耐碳青霉烯类肠杆菌目细菌耐药性、临床感染特征及mcr基因分析

 目的 分析耐碳青霉烯类肠杆菌目细菌(CRE)临床感染特征及耐药机制,为临床防治CRE感染提供参考。方法 收集2021年7月—2022年6月某三甲医院临床分离的CRE菌株及患者资料,采用聚合酶链反应(PCR)检测菌株耐药基因,诱导试验验证mcr-9阳性菌株的诱导耐药性。结果 共纳入167株CRE,以肺炎克雷伯菌(38.9%)和阴沟肠杆菌(35.3%)为主,呈现多重耐药表型,3株(1.8%)对多粘菌素B耐药。CRE以携带bla_NDM(52.1%,87株)为主,其次为bla_KPC(34.7%,58株)。根据碳青霉烯酶将CRE感染患者分为NDM组和KPC组。单因素分析结果显示,在入住ICU日数≥7d、行气管插管、感染前使用碳青霉烯类药物等影响因素方面,KPC组高于NDM组,治愈率低于NDM组(均P<0.05)。多因素logistic回归分析结果显示,置入胃管、肺部疾病及恶性肿瘤为影响携带不同碳青霉烯酶基因CRE感染患者预后的独立危险因素(P<0.05)。多粘菌素B耐药菌株均为mgrB点突变,7株(4.2%)CRE携带mcr-9,且多数同时携带bla_NDM。经多粘菌素B诱导后,4株mcr-9阳性CRE的MIC值较诱导前升高。结论 该地区CRE以携带bla_NDM、bla_KPC为主,少数同时携带mcr-9和bla_NDM,呈现多重耐药。临床应加强防控,预防其临床传播。

Antimicrobial resistance,clinical infection characteristics and mcr genes of carbapenem-resistant Enterobacterales

Objective To analyze the clinical infection characteristics and resistance mechanisms of carbapenem-resistant Enterobacterales (CRE), provide reference for clinical prevention and treatment of CRE infection. Methods Clinically isolated CRE strains and patients information in a tertiary first-class hospital from July 2021 to June 2022 were collected. Antimicrobial resistance genes were detected by polymerase chain reaction. Induced antimicrobial resistance of mcr-9 positive strains was detected by inducing test. Results A total of 167 CRE strains were collected, mainly Klebsiella pneumoniae (38.9%) and Enterobacter cloacae (35.3%). CRE strains demonstrated multiple drug resistance phenotype, with 3 strains (1.8%) exhibiting polymyxin B resistance. Most CRE strains harboured bla_NDM (52.1%, n=87) and bla_KPC (34.7%, n=58). Patients with CRE infection were divided into NDM group and KPC group according to carbapenemase. Univariate analysis showed that in terms of influencing factors as stay in ICU ≥7 days, endotracheal intubation, and use of carbapenems before infection, KPC group was higher than NDM group, however, curing rate was lower than NDM group (P<0.05). Multivariate logistic regression analysis showed that gastric intubation, pulmonary diseases and malignant tumor were independent influencing factors for the prognosis of patients with CRE infection of different carbapenemase genes (P<0.05). Polymyxin B resistant strains all carried mgrB point mutation. 7 (4.2%) CRE strains harboured mcr-9, most of which also harboured bla_NDM. MIC values of 4 mcr-9 positive CRE strains after polymyxin B induction were higher than those before induction. Conclusion CRE in this area mainly harbour bla_NDM and bla_KPC, and a few also harbour mcr-9 and bla_NDM, showing multiple drug resistance. Clinical prevention and control should be strengthened to prevent its clinical transmission.