Clonal Relationships,Antimicrobial Susceptibilities,and Molecular Characterization Of Multi-drug Resistant Escherichia Coli

objective: To investigate the distribution of extended-spectrum β-lactamase gene CTX-M,TEM,SHV and anti-disinfectant gene qacEΔ1,qacE;to analyze the relationship between genes and drug-resistant phenotypes;to analyze the molecular typing of Escherichia coli with ERIC-PCR.Methods: 1.Drug susceptibility test: The susceptibilities of E.coli isolates to antibiotics were determined in accordance with the standard Kirby–Bauer disk diffusion method of the Clinical and Laboratory Standards Institute(CLSI).E.coli ATCC 25922 was used for quality control.2.PCR: PCR technology was used to detect genes(CTX-M,TEM,SHV,qacEΔ1 and qacE).3.ERIC-PCR approach was used to investigate genetic similarity of Escherichia coli.The SPSS 22.0 software was performed for Cluster analysis.Results: 1.Results of susceptibility test: 1.1 The resistance of Escherichia coli: 71.01% isolates were multidrug-resistant.E.coli isolates showed the highest resistance to nalidixic acid(83.33%),followed by sulfamethoxazole(70.29%),cefuroxime(68.12%),streptomycin(63.04%),piperacillin(61.60%),norfloxacin(55.80%),ciprofloxacin(55.80%),gentamicin(46.38%),ceftriaxone(46.38%),cefotaxime(39.86%),levofloxacin(39.13%),aztreonam(28.26%),ceftazidime(16.67%),cefoxitin(2.90%),piperacillin/tazobactam(0.72%),Amikacin(3.62%).1.2 Detection of ESBLs-producing strains: 53.59% were positive for ESBLs in 138 E.coli isolates.2 Results of genes : 2.1 Detection of ESBLs resistance genes:The resistance gene CTX-M(57.25%,n=79),TEM(68.12%,n=94),and SHV(0.72%,n=1)were commonly present in 138 E.coli isolates.71.43% blaCTX-M positive strains,71.43% blaTEM positive strains,48.98% blaCTX-M+blaTEM positive strains were detected in the multi-drug resistant E.coli strain.The gene(blaCTX-M,blaTEM,blaCTX-M+blaTEM)was significantly associated with multi-durg resistance in all isolates(p<0.05).2.2 Detection of disinfectant resistance genes: The gene qacEΔ1(51.45%,n= 71)were commonly present in the 138 E.coli isolates,and no qacE gene was detected.Antibiotic resistance(sulfamethoxazole,nalidixic acid,norfloxacin,cefuroxime,ceftazidime,cefotaxime,ceftriaxone,ciprofloxacin,levofloxacin,gentamicin)were significantly associated with the presence of qacEΔ1 in all isolates(p<0.05).88.73% qacEΔ1 positive strains were detected in the multidrug-resistant.The qacEΔ1 gene was significantly associated with resistance pattern in all isolates(p<0.05).3.Results of ERIC: There were 2 to 7 bands of ERIC-PCR fingerprint amplification,and the products were distributed in 100 bp to 2500 bp;They were divided into 63 patterns.Based on 80% genetic similarity,they are clustered 43 types.There were three common types(E23,E24 and E27).Conclusion: 1.The drug resistance of Escherichia coli in this area is serious to frequently-used antibiotics,and multidrug-resistant is common;However,the sensitivity of Amikacin,beta-lactam antibiotics/ enzyme inhibitors,cephamycin and carbapenems are high.2.blaCTX-M and blaTEM are major ESBLs resistance genes,it is common that blaCTX-M and blaTEM simultaneously exist in multi-drug resistant strains.3.QacEΔ1 is common present,and it is closely related to multi-drug resistance.4.The drug resistance and gene carrying status of the same type strains are scattered in the type of infection and the distribution of the department.