[Haemophilus influenzae: phenotype characteristics of strains isolated in 12 Catalan hospitals over one year].

INTRODUCTION

The purpose of this study was to investigate the antigenic and biochemical characteristics, antibiotic susceptibility, and mechanisms for acquiring resistance of Haemophilus influenzae strains isolated in several Catalan hospitals, to determine the current situation regarding this microorganism in our area.

METHODS

Serotype, biotype and betalactamase production, as well as susceptibility to eight antimicrobial agents (ampicillin, cefuroxime, cefotaxime, cefixime, clarithromycin, co-trimoxazole, chloramphenicol and ciprofloxacin) were determined in 497 H. influenzae strains isolated from 1 May 1999 to 30 April 2000 in 12 Catalan hospitals.

RESULTS

Among the total, 97.5% of strains were nontypable and 50% of the encapsulated strains were serotype b (all isolated from children under 5 years old). There was a predominance of biotype II, though no age or pathologic tropism was found among any of the biotypes. Our series confirms the previously reported trend to decreasing betalactamase mediated ampicillin resistance in our area, mainly in strains from pediatric patients. More betalactamase negative ampicillin-resistant strains (BLNAR) were isolated in children than in adults. One ciprofloxacin-resistant strain was detected.

CONCLUSIONS

Infections caused by encapsulated H. influenzae strains are infrequent in our area and the relative importance of serotype b is decreasing. Mechanisms for acquiring ampicillin resistance other than betalactamase production are emerging. Surveillance of ciprofloxacin susceptibility is required to predict therapeutic failures with this quinolone.