Mark L. Tamplin

Pure-culture broth-based models of the growth of Escherichia coli O157:H7 have been used to estimate its behavior in ground beef, even though these models have not been adequately validated for this food product. This situation limits accurate estimates of the behavior of E. coli O157:H7 in ground beef and introduces uncertainties in risk assessments. In the present study, the growth of single and multiple strains of E. coli O157:H7 were measured in retail ground beef stored at 10°C for up to 12 days, and the results were compared with estimates generated by the U.S. Department of Agriculture's Pathogen Modeling Program (PMP; version 5.1). At pH 5.9, the PMP predicted a maximum population density (MPD) of 9.13 log10 CFU/g, an exponential growth rate (EGR) of 0.052 log10 CFU/h, and a lag time of 56.3 h. Similar parameter values were observed for sterilized ground beef; however, no lag phase was observed. In contrast, the mean MPD and EGR for retail ground beef were 5.09 log10 CFU/g and 0.019 log10 CFU/h, r...

The present study examined the prevalence of Salmonella spp. and the prevalence and quantity of generic (biotype I) Escherichia coli on carcasses or in pig feces at a pork processing plant operatin...

Vibrio spp. cause frank and opportunistic infections of humans through exposure to seafood and seawater. Due to their natural occurrence in coastal environments, traditional indicator organisms, such as E. coli, do not predict their presence. This problem has complicated public health initiatives aimed at reducing the impact of illnesses from Vibrio spp. In the U.S., V. vulnificus has received extensive study due to the severity of its disease in humans. Its numbers increase with warmer summer temperature, and decline to nondetectable levels in colder winter months. In environments with salinities greater than 20 ppt, V. vulnificus numbers decline to levels that do not pose human health risks. A similar response to temperature has been observed for pathogenic strains of V. parahaemolyticus, where recent outbreaks of illness have been associated with El Niño weather conditions. In addition, temperature-induced plankton blooms have been linked to epidemic cholera in certain geographical regions of the world. New research shows that seawater temperature and salinity can be used to develop mathematical models of V. vulnificus incidence in coastal environments. Similar efforts might be extended to other Vibrio spp. to develop indicators that predict human health risk, as well as ecosystem integrity.