Drug Resistance Of Salmonella Spp Isolated From Patients And Characteristic Of Its Plasmid

PrefacesSalmonella is a pathogenic bacteria from food which endanger the health of people.Generally cause typhoid,gastroenteritis,bacteremia and Chronic carrying condition in body.Differents of prevalence and resistance of bacteria often existed in Different areas.Rutine monitor and deep-going Survey is necessary.Our study collected Salmonella isolated from patients of shengjing hospital and large hospital in liaoning province between 2009-2013.Serotype of isolates,detecting of resistance phenotype,PFGE analysis,summarize of patients data,detecting resistance gene of isolates and investigation of plasmid characteristic has been used,to interpret the Salmonella spp on our region.By means of the study,we want to provide significant materials for prevent and threapy of the disease.Methods1、Collection,Culture,Identify,Detect resistant phenotype and PFGE（1）From January 2009 to March 2014,172 isolates was collected.Diverse specimen was cultured in different methods.Bacteria which is suspected were identitied by biochemical test.Serotype been confirmed through serum agglutinate and induce tests.（2）Resistance of Cephalosporin,Fluoroquinolones and other drugs has been detected by means of disk-diffusion and agar dilution.Resistance level of every drugs has been calculated.Special resistance type,such as ACSS_UT,also been added up.（3）homology of same serotype Salmonella has been compared with standard Pulse Net programme.ATCC BAA-664（H9812）is quality control.2、Study of resistant gene induced by plasmid and characteristic of plasmid（1）Isolate resistant to Cephalosporin was selected.Resistant gene related to ESBL(bla _CTX-M、bla_TEM、bla_SHVand bla _OXA)has been detected by PCR and sequence.（2）Isolate resistant to Fluoroquinolones was selected.Resistant gene（qnr A、qnr B、qnr S and aac（6′）-Ib）has been detected by PCR and sequence.（3）Extract the large plasmid through appropriate method.Size and number of plasmids has been estimated by S1-PFGE.Conjugate trial has been made to assessed the the capcity of Conjugate.Results1、Investigation of epidemiology and resistance of Salmonella.（1）S.enteritidis,1,4,[5],12:i:–and S.typhimurium is the fiest three serotypes in all Salmonella.60%of all isolates from children under 3 years.Blood and stool is the main specimen resource.（2）There is no significance difference about lead to Invasive Salmonella Infection（ISI）in S.enteritidis,S.choleraesuis and S.typhi.But significance difference exist in three serotypes and 1,4,[5],12:i:–and S.typhimurium.Higher probability lead to ISI in S.enteritidis,S.choleraesuis and S.typhi.（3）4-9%resistance rate was been found in Cephalosporin.（4）83%resistance rate exist in nalidixic acid.All S.choleraesuis resistant to Ciprofloxacin and Levofloxacin.No significance difference exist in S.enteritidis,1,4,[5],12:i:–and S.typhimurium non-susceptibility rate（82-94%）to Ciprofloxacin and Levofloxacin（comparative in every two serotype）.（5）Isolate rate of S.choleraesuis,S.typhimurium and 1,4,[5],12:i:–with ACSS_UT resistant type is 75%、62%and 38%.There is no significance difference in three serotypes.But significance difference exist between three serotypes and S.enteritidis.Similarly,same results be found in resistant type statistics of≥3 major clinical antibiotic resistante.Isolate rate of S.choleraesuis,S.typhimurium and1,4,[5],12:i:–is 100%、46%and 31%.（6）According to Standard of 80%similarity,almost all serotype Salmonella from same originate.2、Study of resistant gene and characteristic of plasmid（1）14 bla _CTX-M genes has been detected in 15 Cephalosporin resistant isolates.bla _CTX-M-55 is the most,and found the bla _CTX-M-65 in Salmonella from humen for the first time in the world.bla _TEM-1 in 14 isolates.bla _SHV in none.Only one bla _OXA-1 has been detected.However,bla _TEM-1 and bla _OXA-1 is no relationship with Cephalosporin resistant（2）All Salmonellas in our study has been tested the Fluoroquinolones resisitant gene.1 qnr S1,1 qnr B6 and 2 qnr B4 like genes has been found.aac（6’）-Ib-cr was discovered in 20 isolates.Point mutation no significance existed in all qnr B and aac（6′）-Ib-cr gene.Point mutation lead to amino acid exist in qnr B4-like gene,indected the new qnr B gene has been found.（3）2-5 plasmids was found in Salmonella resisitant to Cephalosporin.there is 2lardge plasmids in most isolates,which is 35～50Kb and 100～135Kb.Conjugate rate was 66.7%.MIC of transconjugate to Ceftaxime lower compared with donor.Conclusion1、Easier lead to Invasive Salmonella Infection（ISI）in S.enteritidis,S.choleraesuis and S.typh icompared with 1,4,[5],12:i:–and S.typhimurium.Serious resisitance to classical first-line antimicrobial in 1,4,[5],12:i:–,S.typhimurium and S.choleraesuis.High resistance rate be found in Quinolones,careful use of the drug is necessary.Extended-spectrum Cephalosporin is the first choice of treating infection of Salmonella.2、bla_CTX-Mgene carry on large plasmid is the main reasons result in the resistant of Extended-spectrum Cephalosporin.bla _CTX-M-55is the most common gene.bla _CTX-M-65 has been found in Salmonella from patient in the first time in the world.3、aac（6′）-Ib-cr gene is the main one in Quinolones resistence gene mediated by plasmid,result in the resistance of ciprofloxacin and levofloxacin.Point mutation no significance existed in all qnr B and aac（6′）-Ib-cr gene.Point mutation lead to amino acid exist in qnr B4-like gene,indected the new qnr B gene has been found.