Antimicrobial susceptibility of Proteus mirabilis urinary tract isolates from 1999 to 2005 at Nimes University hospital

Aim of the study. - To analyse antimicrobial resistance trends of Proteus mirabilis urinary tract isolates from 1999 to 2005 at the Nimes University hospital. Materials and methods. - We retrospectively collected non-duplicate urinary tract infections and colonization isolates from inpatients between I January 1999 and 31 December 2005. Results. - One thousand and eight non-duplicate urinary tract isolates were studied, 63.1% were from females and the mean age was 76 years. The mean resistance rate was 59.0% for amoxicillin (AMX), 48.0% for piperacillin (PIP), 3.9% for cefotaxim, 33.9% for amoxicillin plus clavulanic acid (AMC) and 2.8% for piperacillin plus tazobactam (TZP). A significant increase in resistance was observed for AMC and TZP. The mean resistance rate was 35.0% for norfloxacin, 34.8% for ofloxacin and 23.5% for ciprofloxacin. No significant increase in resistance to fluoroquinolones was seen except for ciprofloxacin whereas a significant increase was observed for aminoglycosides. The mean rate resistance for cotrimoxazole was 33.2% with a significant decrease in the resistance during the study period. Conclusion. - P mirabilis stilled sensitive to cefotaxim or ceftazidim and to TZP. The significant increase in the rate resistance to AMC and TZP could be explained by production of beta-lactamases and in particular extended-spectrum beta-lactamases. The increase in resistance observed for fluoroquinolones become a major concern. Amikacine was the most active aminoglycosides. These data suggested for the re-enforcement of the antimicrobial susceptibility surveillance in order to optimise the rational use of antibiotics. (c) 2006 Elsevier Masson SAS. Tons droits reserves.