Detection of enterotoxigenic staphylococcus aureus strains in raw milk of cows reared in Erbil Province Iraq

Abstract EN

Raw milk is usually contaminated with enterotoxin-producing Staphylococcus ¬aureus, which is regularly associated with staphylococcal food poisoning.

The present study was conducted to investigate the occurrence of Staphylococcus aureus and enterotoxin producing strains in cow raw milk in Erbil province and to assess genotypic (multiplex PCR) versus phenotypic by reversed passive latex agglutination (RPLA) assays for staphylococcal enterotoxin detection.

A total of 150 samples of caw raw milk (75 from direct milk and 75 bulk tank milk) were collected randomly from milk collectors and different farms in Erbil city.

The Staphylococcus aureus isolates were identified conventionally and confirmed by PCR.

Then, staphylococcal enterotoxins(SEs) from A to D were examined by RPLA, and types of related genes (sea-sed) were detected by multiplex PCR.

S.

aureus was recovered from 14 (18.6%) samples from direct milk and 32 samples (42.6%) from bulk tank milk.

Of the total strains studied, 65.2% were determined to have some staphylococcal enterotoxin genes; however, only 34.7% produced a detectable amount of the staphylococcal enterotoxins.

The most frequently produced enterotoxin gene was type A (60%), followed by sec (30%), sea+sec (10%) and genes seb and sed did not occur.

A relatively high discrepancy was observed between the results of RPLA and multiplex PCR, especially with SEA.

Our findings showed that cow raw milk in Erbil city is contaminated with toxigenic strains of S.aureus.