Community Acquired Pneumonia

Question 1

Define pneumonia

Answer 1

A Lower RTI

Infection of lung parenchyma (bronchioles & alveoli); microbes proliferate in the alveolar level

Question 2

Describe the pathogenesis of pneumonia

Answer 2

1) Aspiration of oropharyngeal secretions
2) Inhalation of aerosols (droplets may contain bacteria)
3) Hematogenous spreading (via bloodstream) from infection @ other body sites

Question 3

What are the typical signs & symptoms of Pneumonia?

Answer 3

1) Cough, chest pains, SOB, hypoxia
2) Fever> 38°C, chills
3) Tachypnea (>22 breaths per min)
4) Tachycardia (>90bpm)
5) Hypotension (SBP< 100)
6) Leukocytosis: WBC < 4x10^9 OR > 10x10^9
7) Fatigue, Change in mental status
8) anorexia (loss of appetite)
9) Nausea

Question 4

Upon physical examination of a pneumonia patient, what can be observed?

Answer 4

• Diminished breath sounds over the affected area

- Inspiratory crackles during lung expansion

Question 5

What radiographic findings can be observed in pneumonia patients?

Answer 5

dense consolidations/ new infiltrates

Question 6

What are 2 respiratory samples that can be used for culture?

Answer 6

Sputum, Lower RT samples

Question 7

What is a limitation associated with each of the 2 types of respiratory samples used for culture?

Answer 7

Sputum: contaminated by oropharyngeal secretions

Lower RT samples: less contamination but invasive & require sedation (e.g. bronchoalveolar lavage)
**reserved for critically ill/ immunocompromised patients

Question 8

What organisms do urinary antigen tests test for?

Answer 8

Strep pneumo, Legionella pneumophilia

Question 9

Why are Urinary antigen tests not often used in the diagnosis of pneumonia?

Answer 9

1) only indicates exposure to the pathogen; not necessarily infection
2) Despite antibiotic treatment, may remain positive for days~ weeks

Question 10

Define Community-Acquired Pneumonia

Answer 10

Onset of symptoms in community/ <48hrs after hospital admission

Question 11

What are possible risk factors for CAP?

Answer 11

1) old age (>65y/o)
2) previous hospitalisation for CAP
3) Smoking
4) Comorbidities: COPD, DM, Heart Failure
5) immunosuppression/ cancer

Question 12

How can CAP be prevented?

Answer 12

1) smoking cessation
2) Immunization
- Influenza (post-influenza viral pneumonia is a serious complication)
- Pneumococcal (pneumococcus is a common pathogen)

Question 13

What are the common microbes causing outpatient CAP?

Answer 13

1) Strep pneumo
2) H. influenzae
3) Atypicals (Mycoplasma pneumoniae, chlamydophila pneumoniae)

Question 14

Suggest suitable antibiotic options for outpatient treatment of patients who are generally healthy

Answer 14

First line: Amoxicillin

Penicillin Allergy: Resp FQ (Levo/Moxifloxacin)

Question 15

Why is Respiratory FQ not used as first-line therapy?

Answer 15

1) extensive ADRs (e.g. tendonitis, neuropathy, QT prolongation, CNS disturbances etc)
2) Collateral damage; resistance with overuse
3) Preserved for P. aeruginosa coverage (only PO agent for P. aeruginosa) & Pencillin allergy

Question 16

Which groups of outpatient patients warrant a different antibiotic regimen?

Answer 16

Those with weakened immunity:

• chronic heart/ lung/ liver/ renal disease
• DM
• alcoholism
• malignancy
• asplenia

Question 17

Suggest suitable antibiotic options for outpatient treatment of patients who have weakened immunity/ comorbidities.

Answer 17

First line: β-lactam (Augmentin/ cefuroxime) + Macrolide(C/A)/ Doxycycline

Penicillin allergy: Resp FQ (Levo/Moxifloxacin)

Question 18

What are the common microbes causing non-severe inpatient CAP?

Answer 18

1) Strep pneumo
2) Haemophilus influenza
3) Atypicals (Mycoplasma pneumoniae, chlamydophila pneumoniae, Legionella pneumophilia)

Question 19

Suggest suitable empiric therapy for non-severe inpatient CAP

Answer 19

First line: (IV; macrolide/doxy given PO if possible)
Augmentin/ Ceftriaxone + Macrolide/Doxycycline

Penicillin Allergy: Resp FQ

Question 20

What are the criteria for deciding if a patient has severe CAP? What are the requirements for severe CAP?

