Susceptibility of Enterobacteriaceae to beta-lactam agents and fluoroquinolones: a 3-year survey in France.

Objective: To assess trends in the susceptibility to beta-lactam agents and to fluoroquinolones of clinically relevant Enterobacteriaceae isolated over a 3-year period in 14 French hospital laboratories.

Methods: During the second quarter of 1996, 1997 and 1998, 180 consecutive non-duplicate isolates of Enterobacteriaceae were collected in each center. Sixteen beta-lactams and four quinolones were tested by the disk diffusion method. In addition, the double-disk synergy test was used to screen for the production of extended-spectrum beta-lactamase (ESBL).

Results: Totals of 2507, 2312 and 2506 clinical isolates were obtained in each period, respectively. The distribution of Enterobacteriaceae species according to clinical specimens and wards was similar in each study period. No significant variation in the susceptibility rates to beta-lactams and fluoroquinolones was observed, except in Klebsiella pneumoniae and Enterobacter aerogenes. The prevalence of ESBL-producing isolates decreased from 18% to 9% in the former, while it increased from 32% to 54% in the latter. At the same time, the susceptibility to ofloxacin and pefloxacin increased for K. pneumoniae (P < 0.003) and cephalosporinase-producing species (P < 0.05), except Enterobacter spp.

Conclusion: Over the 3-year study period beta-lactams and fluoroquinolones remained highly active against Enterobacteriaceae clinical isolates, with the exception of E. aerogenes, probably as a result of the dissemination of multiresistant clones in French hospitals.