1株鸡源肠炎沙门氏菌的分离鉴定及致病性分析

【目的】确定云南某蛋鸡场送检的疑似沙门氏菌病病料中的主要病原菌种类,并测定其致病性及药物敏感性。【方法】通过细菌分离培养、形态观察、生化试验、血清学鉴定及分子学方法进行细菌分离鉴定;通过对鸡的致病性试验及毒力基因检测分析分离菌的致病性;通过药物敏感性试验检测分离菌耐药情况。【结果】分离菌株在沙门氏菌显色培养基上形成紫色菌落,镜检为革兰氏阴性短杆菌,疑为沙门氏菌,命名为S2;生化试验结果显示,菌株S2赖氨酸脱羧酶、硫化氢、卫矛醇试验结果均为阳性;靛基质、尿素酶、氰化钾、山梨醇、水杨苷、β-半乳糖苷、丙二酸盐生化试验结果均为阴性,判断菌株S2为典型沙门氏菌属;血清学鉴定结果显示,菌株S2属于D群肠炎沙门氏菌,其抗原式为1,9,12:g,m;遗传进化分析结果显示,菌株S2与肠炎沙门氏菌MT621365处于同一分支,自展值为99%;致病性试验结果表明,分离菌株对雏鸡有较强的致病性,感染6 d后雏鸡全部死亡(10/10);毒力基因检测结果显示,菌株S2携带invJ、hilA、ssaB、misL、mgtC、orf319、sopB、spvA、spvB、spvC、spvR、stn和fimA毒力基因,不携带sopA、fliC毒力基因;菌株S2对多数抗菌药敏感程度很高,对阿莫西林-克拉维酸、头孢西丁、四环素等12种抗菌药均敏感,对甲氧嘧啶、复方新诺明和林可霉素耐药。【结论】本研究分离到了1株肠炎沙门氏菌,其毒力较强,可造成雏鸡较高的死亡率,对大部分常用抗菌药敏感,对甲氧嘧啶、复方新诺明和林可霉素具有耐药性。本研究结果可为沙门氏菌病的临床诊断和药物有效性评价提供一定参考依据。

Isolation,Identification and Pathogenicity Analysis of a Strain of Salmonella Enteritidis from Chicken

【Objective】 The purpose of the test was to determine the main pathogenic bacteria in the suspected Salmonella disease materials sent by a laying hens farm in Yunnan,and to determine their pathogenicity and drug sensitivity.【Method】 The strains were identified by bacterial isolation and culture,morphological observation,biochemical test,serological identification and molecular methods.The pathogenicity of the isolated bacteria was analyzed through the pathogenicity test of chicken and the detection of virulence genes.The drug resistance of strains was studied by antibiotic sensitivity test.【Result】 The isolated strain formed purple colony on the Salmonella chromogenic medium,and was Gram-negative Brevibacterium and suspected to be Salmonella,named S2.The results of biochemical test showed that the results of lysine decarboxylase,hydrogen sulfide and dulcite were positive,and indol,urease,KCN,sorbitol,salicin,β-galactoside and malonate were negative,and S2 was judged to be a typical Salmonella.The results of serological identification showed that S2 belonged to Salmonella Enteritidis group D,and its antigen formula was 1,9,12:g,m.The results of genetic evolution analysis showed that S2 and Salmonella Enteritidis MT621365 were in the same branch,and the self-development value was 99%.The results of pathogenicity test showed that the isolated strain had strong pathogenicity to chickens,and all chickens died after 6 days of infection (10/10).The results of virulence gene detection showed that S2 carried invJ,hila,ssaB,misL,mgtC,orf319,sopB,spvA,spvB,spvC,spvR,stn and fimA virulence genes,but did not carried sopA and flic virulence genes.The isolated strain S2 was highly sensitive to most antibiotics,and it was sensitive to 12 antibacterial drugs including amoxicillin-clavulanic acid,cefoxitin,tetracycline and so on,but it was resistant to methoxypyrimidine,compound sulfamethoxazole and lincomycin.【Conclusion】 A strain of Salmonella Enteritidis was isolated in this study.It had strong virulence which could cause high mortality of chickens,and it was sensitive to most commonly used antibiotics,but was resistant to methoxypyrimidine,compound sulfamethoxazole and lincomycin.This study provided a certain reference basis for the clinical diagnosis of salmonellosis and the evaluation of drug effectiveness.