泰州地区鸡胚源沙门氏菌的分离鉴定及耐药基因和毒力基因的检测

Isolation and identification of chicken embryo-derived salmonella in Taizhou area and detection of drug resistance genes and virulence genes

为探究泰州地区某规模化孵化场鸡胚源沙门氏菌的生物学特征,试验对临床疑似沙门氏菌感染的死亡鸡胚中的沙门氏菌进行选择性增菌和分离,并对分离菌进行革兰氏染色鉴定、特异性基因扩增、毒力基因检测、药物敏感试验和耐药基因检测。结果表明:共分离到6株细菌,在沙门氏菌显色培养基上均呈现紫色小菌落,均为革兰氏阴性菌,特异性基因扩增鉴定为鸡伤寒沙门氏菌;从6株菌中共检测出15种毒力基因,除均不携带sopE基因外,sipA、sopA、sopB、ssaB、mgtC、misL、siiE、pipC、stn、fimA基因携带率为100%(6/6),sipC、sseL基因携带率为83.3%(5/6),ssaR、spvB基因携带率为66.7%(4/6);6株菌对大部分抗生素敏感,仅对多西环素(66.7%,4/6)、林可霉素(100%,6/6)、阿奇霉素(83.3%,5/6)和多黏菌素B(83.3%,5/6)的耐药率高于50.00%,3重耐药率为83.3%(5/6),4重耐药率为66.7%(4/6),5重耐药率为16.7%(1/6),6重耐药率为0(0/6);从6株菌中共检测出5种耐药基因,其中tet(A)、tet(B)和Sul2基因检出率均为100%(6/6),bla_(SHV)基因检出率为83.3%(5/6),Sul1基因检出率为66.7%(4/6),bla_(KPC)、bla_(NDM)、bla_(CTX)、bla_(TEM)、aadA1、aadB、floR、qnrA、qnrB、qnrS、mcr-1基因均未检测出。说明分离到的6株鸡伤寒沙门氏菌表现为多重耐药且携带大量毒力基因,可能是引起该规模化孵化场鸡胚死亡的重要病原之一。

In order to explore the biological characteristics of chicken embryo-derived Salmonella in a large-scale hatchery in Taizhou area,in this experiment,Salmonella was selectively enriched and isolated from clinically dead chicken embryos infected with suspected Salmonella.Gram staining identification,specific gene amplification,virulence gene detection,drug susceptibility test and drug resistance gene detection were performed on the isolated bacteria.The results showed that a total of 6 bacteria were isolated,all of which showed small purple colonies on the chromogenic medium of Salmonella.All of them were Gram-negative bacteria,and were identified as Salmonella enterica subsp.enterica serovar Typhimurium by identification of specific gene amplification.A total of 15 virulence genes were detected from the 6 strains,except that none of them carried sopE gene;the carrying rate of sipA,sopA,sopB,ssaB,mgtC,misL,siiE,pipC,stn and fimA genes was 100%(6/6);the carrying rate of sipC and sseL genes was 83.3%(5/6);the carrying rate of ssaR and spvB genes was 66.7%(4/6).The 6 strains were sensitive to most antibiotics,and only the resistance rates to doxycycline(66.7%,4/6),Lincomycin(100%,6/6),azithromycin(83.3%,5/6)and polymycin B(83.3%,5/6)were higher than 50.00%.The 3-fold resistance rate was 83.3%(5/6);the 4-fold resistance rate was 66.7%(4/6);the 5-fold resistance rate was 16.7%(1/6),and the 6-fold resistance rate was 0(0/6).A total of five resistance genes were detected in 6 strains,in which all detection rates of tet(A),tet(B)and Sul2 genes were 100%(6/6);the detection rate of bla_(SHV) was 83.3%(5/6);the detection rate of Sul1 was 66.7%(4/6);bla_(KPC),bla_(NDM),bla_(CTX),bla_(TEM),aadA1,aadB,floR,qnrA,qnrB,qnrS,mcr-1 genes were not detected.The results suggested that the 6 isolated strains of Salmonella enterica subsp.enterica serovar Typhimurium exhibited multi-drug resistance and carried a large number of virulence genes,which might be one of the important pathogens causing the death of chicken embryos in this large-scale hatchery.