Occurrence and PCR identification of Salmonella Spp. from milk and dairy products in Mansoura, Egypt

This study was executed to determine the prevalence, serotypes and virulence profiling of Salmonella isolated from raw milk and dairy products purchased randomly from small private dairy farms, local groceries and street vendors in Mansoura, Egypt during the period from April through October 2015. A total of 200 samples that comprising 100 raw milk (market and bulk farm, 50 per each) and 100 dairy products (pickled white cheese, fresh soft cheese, Kareish cheese and ice cream, 25 per each) were tested for the presence of Salmonella by conventional bacteriological methods followed by serotyping. Salmonella strains were molecularly screened by PCR for the presence of virulence associated genes. By culturing, 58 Salmonella isolates were recovered with an overall occurrence of 29%, distributed as 52% (26/50), 14% (7/50), 20% (5/25), 8% (2/25), and 72% (18/25) from market milk, bulk farm milk, fresh soft cheese, Kareish cheese and ice cream, respectively. No Salmonella isolates were detected from pickled white cheese. Approximately 85% of all Salmonella isolates were identified into S. Enteritidis (25/58), S. Typhimurium (15/58) and S. Infantis (9/58). By PCR, all the representative Salmonella serovars possessed both invA and stn genes. Meanwhile, 77.8% of the screened isolates carried the specific amplicon of avrA at 422 bp. This study concluded that there is a need for continuous surveillance and monitoring of milk and dairy products especially the locally produced ones to minimize the possibility of human infections with Salmonella