Rapid estimation of Salmonella enterica contamination level in ground beef – Application of the time-to-positivity method using a combination of molecular detection and direct plating

Little progress has been made in decreasing the incidence rate of salmonellosis US over past decade. Mitigating contribution contaminated raw meat to requires rapid methods for quantifying Salmonella, so that highly products can be removed before entering food chain. Here we evaluated use Time-to-Positivity (TTP) as a rapid, semi-quantitative approach estimating Salmonella contamination levels ground beef. Growth rates 14 strains (inoculated at log 1 −2 CFU/g) were characterized lean beef mTSB enrichments and time-to-detection was determined using culture molecular detection methods. Enrichments sampled five timepoints results used construct prediction model estimated level by TTP (superscript indicates time hours) defined TTP4: ≥5 CFU/g; TTP6: ≤5, ≥1 TTP8: ≤1, ≥0.01 with samples negative 8 h ≤0.01 CFU/g. Model performance measures showed high sensitivity (100%) specificity (83% 93% two methods) TTP4, false 0%.