耐碳青霉烯类阴沟肠杆菌整合子分布与多位点序列分析

目的通过检测临床分离耐碳青霉烯类阴沟肠杆菌(Carbapenem-resistant enterobacter cloacae,CRECL)整合子,采用多位点序列分型(Multilocus sequence typing,MLST)了解其流行特点,为医院控制感染提供依据。方法收集并保存临床CRECL 15株;鉴定与药敏试验采用BD phoenix M50全自动细菌鉴定仪;整合子、可变区、MLST和碳青霉烯酶测定采用聚合酶链式反应(Polymerase chain reaction,PCR)和琼脂糖凝胶电泳,并对可变区阳性、七对管家基因和碳青霉烯酶的菌株DNA测序,所得数据与数据库比对分析。结果 15株CRECLⅠ类整合子阳性检出率80.0%(12/15),未检出II类及III类整合子;全部CRECL菌株均扩增出可变区,其中11株检测出耐药基因盒,分别为aacA 4-cr、blaOXA30、CatB 3、ARR-3、QacEdelta 1共5种;15株CRECL菌株检出5种序列分型(ST),其中11株为ST 93型,其余为ST 167型、ST 1108型、ST 136型、ST 4型;12株菌株检测出新德里金属-β-内酰胺酶1基因(NDM-1)。结论Ⅰ类整合子与阴沟肠杆菌耐药存在相关性,可能在耐药基因传播中起重要作用;医院CRECL整合子阳性菌株检出率较高;ST型主要为ST 93型,整合子阳性菌株及NDM-1与ST型有较好一致性。

Integron distribution and multi-locus sequence analysis of carbapenem-resistant Enterobacter cloacae

OBJECTIVE To detect the integron of carbapenem-resistant Enterobacter cloacae(CRECL) by using multilocus sequence typing(MLST), to analyze the epidemic characteristics and to provide the basis for the control of infection. METHODS Fifteen CRECL strains from clinical specimens were collected and preserved. The identification and drug susceptibility test were performed by using BD phoenix M50 automatic bacterial identification instrument;integron variable region, multilocus sequence typing(MLST) and carbapenemase were determined by Polymerase Chain reaction(PCR) amplification and agarose gel electrophoresis;the variable region of integron, seven pairs of housekeeping genes and carbapenemase in the strains were sequenced and searched in the database. RESULTS The positive rate of 15 CRECL class I integron was 80.0%(12/15), and class II and class III integrons were not found. Variable regions in all CRECL strains were amplified, 11 of which 5 drug resistance gene cassettes named aacA 4-cr, blaOXA30, CatB 3, ARR-3, QacEdelta 1 were detected. Five genotype was detected in 15 strains: 11 strains were ST 93, and the rest of them were ST 167, ST 1108, ST 136 and ST 4. New Delhi metal-β-lactamase 1 gene(NDM-1) was detected in 12 strains. CONCLUSION There was a correlation between class I integrons and drug resistance in CRECL, which may play an important role in the transmission of drug resistance genes. The detection rate of CRECL integron-positive strains in our hospital was high, mainly ST 93 type. The strains with positive integrons and NDM-1 have good consistency with the ST type.