Community-acquired Pneumonia Flashcards Preview

PR3124 CA2 > Community-acquired Pneumonia > Flashcards

Flashcards in Community-acquired Pneumonia Deck (39)
Loading flashcards...
1
Q

Where does pneumonia occur?

A

Lower respiratory tract infection of lung parenchyma

Proliferation of microbial pathogens in the alveolar level

2
Q

What is the most common type of pneumonia?

A

Bacterial

Less common: viral, fungal

3
Q

How does pneumonia enter the lower respiratory tract?

A
  1. Aspiration of oropharyngeal secretions
  2. Inhalation of aerosols: aerosolized droplets
  3. Hematogenous spreading: bacteremia from extra-pulmonary source
4
Q

What are signs and symptoms of pneumonia?

A
  1. Respiratory: cough, chest pain, SOB, hypoxia
  2. Systemic: fever >38C, chills, tachypnea RR >24bpm, tachycardia HR >90bpm, hypotension SBP <100
  3. Lab: leukocytosis - elevated WBC
  4. Elderly: fatigue, anorexia, nausea, changes in mental status
5
Q

How might you detect pneumonia in a physical examination?

A
  1. Diminished breath sounds

2. Inspiratory crackles during lung expansion

6
Q

Radiographic findings that assist in diagnosing pneumonia

A

Look for infiltrates or dense consolidations

  1. Chest x-ray (CXR): more common bc cheaper and more available
  2. CT scan: reserved for immunocompromised people or not responding to normal therapy
7
Q

What kind of culture should be used to diagnose pneumonia?

A
  1. Sputum: low yield due to frequent contamination from oropharyngeal secretions
    - Quality: >10 neutrophils and <25 epithelial cells per LPF
  2. Lower respiratory tract: preferred but invasive (bronchoalveolar lavage BAL)
    - Use only if pt is not responding or they’re very ill in ICU bc sedation is required
  3. Blood culture: rule out bacteremia bc it crosses over easily
8
Q

What kind of diagnostic tests are not routinely used for diagnosis?

A
  1. Laboratory findings (CRP, procalcitonin): non-specific
  2. Urinary antigen tests: indicate exposure but remain positive for days to weeks despite abx tx
    - for Streptococcus pneumoniae, Legionella pneumophilia (serogroup 1 only)
9
Q

When is the onset of CAP and nosocomial pneumonia?

A

CAP: <48h post-admission

HAP/NAP: >48h post-admission or post-mechanical ventilation

10
Q

What are the risk factors for CAP?

A
  1. Age >65y/o
  2. Previous hospitalization for CAP
  3. Smoking
  4. Underlying conditions: COPD, DM, HF, cancer, immunosuppression
11
Q

How can we prevent CAP?

A
  1. Smoking cessation
  2. Prevent postviral infections: immunization
    - pneumococcal: PCV10/13 or PPSV23
    - influenza
12
Q

Why is Burkholderia pseudomallei a concern?

A

Gram-negative bacilli that causes melioidosis: group of infections including severe pneumonia
Prevalence in SG is 3rd highest in the world

13
Q

What are the criteria for risk stratification?

A
  1. Pneumonia Severity Index (PSI): 20 variables, 5 mortality risk classes
  2. CURB-65 Score: more common in clinical, only 5 variables & 3 mortality risk classes
  3. IDSA-ATS criteria for severe CAP: >1 major or >3 minor criteria
14
Q

What are the major criteria under IDSA/ATS criteria?

A
  1. Mechanical ventilation

2. Septic shock requiring vasoactive medications: to support BP in hypotension

15
Q

What are the minor criteria under IDSA/ATS criteria?

A
  1. RR >30bpm
  2. PaO2/FiO2 <250 (measure hypoxia)
  3. Multilobar infiltrates
  4. Confusion/disorientation
  5. Uremia (urea >7 mmol/L)
  6. Leukopenia (WBC <4 x 10^9/L)
  7. Hypothermia (temp <36C)
  8. Hypotension req aggressive fluid resuscitation
16
Q

What is the treatment duration for pneumonia?

A

At least 5 days with clinical stability (usually within 48-72h)
- Afebrile, maintain oral intake
- Normal vitals, O2 saturation and mental status
Exception:
- MRSA or Pseudomonas: 7 days
- Burkholderia pseudomallei: 3-6 months

17
Q

Standard regimen for healthy outpatient

A
  1. PO Amoxicillin 1g TDS OR
  2. PO Levofloxacin 750 OD/moxifloxacin
    - restrict to penicillin allergies
18
Q

Who is the population that is not considered generally healthy outpatient?

A
  1. Chronic disease: heart, lung, liver, renal
  2. Diabetes mellitus
  3. Malignancies
  4. Alcoholism
  5. Asplenia
19
Q

Why is ciprofloxacin not used?

A

Poor activity against Streptococcus pneumoniae

20
Q

Why do we reserve respiratory fluoroquinolones for patients with penicillin allergy?

