耐碳青霉烯类大肠埃希菌产碳青霉烯酶基因型和同源性检测及分析

Detection and analysis of genotype and homology of carbapenem-resistant Escherichia coli with carbapenemase production

目的检测并分析耐碳青霉烯类大肠埃希菌(CRECO)产碳青霉烯酶基因型及其同源性。方法对2020年湖北省十堰市3家三甲医院临床分离的31株CRECO采用MALDI-TOF质谱仪进行菌种再鉴定,K-B纸片扩散法和E test条复核药敏结果,得到23株CRECO。采用碳青霉烯类药物的协同试验初筛产碳青霉烯酶基因型,PCR法检测8种常见碳青霉烯酶基因型并对阳性产物测序,用肠杆菌科基因间重复一致序列(ERIC)PCR法检测其同源性。结果23株CRECO中,9株产NDM-5酶,6株产KPC-2酶,2株产IMP-4酶。产碳青霉烯酶的大肠埃希菌大多从呼吸系统标本中分离出,多数来自呼吸重症病房,大多数为70岁以上老年患者,且患者经历过机械辅助通气、留置尿管或外科手术等侵入性操作。23株CRECO只对少数几种抗生素(阿米卡星、庆大霉素、复方新诺明)耐药率较低。同源性分析结果显示,本地区CRECO分7型,未见覆盖本地区的优势型别。结论十堰地区CRECO耐药机制复杂,产酶基因型主要是NDM-5和KPC-2基因,菌株对多种抗生素耐药。未发现本地区的克隆菌株爆发流行。

Objective To detect the genotypes and the homology of carbapenem-resistant Escherichia coli(CRECO)with carbapenemase production.Methods A multi-center study was conducted on 31 CRECO strains clini⁃cally isolated in 2020 from 3 Three-A hospitals in a certain area.The MALDI-TOF mass spectrometer was used to re-identi⁃fy the strains.After the K-B disc diffusion method and E test strips reviewed the drug sensitivity results,23 CRECO strains were obtained.The collaborative test of carbapenem drugs was used to initially screen the enzyme genotypes.Poly⁃merase chain reaction(PCR)was used to detect 8 common carbapenemase genotypes and the positive products were se⁃quenced.Finally,the homology was detected by enterobacterial repetitive intergenic consensus-polymerase chain reaction(ERIC-PCR).Results Among 23 CRECO strains,9 strains produced NDM-5 enzyme,6 strains produced KPC-2 en⁃zyme,and 2 strains produced IMP-4 enzyme.Most patients with drug resistance genes were elderly male patients who un⁃derwent invasive procedures and antibiotic treatment.The 23 CRECO strains had low resistance rates to a few antibiotics(amikacin,gentamicin,or compound sulfamethoxazole).The result of homology analysis showed that there were 7 types of CRECO in this region,and no dominant type covering this region was found.Conclusions The resistance mechanism of CRECO in this area is complex,and the enzyme-producing genotypes are mainly NDM-5 and KPC-2 genes.The strains are resistant to many antibiotics.No outbreak of cloned strains in this area has been found.