Preliminary Quantitative Microbial Risk Assessment for Staphylococcus enterotoxins in fresh Minas cheese, a popular food in Brazil

Abstract

The main objective of this work was to assess the risk associated with staphylococcal enterotoxins (SE) intoxication after the consumption of fresh Minas cheese by the Brazilian population. Coagulase-positive staphylococci data from 350 samples were obtained from monitoring programs, and were used as a proxy for S. aureus contamination, considering that 73% of the strains were toxigenic. The Combined Database for Predictive Microbiology (ComBase) and the Pathogen Modeling Program (PMP) models were used to predict S. aureus growth rate and lag-phase in fresh Minas cheese at different pH, salt concentration and storage temperature in a household refrigerator, up to 7 days before consumption. Change in storage temperature had the largest impact on the growth rate and lag-phase obtained from both models. Cumulative probability of SE intake events equal to or higher than the toxigenic dose of 100 ng were calculated using Monte Carlo simulations performed by the @Risk software. The toxic dose was exceeded at the 99.95th percentile of exposure in the ComBase model (upper bound) for the adult population, the lowest percentile identified in the study. The S. aureus initial concentration was the parameter that most impacted the output obtained by @risk, indicating the importance of good manufacturing practices for fresh Minas cheese production, and proper storage conditions at the point of sale. This preliminary assessment indicated that the risk of staphylococcal intoxications from the consumption of fresh Minas cheese by the Brazilian population is probably low. The study identified many data gaps that needs to be addressed to improve the risk assessment.