Detection of Arcobacter spp. in environmental and food samples collected in industrial and artisanal sheep's milk cheese-making plants

The genus Arcobacter include species considered as human foodborne enteropathogens. In recent years, Arcobacter spp. have been frequently isolated from various food of animal origin such as meat, fish and dairy products. However, there is still little information on the occurrence of Arcobacter spp. in the dairy sheep chain. The present study was aimed to assess the prevalence of Arcobacter spp. in the processing environment of 10 industrial and 10 artisanal cheese making plants using sheep milk. A total of 250 samples were collected including food contact and non-food contact surfaces, cheeses, water and wastewater samples. Species identification of isolates was conducted by multiplex PCR and PCR-RFLP. Arcobacter spp. were isolated in 11 out of 20 cheese-making plants (55.0%) with an overall prevalence of 19.2%. Of Arcobacter positive samples 32 (66.6%) were detected from environmental surfaces, 11 (22.9%) from food samples and 5 from wastewater (10.4%). Arcobacter was never recovered from water samples. No differences were observed between industrial and artisanal cheese-making plants. Of 48 isolated strains, 39 (81.3%) were A. butzleri, 5 (10.4%) A. cryaerophilus and 4 (8.3%) A. skirrowii. This is the first investigation reporting the detection of A. cryaerophilus and A. skirrowii from both environmental surfaces and cheeses in dairy plants using sheep milk. Contamination was observed respectively in 6 ricotta (20.0%) and in 3 fresh cheeses (23.1%). The present study indicates the potential risk for human health associated to cheese obtained with pasteurized milk due to cross contamination originating from the processing environment. To minimize the risk of transmission of Arcobacter spp. to consumers through the ingestion of contaminated foods it is essential the implementation of environmental monitoring programs to collect samples from food processing surfaces and to detect the presence of this potential human pathogen.