摘要
      本研究调查了2018年6月至10月从中国河北省13个地区的超市和湿货市场采集的210份零售肉类样本（105只生鸡肉和105只生猪肉）中沙门氏菌的流行情况。对所有125个沙门氏菌分离株进行全基因组测序，以研究它们的遗传关系。对77个具有代表性的分离株进行了核心基因组多点序列分型，以进一步阐明从零售肉中分离的沙门氏菌之间的遗传相关性。
所有样本中沙门氏菌的平均检出率为59.5%（125/210）。鸡和猪肉中沙门氏菌的患病率分别为53.3%（56/105）和65.7%（69/105）。在7月份采集的鸡肉和猪肉样本中，沙门氏菌的检出率最高。分离株被分为19个血清型，其中德比链球菌、伦敦链球菌和汤普森链球菌是最常见的血清型。在89.6%的分离株中观察到对四环素（主要用于治疗细菌感染）的耐药性，84.0%的分离株对多西环素（也是一种四环素抗生素）或吉米沙星（常用于临床治疗人类急性支气管炎）有耐药性。80%以上的分离株具有多药耐药性。共鉴定出21种序列类型。序列型40（ST-40）是所有分离株中的主要基因型，仅在猪肉中发现；鸡分离株的序列类型更为多样。
在125个分离株中共检测到58个不同的抗生素抗性基因（ARGs）。大多数类型的ARGs与氨基糖苷类和β-内酰胺类耐药性有关。然而，四环素抗性基因tet（A）是所有分离株中最常见的ARG，占78.4%。ST-26的多个分离株含有20个ARG。ST-40的所有分离株被分为两个簇，它们之间至少有160个等位基因差异。
研究结果强调需要持续监测食源性沙门氏菌中的ARGs，特别是ST-40和ST-26；监测应包括研究区域内尽可能多的零售肉类类型。
Abstract
This study investigated the prevalence of Salmonella in 210 retail meat samples (105 raw chicken and 105 raw pork) collected from supermarkets and wet markets in 13 areas of Hebei Province, China, from June to October 2018. Whole-genome sequencing was performed on all 125 Salmonella isolates to investigate their genetic relationship. Core genome multilocus sequence typing of 77 representative isolates was used to further elucidate the genetic relatedness among the Salmonella isolated from retail meat.

The mean detection rate of Salmonella in all samples was 59.5% (125/210). The prevalence of Salmonella was 53.3% (56/105) in chicken and 65.7% (69/105) in pork. Chicken and pork samples collected in July had the highest detection rate of Salmonella among the sampling months. The isolates were assigned to 19 serotypes, with S. Derby, S. London, and S. Thompson being the most frequent serotypes. Resistance to tetracycline (primarily used for the treatment of bacterial infections) was observed in 89.6% of the isolates, and 84.0% were resistant to doxycycline (also a tetracycline antibiotic) or gemifloxacin (commonly used for clinical treatment of human acute bronchitis). More than 80% of the isolates were multidrug resistant. A total of 21 sequence types were identified. Sequence type 40 (ST-40), the predominant genotype among all isolates, was found only in pork; the sequence types of chicken isolates were more diverse.

A total of 58 different antibiotic resistance genes (ARGs) were detected in the 125 isolates. Most types of ARGs were associated with aminoglycoside and β-lactam resistance. Nevertheless, the tetracycline resistance gene tet(A) was the most frequently occurring ARG in all isolates at 78.4%. Multiple isolates of ST-26 contained 20 ARGs. All isolates of ST-40 were divided into two clusters, with at least 160 allelic differences between them.

The findings highlight the need to continually monitor ARGs in foodborne Salmonella with particular emphasis on ST-40 and ST-26; the monitoring should include as many retail meat types as possible in the study area.

https://www.sciencedirect.com/science/article/abs/pii/S016816052100475X