Short communication: Enterotoxigenic potential of coagulasenegative staphylococci isolated from bovine milk in Poland

摘要

Our objective was to assess the enterotoxigenicpotential of coagulase-negative staphylococci (CNS)isolated from bovine milk in Poland. We analyzed CNSisolates collected from 133 bovine milk batches fromdairy farms in the Western Pomerania district during2 milking seasons. A total of 163 isolates were screenedby multiplex/duplex PCR for the presence of 18 of 25enterotoxin genes identified so far in Staphylococcusaureus. The CNS strains presumed to be potentially enterotoxigenicwere identified at the species level basedon MALDI-TOF mass spectrometry analysis. Basedon the presence of an amplicon matching D, G, orO enterotoxin genes, we initially identified 32 of the163 CNS isolates tested as potentially enterotoxigenic.However, only 8 of these strains were confirmed as such.All 8 of these CNS strains, identified as Staphylococcushaemolyticus, harbored the seg genes, a prerequisitefor enterotoxin G production, but so far not connectedwith staphylococcal foodborne poisoning cases. Noneof the CNS bovine milk isolates tested was a potentialproducer of classical A to E staphylococcal enterotoxins.Results of our surveys revealed a low prevalenceof enterotoxigenic CNS among the milk isolates fromdairy farms in the Western Pomerania district, Poland,suggesting that they pose only a mild health risk inmilk. In our opinion, confirmed formation of nonspecificamplicons leading to false-positive results excludesmultiplex/duplex PCR as the sole method for assessingthe enterotoxigenic potential of CNS.