Antimicrobial resistance in Chinese Clostridium difficile strains
Abstract number: O488
Huang H., Weintraub A., Fang H., Wu S., Zhang Y., Nord C.E.
Objectives:Clostridium difficile infection is the leading cause of nosocomial diarrhea. The emergence and spread of resistance in C. difficile are complicating the treatment and prevention. The purpose of the present study was to investigate the antimicrobial susceptibility patterns and resistance mechanisms of Chinese C. difficile strains.
Methods: 110 toxigenic C. difficile isolates collected between December 2008 and May 2009 at Fudan University Hospital Huashan were analyzed for their antibiotic susceptibility patterns using the agar dilution method. The heteroresistance to metronidazole in fresh isolates were detected by disc diffusion and Etest methods. Resistance molecular basis was investigated using polymerase chain reaction (PCR) and DNA sequencing.
Results: 16 different PCR ribotypes were identified with a dominant clone 017 accounting for 37.3% of the isolates, followed by 001 and H. Ribotype 027 was not found but one isolate belonged to ribotype 078. All the isolates were susceptible to vancomycin and piperacillin/tazobactam. However, 18 of 78 (23.1%) isolates were found to be transient heteroresistant to metronidazole. Resistance to moxifloxacin, ciprofloxacin, levofloxacin, erythromycin, clindamycin, tetracycline, rifampin, rifaximin and fusidic acid was found in 61.8%, 100%, 66.4%, 85.3%, 88.1%, 62.7%, 29.1%, 29.1% and 8.2% of the isolates, respectively. The isolates of common PCR ribotypes were more resistant than the uncommon ribotypes. The prevalence of resistance genes and mutations among the resistant isolates was as follows: ermB, 69.1%; tetM, 97.1%; gyrA mutation, 63.2%; gyrB mutation, 4.4%; gyrA and gyrB mutation, 32.4%, rpoB mutation, 100%, respectively. The fusA mutation was only found in one isolate with minimum inhibitory concentration (MIC) of 4 mg/L.
Conclusions: Many C. difficile isolates now show an alarming pattern of resistance to the antimicrobial agents used in China. Isolates of common PCR ribotypes are more resistant than uncommon ribotypes, especially the dominant strain 017. Most of the resistance mechanisms which have been identified in C. difficile are similar to those in other Gram-positive bacteria.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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