合肥市54株产CTX-M型ESBLs大肠埃希菌和肺炎克雷伯菌耐药性分析

Study on the resistance in 54 clinical isolates of Klebsiella pneumoniae and Escherichia coli producing CTX-M type extended-spectrum β-lactamases in Hefei

目的了解合肥市产CTX-M型ESBLs大肠埃希菌和肺炎克雷伯菌耐药性。方法将我省细菌耐药性监控中心保留的54株产CTX-M型ESBLs的临床分离株大肠埃希菌和肺炎克雷伯菌与受体菌E.coliC600进行转移接合试验后,按照2004年NCCLS推荐标准,用琼脂稀释法分别测定野生株和转移接合子对14种不同抗菌药物的MIC,比较并分析两者的不同。结果24株大肠埃希菌和30株肺炎克雷伯菌分别有22株和30株接合成功,野生株的MIC结果显示对哌拉西林、头孢呋辛、头孢曲松钠的耐药率最高,达到100%,对亚胺培南全部敏感;转移接合子的耐药性较野生株有所下降,对氟喹诺酮类的敏感性明显增加。结论合肥市这些菌株所产生的CTX-M型ESBLs对头孢曲松钠和头孢噻肟钠具有超强水解能力,经转移接合试验后,接合子的水解能力有所下降,提示本地区产CTX-M型ESBLs大肠埃希菌和肺炎克雷伯菌中存在着多种耐药机制。

Objective To study the resistance of Klebsiella pneumoniae and Escherichia coli producing CTX-M type extendedspectrum β-lactamases （ESBLs）. Methods To obtain the transconjugants of K. pneumoniae and E. coli, 54 clinical strains producing CTX-M ESBLs preserved in Anhui Center for Surveillance of Antimicrobial Resistance mated with the recipient strain E. coli C600. Their resistances to 14 antimicrobial agents were tested by agar dilution method. MICs of the antimicrobial agents against clinical isolates and the transconjugants were determined. Results Conjugation to E. coli C600 was successful in 22 of 24 E. coli strains and 30 of 30 K. pneumoniae strains. All the clinical strains had the same resistant pattern, with the highest resistance rate （100%） to piperacillin, cefuroxime and ceftriaxone. All the strains were susceptible to imipenem. Compared with clinical strains, the transconjugants showed lower resistance to all the antimicrobial agents. The susceptibility to quinolones was apparently higher. Conclusions The E. coli and K. pneumoniae isolates producing CTX-M type ESBLs have super powerful hydrolytic activity against ceftriaxone and eefotaxime in Hefei. The transconjugants shows weaker ability of hydrolysis. The finding suggests that multiple-antimicrobial resistance may be present in these clinical strains.