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Thermotolerant Campylobacter spp. have been the most common bacterial cause of human gastrointestinal disease in Denmark since 1999. In 2003, the Danish voluntary strategy to control Campylobacter was intensified. The focus was on biosecurity, allocation of meat from Campylobacter-negative broilers to the production of chilled products, and consumer information campaigns. From 2002 to 2007, the percentage of Campylobacter-positive broiler flocks at slaughter decreased from 43% to 27%. After processing, Campylobacter-positive samples of chilled broiler meat fell from 18% in 2004 to 8% in 2007. Furthermore, the number of registered human Campylobacter cases decreased by 12%; from 4379 cases in 2002 to 3865 cases in 2007. We believe that the observed decrease in the occurrence of Campylobacter in broilers and broiler meat and the coincidental fall in the number of registered human cases is, in part, a result of the implemented control strategy.

In this study, seven Danish turkey flocks were investigated at the farm, on arrival to the slaughterhouse, and during and after slaughter. Flocks were selected based on their Campylobacter spp. status at the farm and three Campylobacter negative and four Campylobacter positive flocks were included in the study. At the slaughterhouse, 70-75 samples were collected at different points from the shackling station to packaging of the final meat cuttings. Samples included cloacal swabs, neckskin, liver, heart, meat and environmental samples. Detection of Campylobacter was carried out by conventional culture and by the EiaFoss system (Foss Electric, Hilleroed, Denmark) for detecting Campylobacter spp. in food, using Preston Broth as enrichment medium. The two methods were compared and sensitivities and specificities were calculated using the conventional culture as gold standard. The three negative flocks were consistently negative from the farm and all through processing. Among the samples from the positive flocks, the frequency of positive samples obtained at the slaughterhouse varied. The frequency of positive samples obtained from the four positive flocks varied and was found to be 4%, 49%, 87% and 96%, respectively. In 31 out of 424 samples, discrepancies were observed between results obtained by the EiaFoss system and the conventional culture technique. The sensitivity for the EiaFoss system was calculated to be 0.94 for meat and neckskin samples. A total of 161 strains were genotyped by pulsed-field gel electrophoresis (PFGE) in order to investigate possible changes in carriage of Campylobacter spp. strains during processing. In three flocks, only one PFGE type was encountered in samples collected at the farm level and, in one flock, two different types were observed. In two flocks, the strain from the farm was also isolated in samples collected at the slaughterhouse. Changes in carriage were observed in two flocks during processing, in particular post chilling.

A total of 117 Campylobacter jejuni isolates from Danish turkeys were tested for the presence of seven virulence and toxin genes by PCR. One hundred seventeen (100%) isolates were positive for flaA, cadF, and ceuE gene primers. One hundred three (88%) isolates were positive for cdt gene cluster PCR detection (cdt gene cluster-PCR), whereas 101 (86.3%), 102 (87.2%), and 110 (94%) isolates were positive for cdtA-, cdtB-, and cdtC-PCR, respectively. Only 39 (33.3%) isolates were positive for virB11. Of 117 isolates, 114 (97.4%) produced cytolethal distending toxin (CDT) in Vero cell assays, 105 (89.7%) in Colon 205 assays, and 109 (93.2%) in chicken embryo cell assays. The CDT titers were determined in Vero cell assays. Of 117 isolates, 50 (42.7%) produced a CDT titer of 1:100, 29 (24.8%) of 1:50, and 27 (23%) of 1:5 to 1:10; 8 (6.8%) produced a CDT titer at undiluted supernatants and 3 (2.6%) produced no toxin. Twenty-nine C. jejuni isolates that were PCR negative for one or more individual cdt toxin genes also produced low or no CDT toxin. The high prevalence of the seven virulence and toxin genes demonstrates that these putative pathogenic determinants are widespread among Campylobacter isolates from turkeys and calls for further investigation for the elimination of Campylobacter infection in industrial turkey production and in industrial food chains.

Aims: To use amplified fragment length polymorphism (AFLP) analysis to evaluate the genetic relatedness among 254 Campylobacter jejuni reference and field strains of diverse origin representing all defined 'Penner' serotypes for this species., Methods and Results: Field strains (n = 207) from human diarrhoea and diverse animal and environmental sources were collected mainly through a National surveillance programme in Denmark and serotyped by use of the established 'Penner' scheme. Genetic relationships among these isolates, and the archetypal serotype reference strains, were assessed by numerical analysis of AFLP profiles derived from genomic DNA. Extensive genetic diversity was seen among the strains examined; however, 43 groups of isolates were identified at the 92% similarity (S-) level. Thirteen groups contained isolates from a single host, possibly representing genotypes of 'low risk' to human health. The remaining 30 groups contained isolates from humans, chickens and associated food products, cattle, sheep, turkeys, ostriches and/or dogs. Strains assigned to serotypes 2, 6/7, 11 and 12 formed major clusters at the 77.6% S-level. Most other serotypes did not form homogeneous clusters., Conclusions: High-resolution genotyping applied to strains from a comprehensive range of sources provides evidence for multiple sources of sporadic C. jejuni infection. The results suggest that public health protection measures should be directed at all foods of animal origin., Significance and Impact of the Study: The genetic relatedness among all 'Penner' serotypes of C. jejuni is assessed by AFLP analysis. In addition, further evidence of epidemic and host-specific clones of C. jejuni is provided.

The prevalence of Salmonella serovars and their antimicrobial resistance patterns were investigated among Danish turkeys between 1995 and 2000, by sampling the flocks approximately 14 days before they were slaughtered. Within the flocks, the prevalence of salmonella varied from 7.1 per cent to 25 per cent, and 24 different serovars were detected. The five most prevalent, which accounted for 58.5 per cent of the isolates were Salmonella Heidelberg (16.2 per cent of the isolates), Salmonella Agona (15.8 per cent), Salmonella Derby (12.4 per cent), Salmonella Muenster (7.3 per cent) and Salmonella Anatum (6.8 per cent). In addition, a few rough isolates and isolates belonging to the antigenically incomplete formulae 6,7:-:- and 4,12:b:- were found. The level of antimicrobial resistance was low; the highest resistance was recorded to ampicillin (13.7 per cent) and streptomycin (9.0 per cent) followed by tetracycline (8.5 per cent), sulphonamides (7.7 per cent) and spectinomycin (4.7 per cent). Resistance to quinolones was very low: four isolates were resistant to nalidixic acid, and only one was resistant to enrofloxacin. No resistance was recorded to colistin, apramycin, ceftiofur, florfenicol, or amoxycillin with clavulanic acid. Only 24 isolates were resistant to two or more compounds in various combinations of up to six compounds; one Salmonella Havana isolate was resistant to six compounds. Six isolates were serovar Typhimurium, but none of them belonged to phage type DT104.