儿科患者中对碳青霉烯类不敏感肠杆菌科细菌耐药性和耐药基因的研究

Characterization of antibiotic resistance and carbapenemase-producing in carbapenem no-susceptibil- ity Enterobacteriaceae from pediatric patients

目的研究儿科临床分离的对碳青霉烯类抗生素不敏感的肠杆菌科细菌耐药性和产生碳青霉烯酶的耐药基因特征。方法收集2008年1月至2010年12月北京儿童医院住院患儿分离出的46株对碳青霉烯类抗生素不敏感的肠杆菌科细菌。使用琼脂稀释法进行药敏试验，测定抗菌药物的最低抑菌浓度（MIC）值，按照临床实验室标准化研究所（CLSI）2011年推荐标准判断结果。使用改良Hodge试验和双纸片协同试验，进行产碳青霉烯酶的表型确证。使用PCR方法进行碳青霉烯酶相关耐药基因的检测。采用WHONET5．6软件进行数据分析。结果46株对碳青霉烯类抗生素不敏感的肠杆菌科细菌，26株为肺炎克雷伯菌，占56．5％，13株为阴沟肠杆菌，占28．3％，7株为大肠埃希菌，占15．2％。对亚胺培南和美罗培南不敏感率分别为肺炎克雷伯菌69．2％和80．8％，阴沟肠杆菌76．9％和100％，大肠埃希菌85．7％和100％。46株肠杆菌科细菌，改良Hodge试验阳性40株（87．0％），双纸片协同试验阳性41株（89．1％）。IMP基因阳性38株（82．6％），其余8株均未扩增出特异性条带检测均为阴性。结论目前儿科临_『爪分离对碳青霉烯类抗生素不敏感菌株中，肺炎克雷伯菌最多，占56．5％。肺炎克雷伯菌、阴沟肠杆凶干¨大肠埃希菌对碳青霉烯类抗生素亚胺培南不敏感程度低于美罗培南，对碳青霉烯不敏感肠杆菌科细菌主要产生B类金属酶，均为IMP基因型。

Objective To analyze the antibiotic resistance of the carbapenem no-susceptibility Enterobacteriaceae isolated from pediatric patients and the resistant genes of carbapenemase-producing. Meth- ods In all, 46 carbapenem no-susceptibility Enterobaeteriaceae strains were isolated from patients at Beijing Children＇s Hospital between January 2008 and December 2010. Agar dilution method recommended by the Clinical and Laboratory Standards Institute was used to examine the minimum inhibitory concentrations （MICs） of 14 antimicrobial agents. Phenotypic testing for carbapenemase-producing was eondueted using Hodge test and double-disk synergy test. PCR was used to detect the expression of the carbapenemase-related genes KPC, GES,tMI/MMC-A, SME, IMP, VIM, GIM, SPM ,SIM and OXA. WHONET5.6 was used to perform resistance analysis. Results Among 46 earbapenem no-susceptibility Enterobacteriaeeae strains, 26 （56.5% ） were Klebsieila pneumoniae strains, 13（28.3 % ） were Enterobacter cloacae and 7（ 15.2% ） were Escherichia coli. The rates of imipenem and meropenem no-susceptibility Klebsiella pneumoniae were 69.2% and 80.8% , Enterobacter cloacae were 76.9% and 100% and Escherichia coli were 85.7% and 100% , respectively. 40 （87.0%） strains were positive of Hodge test. 41 （89.1% ） strains were positive of double- disk synergy test. 38 （ 82.6% ） were positive for the IMP genotype. The carbapenemase-related genes were not found in other 8 strains. Conclusion The prevalence of carbapenem no-susceptibility Enterobacteriaceae strains in Klebsiella pneumoniae isolates is relatively high in children. Resistance to imipenem was lower than that to meropenem from Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli strains. Many earbapenem no-susceptibility Enterobacteriaceae isolated from pediatric patients carry the bla_IMP gene. No the KPC gene was found.