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1.
Human illness due to infections with Escherichia coli O157 is a serious health concern. Infection occurs through direct contact with infected animals or their faeces, through contaminated food or water and/or through person‐to‐person transmission. A reduction in faecal E. coli O157 shedding in cattle might reduce the burden of human infections. We used systematic review and meta‐analysis to assess the efficacy of direct‐fed microbials (DFM), compared with placebo or no treatment, fed during the pre‐harvest stage of production in reducing faecal E. coli O157 shedding in beef cattle during field trials. Four electronic databases, Nebraska Beef Reports and review article reference lists were searched. A total of 16 publications assessing faecal shedding at the end of the trial and/or throughout the trial period were included. The majority of publicly disseminated trials evaluated the prevalence of E. coli O157 faecal shedding; only two evaluated the concentration of organisms in faeces. The prevalence of faecal E. coli O157 shedding in cattle is significantly reduced by DFM treatments (summary effect size for all DFM – OR = 0.46; CI = 0.36–0.60). The DFM combination Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24) was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period compared with the group of other DFM, although this difference was not statistically significant. Furthermore, we found that the combination [NP51 and NP24] treatment was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period when fed at the dose of 109 CFU/animal/day than any lesser amount, although this difference was not statistically significant. Feeding beef cattle DFM during the pre‐harvest stage of production reduces the prevalence of E. coli O157 faecal shedding and might effectively reduce human infections.  相似文献   

2.
A feedlot trial was conducted to assess the efficacy of an Escherichia coli O157:H7 vaccine in reducing fecal shedding of E. coli O157:H7 in 218 pens of feedlot cattle in 9 feedlots in Alberta and Saskatchewan. Pens of cattle were vaccinated once at arrival processing and again at reimplanting with either the E. coli O157:H7 vaccine or a placebo. The E. coli O157:H7 vaccine included 50 microg of type III secreted proteins. Fecal samples were collected from 30 fresh manure patties within each feedlot pen at arrival processing, revaccination at reimplanting, and within 2 wk of slaughter. The mean pen prevalence of E. coli O157:H7 in feces was 5.0%; ranging in pens from 0% to 90%, and varying significantly (P < 0.001) among feedlots. There was no significant association (P > 0.20) between vaccination and pen prevalence of fecal E. coli O157:H7 following initial vaccination, at reimplanting, or prior to slaughter.  相似文献   

3.
Shiga toxigenic Escherichia coli (STEC) are an important group of pathogens and can be transmitted to humans from direct or indirect contact with cattle faeces. This study investigated the shedding of E. coli O157 and O26 in cattle at the time of slaughter and factors associated with super‐shedding (SS) animals. Rectoanal mucosal swab (RAMS) samples were collected from cattle (n = 1,317) at three large Irish commercial beef abattoirs over an 18 month period, and metadata were collected at the time of sampling regarding farm of origin, animal age, breed and gender. RAMS swabs were examined for the presence and numbers of E. coli O157 and O26 using a previously developed quantitative real‐time PCR protocol. Samples positive by PCR were culturally examined and isolates analysed for the presence of stx subtypes, eae and phylogroup. Any samples with counts >104 CFU/swab of STEC O157 or O26 were deemed to be super‐shedders. Overall, 4.18% (55/1,317) of RAMS samples were positive for STEC O157, and 2.13% (28/1,317) were classified as STEC O157 SS. For STEC O26, 0.76% (10/1,317) of cattle were positive for STEC O26, and 0.23% (3/1,317) were classified as super‐shedders. Fewer STEC shedders and SS were noted among older animals (>37 months). There was a seasonal trend observed for STEC O157, with the highest prevalence of shedding and SS events in the autumn (August to October). The majority of E. coli O157 (50/55) isolates had stx2 and were eae positive, with no significant difference between SS and low shedders (LS). Interestingly, all STEC O26 (n = 10) were eae negative and had varied stx profiles. This study demonstrates that, while the overall shedding rates are relatively low in cattle at slaughter, among positive animals there is a high level of SS, which may pose a higher risk of cross‐contamination during slaughter.  相似文献   

