2015—2017年广西鸡源沙门氏菌耐药性与致病性的相关性分析

Correlation between antimicrobial resistance and pathogenicity of Salmonella from chicken in Guangxi during 2015-2017

【目的】明确鸡源致病性沙门氏菌耐药表型与致病性的相关性,为有效防控鸡沙门氏菌病提供科学依据。【方法】采用玻片凝集试验对55株鸡源沙门氏菌广西分离株进行血清型鉴定,以纸片扩散(K-B)法和PCR分别测定其耐药表型及耐药基因,通过小鼠攻毒试验检测其致病性,并分析鸡源沙门氏菌广西分离株耐药表型与致病性的相关性。【结果】55株沙门氏菌广西分离株以鼠伤寒沙门氏菌和鸡白痢沙门氏菌为主,对青霉素G、阿莫西林、苯唑西林、头孢噻吩、红霉素和利福平的耐药率均达100.00%,而对庆大霉素和大观霉素较敏感(耐药率在10.00%以下)。55株沙门氏菌广西分离株中有1株(占1.82%)携带7种耐药基因、6株(占10.91%)携带6种耐药基因、20株(占36.36%)携带5种耐药基因、12株(占21.82%)携带4种耐药基因、13株(占23.64%)携带3种耐药基因、3株(占5.45%)携带2种耐药基因;16种耐药基因中,blaTEM、tetX、sul3和aadA1基因检出率较高,qepA、blaCMY和tetB基因检出率较低,而qnrA、qnrB、Aph(3)-IIa、blaPSE和aadA2基因等未被检出。55株沙门氏菌广西分离株对昆明小白鼠均具有致病性,致死率为20%~100%;随机选取10株分离株对昆明小白鼠的半数致死量(LD50)为4.00×107~3.18×108 CFU/mL。沙门氏菌分离株耐药种类数量与LD50对数值的线性回归方程为y=-0.086x+8.971(R2=0.9329),耐药基因数量与LD50对数值的线性回归方程为y=-0.148x+8.673(R2=0.5748),即沙门氏菌的耐药性与其致病性呈正相关。【结论】2015—2017年从广西发病鸡分离获得的致病性沙门氏菌以鼠伤寒沙门氏菌和鸡白痢沙门氏菌为主,普遍存在耐药性,且多重耐药现象严重。鸡源致病性沙门氏菌的耐药表型与其致病性间呈正相关,因此,生产上要加强临床用药管理,加大细菌耐药监测与防范。

【Objective】The correlation between antimicrobial resistance and pathogenicity of Salmonella isolates from chicken were analyzed for supporting scientific bases of effective prevention and control of poultry Salmonella disease.【Method】The serotypes of 55 Salmonella Guangxi isolates from chicken were determined by tablet agglutination test.The paper diffusion K-B agar method was used to determine their resistant phenotype and PCR was used to detect the resistance genes.The pathogenic experiment in mice was used to determine their pathogenicity.The correlation between resistant phenotype of Salmonella Guangxi isolates from chicken and pathogenicity was also analyzed.【Result】The 55 Salmonella Guangxi isolates mainly consisted of S.typhimurium and S.pullorum.All of them were 100.00%resistant to penicillin G,amoxicillin,oxacillin,cefalotin,erythromycin and rifampicin,but were sensitive to entamicin and spectinomycin(resistance rate less than 10.00%).Of the 55 Salmonella Guangxi isolates,one strain(1.82%)contained seven resistant genes,six strains(10.91%)contained six resistant genes,twenty strains(36.36%)contained five resistant genes,twelve strains(21.82%)contained four resistant genes,thirteen strains(23.64%)contained three resistant genes and three strains (5.45%)contained two resistant genes. Of 16 kinds of resistant genes,blaTEM,tetX,sul3 and aadA1 had high positiverate,qepA,blaCMY and tetB had low positive rate,while qnrA,qnrB,Aph(3)-IIa,blaPSE and aadA2 were negative. Allthe 55 Salmonella Guangxi isolates were pathogenic to Kunming mice,and the mortality rate of them was 20%-100%.The median lethal dose(LD50)of 10 randomly selected isolates to Kunming mice was 4.00×107-3.18×108 CFU/mL. Thelinear regression equation between the numbers of drug resistant types and the logarithm values of LD50 was y=-0.086x+8.971(R2=0.9329),and the linear regression equation between the numbers of resistant genes and the logarithm values ofLD50 was y=-0.148x+8.673(R2=0.5748),which indicated that there existed positive relationship between antimicrobial resistanceand pathogenicity of salmonella isolates.【Conclusion】The pathogenic Salmonella isolates from Guangxi diseasedchicken during 2015-2017 mainly consist of S. Typhimurium and S. pullorum,and they commonly show resistance to antimicrobialsand their multi-drug resistance is serious. There exists positive correlation between resistance phenotype andpathogenicity of the chicken Salmonella isolates,so it is necessary to strengthen clinical drug administration and increasebacterial drug resistance monitoring and prevention.