Establishing a campylobacter-free pig population through a top-down approach

Microbiological Safety of Leafy Vegetables Produced at Houeyiho and Sèmè-Kpodji Vegetable Farms in Southern Benin: Risk Factors for Campylobacter spp

Foodborne infections, mainly those attributable to Campylobacter, are one of the most common causes of intestinal diseases, of bacterial origin in humans. Although the vehicle of transmission is not always identified, the most common vehicles are poultry, poultry products, and contaminated water. In Southern Benin, an excessive use of poultry manure as fertilizer in vegetable farms was noted. This survey aimed to determine the prevalence and concentration of Campylobacter spp., especially Campylobacter jejuni and Campylobacter coli, in selected environmental samples (poultry manure, and irrigation water) and freshly harvested leafy vegetables in two (Houeyiho and Sèmè-Kpodji) vegetable farms in southern Benin. To achieve this objective, we analyzed 280 samples, including 224 samples of leafy vegetables (Solanum macrocarpon and Lactuca sativa capita), 28 samples of irrigation water, and 28 samples of poultry manure. The analysis of the samples taken was carried out according to the modified NF EN ISO 10272-1 standard. Of the 280 samples analyzed in this survey, 63 were positive for Campylobacter contamination. For leafy vegetable samples analyzed in this survey, the contamination rate was of 15.63%. 60.71% of poultry manure samples analyzed were contaminated with Campylobacter spp. and 39.29% of irrigation water samples were contaminated. The statistical analysis of these results showed that there is a correlation between the contamination of leafy vegetables, poultry manure, and irrigations (p < 0.01). Campylobacter jejuni (53.97%) was more involved in contaminations than Campylobacter coli (36.57%). This study has shown that there is a real risk of food poisoning by Campylobacter jejuni and Campylobacter coli among consumers of leafy vegetables in southern Benin. The origin of contamination of these leafy vegetables is poultry manure used as fertilizer in vegetable gardens and irrigation water used.

A national investigation of the prevalence and diversity of thermophilic Campylobacter species in agricultural watersheds in Canada

The occurrence and diversity of thermophilic Campylobacter species (C. jejuni, coli, and lari) were studied in water samples from four river basins located across Canada. These basins located in Quebec (Bras d'Henri), Alberta (Oldman), Ontario (South Nation), and British Columbia (Sumas) represented some of the most intensive farming areas in Canada for hog, beef cattle, dairy cattle, and poultry, respectively. This study analyzed 769 water samples collected from 23 monitoring sites with agricultural influence, and four reference sites with limited or no agricultural influence. Water samples were collected bi-weekly over two years and analyzed for Campylobacter using a semi-quantitative minimum probable number (MPN) enrichment protocol. Putative isolates were confirmed by genus- and species-specific multiplex polymerase chain reaction (PCR) assays. A total of 377 (49%) water samples were positive for campylobacters with 355 samples having a cell density ranging from 4 to 4000 MPN L(-1). Campylobacters were more common at agricultural than reference sites in each river basin, although this difference was not significant in the Oldman and South Nation (p > 0.05). Campylobacter was significantly more common in the Bras d'Henri and Sumas (63%) compared to the South Nation (45%) and Oldman (33%) River basins (p < 0.05). C. jejuni, C. coli and C. lari were detected in each river basin, and these species occurred in 45% (n = 168), 34% (n = 128) and 19% (n = 73), of all Campylobacter positive samples, respectively. The remaining Campylobacter positive water samples without these three species (n = 67; 18%) were identified as other Campylobacter species. C. jejuni was the predominant species occurring in the Sumas, Oldman and South Nation River basins. However, in the Bras d'Henri River basin with intensive hog production, C. coli was the predominant species. This study found campylobacters to be common in some agricultural systems with intensive livestock farming activities, and different river basins could have strikingly different profiles of either C. jejuni or C. coli as the predominant waterborne thermophilic Campylobacter species.

