Evaluation of the adhesive capacity of Escherichia coli isolates associated with avian cellulitis

It has been shown that Escherichia coli isolates from lesions of cellulitis belong to a limited number of clonal groups distinct from those of isolates found in the environment of these birds. In this study, different in vitro methods were used to evaluate adherence properties of E. coli isolates from cellulitis lesions and environments of high- and low-cellulitis prevalence broiler flocks. One hundred isolates were tested by hemagglutination. Adherence to frozen sections of chicken skin and binding to soluble fibronectin were examined for 40 of these 100 isolates by immunofluorescence and by immunocytofluorometry, respectively. Localization of bacterial adherence to skin tissues was confirmed by immunohistochemistry. It was demonstrated that O78:K80 isolates from cellulitis lesions adhered to skin sections to a much greater extent in deeper than in superficial tissue layers. A greater bacterial adherence following growth in TSB at 37 C was demonstrated for isolates from flocks with high prevalence of cellulitis than for isolates from flocks with low prevalence of cellulitis. MANOVA analysis results showed a significant difference between superficial and deep tissue layers only for one set of isolates from flocks with high prevalence of cellulitis. Hemagglutinating activity was variable among the O78:K80 isolates obtained from flocks with high prevalence of cellulitis. The results obtained for some O78:K80 isolates following growth in TSB suggest a role for type 1 fimbriae or F1 in adherence to skin sections. This was reinforced by the finding that adherence was inhibited by D-mannose. Poultry E. coli isolates that express F1 had no affinity for soluble fibronectin, although localization of the adherence in skin sections suggested a role for extracellular matrix components such as collagen and insoluble fibronectin.     

Evidence of cross-contamination by Campylobacter spp. of broiler carcasses using genetic characterization of isolates

Campylobacter is recognized as one of the leading cause of gastroenteritis worldwide, and is frequently isolated from the small intestines and ceca microflora of chickens. Twenty-one out of 81 Campylobacter-positive poultry flocks were selected to evaluate the genetic diversity of Campylobacter isolates and to study the distribution of genotypes among flocks. Campylobacter isolates recovered from chicken carcasses and ceca were analyzed by pulsed-field gel electrophoresis (PFGE). Little diversity was found among Campylobacter strains isolated from a given carcass, with a maximum of 2 different genotypes being present. However, at flock level, as many as 4 different profiles were observed. Typing of strains showed that most strains isolated from ceca were similar to those isolated from corresponding broiler carcasses. A total of 39 different macrorestriction profiles were observed, with evidence of Campylobacter cross-contamination among broiler flocks in Quebec slaughterhouses. Surprisingly, some flocks shared related genotypes both with and without sharing similar rearing practices. Existence of such cross-contamination must be considered to in developing strategies to control Campylobacter in chickens, and to avoid bacteria contamination of noncolonized flocks. Further typing studies of Campylobacter found in hatcheries, farm environment, and crates or trucks in Quebec might be helpful in elucidating the kinetics of broiler chicken Campylobacter contamination.     

禽产品安全控制研究进展

在食品安全方面,最重要的发现之一是冷链系统在食品运输中的发展。从那以后,HACCP的采用已经在食品生产业中成为另一项改革,而分子生物学的最新进展使得快速微生物学方法的发展和运用相对于传统的方法来说是一种改革。公众在与食品中细菌传播有关的风险因子方面的知识已得到提高,但对弯曲杆菌的了解仍然很少。在这种情况下,本文将讨论一些细菌诊断工具,细菌收获前后的控制措施和收获后处理方法的优化。     

Drug use and antimicrobial resistance among Escherichia coli and Enterococcus spp. isolates from chicken and turkey flocks slaughtered in Quebec,Canada

