What are the treatment guidelines for community-acquired pneumonia?

Treatment Guidelines for Community-Acquired Pneumonia

For community-acquired pneumonia (CAP), treatment should be based on severity of illness, with specific antibiotic regimens for outpatient, non-ICU inpatient, and ICU settings to reduce morbidity and mortality. 1

Assessment and Treatment Setting

First, determine the appropriate treatment setting using validated tools:

• Pneumonia Severity Index (PSI) or CRB-65 score
• PSI classes I-III: consider outpatient management
• PSI classes IV-V or CRB-65 ≥2: consider inpatient management 1

Clinical stability is defined as no more than one of:

• Temperature >37.8°C
• Respiratory rate >24/min
• Heart rate >100/min
• Systolic blood pressure <90 mmHg
• Oxygen saturation <90%
• Altered mental status 1

Antibiotic Therapy by Setting

Outpatient Treatment

For patients without comorbidities:

• Macrolide (azithromycin 500mg on day 1, then 250mg daily for days 2-5) 2
• Doxycycline 100mg twice daily 2

For patients with comorbidities (chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancies; immunosuppression; recent antibiotic use):

• Respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin 750mg) 2
• OR a β-lactam plus a macrolide (high-dose amoxicillin or amoxicillin-clavulanate plus azithromycin/clarithromycin) 2, 1

Non-ICU Inpatient Treatment

• Respiratory fluoroquinolone (levofloxacin, moxifloxacin) 2
• OR β-lactam (cefotaxime, ceftriaxone, ampicillin) plus a macrolide (azithromycin, clarithromycin) 2

ICU Treatment

• β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin or a respiratory fluoroquinolone 2

For patients with risk factors for Pseudomonas aeruginosa:

• Antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, meropenem) plus either:
  • Ciprofloxacin or levofloxacin (750mg)
  • OR aminoglycoside plus azithromycin
  • OR aminoglycoside plus antipneumococcal fluoroquinolone 2

For suspected community-acquired MRSA:

• Add vancomycin or linezolid to standard regimen 2

Duration of Treatment

• Minimum treatment duration: 5 days 1
• Patient should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuation 1
• For non-severe, uncomplicated pneumonia: 7 days of appropriate antibiotics 2
• For severe, microbiologically undefined pneumonia: 10 days 2
• For Legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia: 14-21 days 2

Route of Administration

• Use oral route for non-severe pneumonia when there are no contraindications 2
• For patients initially on parenteral antibiotics, switch to oral when:
  • Clinical improvement occurs
  • Temperature has been normal for 24 hours
  • Patient is hemodynamically stable
  • Patient can take oral medications
  • Gastrointestinal tract is functioning normally 2, 1

Management of Treatment Failure

For patients who fail to improve:

1. Review clinical history, examination, prescription chart, and investigation results 2
2. Consider additional investigations (repeat chest radiograph, CRP, WBC, microbiological testing) 2
3. Consider changing antibiotics:
   • For non-severe pneumonia on amoxicillin monotherapy: add or substitute a macrolide 2
   • For non-severe pneumonia on combination therapy: change to a fluoroquinolone with effective pneumococcal coverage 2
   • For severe pneumonia not responding to combination therapy: consider adding rifampicin 2

Prevention

• Influenza vaccination for high-risk groups (chronic lung, heart, renal, liver disease; diabetes; immunosuppression; age >65) 2, 1
• Pneumococcal vaccination for those aged ≥2 years at risk of pneumococcal infection 2, 1
• Smoking cessation counseling 1

Common Pitfalls to Avoid

1. Delaying antibiotic administration: Administer first dose promptly after diagnosis, especially in severe cases 2, 1

2. Inappropriate route of administration: Don't keep patients on IV antibiotics when they can take oral medications 2

3. Inadequate coverage for atypical pathogens: Ensure coverage for Legionella, Mycoplasma, and Chlamydophila, particularly in severe cases 2

4. Failing to reassess: Review treatment at 48-72 hours to evaluate response 1

5. Prolonged IV therapy: Switch to oral therapy as soon as clinically appropriate to reduce complications and length of stay 2, 1

6. Using macrolide monotherapy in areas with high resistance: In regions with >25% high-level macrolide-resistant S. pneumoniae, avoid macrolide monotherapy 2

7. Ignoring recent antibiotic exposure: If patient received antibiotics in the past 3 months, select an agent from a different class 1