The relative sensitivity for the matrices meat and environmental samples, as well as when BIBF 1120 in vitro all the samples were analyzed together were above 95%, which is the limit considered acceptable according to NordVal [15]. No recommendations concerning the levels for the relative accuracy and relative specificity are given in either the guideline [15] or in the ISO16140 standard [19]. In the collaborative study, complete agreement between the real-time PCR method and the culture-based reference method was obtained for all test characteristics for minced pork and veal meat as well as for poultry neck-skin samples.

For carcass swabs, one of the samples that were not artificially contaminated was positive when analyzed by one of the laboratories. However, investigations after the finalization of the trial pointed to a mix-up of two samples during the set-up of the PCR plate, which Selleckchem AZD8186 presents a reasonable explanation for this false-positive result. One of the participants was excluded from the study, due to too long transportation time (> 5 days) which has a detrimental effect on the PCR master mix. There are some limitations to this study that should be taken into consideration when

implementing the method at other laboratories. Firstly, only one brand of PCR thermo cycler was used in the study. It has previously been reported that PCR results might vary considerable between different thermocyclers [12] and it might be necessary to adjust reagent concentrations and the temperature program slightly to optimize the method. Secondly, the enrichment step of the method was only performed at the see more expert laboratory and pellets were sent out for DNA extraction and PCR analysis. Thus

the reproducibility was assessed for the DNA extraction and PCR steps. This procedure was approved in advance by NordVal. The participating laboratories were experienced laboratories that were familiar with culture based methodologies. However, in other guidelines for collaborative studies, such as ISO 16140, it is recommended that the complete procedure is performed by all participating laboratories [19]. In the last part of the study, the Selleckchem OICR-9429 robustness of the method was verified externally for artificially contaminated pork samples. No significant difference in the result for the real-time PCR method and a commercial SYBR-Green PCR-based analysis system (BAX) was found. However, results were available after 14 h for the real-time PCR method, compared with 20–24 h for the BAX system. In this study, two samples inoculated with a very low level (estimated 2 CFU/25 g) and two samples inoculated at 10 CFU/25 g were negative in both methods, most likely indicating that no surviving Salmonella actually were present in the sample.