CRKP碳青霉烯酶基因检测及同源性分析

Carbapenemase gene detection and homology analysis of carbapenemresistant Klebsiella pneumoniae

目的了解某院耐碳青霉烯类肺炎克雷伯菌(CRKP)碳青霉烯酶基因携带状况,以及菌株间的同源性,为预防和控制CRKP的克隆传播提供实验室依据。方法收集2017年1-12月该院分离自临床各科室的CRKP22株(K1~K22),用药敏纸片扩散法和微量肉汤稀释法对药敏结果进行复核,采用改良Hodge试验和Carba NP试验检测菌株是否产碳青霉烯酶,应用PCR技术扩增产酶菌株常见的碳青霉烯酶基因并测序,运用多位点序列分型(MLST)和肠杆菌科基因间一致重复序列PCR(ERIC-PCR)进行同源性分析。结果 22株CRKP对厄他培南、亚胺培南、美罗培南的耐药率均为100%,对临床其他常见抗菌药物也高度耐药;13株改良Hodge试验阳性,14株Carba NP试验阳性。14株产酶菌株均携带KPC-2基因,K12菌株同时携带NDM-1基因。按MLST法可分为ST11(14株)、ST875(6株)、ST1964和ST571(各1株),按ERIC-PCR法分型可分为A型(15株)、B型(6株)及C型(1株)。分型结果相同的菌株中K1~K6同属ICU,K7~K10同属脑血管外科,K15~K21同属新生儿科,对应患者有共同住院时间,且患者存在转科情况(K2、K8患者均由脑血管外科转入ICU,K13、K14分别从ICU转入血液内科、肾内科)。结论该院2017年存在ST11型和ST875型CRKP的克隆流行,需加强医院感染预防与控制措施。

Objective To understand the carrying status of carbapenemase gene and homology of carbapenem-resistant Klebsiella pneumoniae (CRKP) in a hospital, so as to provide laboratory basis for preventing and controlling transmission of CRKP clone strain. Methods 22 strains of CRKP (K1-K22) isolated from clinical departments in a hospital from January to December 2017 were collected, antimicrobial susceptibility testing results were re -checked by Kirby-Bauer disk diffusion and broth microdilution method, carbapenemase production was detected by modified Hodge test and Carba NP test, common carbapenemase genes of enzyme -producing strains were amplified and sequenced by polymerase chain reaction(PCR), homology analysis was performed by multilocus sequence typing (MLST) and enterobacterial repetitive intergenic consensus PCR(ERIC-PCR). Results Resistance rates of 22 CRKP to ertapenem, imipenem and meropenem were all 100%, resistance to other common clinical antimicrobial agents were also high;13 strains of CRKP were positive for modified Hodge test and 14 were positive for Carba NP test. KPC-2 gene was carried by 14 enzyme-producing strains, NDM-1 gene was also carried by K12 strain. According to MLST method, CRKP strains were divided into ST11 ( n =14), ST875 ( n =6), ST1964( n =1), and ST571( n =1). According to ERIC-PCR method, CRKP strains were divided into type A ( n =15), type B ( n =6) and type C ( n =1). K1-K6 strains with the same typing results were from intensive care unit (ICU), K7-K10 were from cerebrovascular surgery, and K15-K21 were from neonatology, corresponding patients had the same hospital stay, and they had been transferred (patients K2 and K8 were transferred from cerebrovascular surgery to ICU, K13 and K14 from ICU to departments of hematology and nephrology respectively). Conclusion Cloning epidemics of ST11 and ST875 CRKP existed in this hospital in 2017, it is necessary to strengthen the prevention and control measures of healthcare -associated infection.