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Keywords:

  • detection;
  • food;
  • Listeria;
  • polymerase chain reaction;
  • rapid methods;
  • safety

Abstract

Aims:  A rapid real-time PCR-based method for the detection of Listeria monocytogenes was applied to the examination of 44 Quargel cheese samples from a recent outbreak in Austria and compared to the standard method according to ISO-16140.

Methods and Results:  The combined enrichment/real-time PCR method amplifying the prfA locus was performed according to [Rossmanith et al. (2006) Res Microbiol, 157, 763–771]. Qualitative and quantitative examination of the samples was performed according to the standard method ISO-11290. Comparison of the combined enrichment/real-time PCR method with ISO-11290 resulted in 100% relative accuracy, 100% relative sensitivity and 100% relative specificity.

Conclusions:  A previously published study describing the validation of the method, including samples after storage at −80°C, resulted in lower performance values. In contrast, the samples were stored at +4°C in this study. The results of this study indicate an effect of storage, thus masking the true performance of the method.

Significance and Impact of the Study:  The results of this study are discussed together with the previously published data to demonstrate the excellent qualities of this rapid (≤30 h) method when applied to fresh specimens stored at +4°C.