What are the latest antibiotic guidelines for treating various infections?

Latest Antibiotic Guidelines

For treating various infections, the most recent guidelines recommend using the narrowest spectrum antibiotic effective against the suspected pathogen, with specific regimens tailored to the infection site, severity, and local resistance patterns. 1

Skin and Soft Tissue Infections (SSTIs)

Impetigo

• For limited lesions: Topical mupirocin or retapamulin ointment applied twice daily 1
• For extensive disease:
  • Dicloxacillin 250-500 mg four times daily (adults)
  • Cephalexin 250-500 mg four times daily (adults); 25-50 mg/kg/day in 3-4 divided doses (children)
  • Clindamycin 300-400 mg four times daily (adults); 20 mg/kg/day in 3 divided doses (children) 1

Methicillin-Susceptible S. aureus (MSSA) Infections

• First-line parenteral therapy: Nafcillin or oxacillin 1-2 g every 4 hours IV (adults); 100-150 mg/kg/day in 4 divided doses (children) 1
• Alternative for penicillin-allergic patients: Cefazolin 1 g every 8 hours IV (adults); 50 mg/kg/day in 3 divided doses (children) 1
• Oral therapy: Dicloxacillin 500 mg four times daily (adults); 25-50 mg/kg/day in 4 divided doses (children) 1

Methicillin-Resistant S. aureus (MRSA) Infections

• First-line parenteral therapy: Vancomycin 30 mg/kg/day in 2 divided doses IV (adults); 40 mg/kg/day in 4 divided doses IV (children) 1
• Alternatives:
  • Linezolid 600 mg every 12 hours IV/PO (adults); 10 mg/kg every 12 hours IV/PO for children <12 years 1
  • Daptomycin 4 mg/kg every 24 hours IV (adults) 1
  • Ceftaroline 600 mg twice daily IV (adults) 1
• Outpatient MRSA: TMP-SMX 1-2 double-strength tablets twice daily (adults); doxycycline 100 mg twice daily (adults) 1

Necrotizing Infections

• Mixed infections: Piperacillin-tazobactam plus vancomycin OR carbapenem (imipenem, meropenem, ertapenem) 1
• Streptococcal: Penicillin plus clindamycin 1
• Clostridial: Clindamycin plus penicillin 1

Animal and Human Bites

• First-line therapy: Amoxicillin-clavulanate 875/125 mg twice daily (adults) 1
• Alternatives for penicillin-allergic patients:
  • Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida) 1
  • Fluoroquinolone (ciprofloxacin 500-750 mg twice daily) plus metronidazole (250-500 mg three times daily) 1
  • Clindamycin 300 mg three times daily plus TMP-SMX 1

Multidrug-Resistant Gram-Negative Bacilli Infections

Third-Generation Cephalosporin-Resistant Enterobacterales (3GCephRE)

• For bloodstream infections (BSI) and severe infections: Carbapenem (imipenem or meropenem) strongly recommended 1
• For BSI without septic shock: Ertapenem may be used instead of imipenem/meropenem 1
• For low-risk, non-severe infections: Piperacillin-tazobactam, amoxicillin/clavulanate, or quinolones 1
• For complicated UTI without septic shock: Aminoglycosides for short durations or IV fosfomycin 1

Carbapenem-Resistant Enterobacterales (CRE)

• Ceftazidime/avibactam, meropenem/vaborbactam, or imipenem/cilastatin/relebactam 1
• For complicated UTIs: Above agents or aminoglycosides (gentamicin, amikacin, plazomicin) 1
• For complicated intra-abdominal infections: Ceftazidime/avibactam plus metronidazole or tigecycline 1

Vancomycin-Resistant Enterococci (VRE)

• Bloodstream infections: Linezolid 600 mg IV every 12 hours or daptomycin 8-12 mg/kg IV daily for 10-14 days 1
• Pneumonia: Linezolid 600 mg IV every 12 hours for at least 7 days 1
• Complicated intra-abdominal infections: Linezolid 600 mg IV every 12 hours or tigecycline 50 mg IV every 12 hours after 100 mg loading dose 1
• Uncomplicated UTIs: Fosfomycin 3 g PO single dose or nitrofurantoin 100 mg PO four times daily 1

Special Considerations

Doxycycline Dosing

• Adults: 200 mg on first day (100 mg every 12 hours), then 100 mg daily maintenance dose 2
• For severe infections: 100 mg every 12 hours 2
• Children >8 years: 2 mg/lb divided into two doses on first day, then 1 mg/lb daily 2

Antibiotic Stewardship Principles

• Use narrow-spectrum antibiotics whenever possible 1
• Consider step-down therapy from broad-spectrum to targeted antibiotics once culture results are available 1
• Reserve newer agents (like new β-lactam/β-lactamase inhibitors) for extensively resistant bacteria 1
• Optimize dosing regimens to prevent resistance development 3

Common Pitfalls to Avoid

• Using broad-spectrum antibiotics for infections likely caused by susceptible organisms 4, 5
• Continuing empiric broad-spectrum therapy when culture results allow for targeted therapy 1
• Inappropriate duration of therapy (too long or too short) 1
• Failing to adjust dosing for renal impairment 2
• Using fluoroquinolones in children under 18 years when alternatives exist 1
• Using tetracyclines in children under 8 years of age 1, 2

The appropriate selection of antibiotics should be guided by local resistance patterns, patient factors (allergies, comorbidities), infection severity, and culture results when available 1.