Campylobacter in Finnish organic laying hens in autumn 2003 and spring 2004.

A total of 642 fecal samples and 360 table eggs from Finnish organic laying hens were collected in autumn 2003 (19 farms) and spring 2004 (17 farms) and studied for the presence of Campylobacter. In autumn, 84% of the farms were positive for Campylobacter and in spring, 76%. The percentage of positive samples within a flock varied between 5 and 100%. In addition, Campylobacter was isolated in a single eggshell sample. Campylobacter jejuni was the species isolated most often, although Campylobacter coli was detected on 3 farms in autumn and on 4 farms in spring. KpnI pulsed-field gel electrophoresis genotyping revealed a high level of diversity among the isolates; 47 different patterns were detected among a total of 162 isolates studied. On most of the farms, the genotypes identified in autumn and spring were different, also indicating temporal diversity among colonizing isolates. However, some predominant persistent genotypes were also detected among the isolates. These results suggest that the pool of colonizing isolates may include both variants with capability for persistent intestinal colonization in hens as well as variants with short-term colonization characteristics. In antimicrobial susceptibility testing, the majority of isolates were susceptible to ciprofloxacin, tetracycline, ampicillin, and nalidixic acid. On 2 farms, isolates resistant to nalidixic acid and to ciprofloxacin were detected. In conclusion, Finnish organic laying hens are often colonized by a diversity of Campylobacter pulsed-field gel electrophoresis genotypes.