Campylobacter spp., Yersinia enterocolitica, and Salmonella enterica and their simultaneous occurrence in German fattening pig herds and their environment

Campylobacter spp., Salmonella enterica, and Yersinia enterocolitica are common causes of foodborne infections in humans with pork as a potential source. Monitoring programs at farm level are, to date, only implemented for S. enterica, while epidemiological knowledge of the other two pathogens is still lacking. This study aimed to assess the pathogen load (in the pigs' environment) in fattening pig herds, their simultaneous occurrence, and the occurrence of Campylobacter spp. and Y. enterocolitica in herds in different Salmonella risk categories. In 50 fattening pig herds in northern Germany, four pooled fecal samples and 10 swab samples from the pigs' direct environment (pen walls, nipple drinkers), indirect environment (hallways, drive boards), and flies and rodent droppings were collected from each herd and submitted for cultural examination. Campylobacter spp. were detected in 38.1% of fecal, 32.7% of direct environment, 5.3% of indirect environment, and 4.6% of flies/pests samples collected, and Y. enterocolitica in 17.1, 8.1, 1.2, and 3.1% and S. enterica in 11.2, 7.7, 4.1, and 1.5%, respectively. For Campylobacter spp., Y. enterocolitica, and S. enterica, 80, 48, and 32% of herds were positive, respectively; 22 herds were positive for both Campylobacter spp. and Y. enterocolitica, 12 for Campylobacter spp. and S. enterica, and 7 for Y. enterocolitica and S. enterica. There was no significant association between the pathogens at herd level. Campylobacter spp. and Y. enterocolitica were found more often in samples from the low Salmonella risk category (odds ratio, 0.51; confidence interval, 0.36 to 0.73, and 0.3, 0.17 to 0.57), and this was also the case for Y. enterocolitica at herd level (odds ratio, 0.08; confidence interval, 0.02 to 0.3). This study provides evidence that the pigs' environment should be accounted for when implementing control measures on farms against Campylobacter spp. and Y. enterocolitica. An extrapolation from the current Salmonella monitoring to the other two pathogens does not seem feasible.

Arcobacter population dynamics in pigs on farrow-to-finish farms

Healthy pigs are an important reservoir for the emerging human pathogen Arcobacter which can result in contamination of porcine carcasses and pork and the spread of arcobacters into the environment. Up to now, the excretion of arcobacters by pigs has been studied, but information about the transmission routes in fattening pigs is lacking. The present study aimed to elucidate the Arcobacter population dynamics in pigs during the fattening period on four farrow-to-finish farms. On each farm, 30 clinically healthy, 12-week-old piglets were selected. Fecal samples were collected on 10 sampling occasions until a slaughter age of 30 weeks was reached. Arcobacter spp. were isolated by a selective method and identified by multiplex PCR. The genetic diversity was examined by amplified fragment length polymorphism and enterobacterial repetitive intergenic consensus PCR. The Arcobacter presence in the fecal samples on the four farms ranged from 11.3 to 50.0%, with excretion levels of up to 10(4) CFU/g feces. The ratio in which Arcobacter species were isolated varied between the farms and over time. Characterization revealed a high degree of genotypic diversity among the isolates. Arcobacter strains persisted and spread within the finishing unit during the fattening period. The occurrence of both unique and shared genotypes in pigs in adjacent and nonadjacent pens demonstrates that transmission routes other than fecal-oral transmission occur.

Prevalence and risk factors for bacterial food-borne zoonotic hazards in slaughter pigs: a review

The Hygiene Package and Regulation EC-2160/2003 require information flow from farm to slaughterhouse to enhance European consumers protection in a 'farm to fork' approach. This obligation especially concerns food-borne zoonotic hazards transmitted to humans through pork consumption, such as thermophilic Campylobacter spp., Listeria monocytogenes, Salmonella enterica and Yersinia enterocolitica. Prevalence estimates of these four hazards are affected by the sampling strategy and diagnostic procedure. Individual prevalence estimates for pig carriage (from digestive contents or lymph nodes collected at slaughterhouse) were higher than individual prevalence estimates for pig shedding (from faeces). Among risk factors described in the literature, poor pen cleaning and disinfection after pig departure to slaughterhouse and poor bio-security measures are of major significance. Moreover, whereas wet feed increases the risk of pig infection by L. monocytogenes, dry feed is a risk factor for Salm. enterica. Mixing batches of pigs, notably in fattening herds, represents a risk for the transmission of Salm. enterica and Y. enterocolitica. Whereas small herds are more infected by thermophilic campylobacters and Y. enterocolitica, higher prevalence of Salmonella is observed in large herds due to a more frequent mixing of batches. Antibiotic treatment during the finishing period increases the risk of transmission of Salm. enterica. The forenamed elements should be taken into account to characterize farms in a risk assessment approach and to improve zoonotic hazard management in the pork food chain.

