Occurrence and genetic diversity of Arcobacter butzleri in an artisanal dairy plant in Italy

The present study aimed to investigate the presence, distribution and persistence of Arcobacter spp. in an artisanal dairy plant, and to test the isolates to determine different genotypes in the processing plant and in foods. Samples were collected in an artisanal cheese factory on four occasions between October and December 2012: food samples (raw milk, ricotta cheese, mozzarella cheese and conditioning liquid), water samples and environmental samples were analyzed by cultural method; isolates were identified by multiplex-PCR and genotyped by PFGE analysis. Arcobacter butzleri was isolated from 29 out of 59 samples (46.6%), 22 from environmental and 7 from food samples respectively; cluster analysis divided the strains into 47 PFGE patterns: 14 PFGE clusters and 33 unique types. Our findings indicate that the plant harbored numerous A. butzleri pulsotypes and that the manual cleaning and sanitation in the studied dairy plant does not effectively remove Arcobacter. The recurrent isolation of A. butzleri suggests that the environmental conditions in the dairy plant constitute a good ecological niche for the colonization of this microorganism. In some cases, the presence of indistinguishable strains isolated from the same facilities on different sampling days showed that these strains were persistent in the processing environment.