An observational study was conducted of chicken and turkey flocks slaughtered at federal processing plants in the province of Quebec, Canada. The objectives were to estimate prevalence of drug use at hatchery and on farm and to identify antimicrobial resistance (AMR) in cecal Escherichia coli and Enterococcus spp. isolates and factors associated with AMR. Eighty-two chicken flocks and 59 turkey flocks were sampled. At the hatchery, the most used antimicrobial was ceftiofur in chickens (76% of flocks) and spectinomycin in turkeys (42% of flocks). Virginiamycin was the antimicrobial most frequently added to the feed in both chicken and turkey flocks. At least 1 E. coli isolate resistant to third-generation cephalosporins was present in all chicken flocks and in a third of turkey flocks. Resistance to tetracycline, streptomycin, and sulfisoxazole was detected in > 90% of flocks for E. coli isolates. Antimicrobial resistance (AMR) was observed to bacitracin, erythromycin, lincomycin, quinupristin-dalfopristin, and tetracycline in both chicken and turkey flocks for Enterococcus spp. isolates. No resistance to vancomycin was observed. The use of ceftiofur at hatchery was significantly associated with the proportion of ceftiofur-resistant E. coli isolates in chicken flocks. In turkey flocks, ceftiofur resistance was more frequent when turkeys were placed on litter previously used by chickens. Associations between drug use and resistance were observed with tetracycline (turkey) in E. coli isolates and with bacitracin (chicken and turkey), gentamicin (turkey), and tylosin (chicken) in Enterococcus spp. isolates. Further studies are needed to provide producers and veterinarians with alternative management practices and tools in order to reduce the use of antimicrobial feed additives in poultry.     

Immune response following vaccination against Salmonella Enteritidis using 2 commercial bacterins in laying hens

The humoral and cell-mediated immune (CMI) response to 2 commercial killed Salmonella Enteritidis (SE) vaccines (Layermune and MBL SE4C) was evaluated in laying hens. Layers were distributed in 2 experimental groups. The first received a single immunization at 16 wk of age, while the second experimental group was immunized at 12 wk of age and again at 18 wk of age. Serum immunoglobulin (Ig)G antibodies were measured using a commercial SE ELISA kit and showed persistent levels from 3 to 32 and 34 wk post-vaccination. The vaccination protocol using 2 immunizations showed a higher seroconversion level than the single vaccination. However, our results for bacterial intracellular survival indicated that IgG titers were not linked with bacterial killing. Local IgA production was measured in the intestines and oviducts with an in-house SE whole cell antigen ELISA. Only the MBL SE4C vaccine elicited IgA antibody production when tested on intestine and oviduct mucosal secretions, 3-weeks post-vaccination in both immunization protocol groups. To evaluate the CMI response, the splenic T-cells and B-cells populations were analyzed using flow cytometry. The CD3/B-cell ratio decreased 3 wk after the second immunization in the twice vaccinated Layermune group due to an increase in B-cells.     

Cellulitis in broiler chickens: a one-year retrospective study in four Québec abattoirs

A 1-yr retrospective study was undertaken to verify whether the prevalence of cellulitis in broiler chicken flocks was associated 1) with sex and average body weight controlling for the time of year and 2) with some other condemnation causes such as air-sacculitis, ascites, cyanosis, emaciation, valgus varus deformity, peritonitis, and total condemnation rate controlling for sex, average body weight, and time of year. Data were collected from four Québec abattoirs between October 1992 and September 1993. Data from 2452 unisex male and female broiler flocks were compiled and analyzed with univariate and multivariate models. The prevalence of cellulitis among flocks was 42.2 per 10,000 birds slaughtered. Cellulitis was associated with sex and increased with time of year (P < 0.0001). The prevalence was higher in male (mean +/- SD, 50.7+/-24.3; median, 31.8) than in female flocks (mean +/- SD, 34.2+/-15.6; median, 20.0) but showed no relationship with average body weight. Associations between condemnation causes and cellulitis were relatively weak; increases in the prevalence of cellulitis correlated with increases in total condemnation rate (r2 = 0.19), ascites (r2 = 0.09), airsacculitis (r2 = 0.0), cyanosis (r2 = 0.04), peritonitis (r2 = 0.03), emaciation (r2 = 0.02), and valgus varus deformity (r2 = 0.02). These results suggest that flock sex is a potential correlate of cellulitis prevalence in broiler chickens. Associations between the prevalence of cellulitis and other diseases observed at the abattoir were not very strong. However, it appears here that general disease status of Québec broiler flocks is a better indicator of cellulitis occurrence than the main diseases considered individually.     

The effects of lactoferrin on the intestinal environment of broiler chickens

1. The influence of in-feed lactoferrin (Lf) on bird production, intestinal microbiota, mucosal immune system and gut microarchitecture was assessed in male Cobb 500 broiler chickens.

2. Birds were given one of four diets from day of hatch: Control (basal diet with no additives), ZnB (basal diet?+?50?mg/kg zinc bacitracin), Lf 250?mg/kg (basal diet?+?250?mg/kg Lf) and Lf 500?mg/kg (basal diet?+?500?mg/kg Lf); n?=?24 birds/treatment. An apparent metabolisable energy study was performed between d 25-32.

