Aspects of epidemiology of Campylobacter in poultry.

Campylobacter bacteria, which in humans cause infections with severe symptoms of diarrhoea, are mainly transmitted by food, especially poultry meat products. Several studies on Campylobacter colonization in breeders, laying hens, and broilers were carried out. Isolates were serotyped, using a modification of the Penner system, in order to identify epidemiological factors contributing to the Campylobacter colonization of poultry. No evidence was found for vertical transmission from breeder flocks via the hatchery to progeny, nor for horizontal transmission from one broiler flock to the next via persistent contamination of the broiler house. The major route for Campylobacter colonization of poultry is horizontal transmission from the environment. Pigs and poultry flocks (broilers, laying hens, and breeders), and to a lesser extent sheep and cattle, were found to be potential sources of Campylobacter contamination. Horizontal intervention procedures at the farm level have to be studied further to evaluate the effectiveness of strict hygienic practices during the whole production period. Screening for antibiotic resistance revealed 181 out of 617 Campylobacter isolates (29%), originating from a large number of broiler flocks, to be quinolone resistant. Quinolone treatment of Campylobacter colonized broiler chicks was found to induce quinolone resistance under experimental conditions. Therefore, quinolone treatment should not be seen as an answer to the problem of Campylobacter colonization in poultry flocks.