The detection and analysis on drug resistance and drug-resistant mechanisms of Clostridium difficile in Guang-zhou

WU Ai-wu; TANG Hai-xian; WANG Li-si; CHEN Ding-qiang; LI Hong-yu; TANG Xiao-hua

Abstract：Objective To investigate the drug resistance and the possible mechanisms of Clostridium difficile ( CD) on patients with diarrhea in Guangzhou.Methods A total of 467 stool samples were collected from patients with diarrhea from 3 hospitals in Guangzhou.PCR methods was used to detect the CD species-specific tpi gene, so as the CD spores were enriched from the stool specimens with positive gene tpi, innoculated on the CCFA medium, and incubated in anaerobic environment.Suspicious colonies were subcultured and identified by PCR methods.MIC values of isolated CD to common drugs were tested by the Etest method.To the drug-resistance strains, drug-resistance-associated genes, in-cluding clindamycin-resistance-associated gene ermB and quinolone resistance-associated DNA gyrase gene gyrA and gyrB were detected by PCR and sequenced.Results Gene tpi was obtained from 29 of 467 stool specimens, from which 22 CD strains were isolated.Drugs susceptibility test showed that all the 22 strains were sensitive to metronidazole, vanco-mycin, amoxicillin/clavulanic acid, piperacillin and piperacillin/tazobactam, while none of 22 CD strains was resistant or intermediary to the 5 drugs.The drug-resistance rates to clindamycin, penicillin and moxifloxacin were 90.9% ( 20/22), 27.3%(6/22) and 13.6%(3/22), respectively;among which 2 CD strains were resistant to clindamycin, moxi-floxacin and penicillin, presenting as multidrug resistance CD strains.Gene ermB was obtained from 8 of 20 clindamycin-resistance CD strains, with the positive rate of 40% (8/20).The mutations of gene gyrA and gyrB were observed in 3 moxifloxacin-resistance strains.Conclusion There are not prominent drug -resistance of CD to antimicrobial agents commonly used in hospitals in Guangzhou, though there is a high drug-resistance rate to clindamycin.The gene ermB is one of the reasons of drug-resistance to clindamycin, while the mutations of the gene gyrA and gyrB are correlated with quinolone resistance in CD strains.Multidrug resistance CD strains have been found.