What are the preferred antibiotics for bacterial infections?

Preferred Antibiotics for Bacterial Infections

For bacterial infections, the preferred antibiotics should be selected based on the type of infection, suspected pathogens, and local resistance patterns, with narrow-spectrum agents preferred for mild-to-moderate community-acquired infections and broader-spectrum agents reserved for severe or healthcare-associated infections. 1, 2

Community-Acquired Infections

Mild-to-Moderate Severity

• For mild-to-moderate community-acquired infections, narrower-spectrum agents are preferred to avoid promoting resistance and minimize toxicity 1
• Recommended single-agent options include:
  • Beta-lactam/beta-lactamase inhibitors: Ticarcillin-clavulanic acid 1
  • Carbapenems: Ertapenem 1
  • Cephalosporins: Cefoxitin 1
  • Tetracyclines: Tigecycline 1
  • Fluoroquinolones: Moxifloxacin 1
• Recommended combination regimens include:
  • Metronidazole plus cefazolin or cefuroxime 1
  • Metronidazole plus ceftriaxone, cefotaxime, or ceftizoxime 1
  • Metronidazole plus ciprofloxacin or levofloxacin 1

High-Severity Infections

• For more severe community-acquired infections, broader-spectrum agents are recommended 1
• Recommended single-agent options include:
  • Beta-lactam/beta-lactamase inhibitors: Piperacillin-tazobactam 1
  • Carbapenems: Imipenem-cilastatin or meropenem 1
• Recommended combination regimens include:
  • Metronidazole plus third/fourth-generation cephalosporins (cefotaxime, ceftriaxone, ceftizoxime, ceftazidime, cefepime) 1
  • Metronidazole plus ciprofloxacin 1
  • Metronidazole plus aztreonam 1

Healthcare-Associated Infections

• For postoperative or nosocomial infections, complex multidrug regimens are recommended due to more resistant flora 1
• These infections may involve Pseudomonas aeruginosa, Enterobacter species, Proteus species, methicillin-resistant Staphylococcus aureus, enterococci, and Candida species 1
• Local nosocomial resistance patterns should dictate empirical treatment 1

Special Considerations

Specific Pathogens

• For MRSA infections, preferred options include vancomycin, linezolid, clindamycin, daptomycin, ceftaroline, doxycycline, or sulfamethoxazole-trimethoprim 2
• For Bacteroides fragilis group infections, avoid clindamycin, cefotetan, cefoxitin, and quinolones as monotherapy due to substantial resistance 1
• For Salmonella septicemia, fluoroquinolones (primarily ciprofloxacin) are usually preferred for susceptible organisms 1

Specific Conditions

• For osteomyelitis with purulent drainage, amoxicillin-clavulanic acid is recommended as it provides excellent coverage against gram-positive organisms, gram-negative bacteria, and anaerobes 3
• For respiratory tract infections, amoxicillin-clavulanate is highly effective against common respiratory pathogens including beta-lactamase-producing H. influenzae and M. catarrhalis, as well as S. pneumoniae with reduced penicillin susceptibility 4, 5, 6

Important Caveats

• Ampicillin-sulbactam is not recommended for community-acquired infections due to high rates of resistance among E. coli 1
• Cefotetan and clindamycin are not recommended due to increasing resistance among the Bacteroides fragilis group 1
• Aminoglycosides are not recommended for routine use in adults with community-acquired infections due to availability of less toxic alternatives 1
• Empiric coverage of Enterococcus is not necessary in patients with community-acquired infections 1
• Empiric antifungal therapy for Candida is not recommended for community-acquired infections 1
• Patients should be counseled that antibiotics should only be used to treat bacterial infections, not viral infections, and that the full course should be completed to prevent resistance development 7

Antibiotic Stewardship

• Use narrow-spectrum agents for mild-to-moderate infections to reduce the risk of promoting resistance 1, 8
• Consider local resistance patterns when selecting antibiotics 1, 2
• For most community-acquired infections, 5-7 days of appropriate therapy is sufficient, while more severe infections may require longer courses (10-14 days) 2
• Clinical improvement should be expected within 3 days of starting appropriate antibiotic therapy 2