Exploiting a MPN-PCR technique to quantify Escherichia coli in minced meat

MPN-culture and MPN-PCR methods were used to determine Escherichia coli concentration in 54 retail minced meat samples. The MPN-PCR is based on the combination between the conventional Most Probable Number and the Polymerase Chain Reaction technique targeting the uidA gene. The conventional MPN-culture technique revealed about 94% of the samples to be positive for E. coli, while MPN-PCR showed only 87%; this difference in detection can be attributed to different factors. MPN-PCR showed values of relative accuracy, sensitivity and specificity of, respectively, 85,8%, 81,6% and 93,5%, and the analysis took only one day, compared with the 4-6 days needed using MPN-culture. The alternative method is reliable when microrganisms are present at low concentration levels.