4.
OBJECTIVE: To determine whether viable shiga-toxigenic Escherichia coli (STEC) O157 could be isolated from hide surface locations and the oral cavity of finished beef feedlot cattle. DESIGN: Within-animal prevalence distribution survey. ANIMALS: 139 finished cattle in 4 pens in a feedlot in Nebraska; prevalence of fecal STEC O157 shedding ranged from 20 to > 90%. PROCEDURE: Samples were collected from 7 sites from each animal: feces, oral cavity, and 5 hide surface locations (lumbar region, ventral aspect of the neck, ventral abdominal midline [ventrum], dorsal thoracic midline [back], and distal aspect of the left hind limb [hock]). RESULTS: Viable STEC O157 were isolated from the oral cavity or 1 or more hide surfaces of 130 cattle, including 50 fecal isolation-negative cattle. Site-specific prevalence of STEC O157 was 74.8% for oral cavity samples, 73.4% for back samples, 62.6% for neck samples, 60.4% for fecal samples, 54.0% for flank samples, 51.1% for ventrum samples, and 41.0% for hock samples. Only 5 cattle tested negative for STEC O157 at all 7 sites. Multiple correspondence and cluster analyses demonstrated that bacterial culture of feces, oral cavity samples, and back samples detected most cattle with STEC O157. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that viable STEC O157 may be isolated from the oral cavity, multiple hide surfaces, and feces of a high percentage of fed beef cattle and that bacterial culture of feces alone generally underestimates the percentage of fed beef cattle from which STEC O157 can be isolated.  相似文献   

5.
OBJECTIVE: To describe shiga-toxigenic Escherichia coil O157:H7 (STEC O157:H7) fecal shedding prevalence, seasonal fecal shedding patterns, and site-specific prevalence from the oral cavity, skin, and feces of dairy cattle. DESIGN: Cross-sectional study. ANIMALS: Adult dairy cattle from 13 herds in Louisiana. PROCEDURE: Samples were cultured for STEC O157 by use of sensitive and specific techniques, including selective broth enrichment, immunomagnetic separation, monoclonal antibody-based O:H enzyme immunoassay serotyping, and polymerase chain reaction virulence gene characterization. Point estimates and 95% confidence intervals were calculated for fecal shedding prevalence as well as site-specific prevalence from the oral cavity, skin, and feces. Logistic regression was used to assess seasonal variation and differences at various stages of lactation with respect to fecal shedding of STEC O157 in cattle sampled longitudinally. RESULTS: Summer prevalence in herds in = 13) was 38.5%, with a cow-level prevalence of 6.5%. Among positive herds, prevalence ranged from 3% to 34.6%. Samples from 3 of 5 herds sampled quarterly over 1 year yielded positive results for STEC O157. In herds with STEC O157, an increase in cow-level prevalence was detected during spring (13.3%) and summer (10.5%), compared with values for fall and winter. Site-specific prevalences of STEC O157:H7 from oral cavity, skin, and fecal samples were 0%, 0.7%, and 25.2%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Our data indicated that STEC O157:H7 was commonly isolated from dairy cows in Louisiana, seasonally shed, and isolated from the skin surface but not the oral cavity of cows.  相似文献   

6.
The O157:H7 (EcO157) epidemiology of Shiga‐toxin‐producing Escherichia coli (STEC) in cattle is complex, and myths about pre‐harvest control are perpetuated. The objectives of this project were to identify perpetuated misinformation and inform four audiences about evidence‐based risks and pre‐harvest control of EcO157 by addressing: (i) EcO157 epidemiology and pre‐harvest control; (ii) how food safety policy is created; and (iii) how to present accurate information about EcO157. An environmental scan using a daily Internet search helped identify themes for education. A literature review of pre‐harvest control measures contributed to the development of educational materials (fact sheets, website, web presentations and conferences). Conference 1 was a webinar with 315 registrants, 10 countries including 41 US states and four Canadian provinces. Most participants felt confident in using their new knowledge, more than half felt confident enough to answer EcO157 questions from the public and many would recommend the recorded version of the webinar to colleagues. Conference 2 was live in the Washington, DC, area with most participants employed by the US government. All agreed that they better understood pre‐harvest control, how food safety policy was made, and were confident they could create an effective message about STEC pre‐harvest control. Videos were posted and received 348 Internet visitors within 2 months. Conference 3 was a webinar with a live audience and Twitter feeds, targeting people who give nutrition advice. Almost all ranked the programme good to excellent and relevant to their work. About 25% indicated that they would share: ‘grass‐fed beef is not safer than grain‐fed’, 25% would share information on effectiveness of cattle vaccines, and 14% would share information on message mapping. Across all conferences, major changes in knowledge included the following: there is no additional risk of EcO157 shedding from grain‐fed versus grass‐fed cattle, pre‐harvest vaccination is efficacious, and production systems (pasture versus confinement) do not affect EcO157 shedding rates.  相似文献   

