|Meinersmann, Richard - Rick|
Submitted to: Foodborne Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2005
Publication Date: 11/3/2005
Citation: Eifert, J., Curtis, P.A., Bazaco, M.C., Kernodle, S., Meinersmann, R.J., Berrang, M.E., Stam, C., Jaykus, L.A., Kathariou, S. 2005. Molecular characterization of listeria monocytogenes of the serotype 4b complex (4b, 4d, 4e) from two turkey processing plants. Foodborne Diseases. 2(3):192-200. Interpretive Summary: Listeria monocytogenes is a bacterial species that is associated with foodborne infection and may have serious consequences especially in pregnant women and with the elderly. A subgroup of L. monocytogenes known as serotype 4b complex strains has been associated with a number of outbreaks of disease. The bacteria has been associated with products made with turkey meat but the association of disease causing Listeria with turkey carcasses at the processing plant has not been well described. In this study samples were taken from a turkey processing plant and tested for the presence of L. monocytogenes. Listeria was found and this included members of the serotype 4b complex. Further characterization showed that these were not the same as types that have been associated with historical outbreaks. In addition, there were minor differences in some of the recovered bacteria that indicated development of new types at the site. Since we do not fully understand how L. monocytogenes causes disease, it can not be ruled out that the bacteria found in turkey processing may represent a health hazard.
Technical Abstract: Most foodborne outbreaks of listeriosis have been found to involve a small number of closely related strains of Listeria monocytogenes serotype 4b. The ecology of these organisms and their reservoirs in nature or in the processing plant environment, however, remain poorly understood. Surveys of environmental samples from two turkey processing plants in the United States indicated presence of serotype 4b complex strains (serotype 4b and the closely related serotypes 4d and 4e). Environmental and raw product samples from one plant, in addition, repeatedly yielded isolates with genetic markers typical of two major known epidemic clonal groups. The pulsed field gel electrophoresis profiles of these isolates, however, were clearly distinct from those of confirmed epidemic-associated strains. In addition, minor but consistent differences in PFGE profile of isolates of the same clonal group, and obtained at different sampling times from the same plant were observed. The findings suggest that genomic diversification of certain clonal groups of L. monocytogenes serotype 4b may be taking place in the processing plant environment. These findings also suggest that the genomic adaptations and ecology of epidemic-associated strains of this organisms are more complex than commonly thought, and would need to be taken into consideration in further efforts to elucidate the epidemiology of these organisms.