The Characteristics Of Antimicrobial Resistance And Resistant Genes Of Salmonella Enteritidis Isolates

Salmonella enterica serovar Enteritidis(S.Enteritidis)is an important food-borne pathogen that can cause gastroenteritis in human and animals,despite substantial efforts to prevent foodborne salmonellosis in developed countries,incidence of human illness has remained constant.Since the 1980s,find S.Enteritidis resistance against many conventional antimicrobials,such as ampicillin and chloramphenicol.Emergence of different antimicrobials resistance mechanisms adds another important dimension to the challenge of S.Enteritidis control.The widely use of fluorquinolone in human and animals has led to significantly incresasing resistance to quinolones,especially with the emergence of the plasmid-mediated quinolone(PMQR)genes.In order to monitor the trends in the occurrence of antimicrobial resistance and antimicrobial genes in S.Enteritidis,we described the prevalence and resistance genes in S.Enteritidis isolates,361 S.Enteritidis isolates from various sources were tested for their susceptibility to 18 antimicrobials using MIC.Moreover through the whole genome sequencing technology won the 63 strains of S.Enteritidis major resistance genes,analyzed the resistance genotype and its correlation with phenotype to explain the feasibility that whole genome sequencing technology in the prediction of resistant phenotype.1 The characteristics of antimicrobial resistance in S.Enteritidis isolates in terms of sourceThe antimicrobial susceptibility of S.Enteritidis isolates was assessed by tests performed in 2009 and 2016.MICs of S.Enteritidis isolates to 18 antimicrobial agents were determined by using the broth micro dilution method.Resistance to NAL was most common and was observed in 83.4%(MIC50=512?g/mL).The next was AMC(60.1%)and AMP(60.1%),The isolates were less frequently resistant to MEM(0.5%)and NIT(0.8%).Resistance to CFZ,TET and STR were detected with more than 28%.However,no resistant strain resistance to AMK.This study illustrates that antimicrobial resistance of S.Enteritidis strains with source and production are closely linked.In the S.Enteritidis isolates from poultry,show the highest resistance levels were found against TET(26.0%)and STR(40.7%).In addition,in terms of production process and breeding process isolates have a high resistance in 18 antibacterial agents.For the incubation process isolates,AMP,AMC,STR,NAL showed the highest levels of resistance.The multiple-drug resistance results of S.Enteritidis isolates indicated that 58.4%of strains resistant to at least three of antibacterial agents,resistant to 3 or 4 kinds of antimicrobials accounted for 16.6%and 24.4%.The mltiple-drug resistant strains in different source showed different.S.Enteritidis isolates from the production multiple-drug resistante were up to 69.2%,followed by breeding process multiple-drug resistant rate of 60.2%.Quinolone-resistant S.Enteritidis isolates were screened for presence of PMQR determinants by PCR.The assay showed that 6.9%of 361 isolates were positive for PMQR,Respectively,1.9%isolates were positive for aac(6')-Ib-cr and 0.8%were positive for oqxAB.2 Predicting the resistance genes of S.Enteritidis isolates based on whole genome sequencesThe aim of this study was to evaluate the correlation between antimicrobial resistance and antimicrobial genes,identification of antimicrobial genes in whole genome sequence data.All of 63 isolates had the mdtK,emrA,marA,H-NS,acrR,mdsB,robA,sdiA,ileS,acrB-TolC,mdtG,emrD,mdfA.Morever beta-lactam antimicrobials resistant gene proportion is higher.21 kinds of resistance genes,included aminoglycosides resistance genes aph(3")-Ib,cysB,alaS,aac(3)-?c,aadA11,aph(6)-Id;P-lactams resistance genes blaCTX-M-55,blaTEM-145,blaTEM-94,blaCTX-M-3,blaOXA-1,blaTEM-190,blaTEM-1;sulfonamides resistance genes sull,dfrA25,dfrAl,sul2,dfrA17;tetracyclines resistance genes tetC,tetA;chloramphenicol resistance genes catB3,the genotype of chloramphenicol was in concordance with the phenotype and the coincidence rate was 100%.Of the isolates tested,there are 6 species associated with aminoglycoside resistance genes,16 strains at the same time have cysB,alaS,baeR and baeS,phenotypic and genotypic correlation was 33.3%-85.0%for STR,phenotypic and genotypic coincidence rate was 100%for AMP,AMC,CFZ,and 85.7%for TET.19 isolates resistant to SXT had the gene sul2 and dfrAl,dfrA17 coincidence rate was 100%.