FIG. 1.

Dose-response models for L. monocytogenes systemic infection derived from human and food epidemiological data and models derived from guinea pig experiments. Guinea pig results were from the work of Van Stelten (39). Results from the exponential model obtained from epidemiological data (⧫) in the study reported here are shown for the subgroup without inlA PMSCs (A) and for the subgroup with inlA PMSCs (B). For comparison, three models (beta-Poisson, log-logistic, and exponential) that provided acceptable fit to L. monocytogenes numbers recovered from infected guinea pigs are shown; guinea pig dose-response curves for an L. monocytogenes isolate encoding a full-length InlA (isolate CUFSL N1-054, H7550; obtained from a human case associated with the 1998-1999 listeriosis outbreak in the United States reported by the CDC [4]) are shown in panel A, while guinea pig dose-response curves for an L. monocytogenes isolate with an inlA PMSC (isolate CUFSL N1-040) are shown in panel B. The models derived from guinea pig data were represented in both panels by the following symbols: ▪, log-logistic; •, beta-Poisson; and ▴, exponential.