单核细胞增生李斯特菌,一种细胞内食源性病原体,能够引起李斯特菌病,比如脑膜炎,脑膜脑炎,和堕胎。近年来,一些国家已经报道了食用蘑菇产品中单核细胞增生李斯特菌的发生。我国尚无蘑菇制品中单增李斯特菌的定性和定量检测指南。因此,本研究旨在调查中国市场食用蘑菇中单核细胞增生李斯特菌的患病率和污染水平,并确定这些分离株的抗生素耐药性和序列类型(STs),为风险评估提供数据.约21.20%(141/665)的食用菌样品为单核细胞增生李斯特菌阳性,而57.44%(81/141)的阳性样品的污染水平低于10MPN/g。来自阳性样品的180个分离株属于血清群I.1(1/2a-3a,n=111),其次是血清群II.2(1/2b-3b-7,n=66),和血清群III(4a-4c,n=3)。抗生素敏感性试验表明,95%以上的单核细胞增生李斯特菌分离株对青霉素耐药,氨苄青霉素,苯唑西林,和克林霉素,而超过90%的人对16种抗生素敏感,抵抗的机制仍有待阐明。根据多位点测序分型,180个分离株代表21个STs,其中一个是第一次被确认。有趣的是,ST8和ST87在食用菌产品中占主导地位,表明特定的STs可能具有不同的生态位。潜在的毒力谱表明,大多数分离株含有全长inlA基因,在分离株2035-1LM(位置1380,TGG→TGA)和3419-1LM(位置1474,CAG→TAG)中发现了新的过早终止密码子。属于血清群II.2的五个分离株携带来自李斯特菌致病性岛(LIPI)-3的llsX基因,存在于ST224,ST3和ST619中;53(29.44%)携带来自LIPI-4的ptsA基因,存在于ST3,ST5,ST87,ST310,ST1166和ST619中。鉴定出5种携带所有这3种毒力因子的潜在高毒力分离株,建议食用蘑菇可能作为潜在的高毒力单核细胞增生李斯特菌的可能传播途径,这可能是消费者对公共健康的极大关注。根据我们的发现,探索控制单核细胞增生李斯特菌污染的新方法对于确保食用蘑菇产品的微生物安全性是必要的。
Listeria monocytogenes, an intracellular foodborne pathogen, is capable of causing listeriosis, such as meningitis, meningoencephalitis, and abortion. In recent years, the occurrence of Listeria monocytogenes in edible mushroom products has been reported in several countries. There are no guidelines for qualitative and quantitative detection of L. monocytogenes in mushroom products in China. Therefore, this study aimed to investigate the prevalence and contamination level of L. monocytogenes in edible mushrooms in Chinese markets and to determine the antibiotic resistance and sequence types (STs) of these isolates to provide data for risk assessments. Approximately 21.20% (141/665) of edible mushroom samples were positive for L. monocytogenes, while 57.44% (81/141) of positive samples contained contamination levels of less than 10 MPN/g. The 180 isolates derived from positive samples belonged to serogroup I.1 (1/2a-3a, n = 111), followed by serogroup II.2 (1/2b-3b-7, n = 66), and serogroup III (4a-4c, n = 3). Antibiotic susceptibility testing showed that over 95% of L. monocytogenes isolates were resistant to penicillin, ampicillin, oxacillin, and clindamycin, while over 90% were susceptible to 16 antibiotic agents, the mechanisms of resistance remain to be elucidated. According to multilocus sequencing typing, the 180 isolates represented 21 STs, one of which was identified for the first time. Interestingly, ST8 and ST87 were predominant in edible mushroom products, indicating that specific STs may have distinct ecological niches. Potential virulence profiles showed that most of the isolates contained full-length inlA genes, with novel premature stop codons found in isolate 2035-1LM (position 1380, TGG→TGA) and 3419-1LM (position 1474, CAG→TAG). Five isolates belonging to serogroup II.2 carried the llsX gene from Listeria pathogenicity island (LIPI)-3, present in ST224, ST3, and ST619; 53 (29.44%) harbored the ptsA gene from LIPI-4, presenting in ST3, ST5, ST87, ST310, ST1166, and ST619. Five potential hypervirulent isolates carrying all three of these virulence factors were identified, suggesting edible mushrooms may serve as possible transmission routes of potential hypervirulent L. monocytogenes, which may be of great public health concern to consumers. Based on our findings, the exploration of novel approaches to control L. monocytogenes contamination is necessary to ensure the microbiological safety of edible mushroom products.