Growth of a pYV-bearing Yersinia pestis KIM5 in retail raw ground pork.

Yersinia pestis can cause oropharyngeal 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 oropharyngeal plague. The growth of a conditionally virulent pYV-bearing rifampicin-resistant Y. pestis KIM5 (rif-Y. pestis KIM5) in retail raw ground pork (RGP) was studied at temperatures ranging from 4 to 30°C. At 4°C, rif-Y. pestis KIM5 did not grow but survived. In RGP, rif-Y. pestis KIM5 grew at refrigerated temperatures of 10 and 15°C with growth rates of 0.05 and 0.16 log(10) colony-forming units (CFU)/h. The growth rates at abusive temperatures of 20, 25, and 30°C were 0.26, 0.30, and 0.77 log(10) CFU/h. The growth rate was increased 15.4-fold with the increase of storage temperatures from 10°C to 30°C. The maximum population density ranged from 6.76 to 8.66 log(10) 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 oropharyngeal plague if the meat was not properly cooked. The individual infected by Y. pestis in food is a potential reservoir who can infect others, leading to outbreaks of plague.