Beginning in September 1975, and with records continuing through May, 1997, a laboratory class in food safety has been conducted at Iowa State University in 2-week rotations of 6–9 students each. As a component of the class, inspections has been made of local food establishments and a total of 825 meats and meat products have been purchased for microbiological laboratory cultures, with 77.6% positive for total aerobic plate counts, 55.3% positive for fecal coliforms, and 54.9% positive for Staphylococcus aureus. Titers ranged between 102.3 and 107.2 colony forming units (CFU) per gram. Analysis by 5-year periods has identified no progress over the 23 year period in lower prevalence or lower titers of contamination by these bacteria.
Iowa State University
Beran, George W. and Proescholdt, Terry A., "A Longitudinal Study of Bacterial Contamination in Retail Meats and Meat Products" (1998). Swine Research Report, 1997. 37.