What are the recommended antibiotic regimens for pneumonia and urinary tract infections (UTI)?

Recommended Antibiotic Regimens for Pneumonia and Urinary Tract Infections (UTI)

For pneumonia and UTI treatment, the choice of antibiotics should be based on the specific pathogen, patient risk factors, and severity of illness, with empiric therapy guided by local resistance patterns.

Pneumonia Treatment

Community-Acquired Pneumonia (CAP)

Outpatient Treatment

• For healthy adults without comorbidities:

  • Amoxicillin 1 g three times daily 1, OR
  • Doxycycline 100 mg twice daily 1, OR
  • Macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) only in areas with pneumococcal resistance to macrolides <25% 1

• For adults with comorbidities (chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancy; asplenia):

  • Combination therapy:
    • Amoxicillin/clavulanate (500/125 mg three times daily, 875/125 mg twice daily, or 2000/125 mg twice daily) OR cephalosporin (cefpodoxime 200 mg twice daily or cefuroxime 500 mg twice daily); AND
    • Macrolide (azithromycin 500 mg on first day then 250 mg daily or clarithromycin 500 mg twice daily) 1, OR
  • Monotherapy:
    • Respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1

Inpatient Treatment (Non-ICU)

• Combination therapy:
  • β-lactam (ampicillin+sulbactam 1.5-3 g every 6h, cefotaxime 1-2 g every 8h, ceftriaxone 1-2 g daily, or ceftaroline 600 mg every 12h) AND
  • Macrolide (azithromycin 500 mg daily or clarithromycin 500 mg twice daily) 1, OR
• Monotherapy:
  • Respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) 1

Hospital-Acquired Pneumonia (HAP)

• Not at high risk of mortality and no MRSA risk factors:

  • Piperacillin-tazobactam 4.5 g IV q6h, OR
  • Cefepime 2 g IV q8h, OR
  • Levofloxacin 750 mg IV daily, OR
  • Imipenem 500 mg IV q6h, OR
  • Meropenem 1 g IV q8h 1

• Not at high risk of mortality but with MRSA risk factors:

  • One of the above antibiotics PLUS
  • Vancomycin 15 mg/kg IV q8-12h or Linezolid 600 mg IV q12h 1

• High risk of mortality:

  • Two antipseudomonal agents (avoid two β-lactams) PLUS
  • MRSA coverage (vancomycin or linezolid) 1

Pathogen-Specific Treatment

Streptococcus pneumoniae

• Penicillin MIC <2:
  • Penicillin G 2-3 MU IV q4h, OR
  • Amoxicillin 1 g PO q8h, OR
  • Amoxicillin/clavulanate 1.2 g IV/PO q12h 1

Staphylococcus aureus

• MSSA: Oxacillin 2 g IV q4-6h, Cefazolin 2 g IV q8h 1
• MRSA: Vancomycin 15-20 mg/kg IV q8-12h or Linezolid 600 mg PO/IV q12h 1

Atypical Pathogens

• Mycoplasma pneumoniae: Doxycycline 100 mg IV/PO bid x 7-14 days or Azithromycin 500 mg PO on day 1, then 250 mg PO qd x 4 days 1
• Legionella species: Levofloxacin 750 mg IV/PO qd or Azithromycin 1000 mg IV day 1, then 500 mg IV/PO qd 1

Duration of Therapy

• Community-acquired pneumonia: 5-7 days if clinically stable (afebrile for 48 hours, stable vital signs) 1
• Hospital-acquired pneumonia: 7 days for most pathogens 1
• Atypical pneumonia: 7-14 days for Mycoplasma, 7-10 days for Legionella 1

Urinary Tract Infection Treatment

Uncomplicated UTI

• First-line:
  • Trimethoprim-sulfamethoxazole (TMP-SMX) 1 DS tablet every 12 hours for 3 days 2
  • Nitrofurantoin 100 mg PO qid for 5 days 1
  • Fosfomycin 3 g PO single dose 1

Complicated UTI

• First-line:
  • Fluoroquinolones (levofloxacin 750 mg IV/PO daily) for 5-7 days 1
  • Ceftriaxone 1-2 g IV daily 1
  • Amoxicillin-clavulanate 875/125 mg PO twice daily for 7-14 days 3

For ESBL-producing organisms

• Preferred:
  • Carbapenems (ertapenem 1 g IV qd, imipenem 500 mg IV q6h, meropenem 1 g IV q8h) 1
  • Ceftazidime/avibactam 2.5 g IV q8h 1

For Pseudomonas aeruginosa

• Preferred:
  • Antipseudomonal β-lactams (ceftazidime 1-2 g IV q8-12h, cefepime 2 g IV q8h) plus
  • Aminoglycoside (amikacin 20 mg/kg/day) or fluoroquinolone 1

Special Considerations

Duration of Therapy

• Uncomplicated UTI: 3 days for TMP-SMX, 5 days for nitrofurantoin 2
• Complicated UTI: 5-7 days if good response, 10-14 days for severe infections 1, 3

Switching from IV to Oral Therapy

• Consider oral switch when patient is clinically stable (afebrile for 48 hours, normal vital signs, able to maintain oral intake) 1

Common Pitfalls to Avoid

• For pneumonia:

  • Failure to cover atypical pathogens in CAP can lead to treatment failure 1
  • Overuse of fluoroquinolones increases resistance and adverse events 1
  • Delayed ICU transfer for severe pneumonia increases mortality 1

• For UTI:

  • Treating asymptomatic bacteriuria (except in pregnancy or before urologic procedures) 1
  • Using fluoroquinolones for uncomplicated UTI when narrower-spectrum options are available 1
  • Inadequate duration of therapy for complicated UTI can lead to relapse 1

The evidence strongly supports pathogen-directed therapy whenever possible, with empiric therapy guided by local resistance patterns and patient risk factors for resistant organisms. For both pneumonia and UTI, shorter courses of appropriate antibiotics are as effective as longer courses for most patients, reducing the risk of adverse events and antimicrobial resistance.