What oral antibiotics are recommended for common infections?

Oral Antibiotics for Common Infections

For common bacterial infections managed orally, amoxicillin is the first-line choice for acute otitis media and dental infections, while amoxicillin-clavulanate is preferred for community-acquired pneumonia and skin/soft tissue infections requiring hospital admission. 1, 2

Respiratory Tract Infections

Acute Otitis Media

• Amoxicillin is the first-choice oral antibiotic for acute otitis media, with amoxicillin-clavulanate as the second choice 1
• Amoxicillin reduces residual pain at 2-3 days (RR 0.70) and decreases tympanic membrane perforations (RR 0.37) compared to placebo 1
• Dosing: 500-1000 mg every 8 hours for at least 7 days 1

Community-Acquired Pneumonia (Non-Severe, Hospitalized)

• Combined oral therapy with amoxicillin plus a macrolide (erythromycin or clarithromycin) is preferred for patients requiring hospital admission 1
• Amoxicillin monotherapy is appropriate for previously untreated patients or those admitted for non-clinical reasons 1
• Alternative: Levofloxacin (a fluoroquinolone active against S. pneumoniae) for patients intolerant of penicillins or macrolides 1
• Duration: At least 7 days, with clinical review at 6 weeks 1

Chronic Obstructive Pulmonary Disease Exacerbations

• Antibiotics are recommended when there is increased sputum purulence, volume, and dyspnea 1
• Beta-lactam (amoxicillin 500-1000 mg every 8 hours) or beta-lactam with beta-lactamase inhibitor (amoxicillin-clavulanate 1 g every 8 hours) 1
• Alternative: New macrolides (azithromycin 500 mg daily for 3 days or clarithromycin 250-500 mg every 12 hours) 1

Urinary Tract Infections

• Short-course antibiotic durations result in similar treatment success rates as longer courses for complicated UTIs in women when appropriate antimicrobials are used and patients show clinical improvement 1
• Sulfamethoxazole-trimethoprim is recommended as an Access antibiotic for uncomplicated cases 1

Gastrointestinal Infections

Acute Infectious Diarrhea

• Watchful waiting with symptom relief and no antibiotics is appropriate for non-bloody, non-febrile diarrhea 1
• For invasive bacterial diarrhea: Ciprofloxacin is the first choice (500 mg every 12 hours orally) 1
• For confirmed Shigella infections: Ceftriaxone or sulfamethoxazole-trimethoprim 1
• Avoid fluoroquinolones, azithromycin, and clarithromycin when other options are available due to resistance concerns 1

Skin and Soft Tissue Infections

Non-Necrotizing Infections (Mild to Moderate)

• Oral therapy is recommended for mild infections 1
• For MRSA coverage: Trimethoprim-sulfamethoxazole 160/800 mg every 12 hours, doxycycline 100 mg every 12 hours, or minocycline 100 mg every 12 hours 1
• For streptococcal infections: Cephalexin 500 mg four times daily 3
• Short-course durations (7-10 days) are adequate when diagnosis is confirmed and patients show clinical improvement 1, 3

Wound Infections After Tetracycline Failure

• Cephalexin 500 mg four times daily plus metronidazole 500 mg three times daily provides appropriate polymicrobial coverage including anaerobes 3
• Do not continue doxycycline in the face of documented tetracycline resistance 3
• Duration: 7-10 days for uncomplicated infections, extending to 10-14 days for extensive cellulitis 3
• Re-evaluate at 48-72 hours; progression may indicate MRSA requiring IV therapy 3

Oral and Dental Infections

Acute Dental Abscess

• Treatment is primarily surgical (root canal or extraction); antibiotics are not routinely indicated 1
• For acute dentoalveolar abscesses: Incision and drainage, then amoxicillin for 5 days 1
• Do not use antibiotics for acute apical periodontitis, acute apical abscess, or irreversible pulpitis unless systemic involvement is present 1
• Adjunctive antibiotics are recommended only for medically compromised patients, systemic involvement, or progressive infections (first choice: phenoxymethylpenicillin) 1

Chronic Periodontitis

• Do not use antimicrobials for chronic periodontitis or peri-implantitis 1
• Exception: Sub-antimicrobial dose doxycycline (20 mg twice daily for 3-9 months) as adjunct to scaling and root planning 1

Bone and Joint Infections

• Six weeks of antibiotics is adequate for osteomyelitis in the absence of implanted foreign bodies and with surgical debridement 1
• No specific oral antibiotic can be recommended over another based on current evidence 1

Key Principles for Oral Antibiotic Use

Treatment Duration

• Shorter courses are consistently non-inferior to longer courses for pneumonia, UTIs, bacteremia, and skin infections when diagnosis is confirmed and patients improve clinically 1
• Standard duration: 7 days for most infections, with exceptions noted above 1

Oral vs. IV Therapy

• Oral antibiotics with high bioavailability (≥90%) achieve serum/tissue concentrations comparable to IV antibiotics at the same dose 4
• Transition from IV to oral therapy should occur as soon as patients show clinical improvement and can tolerate oral intake 1, 4

Common Pitfalls to Avoid

• Do not use cephalexin monotherapy for established wound infections—it lacks anaerobic coverage 3
• Do not prescribe antibiotics for viral infections or conditions that resolve without antimicrobial therapy 2
• Avoid unnecessarily long courses, as they increase adverse effects, resistance, and microbiome disruption without improving outcomes 1, 5
• Each dose of amoxicillin-clavulanate should be taken with a meal or snack to reduce gastrointestinal upset 2