7.
Inclusion of distillers grains (DG) in cattle diets has been shown to increase fecal shedding of Escherichia coli O157:H7. It is hypothesized that altered gut fermentation by DG may be responsible for the positive association. Therefore, feed additives affecting ruminal or hindgut fermentation of DG also may affect fecal shedding of E. coli O157:H7. The objectives of the study were to evaluate effects of monensin (33 or 44 mg/kg of DM), supplemental urea (0, 0.35, or 0.70% of DM), and ractopamine (0 or 200 mg/steer daily administered during the last 42 d of finishing) in a steam-flaked corn grain-based diet containing 30% wet sorghum DG on fecal shedding of E. coli O157:H7. Seven hundred twenty crossbred beef steers, housed in 48 pens (15 steers/pen), were assigned to dietary treatments in a randomized complete block design with a 2 × 3 × 2 factorial treatment arrangement. Fresh pen floor fecal samples (10 per/pen) were collected every 2 wk for 14 wk (July through November) and cultured for E. coli O157:H7. Isolation of E. coli O157:H7 was by selective enrichment of fecal samples in an enrichment broth, immunomagnetic separation, followed by plating onto a selective medium. Samples that yielded sorbitol-negative colonies, which were positive for indole production, O157 antigen agglutination, and contained rfbE, fliC, and stx2 were considered positive for E. coli O157:H7. Fecal prevalence data were analyzed as repeated measures using negative binomial regression to examine effects and interactions of sampling day, urea, monensin, and ractopamine. Mean fecal prevalence of E. coli O157:H7 was 7.6% and ranged from 1.6 to 23.6%. Cattle fed monensin at 44 mg/kg of feed had less (P = 0.05) fecal E. coli O157:H7 prevalence than cattle fed 33 mg/kg (4.3 vs. 6.8%). Although the reason for the reduction is not known, it is likely because of changes in the microbial ecosystem induced by the greater amount of monensin in the hindgut. Supplemental urea at 0.35 or 0.70% had no effect (P = 0.87) on fecal shedding of E. coli O157:H7. Fecal prevalence of E. coli O157:H7 were 5.3, 5.7, and 5.9% for groups fed 0, 0.35, and 0.7% urea, respectively. The inclusion of ractopamine at 0 or 200 mg/(animal?d) had no effect (P = 0.89) on fecal prevalence of E. coli O157:H7 (4.4 vs. 4.0%). Additional research is needed to confirm the reduction in fecal shedding of E. coli O157:H7 in cattle fed monensin at 44 mg/kg of feed compared with cattle fed 33 mg/kg of feed.  相似文献   

8.
The aim of this study was to investigate faecal shedding and transmission of Campylobacter spp. in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with faecal shedding of Campylobacter spp. A cohort of 133 heifers housed in four adjacent pens was examined over a five and a half month period, from entering the feedlot to slaughter. A parallel investigation of individual rectal faecal samples and pen environmental samples were taken at monthly intervals from November to February. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter. Campylobacter spp. were isolated from 322 (54%) of the 600 rectal faecal samples. Campylobacter jejuni and C. coli accounted for 69 and 29.7% of the isolate recovered, respectively. A total of 159 environmental samples were examined, of these Campylobacter spp. was isolated from 46 samples (29%). Campylobacter jejuni and C. coli accounted for 35 and 59% of these isolates, respectively. Campylobacter spp. was not isolated from any of the dressed carcasses. Logistic regression indicated prevalence of Campylobacter spp. faecal shedding within pens was positively correlated to the pen, the month of sampling and the Campylobacter spp. contamination status of the pen dividing bars and the water trough surface. Campylobacter spp. should be considered as a pathogen shed in the faeces of a substantial proportion of feedlot cattle. However, with good hygienic practice during harvest, a very low level of this pathogen can be achieved on dressed carcasses.  相似文献   

