Quantitative microbial risk assessment for Staphylococcus aureus and Staphylococcus enterotoxin A in raw milk

Area of Science:

• Food Safety
• Microbiology
• Risk Assessment

Background:

• Raw milk consumption presents potential microbial risks.
• Staphylococcus aureus (S. aureus) and its enterotoxins are significant foodborne pathogens.
• Quantitative Microbial Risk Assessment (QMRA) is a valuable tool for evaluating food safety.

Purpose of the Study:

• To determine consumer risk associated with Staphylococcus aureus and staphylococcal enterotoxin in raw milk.
• To develop a Monte Carlo simulation model for assessing risk from raw milk consumption.
• To evaluate the impact of storage conditions on pathogen growth and toxin production.

Main Methods:

• Utilized data from 2,336 California dairies (2005-2008) on S. aureus levels.
• Incorporated U.S. milk consumption data (2003-2004) from the National Health and Nutrition Examination Survey.
• Developed four simulation modules for pathogen growth and staphylococcal enterotoxin A (SEA) production under various time/temperature conditions.

Main Results:

• Growth modules predicted S. aureus levels exceeding 10(5) CFU/ml at the 99.9th/99.99th percentile of servings.
• SEA production module predicted potential for intoxication across all consumer age groups at the 99.99th percentile.
• QMRA effectively identified potential consumer risks associated with raw milk.

Conclusions:

• Raw milk consumption poses a potential risk due to S. aureus proliferation and SEA production.
• The developed QMRA model demonstrates utility in identifying critical food safety issues.
• Findings underscore the importance of understanding microbial dynamics in raw milk for public health protection.