Detection and expression of superantigens and resistance in isolates from women carriers of Staphylococcus aureus who take care of and feed children

Abstract

Introduction: Staphylococcus aureus colonizes mucous membranes and skin causing severe infections in humans and animals. It is important to determine carrier status of enterotoxigenic strains of this microorganism in food handlers to prevent food poisoning. Objective: To establish the correlations among classic enterotoxigenic genes, tsst-1 gene, the production of toxins in cultures and antimicrobial resistance in S. aureus isolates from women who handle the food, feed and take care of children in their communities. Materials and methods: Nasal swab and finger samples were cultured and S. aureus was identified using routine methods and automated systems. DNA extraction was done by the CTAB modified method, and superantigen detection by simple and multiplex PCR, while toxins were detected using commercial kits. Results: We found that 22.0% of subjects were S. aureus carriers: 17.0% corresponded to nose samples, 5.0% to hands and 6.7% to both nose and hands. The prevalence of superantigens was 73.7%. The most frequent genotype was sea-tsst-1 with 10%. Resistance to one antibiotic was 74.7%, and to four antibiotics, 3.2%; 93.7% of the isolates were betalactamase-positive. Classical genes and tsst-1 gene were detected by PCR in 48.4% of samples and toxins in supernatant were detected in 42.1% of them with 95.7% of correlation.The highest correlations were established for TSST-1 and SEA with 100% and 94.4%, respectively. The correlation of tsst-1 gene with toxin production and resistance was 100%. All isolates with genotype sea-tsst-1 were toxin-positive and resistant. Conclusion: The rate of toxigenic and resistant S. aureus isolates from women in charge of feeding and taking care of children was higher than 70%, which demonstrates its high virulence. This requires the strict application of hygienic and sanitary regulations in order to avoid the risk of food poisoning.

Keywords

• Staphylococcus aureus
• enterotoxinas
• farmacorresistencia microbiana
• superantígenos
• genotipo
• variación genética