What are the prevention and treatment options for infections caused by Haemophilus influenzae (H. influenzae) and Streptococcus pneumoniae?

Prevention and Treatment of Haemophilus influenzae and Streptococcus pneumoniae Infections

Vaccination: The Primary Prevention Strategy

All adults and children should receive vaccination against both Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae as the cornerstone of prevention, with specific timing and populations determined by age and immune status. 1

Pneumococcal Vaccination

• Administer 23-valent polysaccharide pneumococcal vaccine (PPV) to all adults with CD4+ counts >200 cells/µL if not vaccinated in the previous 5 years 1
• For HIV-infected adults with CD4+ counts <200 cells/µL, vaccination can be offered though efficacy is reduced; consider revaccination once CD4+ counts increase to >200 cells/µL on antiretroviral therapy 1
• Revaccinate every 5 years to maintain protection, though clinical benefit from revaccination remains unproven 1
• The recommendation is increasingly critical given rising rates of drug-resistant S. pneumoniae strains (including TMP-SMX-, macrolide-, and β-lactam-resistant organisms) 1

Haemophilus influenzae Type b Vaccination

• Hib vaccine is NOT routinely recommended for adults due to low incidence of Hib infection in this population 1
• For children, complete the primary vaccination series with booster doses according to standard schedules 1
• Vaccination remains essential for children despite overall disease rarity, as unimmunized and underimmunized children continue to face significant risk 1

Special Populations Requiring Vaccination

• HIV-infected individuals: Vaccinate when CD4+ counts are optimized (>200 cells/µL preferred) 1
• Multiple myeloma patients: Despite limited immunogenicity, vaccination is still recommended because most patients have low baseline antibody levels post-transplantation 1
• Asthmatic children: Vaccination provides beneficial effects on asthma control and reduces respiratory infections 2

Chemoprophylaxis for High-Risk Contacts

Hib Disease Contacts

Rifampin chemoprophylaxis is the standard for preventing secondary Hib transmission because it achieves high respiratory secretion concentrations and eradicates nasopharyngeal carriage in >95% of carriers 1

Index Patients

• Administer rifampin to index patients <2 years old treated with antibiotics OTHER than cefotaxime or ceftriaxone prior to hospital discharge 1
• No prophylaxis needed if treated with cefotaxime or ceftriaxone, as these agents eradicate Hib colonization 1

Household Contacts

• Give rifampin to ALL household contacts when the household includes children <4 years who are not fully vaccinated OR immunocompromised individuals <18 years (regardless of vaccination status) 1

Child Care Contacts

• Prescribe rifampin to all attendees (regardless of age/vaccine status) and child care providers when ≥2 cases of invasive Hib disease occur within 60 days AND unimmunized/underimmunized children attend the facility 1

Critical Limitation

• Do NOT provide chemoprophylaxis for contacts of nontype b H. influenzae disease, as secondary transmission has not been documented 1

Antibiotic Treatment for Active Infections

Haemophilus influenzae Treatment

Amoxicillin-clavulanate is first-line therapy for H. influenzae infections due to increasing β-lactamase production (up to 25% in some regions) 3, 4

• Adults: Amoxicillin-clavulanate 625 mg three times daily orally for 7 days 3
• Children <12 years: Co-amoxiclav (amoxicillin component 90 mg/kg/day in 2 divided doses) 3
• Penicillin allergy alternatives: Macrolides (clarithromycin 500 mg twice daily or azithromycin) or respiratory fluoroquinolones 3
• In areas with documented low β-lactamase prevalence, ampicillin alone remains acceptable 3

Streptococcus pneumoniae Treatment

Ceftriaxone is indicated for lower respiratory tract infections, bacterial septicemia, and meningitis caused by S. pneumoniae 5

• Ceftriaxone covers both H. influenzae and S. pneumoniae for severe infections including meningitis 5
• For invasive pneumococcal disease, test all isolates for β-lactam susceptibility and consider local resistance patterns when selecting empirical therapy 1

Duration of Therapy

Treat for a minimum of 48-72 hours beyond clinical improvement or bacterial eradication, with shorter courses (5-7 days) acceptable for uncomplicated pneumonia with adequate response 3

Adjunctive Prevention Strategies

TMP-SMX Prophylaxis

• Daily TMP-SMX for Pneumocystis pneumonia (PCP) prophylaxis reduces bacterial respiratory infection frequency and should be considered when selecting PCP prophylaxis agents 1
• However, avoid indiscriminate use when not indicated for PCP prophylaxis to prevent resistant organism development 1

Influenza Vaccination

• Administer annual influenza vaccination to reduce severe respiratory illness and related mortality by approximately 50% in patients achieving protective immunity 1
• Particularly important for immunocompromised patients including those with HIV, multiple myeloma, and asthma 1, 2

Critical Clinical Pitfalls to Avoid

• Never use macrolides as monotherapy for H. influenzae due to poor coverage 3
• Avoid cephalexin, cefaclor, and loracarbef for H. influenzae infections (only 20% susceptibility) 3
• Do not extrapolate infection prevention guidelines from other immunocompromised populations (e.g., CLL guidelines to CML patients), as immune dysfunction patterns differ fundamentally 6
• Monitor for widespread trimethoprim-sulfamethoxazole resistance in H. influenzae when considering prophylaxis 3
• Recognize that pneumococcal vaccine efficacy may be paradoxically reduced in certain populations (one African trial showed increased pneumonia risk, though U.S. observational studies demonstrate benefit) 1