Serotype and genotype diversity and hatchery transmission of Campylobacterjejuni in commercial poultry flocks

We investigated the genotype and serotype diversity of Campylobacter coli a nd C jejuni in two parent flocks of adult hens and their offspring over two rotations in order to evaluate the role of hatchery mediated transmission and/or vertical transmission of campylobacters in broiler flocks. In total, 314 C jejuni and 32 C coli isolates from parent and broiler flocks and fro m the surroundings of broiler houses were typed by flagellin gene PCR/RFLP fla-typing), and selected isolates were also typed by serotyping and macror estriction profiling using PFGE (MRP/PFGE). The combined typing results sho wed that the broiler flocks could be colonised by 1-3 different Campylobact er clones and parent flocks could be colonised by 2-6 different clones. C c oli was isolated from up to 36% of birds in one parent flock, whereas only C jejuni was isolated from broiler flocks. C jejuni clones from different f locks were clearly discriminated by fla-typing as well as by MRP/PFGE, exce pt for a few cases where individual isolates belonging to two different clo nes were found to have altered fla-types. Similarly, one C coli clone showe d pronounced fla-type variation. The present results lead to the conclusion that vertical transmission or horizontal transmission via the hatchery are not significant transmission routes of C jejuni to broiler chickens under Danish conditions. In the cases where more than one Campylobacter clone sim ultaneously colonised flocks, we found that the different clones coexisted in flocks rather than excluding each other. (C) 2001 Elsevier Science B.V. All rights reserved.