What is the recommended management for strep (Streptococcus) pneumonia?

Management of Streptococcus pneumoniae Pneumonia

For outpatient pneumococcal pneumonia in previously healthy adults, amoxicillin 1 gram three times daily is the first-line treatment, while hospitalized non-ICU patients require ceftriaxone 1-2 grams IV daily plus azithromycin 500 mg daily, and ICU patients mandate combination therapy with a β-lactam plus either azithromycin or a respiratory fluoroquinolone. 1, 2

Outpatient Management

Previously Healthy Adults Without Comorbidities

• Amoxicillin 1 gram orally three times daily is the preferred first-line agent, providing superior coverage against S. pneumoniae including most drug-resistant strains with MIC ≤2 μg/mL 1, 2, 3
• Doxycycline 100 mg twice daily serves as an acceptable alternative for patients who cannot tolerate amoxicillin 1
• Avoid macrolide monotherapy (azithromycin, clarithromycin) in areas where pneumococcal macrolide resistance exceeds 25%, as treatment failure rates increase significantly with resistant isolates 1, 2

Adults With Comorbidities or Recent Antibiotic Use

• Combination therapy with high-dose amoxicillin-clavulanate (2 grams twice daily) plus azithromycin 500 mg on day 1, then 250 mg daily, or clarithromycin 500 mg twice daily 1, 2
• Alternative: Respiratory fluoroquinolone monotherapy with levofloxacin 750 mg daily, moxifloxacin 400 mg daily, or gemifloxacin 320 mg daily 1, 2
• If the patient received β-lactam or macrolide therapy within the previous 3 months, select an alternative antibiotic class to prevent selection of resistant organisms 2

Inpatient Non-ICU Management

Standard Regimen

• Ceftriaxone 1-2 grams IV daily plus azithromycin 500 mg daily is the preferred combination, providing coverage for both typical bacterial pathogens and atypical organisms 1, 2
• Alternative β-lactams include cefotaxime 1-2 grams IV every 8 hours or ampicillin-sulbactam 3 grams IV every 6 hours 1, 2
• Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) is equally effective with strong evidence support 1, 2

Penicillin-Allergic Patients

• Respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) is the preferred alternative 1, 2
• For patients with contraindications to fluoroquinolones, aztreonam 2 grams IV every 8 hours plus azithromycin 500 mg IV daily provides adequate coverage 1

ICU/Severe Pneumonia Management

Mandatory Combination Therapy

• All ICU patients require combination therapy—never monotherapy—as dual therapy reduces mortality in bacteremic pneumococcal pneumonia by 20-30% 2
• β-lactam (ceftriaxone 2 grams IV daily, cefotaxime 1-2 grams IV every 8 hours, or ampicillin-sulbactam 3 grams IV every 6 hours) plus either azithromycin 500 mg daily or respiratory fluoroquinolone (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) 1, 2

Special Considerations for ICU Patients

• Obtain blood cultures (two sets from separate sites), urinary antigen tests for S. pneumoniae and Legionella, and sputum for Gram stain and culture before initiating antibiotics 2
• For suspected Staphylococcus aureus coinfection (post-influenza pneumonia, cavitary infiltrates), add vancomycin 15-20 mg/kg IV every 8-12 hours or linezolid 600 mg IV every 12 hours 2
• For influenza coinfection, add oseltamivir 75 mg orally twice daily within 48 hours of symptom onset 2

Pathogen-Directed Therapy After Culture Results

Penicillin-Susceptible S. pneumoniae (MIC <0.06 μg/mL)

• For non-ICU patients, narrow therapy to penicillin G 2-4 million units IV every 4 hours or amoxicillin 1 gram orally three times daily 2
• For ICU patients with bacteremic pneumococcal pneumonia, continue combination therapy even after susceptibility results are known, as dual therapy reduces mortality 2

Penicillin-Resistant S. pneumoniae

• For isolates with MIC ≤2 μg/mL, continue ceftriaxone or cefotaxime, as these agents achieve pulmonary concentrations several times higher than the MIC 4, 5
• For isolates with MIC ≥4 μg/mL (3.5-7.8% of clinical isolates), consider levofloxacin 750 mg IV daily or vancomycin 15-20 mg/kg IV every 8-12 hours 5

Duration of Therapy and Transition to Oral Therapy

Standard Duration

• Treat for a minimum of 5 days and continue for at least 48-72 hours after clinical improvement and defervescence, with most patients requiring 7-10 days total 1, 2
• Clinical stability criteria include temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24 breaths/min, systolic blood pressure ≥90 mmHg, and oxygen saturation ≥90% on room air 6

Transition to Oral Therapy

• Switch from IV to oral therapy when the patient is hemodynamically stable, clinically improving, afebrile for 12-24 hours, and able to tolerate oral intake 2
• Oral step-down options include amoxicillin 1 gram three times daily or levofloxacin 750 mg daily 1, 2

Pediatric Management

Outpatient Treatment (Children ≥3 Months)

• Amoxicillin 45 mg/kg/day divided every 12 hours or 40 mg/kg/day divided every 8 hours for moderate-to-severe infections 7, 2
• For mild infections, amoxicillin 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours 7

Inpatient Treatment (Children ≥3 Months)

• Ampicillin 150-200 mg/kg/day IV every 6 hours or penicillin G 200,000-250,000 units/kg/day IV every 4-6 hours for fully immunized children in regions with low penicillin resistance 7
• Ceftriaxone 50-100 mg/kg/day IV every 12-24 hours or cefotaxime 150 mg/kg/day IV every 8 hours for children who are not fully immunized or in regions with high-level penicillin resistance 7

Penicillin-Resistant Strains in Children

• For isolates with MIC ≥4 μg/mL, use ceftriaxone 100 mg/kg/day IV every 12-24 hours, levofloxacin (16-20 mg/kg/day in 2 doses for children 6 months to 5 years; 8-10 mg/kg/day once daily for children 5-16 years; maximum 750 mg), or linezolid (30 mg/kg/day every 8 hours for children <12 years; 20 mg/kg/day every 12 hours for children ≥12 years) 7

Critical Pitfalls to Avoid

• Never delay antibiotic administration beyond 8 hours in hospitalized patients, as this increases 30-day mortality by 20-30% 1, 2
• Never use macrolide monotherapy in areas where pneumococcal macrolide resistance exceeds 25%, as erythromycin-resistant pneumococci may not respond to macrolide therapy 1, 4
• Never use monotherapy for ICU patients with pneumococcal pneumonia, as combination therapy significantly reduces mortality in bacteremic cases 2
• Avoid indiscriminate use of vancomycin or carbapenems for pneumococcal pneumonia, as third-generation cephalosporins remain effective for most strains with current resistance patterns 4, 8
• Do not extend therapy beyond 7 days in responding patients without specific indications (Legionella, Staphylococcus aureus, Gram-negative enteric bacilli), as this increases antimicrobial resistance risk 7, 1