9.
The objectives of this study were to investigate the diversity of Escherichia coli O157:H7 isolates obtained over a 3-month period from a cattle feedlot in order to assess the relationship between environmental and faecal isolates and to determine the pattern of transmission of E. coli O157:H7 between groups of cattle. Faecal samples were obtained from cattle housed in four adjacent feedlot pens at monthly intervals, with environmental pen samples collected simultaneously. All E. coli O157:H7 isolates obtained were examined by pulsed field gel electrophoresis (PFGE), polymerase chain reaction (PCR) to detect eaeA, ehxA, stx1 and stx2 genes and antibiotic sensitivity profiling. Ten isolates were subjected to acid shock to imitate conditions in the acidic cattle abomasum and assess the effect on PFGE profiles. E. coli O157:H7 was isolated from 69 faecal samples and 26 environmental samples. All isolates (n=95) carried the genes for eaeA, ehxA and stx2 and were sensitive to all antibiotics tested. The PFGE profiles of all isolates differed by no more than two bands and clustered within 80% similarity following dendrogram analysis. Acid shock had no effect on the subsequent PFGE patterns. A total of 8.7% (6/69) of cattle were shedding E. coli O157:H7 in the first month with faecal shedding increasing to 52% (36/69) by the third month of the study. A single isolate of E. coli O157:H7 may be passed rapidly through cattle pens, with the environment acting as a significant reservoir for transmission. PFGE is a useful tool for tracking the direct and indirect transmission of E. coli O157:H7 isolates on the farm.  相似文献   

10.
Shiga toxin-producing Escherichia coli (STEC) are a public health concern. Bacterial culture techniques commonly used to detect E. coli O157:H7 will not detect other STEC serotypes. Feces from cattle and other animals are a source of O157:H7 and other pathogenic serotypes of STEC. The objective of this study was to estimate the pen-level prevalence of Shiga toxins and selected STEC serotypes in pre-slaughter feedlot cattle. Composite fecal samples were cultured and a polymerase chain reaction (PCR) was used to detect genes for Shiga toxins (stx1 and stx2) and genes for O157:H7, O111:H8, and O26:H11 serotypes. Evidence of Shiga toxins was found in 23 pens (92%), O157:H7 in 2 (8%), O111:H8 in 5 (20%), and O26:H11 in 20 (80%) of the 25 pens investigated. Although pen-level prevalence estimates for Shiga toxins and non-O157 serotypes seem high relative to O157:H7, further effort is required to determine the human health significance of non-O157 serotypes of STEC in feedlot cattle.  相似文献   

11.
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12.
The study objectives were to determine the prevalence and serotypes of non-O157 Shiga toxin-producing Escherichia coli (STEC) in pens of feedlot cattle and on corresponding beef carcasses. We collected 25 fecal samples from 84 pens in 21 Alberta feedlots and 40 carcass swabs from each preslaughter pen for analysis by culture and polymerase chain reaction (PCR). Non-O157 STEC were recovered from feces from 12 (14%) of the 84 pens and 12 (57%) of the 21 feedlots by examination of 1 E. coli isolate positive for 4-methylumbelliferyl-beta-beta-glucuronide per sample. Twelve non-O157 serotypes were detected, but 7 of the 15 STEC isolates lacked the accessory virulence genes eae and hlyA. Although 115 (7%) of the carcass broths were PCR-positive, no STEC isolates were recovered from the 1650 carcasses sampled. Our data indicate that multiple non-O157 STEC serotypes may be present in cattle feces, yet are unlikely to be recovered from the corresponding beef carcasses when 20 colonies per sample from PCR-positive broth cultures are analyzed.  相似文献   

