Épidémiologie et évaluation de la sensibilité aux bêta-lactamines des souches de Haemophilus influenzae isolées en 2001 en France

Abstract

The aim of this study was to describe the epidemiology of H. influenzae strains collected in 2001 at the National Reference Center and to evaluate their susceptibility to ß-lactams. Methods. – The demographic characteristics were recorded for each strain, then were determined their capsular serotyping (slide agglutination with specific antisera), as well as their ß-lactamase production (chromogenic cephalosporin test, Nitrocefin), and their MICs (agar dilution method on Haemophilus Test Medium) for amoxicillin (AMX), co-amoxiclav (AMC), cefpodoxime (CPD), cefaclor (CEC), cefuroxime (CXM), and cefotaxime (CTX). Results. – 41.3% of the 752 strains were identified in bronchial secretions, 20.6% in conjunctivitis, 11.3% in otitis media, and 11% in blood cultures. 96.3% of the strains were not capsulated and 3.7% were of type b, d, e or f. 33.8% of the strains were ß-lactamase producers (TEM type), 45.8% of these were identified in otitis pus and 27.7% in bronchial secretions. One hundred and forty-two strains (18.9%) presented reduced susceptibility to ß-lactams (modification of target) associated or not with bla+. MICs 50/90 against bla+ strains were: AMX 1/32, AMC 0.12/1, CTX 0.007/0.03, CPD 0.03/0.12, CEC 1/64, CXM 0.25/1. Against low BLNAR and bla+ strains, MICs 50/90 were: AMX 2/32, AMC 0.25/2, CTX 0.015/0.06, CPD 0.06/0.25, CEC 4/64, CXM 0.25/4. And against low BLNAR strains MICs 50/90 were: AMX 0.25/8, AMC 0.25/8, CTX 0.015/0.12, CPD 0.06/0.50, CEC 4/32, CXM 0.25/4. Conclusions. – Both bla+ and modifications of PBP are widespread among strains isolated in France. CTX, and CPD remain the most active compounds whatever the resistance mechanisms.