北京某医院感染性腹泻患者致泻性大肠埃希菌毒力和耐药特征分析

Analysis of virulence and drug resistance characteristics of diarrheagenic Escherichia coli isolated from patients with infectious diarrhea in a hospital in Beijing

目的明确本院感染性腹泻患者致泻性大肠埃希菌毒力和耐药特征。方法采用VITEK MS微生物质谱检测系统初步鉴定,多重实时荧光PCR检测毒力基因,对本院感染性腹泻患者临床分离的致泻性大肠埃希菌(Diarrheagenic Escherichia coli,DEC)进行5种型别鉴定。微量肉汤稀释法和E-test法药敏试验检测DEC菌株的耐药表型特征。二代测序及生物信息学分析其耐药分子特征。采用Fisher确切概率法进行统计学分析。结果本院DEC检出率为11.9%,其中EAEC占比37.5%,非典型EPEC占比34.38%,ETEC占比25.0%,EIEC占比3.12%,未检出EHEC菌株。32株DEC对氨苄西林、四环素、甲氨苄啶/磺胺异恶唑耐药率最高,分别为53.12%、43.75%和37.5%。ESBLs(+)株占比18.75%,其多重耐药菌株检出率为83.83%,显著高于ESBLs(-)菌株,差异有统计学意义(P=0.042)。32株DEC共有25个ST型,优势基因型为ST10共4株(12.5%),ST28、ST31和ST3153各2株(各占比6.25%),其他21个型别各1株菌(各占比3.13%)。EAEC中检出1株携带bla_(NDM-1)的耐碳青霉烯类菌株。结论我院感染性腹泻患者的DEC以aggR、pic、astA、eae 4种毒力基因较为常见,以EAEC、EPEC为主要型别,基因型别呈高度多态性,检出多重耐药菌株。

Objective To investigate the virulence and drug resistance characteristics of diarrheagenic Escherichia coli isolated from patients with infectious diarrhea in our hospital.Methods The preliminary identification of microbes was carried out by the VITEK-MS microbial mass spectrometry detection system and virulence genes were detected by the multiplex real-time PCR.Five types of diarrheagenic Escherichia coli(DEC)clinically isolated from patients with infectious diarrhea in our hospital were identified.The drug resistance characteristics of DEC strains were detected by the microbroth dilution and E-test.The drug-resistant molecular characteristics were analyzed by the next-generation sequencing and bioinformatics.The Fisher exact probability method was used for statistical analysis.Results The detection rate of DEC in our hospital was 11.9%,with enteroaggregative E.coli(EAEC)accounting for 37.5%,atypical enteropathogenic Escherichia coli(EPEC)accounting for 34.38%,enterotoxigenic E.coli(ETEC)accounting for 25.0%,and enteroinvasive E.coli(EIEC)accounting for 3.12%.None of enterohemorrhagic E.coli(EHEC)strain was detected.The resistance rates of 32 DEC strains to ampicillin,tetracycline,and trimethoprim/sulfamethoxazole were 53.12%,43.75%,and 37.5%,respectively.ESBLs(+)strains accounted for 18.75%,and the detection rate of multidrug-resistant strains was 83.83%,significantly higher than that of ESBLs(-)strains(P=0.042).A total of 25 ST genotypes were obtained from 32 DEC strains.The dominant genotypes were ST10(4 strains,12.5%),followed by ST28(2 strains,6.25%),ST31(2 strains,6.25%),ST3153(2 strains,6.25%),and the other 21 genotypes(1 strain,3.13%).One carbapenem resistant strain carrying the bla NDM-1 gene was detected in EAEC.Conclusion Four virulence genes such as aggR,pic,astA,and eae,are more common in the DEC of patients with infectious diarrhea in our hospital,with EAEC and EPEC as the main subtypes.The genotypes are highly polymorphic,and multidrug-resistant strains have been detected.