Occurrence of putative virulence genes on Arcobacter butzleri isolated from three different environmental sites throughout the dairy chain

Aims: This comparative study investigated the occurrence of cadF, cj1349, ciaB, pldA, tlyA, hecA, hecB, mviN, irgA and IroE genes in 212 Arcobacter butzleri isolated from three different environmental sites linked to the dairy chain (farms, industrial and artisanal dairy plants) located in three Italian regions (Lombardy, Emilia-Romagna and Calabria). Methods and Results: According to the presence of these genes, different pathotypes (P-types) were determined. The main genes detected were ciaB, mviN, tlyA, cj1349, pldA and cadF, while the least common genes were iroE, hecA, hecB and irgA. TlyA, irgA, hecA, hecB and iroE, which were significantly more frequent in isolates recovered in industrial dairy plants. Twelve P-types were detected. The occurrence of the most frequently detected P-types (P-types 1, 2, 3 and 5) differed significantly (P < 0·001) in relation to both the environmental site and geographical area of isolation. The highest diversity in P-types was observed in industrial dairy plants and in the Calabria region. Conclusions: The results of this study show a correlation between the occurrence of putative virulence genes and virulence genotype variability depending on the environmental site and geographical origin of the isolates. Significance and Impact of the Study: The present study provides insights into the similar distribution of putative virulence genes in a dairy chain and other sources’ isolates and also into a geographical distribution of some P-types. We have shown that industrial dairy plants may represent an environmental site favouring a selection of the isolates with a higher pathogenetic pattern.