Research -Occurrence of Campylobacter spp., Salmonella spp. and shiga toxin‐producing Escherichia coli in inline milk filters from Swedish dairy farms

This study investigated the occurrence of shiga toxin‐producing Escherichia coli (STEC), thermotolerant Campylobacter spp. and Salmonella spp. in Swedish dairy milk. A total of 302 inline milk filters were analyzed. Salmonella was not isolated from any filters. Polymerase chain reaction screening detected thermotolerant Campylobacter in 30.5% of the milk filters analyzed and it was isolated from 12.6% of filters. The stx genes (stx ₁, stx ₂, or both) were screened from 71% of the filters and STEC was isolated from 14% of these. Of the STEC isolates, 21 contained the stx ₁ gene, 19 the stx ₂ gene, and five a combination of both stx ₁ and stx ₂ genes. Whole genome sequence typing on 34 of the 45 STEC showed that they belonged to 21 different serotypes, of which STEC O145:H28 was the most common (2%). STEC O157:H7 was only found from one (0.3%) of the filters. A combination of stx ₂ and eae genes was found from 0.7% of the total number of inline milk filters analyzed, while stx _2a was found in 24% of the whole genome‐sequenced isolates. There was a significant positive correlations between number of animals per farm and presence of pathogens on milk filters.