13.
Our objective was to generate hypotheses about associations between management, climate, and the presence of Escherichia coli O157 in feedlot–cattle water tanks and in feedlot–cattle feed. Water samples from 710 tanks on 73 feedlots, and feed-samples from a subset of 504 pens on 54 feedlots, in four US states were tested for E. coli O157. Management and climate factors were ascertained by survey and observation. Escherichia coli O157 were isolated from 13% of the water tanks and at least one water tank was positive on 60% of the feedlots. The factors significantly associated with E. coli O157 in water were greater percentage of cattle shedding E. coli O157 in faeces within the same pen, higher concentration of total E. coli in the water, lack of the clarity of the water, the use of fly traps, the reported frequency of rodent sightings in the pen or alley area, and the weather at the time of sampling. Escherichia coli O157 were isolated from 14.9% of the feed samples obtained from the feedbunks. Factors positively associated with E. coli O157 in feed were higher heat index at the time of sampling, the presence of cottonseed meal in the ration, and the feedlot location (state). Coliform counts in feed, presence of E. coli O157 in water tanks and faecal prevalence of E. coli O157 were not associated with the presence of E. coli O157 in feed.  相似文献   

14.

Background

In the less-sensitive mouse model, Shiga toxin-producing Escherichia coli (STEC) challenges result in shedding that reflect the amount of infection and the expression of virulence factors such as Shiga toxins (Stx). The purpose of this study was to characterize the contribution of STEC diversity and Stx expression to shedding in beef feeder calves and to evaluate the effectiveness of a prebiotic, Celmanax®, to alleviate STEC shedding. Fecal samples were collected from calves at entry and after 35 days in the feedlot in spring and summer. STECs were evaluated using selective media, biochemical profile, serotyping and Stx detection. Statistical analysis was performed using repeated measures ANOVA and logistic regression.

Results

At entry, non-O157 STEC were dominant in shedding calves. In spring, 21%, 14% and 14% of calves acquired O157, non-O157 and mixed STEC infections, respectively. In contrast, 45%, 48% and 46% of calves in summer acquired O157, non-O157 and mixed STEC infections, respectively. Treatment with a prebiotic, Celmanax®, in spring significantly reduced 50% of the O157 STEC infections, 50% of the non-O157 STEC infections and 36% of the STEC co-infections (P = 0.037). In summer, there was no significant effect of the prebiotic on STEC infections. The amount of shedding at entry was significantly related to the number and type of STECs present and Stx expression (r2 = 0.82). The same relationship was found for shedding at day 35 (r2 = 0.85), but it was also related to the number and type of STECs present at entry. Stx - producing STEC infections resulted in 100 to 1000 × higher shedding in calves compared with Stx-negative STECs.

Conclusions

STEC infections in beef feeder calves reflect the number and type of STECs involved in the infection and STEC expression of Stx. Application of Celmanax® reduced O157 and non-O157 STEC shedding by calves but further research is required to determine appropriate dosages to manage STEC infections.  相似文献   

