Climatic factors and prevalence of Campylobacter in commercial broiler flocks in Thailand.

Campylobacter are bacteria associated with human foodborne disease worldwide. Poultry and poultry products are generally considered as a main source of these organisms. Compared to temperate zones, baseline information on Campylobacter in tropical regions is limited. Thus, the objectives of the present study were 1) to determine the prevalence of Campylobacter in Thai broiler flocks and 2) to investigate the association between climatic factors (i.e., rainfall, ambient temperature, and relative humidity) and Campylobacter colonization status of broiler flocks in Thailand. A total of 442 commercial broiler flocks reared in the central and northeastern regions of Thailand during 2012 to 2014 were investigated. Campylobacter positive status was identified in 252 examined flocks (57.01%; 95% CI 52.39 to 61.63%). Prevalence of Campylobacter in the northeastern region (54.46%; 95% CI 44.76 to 63.83%) was slightly lower than that of the central region (57.77%; 95% CI 52.47 to 62.90%). More than 65% of Campylobacter positive flocks in the central and northeastern regions had within-flock prevalence higher than 75%. Generalized estimating equations (GEE) revealed that the increased rainfall and relative humidity were associated with the increase of Campylobacter colonization in broiler flocks (P ≤ 0.05), while no relationship between ambient temperature and Campylobacter colonization status was identified.

Effect of organic acids in drinking water for young broilers on Campylobacter infection, volatile fatty acid production, gut microflora and histological cell changes.

Water is a prominent vehicle for Campylobacter spread throughout a chicken flock. The aim of this study was to evaluate the effect of organic acids administered through the drinking water, as a decontamination method, on gut microflora and the development of lesions in the gastrointestinal tracts of young broilers inoculated with 2 different doses of Campylobacter. The results revealed that most of the chickens were infected with Campylobacter at the end of the experiment. The drinking water was free of Campylobacter throughout the study. No difference of volatile fatty acid levels between treatment and control groups was observed in the crop and cecal contents. In the cecal contents, the total aerobic bacteria numbers were significantly higher in the treatment groups compared with the control groups (P < 0.01 and P < 0.04, respectively). Moreover, no damaged epithelial cells were observed in the chicken gut due to consumption of acidified drinking water. Acidified drinking water could therefore play a crucial role in a biosecurity strategy of preventing Campylobacter spread via drinking water in broiler flocks.

Antagonistic activities of several bacteria on in vitro growth of 10 strains of Campylobacter jejuni/coli.

Chicken meat contaminated with Campylobacter jejuni can be the source of human enteritis. To decrease the risk of human infection, Campylobacter should be controlled at farm levels. Orally given probiotic bacteria could prevent colonisation of chicken with pathogenic bacteria like Campylobacter. The aim of this study was to investigate the effect of different bacteria on Campylobacter growth. Our results demonstrated that bacteria isolated from conventional chicken had potential inhibitory activities against Campylobacter. Other bacteria not isolated from chickens but with known antagonistic capacities, e.g. Enterococcus (56 strains) and Escherichia coli (20 strains), did not show any negative effect on Campylobacter. Interestingly, one Lactobacillus (P93) strain isolated from the chicken gut showed bactericidal activity against all tested Campylobacter. The bactericidal effect was characterised as the production of organic acids in combination with probably production of an anti-Campylobacter protein. In a co-culture study of Campylobacter and Lactobacillus (P93), the culturability of Campylobacter was under the detection limit after 48 h of incubation. A chicken experiment is needed to further evaluate the effect of the promising probiotic bacteria against Campylobacter colonisation in chicken.

Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions.

The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be recovered, even when enrichment media were used. Viable cells, however, could be detected by a double-staining (5-cyano-2,3-ditolyl tetrazolium chloride [CTC]-4',6'-diamidino-2-phenylindole [DAPI]) technique, demonstrating that the treated bacteria changed into a viable but nonculturable (VBNC) form; the number of VBNC forms decreased over time. Moreover, some VBNC forms of Campylobacter could be successfully resuscitated in specific-free-pathogen fertilized eggs via two routes, amniotic and yolk sac injecting.

In vitro study on the effect of organic acids on Campylobacter jejuni/coli populations in mixtures of water and feed.

Gastroenteritis caused by Campylobacter spp. infection has been recognized as one of the important public health problems in the developed countries. Outbreaks mostly originate from the consumption of contaminated poultry or infected water. The aim of this study was to determine the bactericidal activity on Campylobacter spp. of organic acids individually and in combinations at different pH levels and times and to compare bactericidal activities with activities of commercially available products. Ten strains of Campylobacter spp. were added in a mixture of water with commercial broiler feed, separately adjusted by four acids: formic, acetic, propionic, and hydrochloric acids, into pH 4.0, 4.5, 5.0, and 5.5. A combination of three organic acids was used in two different formulation ratios: formic:acetic:propionic at 1:2:3 and 1:2:5, at pH 4.0, 4.5, 5.0, and 5.5. All organic acids showed the strongest bactericidal effect on Campylobacter at pH 4.0. In contrast, at pH 5.0 and 5.5, the bactericidal activity of the four acids was low. The combination of organic acids showed a synergistic bactericidal activity at pH 4.5. Interestingly, the effect of the combined organic acids was stronger than the commercial products. Morphological cell changes were studied by transmission electron microscopy to determine the effect of the organic acids on the cell structure of Campylobacter. Some loss of outer membranes of the bacteria could be found in treated groups. Therefore, it can be concluded that organic acids, individually or in combination, have a strong bactericidal effect on Campylobacter spp. Routine application of organic acids to the water supply on poultry farms could prevent or diminish Campylobacter transmission.