Interlaboratory Proficiency Testing trial on the Detection of Methicillin-resistant Staphylococcus aureus (MRSA) in food in Germany 2016

In the autumn 2016, the National Reference Laboratory for coagulase positive staphylococci (CPS) including Staphylococcus (S.) aureus (NRL-Staph) at the German Federal Institute for Risk Assessment has organized its first interlaboratory profiency testing (ILPT) trial for the detection of methicillin-resistant Staphylococcus aureus (MRSA) in food. The purpose of the ILPT was to assess the analytical competence of the official laboratories of the Federal German 'Lander' authorities. Moreover, it was the intention to gain an overview of the standard methods implemented in the participating laboratories for the purpose of MRSA detection in food. Five minced pork meat samples (1x blank, 2x not contaminated with MRSA but contaminated with methicillin-resistant S. sciuri, and 2x contaminated with MRSA) were sent in blind to each participant. In total, 19 laboratories participated to the ILPT, 18 from 12 Federal German 'Lander, and the NRL-Staph. Data sets from all 19 participating laboratories were included in the analysis. Overall, a specificity of 98.25% (56/57 true negative results), a sensitivity of 100% (38/38 true positive results), and an accuracy of 98.95% (94/95 true results) was achieved. All of the participants (19/19) used the screening method recommended for the detection of MRSA along the farm-to-fork food chain, which has been developed by the NRL-Staph. To conclude on the ILPT in general it is to state that almost all of the participating laboratories correctly identified MRSA contaminated samples demonstrating a very high analytical capacity in Germany. Moreover, the MRSA screening method developed by the NRL-Staph allows a reliable identification of MRSA contaminated samples.