Title: Growth of a plasmid-bearing (pYV) Yersinia pestis KIM5 in retail raw ground pork Authors
Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2013
Publication Date: May 1, 2013
Citation: Bhaduri, S., Phillips, J.G. 2013. Growth of a plasmid-bearing (pYV) Yersinia pestis KIM5 in retail raw ground pork. Foodborne Pathogens and Disease. 10:467-471. Interpretive Summary: Yersinia pestis (YP) is the causative agent of bubonic plague in humans. Although there are few reports of its role in foodborne outbreaks, there is a concern that it could be used as biological weapon, potentially leading to significant morbidity and mortality. Risk assessors are interested in knowing the fate of YP in food, since contaminated food would threaten the health of a large number of individuals. Ground pork is produced in very high quantities where a single process batch represents thousands of servings, and thus contaminated pork could pose a significant threat. The growth of virulence plasmid (pYV)-bearing conditional virulent strain of YP was investigated in raw ground pork (RGP). The YP grew at storage temperatures of 10 to 30 degrees C and reached maximum population density. The YP did not grow at 4 degrees C but survived. To fully assess the potential risk of illness, the stability of pYV in YP during its growth in RGP was studied. The pYV was retained in YP contained in RGP stored at refrigeration temperatures or during its growth at 10 to 30 degrees C. Therefore RGP contaminated with YP could cause oro-pharyngeal plague if RGP is not properly cooked. The resultant disease may lead to outbreaks of highly infectious pneumonic plague.
Technical Abstract: Yersinia pestis can cause oro-pharyngeal plague as a result of consumption or handling of meat from infected animals. Thus, food naturally or intentionally contaminated can have a role in the dissemination of human plague. The growth of a conditionally virulent plasmid (pYV)-bearing rifampicin-resistant Y. pestis KIM5 (rif-Y. pestis KIM5)in retail raw ground pork (RGP) was studied at temperatures ranging from 4-30 degrees C. At 4 degrees C rif-Y. pestis KIM5 did not grow but survived. In RGP rif-Y. pestis KIM5 grew at temperatures of 10 and 15C with growth rates of 0.05 and 0.16 log10 CFU/h, respectively. The growth rates at abusive temperatures of 20, 25, and 30C were 0.26, 0.30 and 0.77 log10 CFU/h, respectively. The growth rate was increased 15.4-fold with the increase of storage temperatures from 10C to 30C. The maximum population density ranged from 8.56 to 8.66 log10 CFU/g. Furthermore, there was no detectable loss of pYV in surviving rif-Y. pestis KIM5 at any of the temperatures tested in retail RGP. This suggests that under these conditions Y. pestis could cause oro-pharyngeal plague if the meat is not properly cooked. The individual infected by Y. pestis in food is a potential reservoir who can infect others leading to outbreaks of plague.