15.
Manipulation of cattle diets has been proposed as a possible preharvest control measure for Escherichia coli O157. Altering hindgut fermentation through diet changes may be a means to reduce fecal shedding of E. coli O157. In Exp. 1, the objective was to determine whether fecal shedding of E. coli O157 was related to fecal starch concentration. Beginning on d 20, and every week thereafter until d 61, steers in 54 pens (6 to 7 steers per pen) were sampled (n = 122) by fecal collection and rectoanal mucosal swabs (RAMS) for E. coli O157 and fecal starch concentration determinations. Escherichia coli O157 prevalence was 3.3% in fecal samples, 4.1% as measured by RAMS, and 4.9% by fecal or RAMS samples. Steers positive for E. coli O157 contained 21% more (P < 0.05) fecal starch than steers that were negative for E. coli O157. In Exp. 2, we attempted to alter the concentration of starch escaping rumen fermentation by feeding finishing diets based on steam-flaked corn (SFC) and dry-rolled corn (DRC) to 30 heifers prescreened for being culture positive for fecal E. coli O157. Beginning on d 13, heifers were sampled (feces and RAMS) weekly to monitor fecal pH and starch concentration, and prevalence of E. coli O157. Prevalence of E. coli O157 remained above 30% for the first 13 d, but declined (P < 0.05) over the entire 7-wk period. Based on RAMS, the prevalence of E. coli O157 tended to be greater (P = 0.08) for heifers fed SFC than for those fed the DRC diet. After d 20, heifers fed DRC had greater (P < 0.05) fecal starch and lower (P < 0.05) fecal pH than heifers fed SFC. Fecal pH was negatively correlated (r = - 0.34; P < 0.05; n = 143) with fecal starch concentration. Fecal starch concentration and pH were not different (P > 0.05) for heifers that were positive or negative for E. coli O157. Our data suggest that fecal shedding of E. coli O157 was not related to fecal pH or starch concentration in cattle fed grain-based diets.  相似文献   

16.
The aim of this study was to investigate faecal shedding and transmission of Campylobacter spp. in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with faecal shedding of Campylobacter spp. A cohort of 133 heifers housed in four adjacent pens was examined over a five and a half month period, from entering the feedlot to slaughter. A parallel investigation of individual rectal faecal samples and pen environmental samples were taken at monthly intervals from November to February. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter. Campylobacter spp. were isolated from 322 (54%) of the 600 rectal faecal samples. Campylobacter jejuni and C. coli accounted for 69 and 29.7% of the isolate recovered, respectively. A total of 159 environmental samples were examined, of these Campylobacter spp. was isolated from 46 samples (29%). Campylobacter jejuni and C. coli accounted for 35 and 59% of these isolates, respectively. Campylobacter spp. was not isolated from any of the dressed carcasses. Logistic regression indicated prevalence of Campylobacter spp. faecal shedding within pens was positively correlated to the pen, the month of sampling and the Campylobacter spp. contamination status of the pen dividing bars and the water trough surface. Campylobacter spp. should be considered as a pathogen shed in the faeces of a substantial proportion of feedlot cattle. However, with good hygienic practice during harvest, a very low level of this pathogen can be achieved on dressed carcasses.  相似文献   

17.
Over a 12 month period, 588 cattle faecal samples and 147 farm environmental samples from three dairy farms in southeast Queensland were examined for the presence of Shiga-toxigenic Escherichia coli (STEC). Samples were screened for Shiga toxin gene (stx) using PCR. Samples positive for stx were filtered onto hydrophobic grid membrane filters and STEC identified and isolated using colony hybridisation with a stx-specific DNA probe. Serotyping was performed to identify serogroups commonly associated with human infection or enterohaemorrhagic Escherichia coli (EHEC). Shiga-toxigenic Escherichia coli were isolated from 16.7% of cattle faecal samples and 4.1% of environmental samples. Of cattle STEC isolates, 10.2% serotyped as E. coli O26:H11 and 11.2% serotyped as E. coli O157:H7, and the E. coli O26:H11 and E. coli O157:H7 prevalences in the cattle samples were 1.7 and 1.9%, respectively. Prevalences for STEC and EHEC in dairy cattle faeces were similar to those derived in surveys within the northern and southern hemispheres. Calves at weaning were identified as the cattle group most likely to be shedding STEC, E. coli O26 or E. coli O157. In concurrence with previous studies, it appears that cattle, and in particular 1-14-week-old weanling calves, are the primary reservoir for STEC and EHEC on the dairy farm.  相似文献   

