Nontypeable Haemophilus influenzae (NTHi) causes acute otitis media (AOM) in infants. Breast-feeding protects against AOM and/or nasopharyngeal (NP) colonization; however, the mechanism of protection is incompletely understood. Children with AOM and healthy children were studied according to feeding status: breastfed,breast/formula fed, or formula fed. Cumulative episodes of AOM, ELISA titers of serum IgG antibodies to whole-cell NTHi and vaccine candidate outer membrane protein P6, bactericidal titers of serum and NP colonization by NTHi were assessed. A lower incidence of AOM was found in breast- versus formula-fed children. Levels of specific serum IgG antibody to NTHi and P6 were highest in breast-fed, intermediate in breast/formula fed, and lowest in formula-fed infants. Serum IgG antibody to P6 correlated with bactericidal activity against NTHi. Among children with AOM, the prevalence of NTHi in the NP was lower in breast- versus nonbreast-fed infants. We conclude that breast-feeding shows an association with higher levels of antibodies to NTHi and P6, suggesting that breast-feeding modulates the serum immune response to NTHi and P6. Higher serum IgG might facilitate protection against AOM and NP colonization in breast-fed children.

Invasive Haemophilus influenzae type b (Hib) disease decreased dramatically after the introduction of conjugate vaccine in routine immunization schedules. We report a case of a fifteen-months-old girl, previously healthy and vaccinated, admitted in the emergency room with fever and vomiting. She was irritable and the Brudzinski's sign was positive. The cerebrospinal fluid (CSF) analysis showed pleocytosis and high protein level. Empiric intravenous antibiotics (ceftriaxone and vancomycin) were administered for suspected bacterial meningitis during 10 days. Serotyping of the Haemophilus influenzae strain found in CSF revealed a serotype b. After one year of follow-up no Hib meningitis sequelae were noted. Despite vaccination compliance and absence of risk factors, invasive Hib disease can occur due to vaccine failure. Efforts to keep the low incidence of invasive Hib disease should be directed to the maintenance of high vaccination coverage rates, combined with the notification and surveillance strategies already implemented in each country.

We present two cases of bacterial meningitis caused by Haemophilus influenzae type b (Hib) which developed a few days after conjugate Hib vaccination. This phenomenon of postimmunization provocative time period is reviewed and discussed. These cases serve as a reminder to clinicians of the risk, albeit rare, of invasive Hib disease in the short period after successful immunization.

BACKGROUND:The generalization of the vaccination against H. influenzae b (Hib), according to its integration in the French vaccinal calendar, led to the incidence decrease of the purulent meningitis with Hib in young children, which became a so rare event.

CASE REPORT:We described the case of a 14-months-old child showing a bacterial purulent meningitis with Hib, despite of a well driven vaccination.

DISCUSSION:The epidemiology of bacterial meningitis was upset by the generalization of the anti-H. influenzae b vaccination. The use of combined vaccines specially reduced the incidence and the gravity of this pathology. Nevertheless, in spite of the excellent vaccinal coverage, the limited but real persistence of epiglottis or meningitis due to H. influenzae b should keep in mind of the biologists and the clinicians. Indeed, the chronic nasopharyngal carriage, the existence of not vaccinated or not answering people allow to consider the persistent risk of H. influenzae b bacterial meningitis.