E. coli O157.H7 in beefburgers produced in the Republic of Ireland; A quantitative microbial risk assessment

A quantitative microbial risk assessment (QMRA) model was developed for E. coli O157:H7 in beefburgers prepared and consumed at home.

Analysis of the risk model indicated the following:
The initial prevalence and numbers of E. coli 0157:H7 on the bovine hide had the greatest impact on overall probability of illness from E. coli O157:H7. Cross contamination at hide removal impacted on predicted risk 
A sensitivity analysis of consumer practices on risk (calculated) from E. coli O157:H7 revealed that one of the most important factors was the cooking preference The higher the internal cooking temperature, the less the risk.
Temperature abuse during retail storage, during transport home and during home storage was deemed a significant parameter influencing model predictions 
The prevalence / contamination levels of E. coli O157:H7 (and calculated risk) in fresh chilled beefburgers and in frozen burgers were compared. Fresh burgers had a greater predicted prevalence and higher mean counts,  mainly due to the higher probability for temperature abuse of fresh burgers during retail display, transport and home storage.
The difference in prevalence / contamination levels of E. coli O157:H7 (and calculated risk) in a beefburger made from 100% beef (meat) was compared with a burger made with added ingredients. As added ingredients were not identified as a significant risk factor in the contamination of beefburgers, they did not contribute directly to the contamination level. However, because of the reduced beef incorporated into burgers with added ingredients, a dilution effect was observed.
The prevalence / contamination levels of E. coli O157:H7 (and calculated risk) from E. coli O157:H7 in beef mince purchased from a butcher shop was compared with product purchased from supermarket and the prevalence and count level was found to be virtually the same in both types of establishment with no difference in predicted risk.