Biotypes and serotypes of Haemophilus influenzae of clinical isolates from Mexican children.

BACKGROUND

Infectious diseases caused by H. influenzae type b are considered preventable through vaccination with Hib conjugate vaccines. Some countries which follow Hib vaccination programs are close to eradication of the disease. In Mexico in particular, little epidemiological information is available.

METHODS

In this study, 90 clinical strains of H. influenzae were obtained from Mexican children who were treated in four pediatric hospitals in Puebla City, and were diagnosed with invasive or localized infectious diseases. The strains were identified by standard bacteriological methods. Biotyping was done by Kilian criteria and serotyping by coagglutination.

RESULTS

H. influenzae infections were found in children younger than 5 years of age, and 68.8% of the children were younger than 24 months. Sixty percent of the isolates belonged to serotype b, 31.1% were nontypeable, and 7.7% were considered non-type b. Serotype b was the most frequent isolate associated with invasive infectious diseases; however, nontypeable strains were isolated more frequently from children with otitis, sinusitis, conjunctivitis, and bronchial secretion. Non-type b serotypes were isolated from invasive and non-invasive infections in few cases. Biotypes I and IV were the most frequent isolates of H. influenzae.

CONCLUSIONS

This study emphasizes the urgent need for an Hib-conjugated vaccine to achieve immunization in a pediatric population.