山东省部分健康猪和病死猪源沙门菌血清型、耐药基因及基因型分析OA

In order to investigate the distribution of serotypes,antibiotic resistance genes and genotypes of Salmonella isolated from healthy and dead pigs in Shandong Province,375 swine anal swab and lymph node samples were collected from farms,slaughterhouses and rendering plants to isolate and identify Salmonella.The isolates were detected for ESBLs phenotype by K-B disk diffusion susceptibility test,for serotypes,15 antibiotic resistant genes and MLST distribution by PCR,and for identification of genetic relationships between S.typhimurium and monophasic variant(S.1,4,[5],12:i:-)by PFGE.The results showed that 48 Salmonella strains(12.80％)were isolated,most from dead pigs(24/135,17.78％)and lymph node samples(44/255,17.25％).8 serotypes were identified,dominated by monophasic variant of S.typhimurium and S.rissen in both healthy and dead pigs,but S.enteritidis was only isolated from the latter.A total of 9 ST types were identified,dominated by ST 11(10/24,41.67％),ST34(5/24,20.83％)and ST469(5/24,20.83％)in Salmonella isolates from dead pigs,but ST34(6/24,25.00％),ST469(6/24,25.00％)and ST 19(5/24,20.83％)in those from healthy pigs.Furthermore,13 PFGE spectrotypes were identified from 18 isolates of S.typhimurium and its monophasic variant,and different between those derived from dead and healthy pigs.The detection rates of resistance genes qnrA,blaSHV,blaTEM-1 and tetA were all over 60％,among which that of blaSHV was higher in isolates from dead pigs than in those from healthy pigs,while those of sul Ⅱ,tetA and aacC3 were higher in isolates from healthy pigs than in those from dead pigs.There were 7 strains of ESBLs-producing Salmonella carrying both β-lactam and quinolone resistance genes,3 and 4 were from healthy and dead pigs,respectively.In conclusion,the predominant serotypes and molecular types of Salmonella isolates from healthy and dead pigs were different,characterized by polymorphism as well as complex and diverse antibiotic resistance gene spectrum.Therefore,porcine Salmonella and its antimicrobial resistance should be further monitored in Shandong Province,with a view to providing more evidence for effective control and eradication of Salmonella,as well as for guiding prudent use of drugs in practice.