Mirzaei R, Golestan L, Fekrirad Zahra
Department of Food Hygiene, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran.
Department of Food Hygiene, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Arch Razi Inst. 2024 Dec 31;79(6):1337-1344. doi: 10.32592/ARI.2024.79.6.1337. eCollection 2024 Dec.
L. monocytogenes is a significant foodborne pathogen that is associated with a range of clinical illnesses, from self-limited gastroenteritis to invasive infection, which can lead to hospitalization of immunocompromised individuals. In the present study, the incidence of L. monocytogenes in ready-to-eat (RTE) food samples from Tehran, Iran, was therefore measured. A total of 110 samples were collected from various ready-to-eat (RTE) foods in different zones of Tehran from April to September of 2022. The samples were obtained from various types of food, including Caesar salad, Olivier salad, burger, schnitzel, sushi, and sausage. The identification of isolates was facilitated by the detection of hlyA and prfA genes through a polymerase chain reaction (PCR) approach. The antimicrobial resistance profile of the isolates was assessed through the use of a disc diffusion assay and the PCR amplification of resistance genes. Among the 110 samples, 14 (12.7%) were identified as Listeria spp., and 6 (5.5%) were confirmed as L. monocytogenes by molecular methods. The prevalence of Listeria spp. was observed to be highest in schnitzel and burgers, with 30% of schnitzel samples and 25% of burger samples being positive. Among the 14 isolates, 6 samples (42%) were identified as L. monocytogenes. The highest rate of L. monocytogenes was observed in burgers, accounting for 20% of the total burger samples. In contrast, no L. monocytogenes was identified in Caesar salad, sausage, and sushi samples. The L. monocytogenes isolates demonstrated resistance to oxacillin, streptomycin, cotrimoxazole, clindamycin, and cefoxitin, and were susceptible to chloramphenicol. Furthermore, the isolates demonstrated intermediate susceptibility to fosfomycin and ampicillin. Furthermore, the isolates demonstrating resistance to erythromycin contained genes associated with resistance to the macrolide class of antibiotics, including ermA and ermB. However, the presence of cfxA and mecA genes was detected in a single isolate resistant to cefoxitin and oxacillin. The prevalence of these findings underscores significant concerns regarding the potential for listeriosis to pose a threat to consumers of ready-to-eat (RTE) food products.
单核细胞增生李斯特菌是一种重要的食源性病原体，与一系列临床疾病相关，从自限性肠胃炎到侵袭性感染，后者可导致免疫功能低下个体住院。因此，在本研究中，对来自伊朗德黑兰即食（RTE）食品样本中的单核细胞增生李斯特菌发生率进行了测定。2022年4月至9月期间，从德黑兰不同区域的各类即食（RTE）食品中总共采集了110份样本。这些样本取自各类食品，包括凯撒沙拉、奥利维尔沙拉、汉堡、炸肉排、寿司和香肠。通过聚合酶链反应（PCR）方法检测hlyA和prfA基因，有助于分离株的鉴定。通过纸片扩散法和耐药基因的PCR扩增评估分离株的抗菌药物耐药谱。在110份样本中，14份（12.7%）被鉴定为李斯特菌属，6份（5.5%）通过分子方法确认为单核细胞增生李斯特菌。观察到炸肉排和汉堡中李斯特菌属的流行率最高，30%的炸肉排样本和25%的汉堡样本呈阳性。在14株分离株中，6份样本（42%）被鉴定为单核细胞增生李斯特菌。在汉堡中观察到单核细胞增生李斯特菌的发生率最高，占汉堡样本总数的20%。相比之下，在凯撒沙拉、香肠和寿司样本中未鉴定出单核细胞增生李斯特菌。单核细胞增生李斯特菌分离株对苯唑西林、链霉素、复方新诺明、克林霉素和头孢西丁耐药，对氯霉素敏感。此外，分离株对磷霉素和氨苄西林表现出中度敏感性。此外，对红霉素耐药的分离株含有与大环内酯类抗生素耐药相关的基因，包括ermA和ermB。然而，在一株对头孢西丁和苯唑西林耐药的分离株中检测到cfxA和mecA基因的存在。这些发现的普遍性凸显了对李斯特菌病可能对即食（RTE）食品消费者构成威胁的重大担忧。
