Recommended Antibiotics for Bacterial Infections
The choice of antibiotic for bacterial infections should be tailored to the specific infection type, suspected pathogens, and local resistance patterns, with first-line options including amoxicillin-clavulanate, cephalosporins, and pathogen-specific targeted therapies based on the most recent WHO and IDSA guidelines. 1
General Principles for Antibiotic Selection
Infection Site-Specific Recommendations
Skin and Soft Tissue Infections
- Impetigo: Oral dicloxacillin, cefalexin, erythromycin, clindamycin, or amoxicillin-clavulanate 1
- Purulent infections (likely S. aureus): Dicloxacillin, cefazolin, clindamycin, cefalexin, doxycycline, or sulfamethoxazole-trimethoprim 1
- MRSA infections: Vancomycin, linezolid, clindamycin, daptomycin, ceftaroline, doxycycline, or sulfamethoxazole-trimethoprim 1
- Non-purulent infections: Benzylpenicillin, phenoxymethylpenicillin, clindamycin, nafcillin, cefazolin, or cefalexin 1
- Necrotizing fasciitis: Vancomycin/linezolid plus piperacillin-tazobactam/carbapenem, or ceftriaxone with metronidazole 1
Respiratory Tract Infections
Sinusitis:
Chronic Bronchitis Exacerbations:
Intra-abdominal Infections
- Mild to moderate: Amoxicillin-clavulanate or ampicillin + gentamicin + metronidazole 1
- Severe: Cefotaxime/ceftriaxone + metronidazole or piperacillin-tazobactam 1
Pathogen-Specific Recommendations
- Streptococcus: Penicillin plus clindamycin 1
- S. aureus (MSSA): Nafcillin, oxacillin, cefazolin, vancomycin, clindamycin 1, 2
- Clostridium spp.: Clindamycin plus penicillin 1
- Aeromonas hydrophila: Doxycycline plus ciprofloxacin or ceftriaxone 1
- Vibrio vulnificus: Doxycycline plus ceftriaxone or cefotaxime 1
Antibiotic Selection Algorithm
Step 1: Identify the Infection Site and Severity
- Determine location (skin/soft tissue, respiratory, intra-abdominal, etc.)
- Assess severity (mild, moderate, severe)
- Consider risk factors for resistant organisms
Step 2: Select Appropriate First-line Therapy
For most community-acquired infections: Amoxicillin-clavulanate is often appropriate 1, 3
For penicillin-allergic patients:
Step 3: Consider Special Circumstances
- Recent antibiotic use: Choose a different class to avoid resistance 1
- Suspected resistant pathogens: Select broader spectrum options 1
- Immunocompromised hosts: Consider broader coverage initially 1
Important Considerations and Pitfalls
Antibiotic Stewardship Principles
- Narrow spectrum when possible: Use the narrowest effective antibiotic to reduce resistance development 1, 7
- Fluoroquinolone and carbapenem sparing: Reserve these classes for when alternatives aren't appropriate 1
- Complete prescribed course: Patients should take the full course even if feeling better 4
Common Pitfalls to Avoid
Overuse of broad-spectrum antibiotics: Amoxicillin-clavulanate should be reserved for suspected resistant bacteria, not used when narrow-spectrum antibiotics would be effective 8
Inadequate dosing: Ensure appropriate dosing based on infection site, severity, and patient factors 4
Inappropriate duration: Most uncomplicated infections require 7-10 days of treatment; some specific infections have shorter or longer recommendations 1, 2
Failing to reassess: Reevaluate therapy at 72 hours to determine if the current regimen is effective 1
Treating viral infections: Antibiotics should only be used for bacterial infections, not viral illnesses like common colds 4
Side Effect Management
- Gastrointestinal effects: Take antibiotics with food to reduce GI upset 4
- Diarrhea: Common with antibiotics; if severe or bloody, contact physician 4
- Allergic reactions: Monitor for rash, itching, or difficulty breathing 4
By following these evidence-based recommendations and principles, clinicians can optimize antibiotic therapy for bacterial infections while minimizing the risk of treatment failure and antibiotic resistance.