A
  1. Increased adverse effects (e.g. tendonitis, tendon rupture, neuropathy, QTc prolongation, CNS disturbances, hypoglycemia)
  2. Collateral damage/resistance with overuse
  3. Preserve Gram-negative activity: levo/cipro only PO options for Pseudomonas
  4. Delay TB diagnosis due to partial treatment
21
Q

Standard regimen for outpatients who have other conditions

A
  1. PO Amoxicillin/clavulanate 625mg TDS or 2g BD OR PO cefuroxime 500mg BD (coverage for B-lactamase producing H. influenzae)
    w/ PO clarithromycin 500mg BD/azithromycin 500mg OD or PO doxycycline 100mg BD (atypical coverage)
  2. PO levofloxacin 750mg OD/moxifloxacin
22
Q

Why is erythromycin not used?

A

It is an older macrolide that causes more GIT side effects

23
Q

Standard regimen for non-severe inpatient

A
  1. IV Amoxicillin/clavulanate 1.2g q8h or IV ceftriaxone 1-2g q24h
    + PO clarithromycin 500mg BD/azithromycin 500mg OD or PO doxycycline 100mg BD
  2. IV levofloxacin 750mg q24h/moxifloxacin
24
Q

Why is IV ceftriaxone preferred over IV cefuroxime?

A

Ceftriaxone has more experience and clinical data for inpatient CAP treatment than cefuroxime

25
Q

What are the organisms to cover for outpatient and non-severe inpatient pneumonia?

A
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals (Chlamydophila pneumoniae, Mycoplasma pneumoniae)
- not needed for healthy outpatient
- Legionella pneumophilia for inpatient
26
Q

Organisms to cover for severe inpatient pneumonia

A
Streptococcus pneumoniae
Haemophilus influenzae
Atypicals
Gram-negative bacilli (Klebsiella pneumoniae, Burkholderia pseudomallei)
Staphylococcus aureus
27
Q

Standard regimen for severe inpatient pneumonia

A
  1. IV Amoxicillin/clavulanate 1.2g q8h + IV ceftazidime 2g q8h
    + PO/IV clarithromycin 500mg BD/q12h/azithromycin 500mg OD/q24h OR PO/IV doxycycline 100mg BD
  2. IV levofloxacin 750mg q8h/moxifloxacin + IV ceftazidime 2g q8h
28
Q

Should we give ceftazidime if inpatient w/ severe pneumonia has a penicillin allergy?

A

depends on severity of allergy

  1. If can tolerate 3rd gen cephalosporin (low chance of cross-reactivity) then add ceftazidime
  2. Omit if reaction is severe e.g. anaphylaxis, and give only respiratory fluoroquinolone
    - Monitor closely and use cultures to direct antibiotics therapy
29
Q

What are the indications for anaerobic coverage?

A

Either lung abscess (pus collection) OR empyema (pus/abscess in pleural space)

30
Q

What are the likely anaerobes in pneumonia?

A

Oropharyngeal space anaerobes: Bacteroides fragilis, Prevotella spp., Porphyromonas spp., Fusobacterium spp.

31
Q

Drugs for anaerobic coverage

A

Add IV/PO clindamycin or metronidazole

Not required if regimen contains amoxicillin/clavulanate or moxifloxacin

32
Q

What are the indications for MRSA coverage and Pseudomonas coverage?

A
  • Prior respiratory isolation in last 1 year
  • Severe CAP only: hospitalization and IV antibiotics treatment in the past 90 days (+ locally validated risk factors)
  • 2nd point does not apply for Pseudomonas bc ceftazidime also covers Pseudomonas for severe CAP
33
Q

MRSA Coverage

A

IV vancomycin OR
IV/PO linezolid
Do not use daptomycin as it is inactivated in the lung surfactant

34
Q

How to modify regimen for Pseudomonal coverage?

A

Change to anti-pseudomonal B-lactam: IV piperacillin/tazobactam, IV ceftazidime, IV cefepime, IV meropenem
Choose IV/PO levofloxacin over moxifloxacin

35
Q

Monitoring for efficacy of therapy

A
  1. Clinical improvement in 48-72h: decrease in signs and symptoms
    - Elderly or multiple comorbidities may take longer
  2. Do not escalate abx in 1st 72h unless culture-directed or significant clinical deterioration
  3. Repeat radiological tests only for clinical deterioration to look for missed complications
    - Radiological improvement lags behind clinical, takes 4-6weeks for resolution
36
Q

Monitoring for safety of therapy

A
  1. Adverse effects of abx (side effects and allergy)

2. Renal function for dose adjustment

37
Q

When should we step down from IV to PO abx?

A
  1. hemodynamically stable
  2. clinically improved/improving
  3. afebrile >24h
  4. normally functioning GIT
  5. can ingest PO medications
38
Q

Benefits of PO step-down therapy

A
  1. pt comfort and mobility
  2. less phlebitis & risk of nosocomial bacteremia
  3. less preparation and administration time
  4. less costs
  5. facilitates discharge
39
Q

How to step down to PO therapy if there are no positive cultures?

A

Use same abx or abx from the same class
- B-lactams: change to PO amox/clav or PO cefuroxime
MRSA/Pseudomonas: stop empiric therapy in 48h if no culture + patient is improving
Burkholderia: if no culture just remove ceftazidime