What antibiotics are recommended to treat Haemophilus influenzae (H. influenzae) infections?

Antibiotic Treatment for Haemophilus influenzae Infections

For Haemophilus influenzae infections, amoxicillin-clavulanate is the first-line antibiotic treatment due to increasing prevalence of β-lactamase-producing strains. 1

First-Line Treatment Options

• For β-lactamase-negative H. influenzae strains, amoxicillin alone (1g PO q8h) is effective 2
• For β-lactamase-producing H. influenzae strains, amoxicillin-clavulanate (1.2g IV/PO q12h) is the preferred treatment 2, 3
• Alternative first-line options include:
  • Cefuroxime (1.5g IV q8h) 2, 4
  • Third-generation cephalosporins like ceftriaxone (2g IV qd) 2, 5

Alternative Treatment Options

• For patients with penicillin allergies, consider:
  • Fluoroquinolones: ciprofloxacin (400mg IV/PO q12h), levofloxacin (750mg IV/PO qd), or moxifloxacin (400mg IV/PO qd) 2
  • Macrolides may be considered in areas with low resistance rates 1
• Tetracyclines like doxycycline can be used but resistance has increased significantly over time 6

Treatment Considerations by Infection Type

• For community-acquired pneumonia where H. influenzae is suspected:
  • Outpatient treatment: high-dose amoxicillin-clavulanate or a respiratory fluoroquinolone 1
  • Hospitalized patients: ceftriaxone, cefotaxime, or IV amoxicillin-clavulanate 2, 1
• For lower respiratory tract infections:
  • Treatment duration should be 7 days for non-severe infections 2
  • For severe infections, extend treatment to 10-14 days 1

Resistance Patterns and Special Considerations

• Approximately 18-42% of H. influenzae strains produce β-lactamase, making them resistant to amoxicillin alone 1, 6
• Amoxicillin and clavulanate potassium should be used only for infections proven or strongly suspected to be caused by β-lactamase-producing bacteria 3
• If no improvement after 48-72 hours of initial therapy, consider switching to ceftriaxone or adding a macrolide if atypical pathogens are suspected 1
• Monitoring local resistance patterns is crucial for guiding empiric therapy 6

Dosing Recommendations

• Amoxicillin-clavulanate: 1.2g IV/PO q12h 2
• Cefuroxime: 1.5g IV q8h 2
• Ceftriaxone: 2g IV qd 2
• Levofloxacin: 750mg IV/PO qd 2
• Moxifloxacin: 400mg IV/PO qd 2

Remember that treatment should be adjusted based on culture and susceptibility results when available to ensure optimal therapy and prevent the development of antimicrobial resistance 3, 7.