Kaptchouang Tchatchouang Christ-Donald, Fri Justine, Montso Peter Kotsoana, Amagliani Giulia, Schiavano Giuditta Fiorella, Manganyi Madira Coutlyne, Baldelli Giulia, Brandi Giorgio, Ateba Collins Njie
Food Security and Safety Focus Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho 2735, South Africa.
Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, PU, Italy.
Pathogens. 2022 Jul 27;11(8):843. doi: 10.3390/pathogens11080843.
Listeriosis is a foodborne disease caused by Listeria monocytogenes species and is known to cause severe complications, particularly in pregnant women, young children, the elderly, and immunocompromised individuals. The aim of this study was to investigate the presence of Listeria species in food and water using both biochemical and species-specific PCR analysis. L. monocytogenes isolates were further screened for the presence of various antibiotic resistance, virulence, and biofilm-forming determinants profiles using phenotypic and genotypic assays. A total of 207 samples (composed of meat, milk, vegetables, and water) were collected and analyzed for presence of L. monocytogenes using species specific PCR analysis. Out of 267 presumptive isolates, 53 (19.85%) were confirmed as the Listeria species, and these comprised 26 L. monocytogenes, 3 L. innocua, 2 L. welshimeri, and 1 L. thailandensis. The remaining 21 Listeria species were classified as uncultured Listeria, based on 16SrRNA sequence analysis results. A large proportion (76% to 100%) of the L. monocytogenes were resistant to erythromycin (76%), clindamycin (100%), gentamicin (100%), tetracycline (100%), novobiocin (100%), oxacillin (100%), nalidixic acid (100%), and kanamycin (100%). The isolates revealed various multi-drug resistant (MDR) phenotypes, with E-DA-GM-T-NO-OX-NA-K being the most predominant MDR phenotypes observed in the L. monocytogenes isolates. The virulence genes prfA, hlyA, actA, and plcB were detected in 100%, 68%, 56%, and 20% of the isolates, respectively. In addition, L. monocytogenes isolates were capable of forming strong biofilm at 4 °C (%) after 24 to 72 h incubation periods, moderate for 8% isolates at 48 h and 20% at 72 h (p < 0.05). Moreover, at 25 °C and 37 °C, small proportions of the isolates displayed moderate (8−20%) biofilm formation after 48 and 72 h incubation periods. Biofilm formation genes flaA and luxS were detected in 72% and 56% of the isolates, respectively. These findings suggest that proper hygiene measures must be enforced along the food chain to ensure food safety.
李斯特菌病是一种由单核细胞增生李斯特菌引起的食源性疾病，已知会引发严重并发症，尤其是在孕妇、幼儿、老年人和免疫功能低下者中。本研究的目的是通过生化分析和种特异性PCR分析来调查食品和水中李斯特菌的存在情况。使用表型和基因型检测方法，对单核细胞增生李斯特菌分离株进一步筛查各种抗生素抗性、毒力和生物膜形成决定因素谱。总共收集了207份样品（包括肉类、牛奶、蔬菜和水），并使用种特异性PCR分析检测单核细胞增生李斯特菌的存在情况。在267株疑似分离株中，53株（19.85%）被确认为李斯特菌属，其中包括26株单核细胞增生李斯特菌、3株无害李斯特菌、2株威氏李斯特菌和1株泰国李斯特菌。根据16SrRNA序列分析结果，其余21株李斯特菌属被归类为未培养的李斯特菌。很大比例（76%至100%）的单核细胞增生李斯特菌对红霉素（76%）、克林霉素（100%）、庆大霉素（100%）、四环素（100%）、新生霉素（100%）、苯唑西林（100%）、萘啶酸（100%）和卡那霉素（100%）耐药。分离株显示出各种多重耐药（MDR）表型，E-DA-GM-T-NO-OX-NA-K是在单核细胞增生李斯特菌分离株中观察到的最主要的MDR表型。毒力基因prfA、hlyA、actA和plcB分别在100%、68%、56%和20%的分离株中被检测到。此外，单核细胞增生李斯特菌分离株在4℃下培养24至72小时后能够形成强生物膜（%），48小时时有8%的分离株形成中度生物膜，72小时时有20%的分离株形成中度生物膜（p<0.05）。此外，在25℃和37℃下，一小部分分离株在培养48小时和72小时后显示出中度（8-20%）的生物膜形成。生物膜形成基因flaA和luxS分别在72%和56%的分离株中被检测到。这些发现表明，必须在整个食物链中实施适当的卫生措施以确保食品安全。
