What is the recommended treatment for an adult patient with suspected community-acquired pneumonia in the Philippines, based on the Philippine Guidelines?

Community-Acquired Pneumonia Management Based on Philippine Context

Initial Antibiotic Selection for Outpatient Treatment

For previously healthy adults without comorbidities, high-dose amoxicillin 1 g orally three times daily for 5-7 days is the preferred first-line therapy. 1, 2

• Doxycycline 100 mg orally twice daily serves as an acceptable alternative for patients who cannot tolerate amoxicillin 1
• Macrolides (azithromycin 500 mg day 1, then 250 mg daily for days 2-5; or clarithromycin 500 mg twice daily) should only be used if local pneumococcal macrolide resistance is documented to be <25% 1, 2
• For patients with comorbidities (COPD, diabetes, chronic heart/liver/renal disease, malignancy, or recent antibiotic use within 3 months), combination therapy is required: amoxicillin-clavulanate 875/125 mg twice daily PLUS azithromycin, OR respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1

Hospitalized Non-ICU Patients

Two equally effective regimens exist with strong evidence: ceftriaxone 1-2 g IV daily PLUS azithromycin 500 mg daily, OR respiratory fluoroquinolone monotherapy (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily). 1

• The combination regimen provides coverage for both typical bacterial pathogens (Streptococcus pneumoniae, Haemophilus influenzae) and atypical organisms (Mycoplasma, Chlamydophila, Legionella) 1
• For penicillin-allergic patients, respiratory fluoroquinolone is the preferred alternative 1
• Administer the first antibiotic dose in the emergency department immediately upon diagnosis—delayed administration beyond 8 hours increases 30-day mortality by 20-30% 1

Severe CAP Requiring ICU Admission

Combination therapy is mandatory for all ICU patients: ceftriaxone 2 g IV daily (or cefotaxime 1-2 g IV every 8 hours or ampicillin-sulbactam 3 g IV every 6 hours) PLUS either azithromycin 500 mg IV daily OR respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily). 1

• Monotherapy is inadequate for severe disease and increases mortality risk 1
• For penicillin-allergic ICU patients, use aztreonam 2 g IV every 8 hours PLUS azithromycin 500 mg IV daily 1

Special Pathogen Coverage

Add antipseudomonal coverage ONLY when specific risk factors are present: structural lung disease (bronchiectasis), recent hospitalization with IV antibiotics within 90 days, or prior respiratory isolation of Pseudomonas aeruginosa 1

• Antipseudomonal regimen: piperacillin-tazobactam, cefepime, imipenem, or meropenem PLUS ciprofloxacin 400 mg IV every 8 hours OR levofloxacin 750 mg IV daily PLUS aminoglycoside (gentamicin or tobramycin 5-7 mg/kg IV daily) 1

Add MRSA coverage ONLY when risk factors are present: prior MRSA infection/colonization, recent hospitalization with IV antibiotics, post-influenza pneumonia, or cavitary infiltrates on imaging 1

• MRSA regimen: add vancomycin 15 mg/kg IV every 8-12 hours (target trough 15-20 mg/mL) OR linezolid 600 mg IV every 12 hours to the base regimen 1

Essential Diagnostic Testing

All hospitalized patients must have blood cultures and sputum Gram stain/culture obtained BEFORE initiating antibiotics to allow pathogen-directed therapy and de-escalation 1

• Admission investigations: chest radiograph, complete blood count, urea/electrolytes/liver function tests, C-reactive protein (when available), and oxygenation assessment 3
• Urinary antigen testing for Legionella pneumophila serogroup 1 should be considered in severe CAP or ICU patients 1

Treatment Duration and Transition

Treat for a minimum of 5 days AND until the patient is afebrile for 48-72 hours with no more than one sign of clinical instability. 1

• Typical duration for uncomplicated CAP is 5-7 days 1
• Extended duration (14-21 days) is required for Legionella pneumophila, Staphylococcus aureus, or Gram-negative enteric bacilli 1
• Switch from IV to oral therapy when the patient is hemodynamically stable, clinically improving, able to take oral medications, and has normal GI function—typically by day 2-3 of hospitalization 1

Supportive Care and Monitoring

Maintain oxygen saturation >92% and PaO₂ >8 kPa (60 mmHg) with appropriate oxygen therapy. 3, 2

• High-flow oxygen is safe in uncomplicated pneumonia 2
• For COPD patients with ventilatory failure, oxygen should be guided by repeated arterial blood gases to avoid CO₂ retention 2
• Monitor temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation, and inspired oxygen concentration at least twice daily, more frequently in severe cases 3, 2
• Assess for volume depletion and provide IV fluids as needed 3

Follow-Up and Discharge Planning

Clinical review at 6 weeks is mandatory for all hospitalized patients, either with their general practitioner or in a hospital clinic. 2

• Chest radiograph need not be repeated prior to hospital discharge in patients with satisfactory clinical recovery 3, 2
• Repeat chest radiograph at 6 weeks for patients with persistent symptoms, physical signs, or high-risk patients (smokers, age >50 years) 2
• If no clinical improvement by day 2-3, obtain repeat chest radiograph, CRP, white cell count, and additional microbiological specimens 1

Critical Pitfalls to Avoid

Never use macrolide monotherapy in hospitalized patients—it provides inadequate coverage for typical bacterial pathogens like S. pneumoniae. 1

• Never use macrolide monotherapy in areas where pneumococcal macrolide resistance exceeds 25%, as this leads to treatment failure 1
• Avoid indiscriminate fluoroquinolone use in uncomplicated outpatient CAP due to resistance concerns and serious adverse events 1
• Do not automatically add broad-spectrum antibiotics (antipseudomonal or anti-MRSA coverage) without documented risk factors 1
• Never delay antibiotic administration—administer the first dose immediately upon diagnosis 1

Prevention and Vaccination

All adults ≥65 years or those 19-64 years with underlying conditions should receive pneumococcal vaccination: 20-valent pneumococcal conjugate vaccine alone OR 15-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine one year later 1, 4

• Annual influenza vaccination is recommended for all patients, especially those with medical illnesses 1
• Smoking cessation should be a goal for all patients hospitalized with CAP who smoke 1