Genomic variability of Haemophilus influenzae isolated from Mexican children determined by using enterobacterial repetitive intergenic consensus sequences and PCR

Genomic fingerprints from 92 capsulated and noncapsulated strains of Haemop hilus influenzae from Mexican children with different diseases and healthy carriers were generated by PCR using the enterobacterial repetitive interge nic consensus (ERIC) sequences. A cluster analysis by the unweighted pair-g roup method with arithmetic averages based on the overall similarity as est imated from the characteristics of the genomic fingerprints, was conducted to group the strains. A total of 69 fingerprint patterns were detected in t he II. influenzae strains. Isolates from patients with different diseases w ere represented by a variety of patterns, which clustered into two major gr oups. Of the 37 strains isolated from cases of meningitis, 24 shared patter ns and were clustered into five groups within a similarity level of 1.0. On e fragment of 1.25 kh was common to all meningitis strains. H. influenzae s trains from healthy carriers presented fingerprint patterns different from those found in strains from sick children. Isolates from healthy individual s were more variable and were distributed differently from those from patie nts. The results show that ERIC-PCR provides a powerful tool for the determ ination of the distinctive pathogenicity potentials of H. influenzae strain s and encourage its use for molecular epidemiology investigations.