Answer 20

Major:

• Mech ventilation
• Septic shock

Minor:

1) RR ≥30 breaths per min
2) PaO2/FiO2 ≤ 250
3) Multilobal infiltrates
4) Confusion/ disorientation
5) Urea > 7 mmol/L
6) WBC < 4x10^9 /L (leukopenia)
7) Temp < 36°C (hypothermia)
8) Hypotension req aggressive fluid resuscitation (SBP<90 or DBP≤60)

Severe CAP = ≥1 major criteria OR ≥3 minor criteria

Question 21

What are the common microbes causing severe inpatient CAP?

Answer 21

1) Strep pneumo
2) Haemophilus influenza
3) Atypicals (Mycoplasma pneumoniae, chlamydophila pneumoniae, Legionella pneumophilia)
4) MRSA
5) Gram neg bacilli:
Klebsiella,
Burkholderia pseudomallei (found in contaminated soil; causes melioidosis; pneumonia is a common presentation)

Question 22

Suggest suitable empiric therapy for severe inpatient CAP

Answer 22

First-line (IV):
Augmentin/ Ceftazidime + Macrolide/ Doxy

Alternative: Resp FQ + ceftazidime (Burkholderia coverage)
** if patient has severe penicillin allergy, may remove ceftazidime

Question 23

When is anaerobic coverage indicated in inpatient CAP?

Answer 23

Presence of lung abscess/ empyema (pus in pleural space)

Question 24

What are the common anaerobes involved in inpatient CAP?

Answer 24

1. Bacteroides fragilis
2. Prevotella
3. Porphyromonas
4. Fusobacterium

Question 25

Suggest appropriate modifications to the inpatient treatment regimen to account for anaerobic coverage

Answer 25

If std regimen does NOT HAVE ANAEROBIC COVERAGE, Add:
Clinda PO/IV
or Metronidazole PO/IV

**Augmentin & moxifloxacin have anaerobic coverage

Question 26

When is MRSA coverage indicated in inpatient CAP?

Answer 26

1) Prior MRSA in the lung in last 1 year

2) For SEVERE CAP: hospitalization & IV antibiotics in last 90 days

Question 27

Suggest appropriate modifications to the inpatient treatment regimen to account for MRSA coverage

Answer 27

Add:
IV Vanco; or
PO/IV Linezolid

Question 28

When is pseudomonal coverage indicated in inpatient CAP?

Answer 28

Prior respiratory isolate of pseudomonas in last 1 year

Question 29

Suggest appropriate modifications to the inpatient treatment regimen to account for pseudomonal coverage

Answer 29

Modify standard regimen to include one of:

1) IV Pip/Tazo
2) IV Ceftazidime
3) IV cefepime
4) IV meropenem
5) PO/IV Levofloxacin

Question 30

Adjunctive corticosteroid therapy is recommended for patients with CAP

a) True
b) False

Answer 30

False; any impact (e.g. reduction in lung inflammation) is small and outweighed by the risk of hyperglycemia

Question 31

When is the clinical improvement of CAP symptoms to be expected?

Answer 31

48~72 hrs
(hence X immediately adjust therapy if no response in first 1~2 days; allow time for response);

elderly/ those with multiple comorbidities may take longer

Question 32

When can empiric MRSA & pseudomonal coverage be stopped?

Answer 32

Stopped within 48 hrs if the patient has improved/ is improving + X MRSA/ P. aeruginosa in culture

Question 33

If the patient is initially given IV antibiotics, under what conditions can they be stepped down to PO antibiotics?

Answer 33

When ALL criteria are met:

1) Hemodynamically stable (normal BP)
2) Clinically improved/ improving
3) Afebrile for ≥ 24 hrs
4) Able to tolerate PO medication (normal GI function)

Question 34

How is a PO regimen selected when stepping down from IV?

Answer 34

1) Choose PO formulation of IV drugs (if available)

2) otherwise: choose PO option in the same class as the initial antibiotic

Question 35

Suggest a suitable antibiotic given that a patient is suitable for step down from IV Ceftazidime

Answer 35

PO cefuroxime

Question 36

How long should CAP patients be treated for?

Answer 36

Until clinical stability is achieved & for AT LEAST 5 DAYS

Question 37

If a patient has MRSA/ P. aeruginosa, how long should treatment duration be?

Answer 37

~7 days

Question 38

If a patient has Burkholderia Pseudomallei (from culture findings), how long should treatment duration be?

Answer 38

3~6 mths