Study of the presence of Campylobacter jejuni and C. coli in sand samples from four Swiss chicken farms.

Chicken farms are frequently infected with Campylobacter jejuni and Campylobacter coli. The objective of the present study was to investigate environmental samples from chicken farms for the presence of C. jejuni and C. coli. Every week between July and November 1997, three sand samples from the runs of four chicken farms were analyzed by culture and directly by polymerase chain reaction (PCR). These two detection methods were compared to each other. A total of 231 samples were tested. Eleven samples (4%) were found to contain Campylobacter cells by culture, whereas 157 samples (68%) were positive by PCR. All samples which were positive by culture were also positive by PCR. All direct PCR products were further typed by restriction fragment length polymorphism (RFLP). Three different RFLP types and mixtures of these types were observed. Direct PCR products of one chicken farm were further typed by direct sequencing and two temporally separated sequence types could be distinguished. Campylobacter strains isolated by culture were also typed by RFLP and direct sequencing revealing close accordance with the corresponding direct PCR products.