Estudio microbiológico y resistencia microbiana de bacterias aisladas de las mayonesas que se expenden en los puestos de comida rápida ambulatorios en los alrededores de la Escuela Superior Politécnica de Chimborazo

Abstract

Mayonnaise is a traditional dressing used to accompany various fast food dishes. However, its preparation from raw ingredients and poor hygienic practices during its preparation, handling and marketing, make it susceptible to microbiological contamination and proliferation of microorganisms capable of producing foodborne diseases. Therefore, the main objective of this research project was to conduct a microbiological and microbial resistance study of bacteria isolated from mayonnaise sold in fast food stands in the surroundings of the Escuela Superior Politécnica de Chimborazo. The microbial load of 10 samples was evaluated in duplicate according to INEN 2295: Mayonnaise, Requirements. The sowing in selective culture media that allowed the quantification of CFU/g of: Mesophilic Aerobes, Molds and Yeasts, Staphylococcus aureus and Coliforms. There was evidence of 80% non-compliance for Mesophilic Aerobes, Molds and Yeasts and Staphylococcus aureus, followed by 80% simultaneous contamination of Coliforms and Escherichia coli. Finally, the presumptive presence of Salmonella spp was determined in 20% of the samples analyzed. Twenty bacterial strains were isolated and Staphylococcus aureus was identified with a frequency of 15%, Staphylococcus epidermidis in 30% and Staphylococcus xylosus in 5%. Escherichia coli and Enterobacter cloacae were identified in 15% and 10%, respectively, and Citrobacter freundii and Klebsiella michiganensis were identified by PCR. Microbial sensitivity indicated that the Staphylococcus genus presented greater resistance to Penicillin, while enterobacteria were resistant to Ampicillin. It is concluded that the analyzed samples exceed the maximum permissible index to identify the good quality level of mayonnaise.