陕西食源性沙门氏菌耐药及相关基因

Antimicrobial susceptibility and related genes of Salmonella serovars from retail food in Shaanxi Province

摘要:

摘要：【目的】研究食源性沙门氏菌对常用抗生素的药敏性及相关耐药基因，更好的了解耐药性的产生和传播途径，确保食品安全。【方法】使用the Clinical and Laboratory Standards Institute推荐的琼脂稀释法测定沙门氏菌的药敏性，PCR和基因序列测定方法确定耐药沙门氏菌中整合子及其携带的耐药基因、与头孢菌素抗性相关的基因、沙门氏菌基因岛及与氟喹诺酮类抗生素耐药相关的基因突变。【结果】359株沙门氏菌中，67%的菌株对磺胺甲恶唑产生抗性，对甲氧苄啶/磺胺甲恶唑、四环素、卡那霉素、萘啶酮酸、氨苄西林、阿莫西林/克拉维酸、链霉素、氯霉素和庆大霉素、环丙沙星、头孢曲松、头孢西丁和头孢哌酮的耐药率分别为58%、56%、37%、35%、33%、32%、29%、26%、21%、16%、 9%和8%。284株耐药菌中，79%的菌株可抗至少1种抗生素，25.9%可抗10种以上抗生素，2.5%可抗14种抗生素。耐药的Ⅰ类整合子以1.4 kb最为常见，携带的耐药基因有aadA1、aadA2、aadA5、tetR、blaPSE-1、blaDHA-1、blaVEB-1、dhfrⅠ、dhfrⅤ、dhfrⅦ和dhfr17等。62株耐头孢曲松和/或头孢哌酮的沙门氏菌中，blaTEM和blaCMY-2基因的检出率分别为51.6%和56.5%。13.6%的沙门氏菌中检出了沙门氏菌基因岛。35株耐氟喹诺酮类抗生素的沙门氏菌的gyrA、parC 和parE基因中共检出68个点突变，gyrA基因中常见突变为Ser83Phe、Ser83Tyr、Asp87Gly和Asp87Asn，parC基因中为Ser80Arg。parE基因中检出了Lys441Ile、Lys428Gln、Asp494Asn、Lys428Gln和Gly442Ser突变，这些点突变均为首次在食源性沙门氏菌中检出。【结论】陕西食源性沙门氏菌耐药状况严重，整合子、沙门氏菌基因岛和β-内酰胺酶编码基因的存在及解旋酶和拓扑异构酶基因突变是导致沙门氏菌耐药的重要机制。

Abstract:

Abstract: [Objective] Salmonella isolates from retail food were examined for antimicrobial susceptibility and further characterized to better understand the development and dissemination of antimicrobial resistance among foodborne Salmonella in China. [Methods] Antimicrobial susceptibility of 359 Salmonella isolates was determined by using agar dilution methods recommended by the Clinical and Laboratory Standards Institute. Antimicrobial resistance integrons and resistance genes were identified using PCR. Mutations in gyrase and Topoisomerase genes related to fluoroquinolones resistance were also determined using PCR and gene sequencing analysis. [Results] Among the 359 Salmonellae isolates, 67% were resistant to Sulfamethoxazole, followed by resistant to trimethoprim/Sulfamethoxazole (58%), tetracycline (56%), kanamycin (37%), nalidixic acid (35%), ampicillin (33%), amoxicillin/clavulanic acid (32%), streptomycin (29%), chloramphenicol and gentamicin (26%), ciprofloxacin (21%), ceftriaxone (16%), cefoxitin (9%) and cefoperazone (8%). Among the 284 resistant isolates, 79% were resistant to at least one antimicrobial, 25.9% to 10 or more than 10 antimicrobials, and 2.5% to 14 antibiotic agents. Integrons were detected in some of sulfamethoxazole-ressitant Salmonella, and the most common integron was 1.4 kb, Antimicrobial resistance genes carried by integrons included aadA1, aadA2, aadA5, tetR, blaPSE-1, blaDHA-1, blaVEB-1, dhfrⅠ, dhfrⅤ, dhfrⅦ and dhfr17. The blaTEM gene was also detected in 51.6% of 62 ceftriaxone and / or cefoperazone resistant isolates, and blaCMY-2 was detected in 56.5% of the isolates. 13.6% of the Salmonella isolates carried Salmonella Gene Island. Sixty-eight point mutations were detected in gyrA, parC and parE of 35 fluoroquinolone-resistant Salmonella isolates. The common mutations in gyrA gene were Ser83Phe, Ser83Tyr, Asp87Gly and Asp87Asn, whereas ser80Arg was detected in parC. Mutations including Lys441Ile, Lys428Gln, Asp494Asn, Lys428Gln and Gly442Ser were detected in parE, which was first reported in Salmonella. [Conclusion] Antimicrobial resistance of Salmonella recovered from food in Shaanxi province was common. Several genetic elements including integron, Salmonella Gene Island, β-lactamase genes and mutations in gyrase and topoisomerase genes played an important role in antimicrobial resistance of Salmonella.