Prevalence, characterization, and control of S. aureus isolated from raw milk and Egyptian soft cheese

Abstract

The present study aimed to detect the prevalence of Staphylococcus aureus )S. aureus( in raw milk, and soft cheese samples in Beni-Suef Governorate, Egypt, and to characterize some resistance and virulence related genes in the recovered S. aureus isolates. An additional objective was to evaluate the effectiveness of thyme oil for controlling S. aureus in cheese. A total of 200 samples of raw milk and cheese, including 100 samples of raw milk and 100 samples of two different types of cheese were used. S. aureus was isolated from 12.5% (25/200) of the raw milk and cheese samples. The highest prevalence was detected in Kareish cheese (18%), followed by raw milk samples (13%) and Talaga cheese (6%). S. aureus isolates showed high resistance to ampicillin (72%), and tetracycline (60%). PCR was applied on 6 multidrug resistant (MDR) S. aureus for detection of mecA and icaA genes which were detected in 66.7% and 33.3% of S. aureus isolates, respectively. As milk and dairy products are good substrates for S. aureus that causes staphylococcal food poisoning, reducing the level of such pathogen in milk and dairy products will lower the risk to consumers. Thyme oil 1% showed moderate inhibition against S. aureus, while using thyme oil 2% showed significant inhibition of S. aureus in Kareish cheese. Therefore, the use of thyme oil in preserving white soft Kareish cheese might be a promising approach to increase the shelf life and safety of the cheese.