School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China.
The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
PLoS One. 2023 Oct 19;18(10):e0292621. doi: 10.1371/journal.pone.0292621. eCollection 2023.
Salmonella can cause severe foodborne diseases. This study investigated the prevalence of Salmonella spp. in fresh foods in Hangzhou market and their harborage of antibiotic resistance and virulence genes, antibiotic susceptibility, and pathogenicity. A total of 500 samples (pork, n = 140; chicken, n = 128; vegetable, n = 232) were collected over a one-year period. Salmonella was found in 4.2% (21) of samples with the detection rate in pork, chicken and vegetables as 4.3% (6), 6.3% (8), and 3% (7), respectively. One Salmonella strain was recovered from each positive sample. The isolates were identified as six serotypes, of which S. Enteritidis (n = 7) and S. Typhimurium (n = 6) were the most predominant serotypes. The majority of isolates showed resistance to tetracycline (85.7%) and/or ciprofloxacin (71.4%). Tetracycline resistance genes showed the highest prevalence (90.5%). The occurrence of resistance genes for β-lactams (blaTEM-1, 66.7%; and blaSHV, 9.5%) and aminoglycosides (aadA1, 47.6%; Aac(3)-Ia, 19%) was higher than sulfonamides (sul1, 42.9%) and quinolones (parC, 38.1%). The virulence gene fimA was detected in 57.1% of isolates. Gene co-occurrence analysis implied that resistance genes were associated with virulence genes. Furthermore, selected S. Typhimurium isolates (n = 4) carrying different resistance and virulence genes up-regulated the secretions of cytokines IL-6 and IL-8 by Caco-2 cells in different degrees, suggesting that virulence genes may play a role in inflammatory transcription. In in vivo virulence test, microbiological counts in mouse feces and tissues showed that all included S. Typhimurium were able to infect mice, with one strain showing significantly higher virulence than others. In conclusion, this study indicates Salmonella contamination in fresh foods in Hangzhou market poses a risk to public health and it should be closely monitored to prevent and control foodborne diseases.
沙门氏菌可导致严重的食源性疾病。本研究调查了杭州市场新鲜食品中沙门氏菌属的流行情况及其对抗生素耐药性和毒力基因的藏匿、抗生素敏感性和致病性。在一年的时间里，共采集了 500 个样本（猪肉，n = 140；鸡肉，n = 128；蔬菜，n = 232）。在 4.2%（21）的样本中发现了沙门氏菌，猪肉、鸡肉和蔬菜中的检出率分别为 4.3%（6）、6.3%（8）和 3%（7）。从每个阳性样本中都分离出了一株沙门氏菌。分离株鉴定为 6 种血清型，其中肠炎沙门氏菌（n = 7）和鼠伤寒沙门氏菌（n = 6）是最主要的血清型。大多数分离株对四环素（85.7%）和/或环丙沙星（71.4%）表现出耐药性。四环素耐药基因的流行率最高（90.5%）。β-内酰胺类（blaTEM-1，66.7%；blaSHV，9.5%）和氨基糖苷类（aadA1，47.6%；Aac(3)-Ia，19%）耐药基因的发生率高于磺胺类（sul1，42.9%）和喹诺酮类（parC，38.1%）。57.1%的分离株检测到毒力基因 fimA。基因共现分析表明，耐药基因与毒力基因有关。此外，携带不同耐药和毒力基因的选定鼠伤寒沙门氏菌分离株（n = 4）在不同程度上上调了 Caco-2 细胞细胞因子 IL-6 和 IL-8 的分泌，提示毒力基因可能在炎症转录中发挥作用。在体内毒力试验中，小鼠粪便和组织中的微生物计数显示，所有包含的鼠伤寒沙门氏菌均能感染小鼠，其中一个菌株的毒力明显高于其他菌株。总之，本研究表明杭州市场新鲜食品中沙门氏菌的污染对公众健康构成了威胁，应密切监测，以预防和控制食源性疾病。
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