

List the 3 most common causative organisms of pneumonia in children 1-6 months old ?

A

Chlamydia trachomatis
Staphylococcus aureus
RSV

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5
Q

List the 2 most common causative organisms of pneumonia in children 6 months - 5 years old ?

A

Mycoplasma pneumonia
Influenza

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6
Q

List the 2 most common causative organisms of pneumonia in people ages 16-30 years old ?

A

Streptococcus pneumonia
Mycoplasma pneumonia

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7
Q

List the 2 typical organisms causing CAP (85% of cases)

A

Streptococcus Pneumoniae
Haemophilus influenza

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8
Q

List the 4 atypical organisms causing CAP

A
  • Legionella
  • Mycoplasma
  • Coxiella burnetii (Q-fever)- exposed to farm animals
  • Chlamydia psittaci (psittacosis)- exposure to birds, you get a haemolytic anaemia
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9
Q

List 3 organisms that cause cavitation on CXR ?

A

Staph aureus (Swiss cheese type pattern)
Klebsiella pneumonia
TB

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10
Q

Which atypical organism of pneumonia is transmitted by inhalation of infected water droplets e.g from saunas, AC and is grown on buffered charcoal yeast extract ?

A

Legionella Pneumophila

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11
Q

What is the antibiotic treatment for atypical CAP ?

A

Macrolide - Azithromycin/ clarithromycin
+
Doxycycline

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12
Q

An auramine stain and ziehl-Nielsen stain are used to identify which organism ?

A

TB

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13
Q

What are the most common causative organisms of HAP ?

A
  • Enterobacteriaciae (e.coli, klebsiella pneumonia)
  • S.aureus
  • Pseudomonas aeruginosa
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14
Q

Which organisms causes bilateral ground glass shadowing (bat’s wing appearance) for pneumonia?

A

Pneumocystis Jirovecii (PCP)

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15
Q

What is a special physical test to diagnose Pneumocystis jirovecii ?

What Ix can you do?

A

The walk test (attach oxygen saturation and get them to walk) - shows desaturation on exertion

Ix: bronchoalveolar lavage

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16
Q

Which organisms causing LRTIs are more common in patients with neutropenia ?

A

Fungi - aspergillus

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17
Q

Which organism typically causes LRTIs in patients with bone marrow failure ?

A

CMV

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18
Q

What is the 1st line antibiotic treatment for HAP ?

A

Ciprofloxacin +- vancomycin (these have gram -ve cover, which is important for HAP)

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19
Q

Which atypical organism causes Pneumonia with cold agglutinins And erythema multiforme (target lesion) on palms ?

A

Mycoplasma Pneumonia

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20
Q

Which organism causes a pneumonia with cough, myalgia and rose spots on the abdomen and is commonly seen in ornithologists (bird handlers)?

A

Chlamydia Psittaci

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21
Q

Which organism causes pneumonia with target shaped lesions on the palm ?

A

Mycoplasma pneumonia

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22
Q

Which 2 organism commonly Infect people with cystic fibrosis ?

A

Pseudomonas aeruginosa
Burkholderia capacia

23
Q

Which organism when stained with Gomori’s methenamine silver stain shows “Flying saucer” shaped cysts ?

A

Pneumocystis jirovecii (PCP)

24
Q

Which coccus bacteria arranges in grape-like clusters ?

A

Staphylococcus aureus

25
Q

Which organism causes acute exacerbation of COPD and otitis media in children ?

A

Moraxella Caterrhalis

26
Q

what is the CURB-65 scale

A

risk stratification fro pneumonia patients

  • confusion
  • urea >7mmol/L
  • RR>30
  • BP <90 systolic, <60 diastolic
  • 65+ years

2 = consider admitting
2-5 manage as severe pneumonia and consider ITU admission

27
Q

what organisms commonly cause bronchitis (4)

A
  • viruses
  • strep pneumoniae
  • hemophilus influenzae
  • moraxelle catarrhalis
28
Q

features of legionella pneumophilia

A

spread via inhalation of infected water droplets
grown on buffered charcoal yeast extract
can cause multi-organ failure

29
Q

features of coxiella burnetii

A
  • common in domestic farm animals
  • transmitted by aerosol or milk
  • inv = serology
  • sensitive to macrolides
30
Q

features of chlamydia psittachi

A
  • spread from birds by inhalation
  • inv = serology
  • sensitive to macrolides
31
Q

What is empyema?

why are empyemas difficult to treat?

A
  • bag of pus within the pleural cavity
  • they have a wall around them and the pus contained is very acidotic which inactivates the antibiotics
32
Q

stains for TB (2)

A
  • auramine stain
  • ziehl-neelsen stain (auer rods are the acid-fast bacilli)
33
Q

what is a HAP

A

pneumonia onset >48 hrs in hospital, typically on ventilation

34
Q

Tx for Pneumocystic jiroveci pneumonia

A

Co-trimoxazole

35
Q

3 types of aspergillus fumigatus

A
  • Allergic bronchopulmonary aspergillosis: chronic wheeze, eosinophilia, bronchiectasis
  • Aspergilloma: fungal ball, often in pre-existing cavities
  • Invasive aspergillosis: immunocompromised, tx = amphotercin B
36
Q

Tx of Aspergillus fumigatus

A

Liposomal Amphotericin B

37
Q

LRTI in HIV patients (3)

A
  • PCP
  • TB
  • atypical mycobacteria
38
Q

LRTI in neutropaenia

A

fungi (esp aspergillus species)

39
Q

LRTI in BM transplant

A

CMV

40
Q

LRTI in splenectomy

A

encapsulated organisms (S Pneumoniae, H influenzae, malaria)

41
Q

what would you use antigen tests for in pneumonia? (2)

A

legionella pneumophilia
strep pneumoniae

42
Q

what would you use antibody tests for in pneumonia (2)

A
  • chlamydia
  • legionella

These since they are difficult to culture

43
Q

what colour are gram +ve and gram -ve bugs

A

gram +ve = blue/purple
gram -ve = prink

44
Q

treatment for mild-moderate CAP

A
  • amoxicillin
  • or erythromycin/clarythromycin
45
Q

treatment for moderate-severe CAP (2)

A

co-amoxiclav
and clarythromycin

(allergic - give cefuroxime + clarythromycin)

46
Q

treatment for HAP

A

1st line = ciprofloxacin +/- vancomycin
2nd line = piptazobactam + vancomycin

47
Q

30-50% of community acquired pneumonia due to what?

A
  • Streptococcus pneumoniae
48
Q

What drug is strept pneumoniae always sensitive to?

A

Penicillin

49
Q

Staph aureus features on CXR

A
  • swiss cheese pattern
  • multiple cavities
50
Q

3 causes of Cavitaties on CXR

A
  • Staphylococcus aureus – get a swiss cheese pattern with multiple cavities
  • Klebsiella pneumoniae
  • TB
51
Q

Haemophilus influenze causes what % of CAP?

Which group of pts is it more common in?

What do they look like on stain?

What enzyme may they produce?

A

15-35%

those with pre-existing lung disease

Gram-negative cocci-bacilli (rod) - INCLUDE PIC

beta-lactamase

52
Q

3 atypical pneumonia sensitive to macrolides

A
  • legionella pneumophilia
  • Coxiella burnetti
  • Chlamydia psittaci
53
Q

Tx of MRSA

A

MRSA = vancomycin