SUMMARYBroiler flocks on two Dutch poultry farms were screened weekly for the presence of campylobacter in fresh caecal droppings during eight consecutive production cycles. Hatchery and fresh litter samples were taken at the start of each new cycle. Water, feed, insects, and faeces of domestic animals, present on the farms were also included in the sampling. Penner serotyping of isolates was used to identify epidemiological factors that contribute to campylobacter colonization in the broiler flocks. Generally, broiler flocks became colonized with campylobacter at about 3-4 weeks of age with isolation percentages of 100 %, and stayed colonized up to slaughter. A similar pattern of serotypes was found within the various broiler houses on one farm during one production cycle. New flocks generally showed also a new pattern of serotypes. Most serotypes isolated from the laying hens, pigs, sheep and cattle were different from those isolated from the broilers at the same time. Campylobacter serotypes from darkling beetles inside the broiler houses were identical to the ones isolated from the broilers. No campylobacter was isolated from any of the hatchery, water, feed or fresh litter samples. Conclusive evidence of transmission routes was not found, but results certainly point towards horizontal transmission from the environment. Horizontal transmission from one broiler flock to the next one via a persistent contamination within the broiler house, as well as vertical transmission from breeder flocks via the hatchery to progeny, did not seem to be very likely.

From March 1992 to March 1993, 187 Dutch broiler flocks were screened to assess their Campylobacter and Salmonella carriage. Every 4 wk at least 10 flocks, at three different slaughterhouses, were screened for presence of these bacteria. Twenty-five cecal samples were taken from each flock. Campylobacter spp. were isolated from 153 out of 187 broiler flocks (82%). Campylobacter carriage of flocks showed seasonal variation, with the highest contamination rate (100%) during the period June to September and the lowest (50%) in March. Salmonella carriage of the flocks did not show a distinct seasonal variation. Salmonella spp. were isolated from 49 out of 181 broiler flocks (27%). A positive correlation was found between Campylobacter and Salmonella colonization within flocks. Data on farming conditions and husbandry practices were studied to identify possible risk factors for Campylobacter and Salmonella colonization of Dutch broiler flocks.

SUMMARYRecently, an increased resistance of Campylobacter to fluoroquinolones, a newer class of antimicrobial agents in both human and veterinary medicine, has been reported. Campylobacter isolates (617) from 150 broiler flocks were tested for their susceptibility to cephalothin (control), ampicillin, tetracycline, erythromycin, and the quinolones nalidixic acid, flumequine, enrofloxacin, and ciprofloxacin by a disc diffusion method. Almost complete cross-resistance was found between the quinolones tested. Campylobacter isolates (181, 29%), originating from 55 flocks (37%), were quinolone resistant. Salmonella isolates (94) from 40 flocks were also tested for their antimicrobial susceptibility. Eight isolates (8.5%), from three broiler flocks (7.5%), showed resistance to nalidixic acid and flumequine (and tetracycline), but not to ciprofloxacin or enrofloxacin.

Meat products are very important sources of protein in the human diet. The contamination of these products with pathogenic microorganisms, such as Salmonella and Campylobacter, make both production and consumption of them a precarious proposition. Several methods can decrease the level of contamination with these pathogenic microorganisms. However, there are still situations of high microbial load which cannot be explained and are often attributed to stress. This paper describes the effect of transport, husbandry and nutrition practices on contamination of slaughtered products. Examples of the stress occurring during fattening, catching and loading, transport and conditioning at the processing plant, are given.

An assay is described for evaluating live-culture treatment material that may be given orally to chicks to prevent intestinal colonization by non-host-specific salmonellae. Both pre-treated and control chicks are challenged with ca 104 salmonellae/chick, using a strain bearing an antibiotic resistance marker. Chicks are examined 5 d after challenge to determine both the proportion of positive birds in treated and control groups and the levels of Salmonella in the caeca of infected individuals. The efficacy of the treatment is determined by calculation of values for Infection Factor and Protection Factor.