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1.
Fecal samples collected from cattle at processing during a 1-year period were tested for verotoxins (VT1, VT2), Escherichia coli O157:H7, and Salmonella. Verotoxins were detected in 42.6% (95% CI, 39.8% to 45.4%), E. coli O157:H7 in 7.5% (95% CI, 6.1% to 9.1%), and Salmonella in 0.08% (95% CI, 0.004% to 0.5%) of the fecal samples. In yearling cattle, the median within-lot prevalence (percentage of positive samples within a lot) was 40% (range, 0% to 100%) for verotoxins and 0% for E. coli O157:H7 (range, 0% to 100%) and Salmonella (range, 0% to 17%). One or more fecal samples were positive for verotoxins in 80.4% (95% CI, 72.8% to 86.4%) of the lots of yearling cattle, whereas E. coli O157:H7 were detected in 33.6% (95% CI, 26.0% to 42.0%) of the lots. In cull cows, the median within-lot prevalence was 50% (range, 0% to 100%) for verotoxins and 0% (range, 0% to 100%) for E. coli O157:H7 and Salmonella (range, 0% to 0%). Verotoxins were detected in one or more fecal samples from 78.0% (95% CI, 70.4% to 84.2%) of the lots of cull cows, whereas E. coli O157:H7 were detected in only 6.0% (95% CI, 3.0% to 11.4%) of the lots of cull cows. The prevalence of verotoxins in fecal samples was lower in yearling cattle than in cull cows, whereas the prevalence of E. coli O157:H7 in fecal samples was higher in yearling cattle than in cull cows. The prevalence of E. coli O157:H7 in fecal samples was highest in the summer months. Rumen fill, body condition score, sex, type of cattle (dairy, beef), and distance travelled to the plant were not associated with the fecal prevalence of verotoxins or E. coli O157:H7. The prevalence of verotoxins in fecal samples of cull cows was associated with the source of the cattle. It was highest in cows from the auction market (52%) and farm/ranch (47%) and lowest in cows from the feedlot (31%). In rumen samples, the prevalence of verotoxins was 6.4% (95% CI, 4.2% to 9.4%), and it was 0.8% (95% CI, 0.2% to 2.3%) for E. coli O157:H7, and 0.3% (95% CI, 0.007% to 1.5%) for Salmonella.  相似文献   

2.
In order to evaluate the prevalence of Shiga toxin-producing Escherichia coli (STEC) strains, 197 fecal samples of healthy cattle from 10 dairy farms, four beef farms and one slaughterhouse at Rio de Janeiro State, Brazil, were examined for Shiga toxin (Stx) gene sequences by polymerase chain reaction (PCR). For presumptive isolation of O157:H7 E. coli, the Cefixime-potassium tellurite-sorbitol MacConkey Agar (CT-SMAC) was used. A high occurrence (71%) of Stx was detected, and was more frequently found among dairy cattle (82% vs. 53% in beef cattle), in which no differences were observed regarding the age of the animals. Dot blot hybridization with stx1 and stx2 probes revealed that the predominant STEC type was one that had the genes for both stx1 and stx2 in dairy cattle and one that had only the stx1 gene for beef cattle. Three (1.5%) O157:H7 E. coli strains were isolated from one beef and two dairy animals by the use of CT-SMAC. To our knowledge, this is the first report of O157:H7 isolation in Brazil. A PCR-based STEC detection protocol led to the isolation of STEC in 12 of 16 randomly selected PCR-positive stool samples. A total of 15 STEC strains belonging to 11 serotypes were isolated, and most of them (60%) had both stx1 and stx2 gene sequences. Cytotoxicity assays with HeLa and Vero cells revealed that all strains except two of serotype O157:H7 expressed Stx. The data point to the high prevalence of STEC in our environment and suggest the need for good control strategies for the prevention of contamination of animal products.  相似文献   

