浙江和上海地区生产及零售端鸡肉源沙门氏菌特性研究

对2016年7—10月采集自浙江和上海部分地区肉鸡屠宰端、零售端鸡肉样品及屠宰场环境样品中的沙门氏菌进行分离,研究102株分离株的血清型及其对常用抗生素的药敏性。使用世界卫生组织(world health organization,WHO)指定的泰国S&A公司沙门氏菌诊断血清,采用玻片凝集法确定沙门氏菌的血清型。使用临床实验室标准化委员会(clinical laboratory standard institute,CLSI)推荐的纸片扩散法测定沙门氏菌的药敏性。研究发现,204份样品中,85份检出沙门氏菌,阳性样品平均检出率为41.67%。脱羽、净膛、清洗、包装、整鸡和预冷检出率依次降低,而冷藏检出率回升到70.00%。102株沙门氏菌共涵盖15个血清型,以德尔卑沙门氏菌(Salmonella Derby,23.53%)、阿贡纳沙门氏菌(Salmonella Agona,17.65%)、印第安纳沙门氏菌(Salmonella Indiana,12.75%)、鼠伤寒沙门氏菌(Salmonella Typhimurium,11.76%)和达布沙门氏菌(Salmonella Dabou,7.84%)较为常见。屠宰端德尔卑沙门氏菌最为流行,零售端则主要为阿贡纳沙门氏菌。所有菌株对阿莫西林/克拉维酸和头孢西丁敏感,75株(73.53%)菌对四环素产生抗性;对氯霉素、氨苄西林、萘啶酮酸、甲氧苄啶/磺胺甲噁唑、链霉素、环丙沙星、头孢曲松、头孢哌酮、卡那霉素、庆大霉素和阿米卡星耐药的菌株比例分别为49.02%、41.18%、38.24%、37.25%、28.43%、23.53%、22.55%、22.55%、20.59%、19.61%和17.65%。零售端样品源沙门氏菌对大部分供试抗生素的抗性显著低于屠宰端和环境样品源沙门氏菌。102株菌中,97株(95.10%)可抗至少1种抗生素,17株(16.67%)可抗10种或10种以上的抗生素。不同地区采集的样品中,源于绍兴的样品沙门氏菌检出率最高(78.95%),且极显著高于湖州及上海地区的阳性样品检出率(P<0.01)。沙门氏菌阳性样品在不同月份的检出率存在极显著差异,9月份检出率最高(80.00%)。研究结果表明,在整个肉鸡生产消费链条中,沙门氏菌检出率、血清型和耐药率、耐药谱呈现明显的变化,即沙门氏菌不是单纯来源于该批次肉鸡携带菌,各环节固有存在和人员携带的菌株也加入了其中,造成终端产品的现状。本研究揭示了沙门氏菌在鸡肉产品中分布的状况和来源,为采取合理的干预措施,预防该省肉鸡生产全产业链中沙门氏菌的污染及耐药菌的出现、确保食品安全提供了相应的数据和理论支持。

Characterization of Salmonella isolates recovered from processing chicken,retail chicken and chicken processing environment in Zhejiang and Shanghai

One hundred and two Salmonella isolates recovered from processing chickens, retail chickens and environment of chicken processing slaughterhouses that collected in Zhejiang and Shanghai during July to October in 2016 were characterized to determine their prevalence, serotype and antimicrobial susceptibility. Serotype of Salmonella was determined via slide agglutination method using Salmonella hyperimmune sera, the antimicrobial susceptibility was tested by disk diffusion method that recommended by the clinical laboratory standard institute (CLSI). Among 204 samples, 85 samples were tested positive to Salmonella. 32 samples collected from processing chickens were positive to Salmonella, the highest rate of Salmonella positive samples was identified in the cold storage section with the ratio of 70.00%. A total of 15 serotypes were identified among the 102 Salmonella isolates. The most common five serotypes were S.Derby (23.53%), S. Agona (17.65%), S. Indiana (12.75%), S. Typhimurium (11.76%) and S. Dabou (7.84%). S. Derby was tested most prevalent in processing chickens while S. Agona was the most commonly found in retail chickens. All isolates were sensitive to amoxicillin/clavulanate and cefoxitin. Seventy five (73.53%) were resistant to tetracycline, followed by to chloramphenicol (49.02%), ampicillin (41.18%), nalidixic acid (38.24%), sulfamethoxazole/trimethoprim (37.25%), streptomycin (28.43%), ciprofloxacin (23.53%), ceftriaxone (22.55%), cefoperazone (22.55%), kanamycin (20.59%), gentamycin (19.61%) and amikacin (17.65%). Salmonella isolates in retail chickens showed significantly lower resistance to most tested antibiotics than those from processing chickens and slaughterhouse environment. Among 102 Salmonella isolates, 97 (95.10%) were resistant to at least one antibiotic, and 17 (16.67%) to 10 or more than 10 antimicrobials. Among all sampling places, Salmonella positive samples were investigated most prevalent in Shaoxing (78.95%), where the rate of Salmonella positive samples was significantly higher than those in Huzhou and Shanghai. The rates of Salmonella positive samples were found significantly different (P<0.01) in different sampling months, and it was found most prevalent (80.00%) in September. In the whole chicken production and consumption chain, the positive rate, serotype, antibiotic resistance rate, and antibiotic resistance phenotype of Salmonella isolates showed significant changes. Salmonella was not only derived from the chickens carrying bacteria in the batch, but also in various links and carried by the personnel also joined, resulting in the status of the terminal products. Prevalence of Salmonella in processing and retail chickens in Zhejiang and Shanghai was common. Chickens in processing, especially in refrigeration stage were more easily contaminated by Salmonella. The serotype of Salmonella isolates was diverse, and these isolates were resistant to multi-antibiotics.