Experimental infection of specific pathogen-free pigs with Campylobacter: excretion in faeces and transmission to non-inoculated pigs

Campylobacter species are leading agents of human bacterial gastroenteritis and consumption of food of animal origin is a major source of infection. Although pigs are known to frequently exhibit high counts of Campylobacter in their faeces, more information is needed about the dynamics of this excretion. An experimental trial was conducted to evaluate the faecal excretion of Campylobacter by 7-week-old specific pathogen-free piglets inoculated per os with three Campylobacter strains (one C. coli isolated from a pig, one C. coli and one C. jejuni from chickens) alone or simultaneously (5x10(7)CFU/strain). Non-inoculated pigs were housed in adjacent pens. Pigs were monitored for 80 days for clinical signs and by bacteriological analysis of faeces. Pigs inoculated with porcine C. coli or with a mix of the three strains excreted from 10(3) to 10(6)CFU/g of faeces with a slight decrease at the end of the trial. Animals inoculated with poultry C. coli or C. jejuni strain excreted a lower quantity and some of them stopped excreting. At the end of the trial, only C. coli was detected in the faeces of pigs inoculated simultaneously with the three bacteria. Moreover, the transmission of Campylobacter was noticed between pens for the two C. coli strains and all the neighbouring animals became shedders with a level of excretion similar to the inoculated pigs. Intermittence in the Campylobacter excretion was also observed. Finally, our study highlighted a host preference of Campylobacter, namely C. coli seems to have a higher colonization potential for pigs than C. jejuni.

The occurrence and characterization of Campylobacter jejuni and C. coli in organic pigs and their outdoor environment

The occurrence and species distribution of thermophilic Campylobacter was investigated in organic outdoor pigs. An increased exposure of outdoor pigs to C. jejuni from the environment may cause a shift from a normal dominance of C. coli to more C. jejuni, which may imply a concern of reduced food safety. Bacteriological methods for determination of Campylobacter excretion level were combined with colony-blot hybridization and real-time PCR for specific detection of C. jejuni in pigs. Campylobacter was isolated from pigs (n=47), paddock environment (n=126) and wildlife (n=44), identified to species by real-time PCR and sub-typed by serotyping (Penner) and pulse-field gel electrophoresis (PFGE) genotyping. All pigs excreted Campylobacter (10(3)-10(7) CFU g(-1) faeces) from the age of 8-13-weeks old. C. jejuni was found in 29% of pigs in three consecutive trials and always in minority to C. coli (0.3-46%). C. jejuni and C. coli were isolated from 10% and 29% of the environmental samples, respectively, while crow-birds and rats harboured C. jejuni. Individual pigs hosted several strains (up to nine serotypes). The paddock environment was contaminated with C. coli serotypes similar to pig isolates, while most of the C. jejuni serotypes differed. C. jejuni isolates of different origin comprised few similar serotypes, just one identical genotype was common between pigs, environment and birds. In conclusion, the occurrence of C. jejuni varied considerably between the three groups of outdoor pigs. Furthermore, transfer of C. jejuni to the outdoor pigs from the nearby environment was not predominant according to the subtype dissimilarities of the obtained isolates.

Prevalences and transmission routes of Campylobacter spp. strains within multiple pig farms

In this work, faecal samples were collected from 15 pig farms to determine the Campylobacter prevalences at different times during the rearing period and to visualize the exchange of strains among the pig population by genotyping specific isolates. All isolated strains were identified as C. coli. Whereas no Campylobacter were detectable in the faeces of piglets at the day of birth, the Campylobacter incidence rose within days to 32.8%. After transfer to the nursery unit the prevalence increased to 56.6%. Approximately two-thirds of the pigs remained C. coli shedders in the fattening unit. In contrast to most farms, one farm expressed a very low Campylobacter incidence during the whole rearing period. Amplified fragment length polymorphism (AFLP) analysis was performed on all C. coli isolates of one farm. Clonal strains were identified from the brood sows and their offsprings or neighbouring piglets. After moving to the nursery unit, new genotypes appeared in that pig group but the original C. coli strains largely remained within that group. C. coli genotypes, identified during the fattening period, replaced the previously isolated genotypes. Transportation to the abattoir had no significant influence on the shedding rate of C. coli. The detection rate before transportation was 79.1% and decreased slightly to 78.2% (n=330). Additionally, eleven of 1474 environmental samples from different sources of the pig farms were positive for C. coli. This study demonstrates the importance of pigs as a reservoir for C. coli. Maternal C. coli strains are the primary source of infection but non-related genotypes from different sources appear during the rearing period and these latter strains constitute largely the final C. coli flora.