Respiratory Tract infections

Question 1

Common pathogens causing hospital-acquired pneumonia?

Answer 1

S. aureus
Klebsiella
Pseudomonas
Haemophilus

Question 2

For the 5 common typical pneumonia causes, what are the key buzzwords/associations?

Answer 2

Strep pneumoniae: Most common. Rusty-coloured sputum. Lobar on CXR. Vaccinated groups at risk

Staph aureus: Assoc. w/ recent viral infection (post-influenza) +/- cavities on CXR

H. influenzae: Assoc. w/ smoking, COPD

Moraxella catarrhalis: Assoc. w/ smoking

Klebsiella pneumoniae: Alcoholics, elderly, haemoptysis

Question 3

Investigations for a patient with suspected pneumonia?

Answer 3

CXR
Calculate CRB-65 (GP setting) or CURB-65 (hospital setting)
Sputum cultures
Atypical screen

C: Confusion - abbreviated mental test (AMT) score <=8/10
U: Urea >7
R: Resp rate >=30
B: Blood pressure 90/60 - Systolic <=90 and/or diastolic <=60
65: Age >=65

CRB65:
0 –> Treat at home
1/2 –> consider hospital assessment
3/4 –> urgent admission

CURB65
0/1 –> Treat at home
2 or more –> consider hospital care
3 or more –> consider intensive care

Question 4

Management of hospital-acquired pneumonia?

Answer 4

1st line = Ciprofloxacin (fluoroquinolone) + Vancomycin (glycopeptide)
If severe = tazocin + vancomycin

Question 5

Name 4 atypical pneumonia causative organisms (+ buzzwords/features)

Answer 5

Legionella pneumophilia: Travel, air conditioning, water towers. Hepatitis, hyponatraemia

Mycoplasma pneumoniae: Uni students/boarding school.
Dry cough, arthralgia. Associated with cold agglutinins which can trigger Autoimmune Haemolytic Anaemia (AIHA). Erythema multiforme [target lesions])

_Chlamydia pneumoniae
Chlamydia psittaci_ (**birds**)

Question 6

Name 5 typical pneumonia causative organisms, and their appearance on microscopy

Answer 6

Staph aureus (+ve cocci **"grape-bunch" clusters**)
Strep pneumoniae (+ve **diplococci**)

Haemophilus influenzae (-ve **cocco-bacilli**)
Moraxella catarrhalis (-ve **cocci**)
Klebsiella pneumoniae (-ve rod, **enterobacter**)

Question 7

What investigations do you need to diagnose pneumonia?

Answer 7

CXR - consolidation (typical)
Sputum MC&S
Atypical screen

Question 8

What does the atypical screen involve?

Answer 8

Legionella urine antigen
Serum antibodies for organisms difficult to culture (Chlamydia, Legionella)

Question 9

What’s the difference between ‘typical’ and ‘atypical’ pneumonia?

Answer 9

Typical = classic signs/Sx + consolidation on CXR, responds to penicillin

Atypical = no/atypical signs/Sx, not in-keeping with CXR, doesnt respond to penicillin (since no cell wall). May have extra-pulmonary features (e.g. hepatitis, hyponatraemia)

Question 10

Which resp infections are patients with Cystic fibrosis susceptible to?

Answer 10

Pseudomonas aeruginosa
Burkholderia cepacia

Question 11

Which resp infections are patients with HIV susceptible to?

Answer 11

Pneumocystis jiroveci (fungal)
TB
Cryptococcus neoformans (encapsulated yeast)

Question 12

Which resp infections are patients with neutropenia susceptible to?

Answer 12

Aspergillus

Question 13

Which resp infections are patients with splenectomy susceptible to?

Answer 13

Encapsulated organisms:

S. pneumoniae
H. influenzae
N. meningitidis

Question 14

Patient has community-acquired pneumonia with CURB score 0-1. What is the management?

Answer 14

Amoxicillin PO 5d

2nd line = Macrolide (ery/azi/clarithromycin)

Treat as outpatient

Question 15

Patient has community-acquired pneumonia with CURB score 2. What is the management?

Answer 15

Amoxicillin PO 5-7d + Clarithromycin PO - 5-7d (to cover atypicals)

Consider admission

Question 16

Patient has community-acquired pneumonia with CURB score 3-5. What is the management?

Answer 16

Co-amox IV 7d + Clarithromycin IV 7d

Admit - consider ITU