临床分离碳青霉烯类耐药肠杆菌目细菌菌株的分子流行病学及碳青霉烯酶抑制剂增强试验的应用

Molecular epidemiology of clinical isolation of carbapenem-resistant Enterobacterales and application of carbapenemase inhibitor enhancement test

目的:碳青霉烯类耐药肠杆菌目细菌(carbapenem-resistant Enterobacterales,CRE)的流行已成为临床抗感染治疗的巨大挑战。本研究探讨本地区CRE耐药情况及分子流行病学特征,并评估碳青霉烯酶抑制剂增强试验在临床实验室的应用价值,旨在为临床合理使用抗菌药物提供依据。方法:收集中南大学湘雅医院临床标本中分离的非重复性CRE,最低抑菌浓度(minimum inhibitory concentration,MIC)联合纸片扩散法(Kirby-Bauer,KB)检测菌株的药物敏感性,PCR方法检测13种碳青霉烯酶基因。使用碳青霉烯酶抑制剂增强试验对126株经PCR确定为产碳青霉烯酶的菌株进行表型检测,了解该方法与金标准PCR结果的符合程度。结果:704株CRE呈现出高度耐药的情况,经检测,501株为产碳青霉烯酶的肠杆菌目细菌(carbapenemase producing Enterobacterales,CPE);CPE菌株以肺炎克雷伯菌为主,其次为阴沟肠杆菌和大肠埃希菌;碳青霉烯酶有9种,包括肺炎克雷伯菌碳青霉烯酶(Klebsiella pneumoniae carbapenemase,KPC)、新德里金属β-内酰胺酶(New Delhi metallo-β-lactamase,NDM)、维罗纳整合子金属酶β-内酰胺酶(Verona integronencoded metallo-β-lactamases,VIM)、亚胺培南酶(imipenemase,IMP)、苯唑西林酶48型(oxacillinase-48,OXA-48)以及罕见的亚胺培南水解β-内酰胺酶(imipenem-hydrolyzingβ-lactamase,IMI)、阿德莱德亚胺培南酶(adelaide imipenemase,AIM)、圭亚那超广谱β-内酰胺酶(guiana extended-spectrumβ-lactamase,GES)和Bicêtre碳青霉烯酶(bicêtre carbapenemase,BIC),KPC型丝氨酸酶检出率最高,为61.7%(309/501);碳青霉烯酶抑制剂增强试验检测单产A类丝氨酸碳青霉烯酶、单产B类金属酶以及同时产A类和B类酶菌株的符合率均为100%。结论:湖南省长沙市CRE菌株分布非常广泛,产碳青霉烯酶(特别是KPC型丝氨酸酶)是这类细菌对碳青霉烯类药物耐药的主要机制。在湖南省长沙市首次检出了肠杆菌目细菌携带GES、IMI型基因。碳青霉烯酶抑制剂增强试验结果显示该方法能准确检测产A类丝氨酸酶和B类金属酶的CRE,且操作简单、结果容易判读,能满足临床微生物实验室丝氨酸碳青霉烯酶和/或金属酶检测的需求,为临床精准用药提供依据。

Objective:The prevalence of carbapenem-resistant Enterobacterales(CRE)presents a significant challenge in clinical anti-infective treatment.This study aims to investigate drug resistance and the molecular epidemiological characteristics of CRE in our area.Additionally,we seek to evaluate practicality of utilizing carbapenemase inhibitor enhancement test in clinical laboratory.Methods:Non-repeated CREs isolated from clinical specimens at Xiangya Hospital,Central South University,were collected.Minimum inhibitory concentration(MIC)combined with Kirby-Bauer(KB)assay was used to detect the drug susceptibility of the strains,and 13 carbapenemase-producing genes were detected by PCR.The phenotype of 126 strains of carbapenemase-producing Enterobacterales identified by PCR was detected by the carbapenemase inhibitor enhancement test to understand the agreement between the method and the gold standard PCR results.Results:Among 704 CRE strains examined,we observed significant drug resistance in 501 strains dentified as carbapenemase-producing Enterobacterales(CPE).Klebsiella pneumoniae was the predominant CPE strain,followed by Enterobacter cloacae and Escherichia coli.A total of 9 carbapenemase types were detected,including Klebsiella pneumoniae carbapenemase(KPC),New Delhi metallo-β-lactamase(NDM),Verona integron-encoded metallo-β-lactamases(VIM),imipenemase(IMP),oxacillinase-48(OXA-48),and rare imipenem-hydrolyzingβ-lactamase(IMI),adelaide imipenemase(AIM),Bicêtre carbapenemase(BIC),and guiana extended-spectrumβ-lactamase(GES).The detection rate of KPC serine carbapenemase was 61.7%(309/501).The carbapenemase inhibitor enhancement test exhibited a 100%consistency rate for the strains producing Class A serine carbapenemase and/or Class B metallo-β-lactamases.Conclusion:CRE strains in Changsha,Hunan,China,are wide distribution and exhibit carbapenemase production.The main mechanism of carbapenem resistance in these bacterias is predominatly attributed to the production of KPC serine carbapenemase.The presence of GES and IMI genes carried by Enterobacterales has been detected for the first time in this region.The carbapenemase inhibitor enhancement test has been proven to be an accurate method for detecting CRE producing Class A serine carbapenemase and/or Class B metallo-β-lactamases.This method offers simpicity of operation and ease of results interpretation,making it weel-suited meeting the clinical microbiology laboratory’s reguirements for the detection of serine carbapenemase and metallo-β-lactamases.