Abstract
The present study aimed to detect the occurrence of Staphylococcus aureus in different cheese varieties in Kafr Elsheikh Governorate, Egypt, and to characterize enterotoxin virulence related genes (Sea, Seb) in the recovered Staph. aureus isolates. An additional objective was to evaluate the effectiveness of thyme oil 1% for controlling staphylococcal species in manufactured kariesh cheese with 1 and 5% salt. A total of 120 samples of different cheese samples including Damietta, kariesh, spreadable processed and Ras cheese (30 of each type) collected from different supermarkets and street-vendor at Kafr El-Sheikh governorate. The obtained results revealed the incidence of Staph. aureus wwere6.67%, 16.67%, 13.33%, and 13.33%, respectively, with overall incidence across all cheese samples was 12.5%. 23S rRNA gene was detected in staph. aureus strains isolated from damietta, kariesh, processed cheese, and Ras cheese at incidence level 6.67%, 10%, 6.67%, and 10% respectively. Seb was detected in a single Staphylococcus aureus isolate from kariesh, processed cheese, and Ras cheese, while Sea could not detect in all examined isolates. Reducing the presence of Staphylococcus aureus in kariesh cheese is crucial, as it is a favorable environment for this pathogen, which can lead to staphylococcal food poisoning. By lowering the pathogen's level in kariesh cheese, the risk to consumers can be minimized. A combination of 1% thyme oil with 1% salt demonstrated moderate inhibition against staphylococcal count, resulting in a 7.34% reduction on the 15th day of storage. Additionally, using 1% thyme oil with 5% salt resulted in a double reduction rate of 15.27% on the 15th day of storage. These findings suggest that incorporating thyme oil in the preservation of white soft kariesh cheese holds promise for enhancing its shelf life and safety.

Key words: Staph. aureus, Thyme oil, cheese varieties, salt, kariesh cheese.