From the Guidelines
Haemophilus influenzae type b (Hib) disease can be effectively prevented through vaccination, which has dramatically reduced the incidence of invasive Hib disease by creating herd immunity and protecting vulnerable populations. Haemophilus influenzae is a gram-negative bacterium that can cause various infections, particularly in children. It exists in both encapsulated (typeable) and non-encapsulated (non-typeable) forms. Type b (Hib) was historically the most virulent strain, causing serious invasive diseases like meningitis, epiglottitis, pneumonia, and septicemia before widespread vaccination 1.
Treatment and Prevention
Treatment for H. influenzae infections typically involves antibiotics such as amoxicillin-clavulanate (for non-severe infections) at 875/125 mg twice daily for adults or 45 mg/kg/day divided twice daily for children. For severe infections, ceftriaxone (1-2 g IV daily for adults) or cefotaxime (1-2 g IV every 8 hours) is recommended. In cases of beta-lactamase production, fluoroquinolones like levofloxacin (750 mg daily) may be used in adults. Treatment duration typically ranges from 7-14 days depending on infection severity and site. Prevention primarily relies on the Hib vaccine, which is part of routine childhood immunization schedules worldwide, typically given at 2,4,6, and 12-15 months of age 1.
High-Risk Populations
Certain populations are at increased risk for invasive Hib disease, including those with functional or anatomic asplenia, HIV infection, immunoglobulin deficiency, early component complement deficiency, receipt of a hematopoietic stem cell transplant, or receipt of chemotherapy or radiation therapy for malignant neoplasms 1. American Indian/Alaska Native (AI/AN) populations have historically had higher rates of Hib disease and colonization than the general U.S. population, with a peak in disease at a younger age 1.
Vaccination Recommendations
The Hib vaccine is recommended for all children as part of routine childhood immunization schedules, with a typical schedule of 2,4,6, and 12-15 months of age. This vaccination has dramatically reduced the incidence of invasive Hib disease by creating herd immunity and protecting vulnerable populations 1.
From the Research
Characteristics of Haemophilus influenzae
- Haemophilus influenzae is a small, nonmotile, non-spore-forming bacterium, and a strict parasite of humans found principally in the upper respiratory tract 2
- The production of capsule is of major significance to clinicians since it is an important virulence factor, with six antigenically distinct capsular types, designated a-f 2
- Spread from one individual to another occurs by airborne droplets or by direct contagion with secretions 2
Disease Patterns and Diagnosis
- Two contrasting patterns of Haemophilus influenzae disease can be identified: invasive infection (e.g. meningitis, septic arthritis, epiglottitis, and cellulitis) and less serious infections (e.g. otitis media, sinusitis) 2
- A provisional diagnosis of meningitis, epiglottitis, facial cellulitis, or septic arthritis will usually be prompted by the history and clinical findings, with confirmation requiring microbiologic studies 2
- Cultures of blood, CSF and other normally sterile fluids are diagnostic and therefore under the appropriate circumstances mandatory 2
Treatment and Management
- Without treatment, infection due to Haemophilus influenzae can be rapidly fatal, particularly by meningitis and epiglottitis 2
- Antibiotic therapy is only one facet of the management of the child with Haemophilus influenzae infection, and critical attention must also be given to supportive therapy 2
- Cefotaxime or ceftriaxone are commonly used agents for the treatment of lifethreatening Haemophilus influenzae infection in children beyond the neonatal period 2
- Ampicillin or amoxicillin for 10 days is often satisfactory for the less severe Haemophilus influenzae infections in the ambulatory setting 2
- Cephalosporins are often chosen for treatment of adults with pneumonia when Haemophilus influenzae is documented 2
Resistance and Chemoprophylaxis
- Cefotaxime resistance in invasive Haemophilus influenzae isolates in Germany 2016-19 was found to be low, with a prevalence of 0.90% 3
- PBP3 mutations were significantly associated with cefotaxime resistance, but were not present in all resistant strains 3
- Rifampin is recommended as a prophylactic treatment for intimate contacts of young children who develop invasive infections with Haemophilus influenzae type B (Hib), with a 4-day course being 95% effective in eradicating pharyngeal colonization with Hib 4
- A 2-day course of rifampin therapy appears to be as effective as 4-day treatment in the eradication of Hib pharyngeal colonization 4