Enterotoxigenic Staphylococcus aureus: sources and strategy for control in food outlets

Abstract

The current study was conducted to investigate the potential sources of enterotoxigenic S. aureus and the efficacy of ISO 22000:2005 with the technical specifications ISO/TS 22002-2:2013 for pathogen control in food outlets. A total of 724 samples (483 food, 120 equipment and 121 hand swabs from food handlers) were collected from 112 food outlets. All samples were processed for isolation and identification of S. aureus using cultural method. Furthermore, enterotoxigenic strains were identified among S. aureus isolates through detection of genes coding SEA-SEE, SEG and SHE by PCR. The isolation rates of S. aureus were 11.8, 3.3 and 10.7% from food, equipment and hand swabs, respectively. While the prevalence of enterotoxigenic S. aureus in the same samples was 3.5, 0.8 and 1.7%, respectively. Raw chicken meat showed highest isolation rate for enterotoxigenic strains (5.1%). Moreover, enterotoxigenic S. aureus possess SEC and/or SED were the most common strains whereas SEA, SEB, SEE were not detected. Phylogenetic analysis of SED sequences revealed that strains from cooked food and used knifes were grouped in the same cluster with the human sequence to highlight the human origin of the contamination. ISO 22000:2005 with technical specifications ISO/TS 22002-2:2013 was applied in all restaurants that yielded S. aureus for 45 days and samples were gathered again for retesting. None of the retested restaurants were positive. In conclusion, food handlers are the main source of cooked food contamination with enterotoxigenic S. aureus regarding ISO 22000:2005 with technical specifications ISO/TS 22002-2:2013 an efficient system for control.