Recovery of the organism in culture is the most reliable method for diagnosis.
- The presence of gram-negative coccobacilli in gram-stained CSF provides strong evidence for meningitis due to H. influenzae.
- Detection of polyribitol ribose phosphate (PRP)—polymers of which form the type b capsule—in CSF allows rapid diagnosis of Hib meningitis before culture results are available.
Treatment: H. Influenzae Infections - Initial therapy for Hib meningitis consists of a third-generation cephalosporin: ceftriaxone (2 g q12h) or cefotaxime (2 g q4-6h) for adults and ceftriaxone (37.5-50 mg/kg q12h) or cefotaxime (50 mg/kg q6h) for children.
- - Children >2 months of age should receive adjunctive dexamethasone (0.15 mg/kg IV q6h for 2 days) to reduce the incidence of neurologic sequelae.
- - Antibiotic therapy should continue for 7-14 days.
- Antibiotic treatment for invasive infections other than meningitis (e.g., epiglottitis) consists of the same antibiotic but at a dosage different from that given for meningitis—e.g., ceftriaxone (2 g q24h) for adults.
- - Treatment duration depends on the clinical response, but a course lasting 1-2 weeks is generally appropriate.
- Most NTHi infections can be treated with oral antibiotics, such as amoxicillin/clavulanate, extended-spectrum cephalosporins, newer macrolides (azithromycin or clarithromycin), and fluoroquinolones (in nonpregnant adults).
- - About 20-35% of NTHi strains produce β-lactamase.
- - The incidence of strains with altered penicillin-binding proteins conferring resistance to ampicillin is increasing in Europe and Japan.
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