Purpose: To estimate pathogen prevalence in raw ground beef and beef manufacturing trimmings (MT43 and MT60 sampling projects, respectively) from raw beef producing establishments using fiscal year 2015 sampling data.
Methods: FSIS collected and analyzed ground beef (MT43) and beef trim (MT60) samples for each pathogen. To estimate pathogen prevalence, the annual production data (average daily volume x production days per month x 12) generated for each establishment by FSIS inspection personnel were used. This avoided stratifying samples into volume groups. Calculations took collected sample weights into account. Prevalence was then calculated as (sum(contaminated volume))/(sum(total volume)).
Results: FSIS analyzed 11,682 MT43 samples collected from 1,180 establishments and 3,277 MT60 samples collected from 426 establishments. Prevalence of E. coli O157:H7 and Salmonella sp. in MT43 samples was 0.05% (95% confidence intervals [CI], 0.01-0.20%) and 2.85% (95% CI, 1.79-4.52%), respectively. Prevalence of E. coli O157:H7, non-O157 STEC and Salmonella sp. in MT60 samples was 0.13% (95% CI, 0.02-0.81%), 0.47% (95% CI, 0.21-1.04%) and 1.66% (95% CI, 0.95-2.90%), respectively.
Significance: FSIS successfully developed and used novel prevalence calculation methods to estimate pathogen prevalence in regulated products. These estimates inform policies relevant to the prevention of pathogen contamination of raw beef products in FSIS-regulated facilities, and to monitor changes over time. This approach has been adapted for use in estimating pathogen prevalence and volume-weighted percent positive results in other regulated commodities (e.g., poultry products).