Microbiological Quality Assessment and Molecular Characterization of Pathogenic Bacteria in Raw Milk from Collecting Centers in Mansoura City Suburbs, EL-Dakahlia Province

This study planned to investigate microbiological quality of raw milk collected from five different collecting centers in Mansoura city suburbs coded (A–E) in Mansoura city, Egypt. A total of 100 raw milk samples were evaluated for bacterial load using aerobic bacteria plate count (APC), Coliforms , and Staphylococcus aureus (S. aureus) counts. Additionally, pathogenic bacteria such as Escherichia coli (E. coli) and Salmonella organisms were isolated, serologically identified, and further characterized for virulence genes using multiplex PCR. The results revealed high microbial contamination across all collecting centers, with collecting centers in district A (Mansoura collecting center) showing the highest levels of contamination, followed by collecting centers in district E (small holders). In contrast, collecting centers in district C (Tokh el Aqlam local unit) demonstrated the lowest microbial load, indicating better hygienic practices. Serotyping and molecular characterization of E. coli isolates showed the presence of pathotypes such as Enterohemorrhagic Escherichia Coli (EHEC), Enterotoxigenic Escherichia Coli (ETEC), and Enteropathogenic Escherichia Coli (EPEC), many of which carried virulence genes like stx1, stx2, hlyA, and eaeA. Similarly, Salmonella isolates were found to carry vital virulence genes including invA, hilA, stn, and fimH, confirming their pathogenic potential. The findings highlight the public health risks associated with raw milk contaminated with potentially pathogenic microorganisms. These risks are particularly significant in rural and semi-urban areas where raw milk consumption is common. This study emphasizes the need for enhanced hygienic practices at the farm level and collecting centers in Mansoura city suburbs, implementation of routine quality control measures, and awareness campaigns targeting dairy farmers and milk handlers.