Investigation of Enterotoxin-Producing Genes (sea, seb, sec, and sed) in Staphylococcus aureus Isolated from Raw Traditionally and Pasteurized Milk Supplied in Tehran, Iran

The issue of milk quality appears to be vital due to its nutritional value and since raw milk can be regarded as an appropriate environment for the growth of several pathogens by producing an enterotoxin. The aim of present study is to investigate enterotoxin-producing genes (sea, seb, sec, and sed) from Staphylococcus aureus isolated from raw traditional and pasteurized milk in Tehran, Iran.

One hundred and fifty samples of raw traditional milk supplied in five districts of Tehran were collected and simultaneously15 pasteurized milk samples from various brands were prepared and examined phenotypically and bio-chemically for the existence of S. aureus. The presence of sea, seb, sec, sed genes was assessed by Polymerase Chain Reaction and ultimately the antibiotic residue was measured with a commercial kit.

In this study, 32 (21.3%) samples of raw traditional milk and one sample (6.7%) of pasteurized milk samples were infected with S. aureus. The frequency of presence of sea, seb, sec, and sed genes regarded to be: 9 (28.12%), 14 (43.75%), 6 (18.75%), 2 (6.25%), respectively however sec gene failed to identify. Basically 38 (33.25%) of raw traditional milk samples as well as 5 (33.33%) of pasteurized milk included antibiotic residue.

 The high prevalence of S. aureus comprising enterotoxin genes in raw traditional milk is considered as a severe warning to the community and highlights the need for a high quality product.