Isolation of Some Food Poisoning Microorganisms From Raw Milk With Special Reference to Verocytotoxigenic E. Coli

Abstract

Milk as it comes from a normal udder of a healthy animal contains a negligible number of harmful organisms but may be contaminated from variable sources. So this investigations were conducted to collection of forty random samples of raw milk were collected from supermarkets in Alexandria governorate for isolation and identification of some pathogenic microorganisms using conventional methods and advanced techniques. incidence of E. coli, Staph. aureus, listeria monocytogens and salmonella were 80, 45, 5 and 0%, respectively by using plating techniques. These results were confirmed by conventional biochemical identifications but by using vitek 2 compact system (automated biochemical identifications), the incidences were 37.5, 2.5, 0 and 0%, respectively. The incidence of Shiga toxin-producing E. coli isolated from the examined raw milk samples (4/10%) and could be identify virulence genes into four different serotypes including O26:H11 (EHEC), O86 (EHEC), O119:H6 (ETEC) and O125:H21 (EHEC). By using multiplex PCR, it was found that O26:H11 had shigatoxin 1 gene, shigatoxin 2 gene and intimin gene; while O86 and O119:H6 serotypes had only shigatoxin1 gene. O125:H21 serotype had both shigatoxin 1 and shigatoxin 2 genes. It could be concluded that vitek 2 compact system is considered as sensitive and accurate method for identification of some food poisoning microorganisms in comparing with conventional biochemical identifications.