3. Lf did not affect growth rate or feed conversion in the period 0-21?d of age, nor performance or energy metabolism during the 7?d metabolism experiment which commenced at 25?d of age.

4. The profiles of caecal microbial communities were significantly different in birds given ZnB compared with birds given a diet with no additives, or supplemented with 250?mg/kg Lf. Birds given 250?mg/kg Lf also had a different microbial profile compared with birds given 500?mg/kg Lf.

5. In comparison to control birds, Lf treated birds showed some differences in the T cell proportions in caecal tonsil and spleen. No differences in ileal villus height, crypt depth or goblet cell proportions were observed amongst dietary treatments.

6. Whilst Lf had little effect on the measured parameters, the use of an integrated approach to study the influence of novel feed additives may facilitate a greater understanding of the relationships between nutrition, gut health and bird performance.     

Cardiac muscle mass distribution in the domestic turkey and relationship to electrocardiogram.

Ventricular weights were measured in 20-week-old male and female heavy turkeys, and electrocardiograms (ECGs) were recorded in 10- and 20-week-old male and female heavy turkeys. Twenty-week-old males had heavier relative left ventricular and total ventricular weights than females of the same age. Left-to-right ventricular weight ratios were 4.4:1 in males and 4.5:1 in females. Heart rate was faster in young birds and in females, and that influenced the duration of the intervals of the ECG. Wave amplitudes were smaller in 10-week-old turkeys than in 20-week-old turkeys. There was no correlation between electrocardiographic parameters and ventricular weights of male and female turkeys. Two-dimensional ECGs were therefore found to be of minimal value for detecting turkeys with heavier ventricles.     

Prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in broiler chicken and turkey flocks slaughtered in Quebec, Canada

We conducted an observational study to estimate prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in poultry. Eighty-one broiler chicken and 59 turkey flocks selected among flocks slaughtered in the province of Quebec, Canada, were included in the study. Flock status was evaluated by culturing pooled caecal contents from about 30 birds per flock. Exposure to potential risk factors was evaluated with a questionnaire. Odds ratios were computed using multivariable logistic regression.

The prevalence of Salmonella-positive flocks was 50% (95% CI: 37, 64) for chickens and 54% (95% CI: 39, 70) for turkeys, respectively. Odds of Salmonella colonization were 2.6 times greater for chicken flocks which failed to lock the chicken house permanently. In turkeys, odds of Salmonella colonization were 4.8–7.7 times greater for flocks which failed to be raised by ≤2 producers with no other visitors allowed onto the premises, or origin from a hatchery.

The prevalence of Campylobacter-positive flocks was 35% (95% CI: 22, 49) for chickens and 46% (95% CI: 30, 62) for turkeys. Odds of colonization were 4.1 times higher for chicken flocks raised on farms with professional rodent control and 5.2 times higher for flocks with manure heap >200 m from the poultry house, and also increased with the number of birds raised per year on the farm and with the age at slaughter. For turkeys, odds of Campylobacter flock colonization were 3.2 times greater in flocks having a manure heap at ≤200 m from poultry house and 4.2 times greater in flocks drinking unchlorinated water.     

Modification of Campylobacterjejuni Broiler Colonization by a Feed Additive Composed of Encapsulated Organic Acids and Essential Oils

The objective of this study was to evaluate the effect of a novel feed additive on chicken intestinal colonization and carcass contamination by Campylobacterjejuni. The feed additive was composed of microencapsulated organic acids and essential oils （OA/EO）. The feed additive tested was provided by Jefo Nutrition Inc., St-Hyacinthe, Quebec, Canada. Day-old birds were separated into two rooms and subdivided into two groups. Chicken were fed with OA/EO or not fed with OA/EO until they reached 35 d of age. At 14 d of age, chickens received an oral suspension of two well characterized C. jejuni strains, depending on the room they were housed in. The levels of C. jejuni were periodically monitored in the caecum and on the carcasses. C. jejuni colonization was further characterized by the use of high-resolution melt analysis of the C. jejuniflaA gene （HRM-flaA）. The effect of the feed additive was strain-dependent. In room two, the feed additive had no effect on the caecal counts. In room one, at 35 d of age, caecal C. jejuni counts were higher with OA/EO, as opposed to carcasses counts which were lower in the treated group. The HRM-flaA analysis showed that an amplification profile was predominant in birds fed with OA/EO at 35 d of age in room one, suggesting the selection of a C. jejuni strain. In conclusion, the OA/EO seemed to be effective to reduce C. jejuni levels but this effect appeared strain dependent.