Document Type : Research article
Authors
1
Department of Zoonosis, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
2
Department of Food Hygiene and Control, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
Abstract
Listeria monocytogenes has been considered a significant food-borne pathogen in recent years, representing a major concern for public health and food safety. Consequently, the objective of the current investigation was to assess the prevalence of L. monocytogenes and other Listeria species in raw milk and certain cheese varieties. The presence of L. monocytogenes was screened in a total of 769 dairy samples, which were randomly collected from farms and dairy shops located in Cairo and Giza governorates. The samples included 212 raw milk samples from farms, 307 raw milk samples from dairy stores, and 250 cheese samples, including Kareish, Talaga, Feta, Processed, Ras, Gouda, and Cheddar (25 each). In total, twenty-two of the analyzed samples were contaminated with Listeria species, representing 2.86%. Additionally, there were only five positive samples for L. monocytogenes, accounting for 0.65%. The prevalence of Listeria spp. in the examined milk samples from dairy shops, farms, and cheese was 6.17%, 0.47%, and 0.8%, respectively. Depending on the outcomes of the biochemical identification assays, L. monocytogenes was detected in 1.30% and 0.47% of the examined milk samples from dairy shops and farms, respectively, while it couldn't be isolated from all cheese samples. L. monocytogenes isolates were confirmed positive using Polymerase Chain Reaction (PCR) targeting the hemolysin (hly A) gene. Furthermore, L.ivanovii and L.grayi were isolated from two samples of Kareish cheese representing 8%. In conclusion, the obtained results indicated a potential risk of milk and cheese contamination with Listeria. Thus, strict hygienic measures and frequent investigations must be applied to control such microorganisms.
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