Risk of nasal colonization of methicillin-resistant Staphylococcus aureus during preparation of contaminated retail pork meat

Methicillin-resistant Staphylococcus aureus (MRSA) has been found in raw retail meat products, including pork. A concern has emerged that MRSA-containing meat products might lead to nasal colonization, a risk factor for infection, in individuals that handle and prepare these foods. A quantitative microbial risk assessment (QMRA) was developed to characterize the risk of becoming nasally colonized with MRSA resulting from preparation of contaminated pork product. An exposure assessment model estimated the MRSA dose delivered to the nose via contaminated fingers. A beta-Poisson dose-response curve (with colonization as the health outcome) was fit to available human data for a methicillin-susceptible Staphylococcus aureus strain (clonal complex 30). The median risk of nasal colonization per preparation event was 7.2 × 10−3 for auto-inoculation during food preparation; this represents a non-negligible risk. The median predicted risk decreased to 8.7 × 10−5 when auto-inoculation occurred post-preparation. Data gaps for MRSA risk assessment remain, mainly MRSA-specific dose-response data, the concentration of MRSA on retail pork meat, and the fraction of MRSA transferred from fingers to surfaces.