Li Hui, Sheng Huanjing, Zhao Jianyun, Zhang Xinhao, Li Menghan, Zhao Lanxin, Li Lanqi, Zhang Xiaoman, Yang Baowei, Fanning Séamus, Wang Yang, Yan Shaofei, Bai Li
Key Laboratory of Food Safety Risk Assessment, National Health Commission of the People's Republic of China, China National Center for Food Safety Risk Assessment, Beijing, China.
Key Laboratory of Food Safety Risk Assessment, National Health Commission of the People's Republic of China, China National Center for Food Safety Risk Assessment, Beijing, China; National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China; College of Food Science and Engineering, Northwest A&F University, Shaanxi, China.
Int J Food Microbiol. 2025 Aug 2;439:111236. doi: 10.1016/j.ijfoodmicro.2025.111236. Epub 2025 May 6.
Listeria monocytogenes is a foodborne pathogen that poses threat to food safety and public health. Generally, the rates of resistance to clinically important antibiotics in L. monocytogenes are low. This study aimed to investigate the prevalence and genetic characteristics of L. monocytogenes with acquired multidrug resistance (MDR) in food samples from China between 2012 and 2022. Of 8344 isolates collected, 34 (0.41 %) were identified as acquired MDR. The majority of acquired MDR isolates (n = 31, 92.3 %) belonged to hypovirulent clonal complex (CC) 9 (Lineage II, IIc), including 3 sequence types (ST) (ST9, n = 29; ST2458, n = 1; ST9-1LV, n = 1), which has remained dominant over the past decade. In 2022, three additional acquired MDR clones emerged: CC87/ST87 (Lineage I, IIb), CC8/ST8 (Lineage II, IIa), and CC155/ST705 (Lineage II, IIa), with CC87/ST87 and CC8/ST8 being notably associated with human listeriosis in Asia. The rep25_2_M640p00130 plasmid was the most common mobile genetic element among these acquired MDR isolates, consistently harboring seven types of antibiotic resistance genes, including aminoglycosides (ant(6)-Ia; aph(3')-III), trimethoprim (dfrG), macrolides, lincosamides and streptogramin B (MLS) (erm(B)), lincosamides (lnu(B)), pleuromutilins, lincosamides and streptogramin A (PLS) (lsa(E)), tetracyclines (tet(S)), and phenicols (catA), and flanked on one side by IS1216E. However, the diversity of acquired MDR-carrying plasmids increased from 2017 to 2022, with an increased prevalence among replicons including rep26_2_repA, rep26_4_repA, and rep26_1_pli0070/rep32_1_pli0023. Importantly, compared to the dominant hypovirulent CC9, which contained premature stop codons in the internalin gene inlA associated with adhesion and invasion, the newly emerged acquired MDR L. monocytogenes CC8/ST8 and CC155/ST705 maintained intact inlA gene and exhibited stronger adhesion and invasion phenotype in Caco-2 cells. These findings emphasize the need for continuous surveillance of acquired MDR L. monocytogenes, particularly the virulent CC8/ST8 and CC155/ST705, to mitigate risks to food safety and human health.
单核细胞增生李斯特菌是一种食源性病原体，对食品安全和公众健康构成威胁。一般来说，单核细胞增生李斯特菌对临床上重要抗生素的耐药率较低。本研究旨在调查2012年至2022年期间中国食品样本中获得性多重耐药（MDR）单核细胞增生李斯特菌的流行情况和遗传特征。在收集的8344株分离株中，有34株（0.41%）被鉴定为获得性MDR。大多数获得性MDR分离株（n = 31，92.3%）属于低毒力克隆复合体（CC）9（谱系II，IIc），包括3个序列类型（ST）（ST9，n = 29；ST2458，n = 1；ST9-1LV，n = 1），在过去十年中一直占主导地位。2022年，又出现了三个获得性MDR克隆：CC87/ST87（谱系I，IIb）、CC8/ST8（谱系II，IIa）和CC155/ST705（谱系II，IIa），其中CC87/ST87和CC8/ST8在亚洲与人类李斯特菌病显著相关。rep25_2_M640p00130质粒是这些获得性MDR分离株中最常见的移动遗传元件，始终携带七种抗生素耐药基因，包括氨基糖苷类（ant(6)-Ia；aph(3')-III）、甲氧苄啶（dfrG）、大环内酯类、林可酰胺类和链阳菌素B（MLS）（erm(B)）、林可酰胺类（lnu(B)）、截短侧耳素类、林可酰胺类和链阳菌素A（PLS）（lsa(E)）、四环素类（tet(S)）和氯霉素类（catA），并且一侧由IS1216E侧翼。然而，2017年至2022年期间，携带获得性MDR质粒的多样性增加，包括rep26_2_repA、rep26_4_repA和rep26_1_pli0070/rep32_1_pli0023等复制子中的流行率增加。重要的是，与在与黏附和侵袭相关的内化素基因inlA中含有过早终止密码子的占主导地位的低毒力CC9相比，新出现的获得性MDR单核细胞增生李斯特菌CC8/ST8和CC155/ST705保持完整的inlA基因，并在Caco-2细胞中表现出更强的黏附和侵袭表型。这些发现强调需要持续监测获得性MDR单核细胞增生李斯特菌，特别是毒力较强的CC8/ST8和CC；155/ST705，以降低对食品安全和人类健康的风险。