18.
Feeding high levels (≥40% dry matter) of distillers grains may increase the risk for cattle to carry enterohemorrhagic Escherichia coli (EHEC) O157. The mechanism for the increased risk is not known nor whether non‐O157 EHEC are similarly affected. Our objective was to test whether the fibre content or other components of modified distillers grains plus solubles (MDGS) affects the probability for cattle to carry EHEC serogroups of public health importance. A 2 × 2 plus 1 factorial treatment arrangement within a randomized block design was utilized. Within each of four blocks, 25 feedlot pens (n = 8 steers/pen) were assigned randomly to (i) corn‐based control diet; (ii) 20% dry matter (DM) MDGS; (iii) 40% DM MDGS; (iv) corn bran added to corn‐based diet to match fibre of 20% MDGS or (v) 40% MDGS. Rectoanal mucosa swabs (RAMS) were collected on day (d)0, d35, d70 and d105; hide swabs were collected on the last feeding day. Samples were tested for EHEC by a molecular screening assay. The effects of fibre source and fibre level on EHEC carriage were tested using multilevel logistic regression (generalized linear mixed models; α = 0.05). EHEC O45 RAMS detection was associated with fibre level, source and sampling day. EHEC O103 RAMS detection increased by feeding 40% MDGS but not the corresponding corn bran diet. Hide contamination by EHEC O45 or O103 was less likely in cattle fed MDGS compared to corn bran diets. EHEC O111 RAMS detection decreased by feeding 40% MDGS but not by feeding the corresponding corn bran diet. Detection of EHEC O157 or O145 was not associated with dietary factors. Feeding 40% MDGS increased the probability for carriage of some EHEC serogroups but decreased probability of others, which indicated that EHEC serogroups have different risk factors associated with feeding MDGS and little association with dietary fibre.  相似文献   

19.
The aim of the study was to investigate the effect of transport and lairage on the prevalence of Escherichia coli O157 faecal shedding and the subsequent contamination of beef carcasses. Individual rectal faecal samples were taken from two cohorts of cattle (109 and 59) at the farm before transport and at the abattoir post-transport and lairage. The entire outer and inner surfaces of the carcass of each animal were swabbed immediately following slaughter and dressing. The prevalence of E. coli O157 shedding in cattle sampled at farm, post-transport and lairage was 18% (20), 13% (14) and 12% (13) for cohort A and 1.7% (1), 1.7% (1) and 0 for cohort B, respectively. No E. coli O157 was recovered from the 168 dressed carcasses. In total, 98% (46 of 47) of the E. coli O157 isolates from cohort A were potentially pathogenic to man. Transport and lairage do not cause an increase in the prevalence of E. coli O157 faecal shedding in cattle. This study demonstrates that even positive cohorts of cattle may be slaughtered and processed to produce clean carcasses by following good hygienic practices.  相似文献   

20.
This study was aimed to understand the relationship of virulence gene distribution and genetic evolution between cattle originated Shiga toxin-producing Escherichia coli (STEC) and human originated enterohaemorrhagic Escherichia coli (EHEC) O157. This experiment collected 18 strains STEC in a dairy farm from Jiangsu province and 9 STEC reference strains (human, sheep, swine and avian), according to the method of U.S. Centers for Disease Prevention and Control Center (PulseNet), using the XbaⅠ enzyme digestion and pulsed field gel electrophoresis (PFGE) analysis, virulence genes were detected in some STEC isolates. The virulence gene distribution of O157 from different origin was remarkably different. The cattle originated STEC O157 and the human originated EHEC O157:H7 (EDL933W) had the most similar virulence gene distribution. In contrast, virulence genes were lack in cattle STEC O18 and O26, even though the cattle STEC O18 and O26 had the similar genotype as human EHEC O157:H7 (EDL933W). PFGE of Xba Ⅰ digested chromosomal DNA from 27 isolates of STEC exhibited 22 profiles. In general,the Dice coefficients of different originated STEC ranged from 72% to 100%.Cattle STEC O157 had a high similarity with two strains of human originated EHEC O157, while a low similarity was demonstrated between cattle STEC O157 and STEC O157 of swine and avian. The Dice coefficients of the cattle STEC O157 and the two strains of human EHEC O157 ranged from 83% to 95%. The Dice coefficients of cattle STEC O26 (Ⅶ,Ⅷ) and the two strains of human EHEC O157 were more than 82%. Therefore, it was concluded that the cattle STEC O157 and human EHEC O157 had a closer relationship in terms of virulence gene distribution and in genetic evolution.  相似文献   

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