What is the treatment for Haemophilus (H) influenzae infection?

Treatment of Haemophilus influenzae Infection

For Haemophilus influenzae infections, co-amoxiclav is the first-line treatment of choice, with clarithromycin or cefuroxime as alternatives for penicillin-allergic patients. 1

Treatment Algorithm by Patient Population

Children Under 12 Years

• First-line: Co-amoxiclav (oral if tolerated) 1
• Penicillin allergy: Clarithromycin or cefuroxime 1
• Severe illness: Add a second agent (clarithromycin or cefuroxime) and administer intravenously 1

Children Over 12 Years and Adults

• First-line: Co-amoxiclav or doxycycline 1
• Penicillin allergy: Clarithromycin or a fluoroquinolone with pneumococcal activity 1
• Severe illness: Intravenous combination therapy with a β-lactamase stable antibiotic (co-amoxiclav or cephalosporin) plus a macrolide 1

Treatment by Infection Site

Lower Respiratory Tract Infections

• Co-amoxiclav is specifically indicated for β-lactamase-producing H. influenzae 2
• For non-severe pneumonia: oral co-amoxiclav or doxycycline for 7 days 1
• For severe pneumonia: IV co-amoxiclav or cephalosporin plus clarithromycin for 10 days 1

Otitis Media and Sinusitis

• Co-amoxiclav is indicated for β-lactamase-producing H. influenzae 2
• Treatment duration: 7-10 days

Invasive Infections (Meningitis, Septicemia)

• Ceftriaxone is indicated for H. influenzae meningitis and septicemia 3
• Dosage: 1-2g IV daily, with longer treatment duration (typically 10-14 days)

Special Considerations

β-lactamase Production

• Approximately 30% of H. influenzae strains produce β-lactamase, rendering them resistant to ampicillin and amoxicillin alone 4
• Always use β-lactamase stable antibiotics (co-amoxiclav, cephalosporins) for empiric therapy 1, 2

Transition from IV to Oral Therapy

• Switch from parenteral to oral antibiotics when:
  • Clinical improvement is observed
  • Temperature has been normal for 24 hours
  • Patient can tolerate oral medication 1

Treatment Duration

• Non-severe, uncomplicated pneumonia: 7 days 1
• Severe pneumonia: 10 days 1
• Invasive infections: 10-14 days

Common Pitfalls to Avoid

1. Inadequate Coverage: Failing to cover for β-lactamase production can lead to treatment failure. Always use β-lactamase stable antibiotics for empiric therapy 1, 4

2. Delayed Antibiotic Administration: For severe infections, antibiotics should be administered within four hours of admission 1

3. Premature Oral Switch: Ensure clear clinical improvement before transitioning from IV to oral therapy 1

4. Inadequate Treatment Duration: Complete the full course of antibiotics to prevent relapse 1

5. Missing Polymicrobial Infections: H. influenzae often coexists with other respiratory pathogens, particularly in elderly patients, requiring broader coverage 5

The evidence strongly supports using co-amoxiclav as first-line therapy for H. influenzae infections, with appropriate alternatives for those with penicillin allergies or severe disease. This approach provides optimal coverage against β-lactamase-producing strains while minimizing the risk of treatment failure and complications.