What is the recommended treatment for common bacterial infections with antibiotics?

Recommended Antibiotic Treatment for Common Bacterial Infections

For common bacterial infections, use short-course, targeted antibiotic therapy based on the specific infection type: 5 days for uncomplicated cystitis (nitrofurantoin), 3 days for cystitis (TMP-SMX), 5-7 days for pyelonephritis (fluoroquinolones), 5-6 days for nonpurulent cellulitis (anti-streptococcal agents), and 5 days for community-acquired pneumonia once clinically stable. 1

Urinary Tract Infections

Uncomplicated Cystitis (Women)

• Nitrofurantoin 100 mg four times daily for 5 days 1
• TMP-SMX (trimethoprim-sulfamethoxazole) for 3 days 1
• Fosfomycin 3 grams as a single dose 1
• Avoid fluoroquinolones for empiric therapy due to adverse effect profile; reserve for resistant organisms 1

Uncomplicated Pyelonephritis

• Fluoroquinolones (ciprofloxacin, levofloxacin) for 5-7 days when susceptibility is confirmed 1
• TMP-SMX for 14 days only after culture confirms susceptibility (do not use empirically) 1
• Recent evidence shows 5-day fluoroquinolone courses achieve 93% clinical cure rates, noninferior to 10-day courses 1
• Critical caveat: TMP-SMX has high resistance rates (18.4% in studies); always obtain cultures before using 1

Skin and Soft Tissue Infections

Nonpurulent Cellulitis

• 5-6 day course of anti-streptococcal antibiotics for patients with close follow-up 1
• First-line options: cephalosporin (cephalexin), penicillin, or clindamycin 1
• Add MRSA coverage (vancomycin, linezolid, daptomycin, TMP-SMX, or doxycycline) if: 1
  • Penetrating trauma
  • Evidence of MRSA infection elsewhere
  • MRSA nasal colonization
  • Injection drug use
  • Systemic inflammatory response syndrome

Purulent Skin Infections

• Incision and drainage is primary treatment; antibiotics often unnecessary 1
• If antibiotics needed: TMP-SMX, doxycycline, or clindamycin targeting MRSA 1

Community-Acquired Pneumonia

Outpatient Treatment

• 5-day course once clinically stable (afebrile for 48 hours) 1
• Clinical stability criteria: temperature ≤37.8°C, heart rate ≤100 bpm, respiratory rate ≤24/min, systolic BP ≥90 mmHg, oxygen saturation ≥90%, ability to take oral medications 1
• A multicenter RCT showed 70% of patients safely completed treatment in 5 days with no difference in clinical success compared to longer courses 1
• Reassess if not improving after 5 days rather than automatically extending duration 1

Acute Bacterial Rhinosinusitis

Mild Disease (No Recent Antibiotic Use)

• Amoxicillin 1.5-4 grams daily divided into 2-3 doses 1
• Amoxicillin-clavulanate for better coverage in moderate disease or recent antibiotic exposure 1
• Lower doses (1.5 g/day) appropriate for mild disease without risk factors 1
• Higher doses (4 g/day) for areas with high penicillin-resistant S. pneumoniae prevalence 1

β-Lactam Allergic Patients

• Respiratory fluoroquinolones (levofloxacin, moxifloxacin) for true allergies or treatment failures 1
• Cephalosporins for non-Type I hypersensitivity reactions 1
• Avoid TMP-SMX, doxycycline, and macrolides due to 20-25% bacterial failure rates 1

Critical Pitfalls to Avoid

Resistance patterns: Always consider local antibiotic resistance data when selecting empiric therapy 1

Duration defaults: Do not automatically prescribe 10-day courses; this increases adverse events by 5% per additional day without benefit 1

Reassessment over extension: If patients fail to improve on appropriate antibiotics, investigate alternative diagnoses rather than reflexively extending duration 1

Fluoroquinolone overuse: Reserve fluoroquinolones for documented resistant organisms or β-lactam allergies due to adverse effect profile and resistance concerns 1

TMP-SMX in pyelonephritis: Never use empirically; only after susceptibility confirmed due to high resistance rates 1

Special Populations

Diabetic Wound Infections

• Mild infections: Dicloxacillin, clindamycin, cephalexin, levofloxacin, amoxicillin-clavulanate, or doxycycline 1
• Moderate-severe infections: Levofloxacin, ceftriaxone, ampicillin-sulbactam, moxifloxacin, ertapenem, or imipenem-cilastatin 1
• Add MRSA coverage (linezolid, daptomycin, vancomycin) if suspected or confirmed 1

Animal/Human Bites

• Amoxicillin-clavulanate is first-line for both oral and IV treatment 1
• Alternative IV options: ampicillin-sulbactam, piperacillin-tazobactam, second/third-generation cephalosporins, carbapenems 1