临床分离阴沟肠杆菌中新型氨基糖苷类乙酰转移酶基因的检测

Detection of the new type of aminoglycoside acetyltransferase gene in Enterobacter cloacae isolates

目的了解临床分离阴沟肠杆菌中新型氨基糖苷类乙酰转移酶基因[aac（6’）---Ib-cr基因]的分布。方法PCR检测aac（6’）-Ib-cr基因并将阳性扩增产物进行测序分析；纸片扩散法测定aac（6’）-Ib-cr基因阳性菌株对13种抗菌药物的敏感性；改良三维试验检测高产AmpC酶和ESBLs；ERIC-PCR法进行aac（6’）-Ib-cr基因阳性菌株同源性检测。结果81株阴沟肠杆菌中，3株aac（6’）-Ib-cr基因阳性（3．7％）；aac（6’）-Ib-cr基因阳性菌株对氟喹诺酮类，氨基糖苷类，氯霉素，氨苄西林，头孢西丁，第2、3代头孢菌素等显示多重耐药2株产ESBLs和AmpC，1株产ESBLs；ERIC-PCR电泳图谱型显示，3株aac（6’）-Ib．cr基因阳性细菌均不属于同一型别。结论临床分离阴沟肠杆菌中存在aac（6’）-Ib-cr基因阳性菌株，为多重耐药、非克隆传播菌株，临床应加强检测和监测。

Objective To investigate the prevalence of aac（6＇）-Ib-cr gene in Enterobacter cloacae isolates. Methods PCR and sequencing were performed on 81 strains of Enterobacter cloacae isolated clinically in Anhui province to identify aac （6＇）-IB-cr gene. Disk diffusion method was used to test the susceptibility of the Enterobacter cloacae isolates with aac （6＇）-Ib-cr gene to fluoroquinolones, aminoglycosides, and other antimicrobial agents. AmpC and extended-spectrum β-lactamases （ESBLs） were detected by modified three-dimensional extract test, and the molecular typing was analyzed by ERIC-PCR. Results aac （6＇）-Ib-cr gene was identified in 3 （3.7 % ） of the 81 Enterobacter cloacae isolates with different ERIC-PCR patterns. The isolates with aac （6＇）-Ib-cr gene were resistant to fluoroquinolones, aminoglycosides, chloramphenicol, ampicillin, cefoxitin, and second and third generation cephalosporins. Two of the 3 isolates produced AmpC and ESBLs, and 1 isolate produced only ESBLs. Conclusion aac （6＇）-Ib-cr gene is prevalent in Enterobacter cloacae isolates with resistance to most of antimicrobial agents and no clone spread in found in them.