3.
Several outbreaks of Escherichia coli O157 have been reported in petting zoos, resulting in hospitalization of many children. At present, no standard procedure has been adopted to monitor the presence of enterohemorrhagic E. coli (EHEC) or Shiga-toxin-producing E. coli (STEC) in petting zoo animals. Direct detection of these strains from rectal swabs of animals in petting zoos was developed and obviated the need to culture the organisms. DNA extracted from bacteria in the swabs was tested for the presence of wecA gene specific for E. coli by polymerase chain reaction (PCR). The wecA positive samples were further tested for Shiga-toxin genes stxl and stx2, and the intimin eae by multiplex PCR and for the presence of O157 and H7. Swabs (n=104) from 15 animal species in a petting zoo were tested; 7 goats and 3 cows were found to carry STEC. The method is rapid and convenient for monitoring potentially pathogenic E. coli in petting zoo animals.  相似文献   

4.
AIM: To determine whether there are differences in postpartum gonadotrophic activity between strains of Holstein-Friesian dairy cows genetically selected on mature liveweight that might explain differences between the strains in fertility, and the interval between calving and the resumption of ovarian follicular activity. METHODS: Mixed-age Holstein-Friesian cows fed generous allowances of ryegrass/white clover pasture, and genetically selected for heavy (H) or light (L) mature liveweight, were given 10 microg buserelin on Days 21, 28, 35 and 42 (Experiment 1a; n=8/group), or Days 7, 14, 21 and 28 (Experiment 1b; n=8/group) postpartum. The same dose of buserelin was also given to first-calved heifers from each strain (Experiment 1c; n=6/group) on Days 7, 14, 21, and 28 postpartum. Luteinising hormone (LH)concentrations were measured in serial blood samples that were taken for up to 240 min after administration of buserelin. In Experiment 2, serial blood samples were taken at 15-min intervals from H and L cows (n=7/group) over 8 h on Days 14, 21, 28 and 35 postpartum, to examine the endogenous secretion patterns of LH and follicle stimulating hormone (FSH).The time-course of the restoration of positive feedback between oestradiol and LH was examined by giving 1 mg oestradiol benzoate(ODB) 48 h after administration of 500 microg cloprostenol to mixed-age cows from each strain on Days 7 and 21 (n=8/group), or 14 and 28 (n=8/group) after calving (Experiment 3). Relationships between nutrition and the restoration of positive feedback were studied by giving 0.75 mg ODB/500 kg liveweight on Day 17 or 18 after calving to pure-bred Holstein (OSH) and New Zealand Friesian (NZF) cows that were fed either pasture (n=12 OSH, 12 NZF) or a total mixed ration (TMR; n=13 OSH,12 NZF) (Experiment 4). Plasma LH and FSH concentrations were measured in samples collected for 42 h (Experiment 3) or 48 h (Experiment 4) after treatment with ODB. Milk progesterone concentrations were measured 3x weekly to define the reproductive status of animals in each experiment. Conception rates were recorded for animals in all of the experiments. RESULTS: First-service conception rates were lower (p<0.05) in H than L cows (46% vs 59%). In Experiments 1b and 1c, LH response to buserelin increased between Days 7 and 28 postpartum (both p<0.001), but did not differ between strains (p=0.77 and p=0.19, respectively). In Experiment 1a, LH responses to buserelin did not change between Days 21 and 42 postpartum, but overall mean peak concentrations were significantly(p<0.001) greater in L than H cows. In Experiment 2, anoestrous H cows had higher mean (p=0.004) and episodic (p=0.001) concentrations of LH than did L cows, but in cows that had active corpora lutea there were no such differences. There were no differences in FSH concentrations between strains. LH secretion in response to exogenous oestradiol (Experiment 3) increased between Days 7 and 28 postpartum (p<0.001), but there were no differences between strains. Responses were also similar in OSH and NZF cows on Day 17 or 18 postpartum, although there was a significant effect of ration upon the proportion of cows that exhibited an LH surge (20/24 cows on grass vs 12/25 on a TMR; p=0.005). CONCLUSION: These results confirm that H cows have poorer first-service conception rates than L cows, but do not support an hypothesis that there are major differences between these strains of Holstein-Friesian dairy cows in the rate of restoration in the hypothalamo-pituitary axis. However, in anoestrous cows, differences between strains in the endogenous release of LH maybe related to an earlier onset of oestrous cycles in H animals.  相似文献   

5.
OBJECTIVE: To estimate the association between ceftiofur use and the isolation of Escherichia coli with reduced ceftriaxone susceptibility from fecal samples of dairy cow populations. ANIMALS: 1,266 dairy cows on 18 farms in Ohio. PROCEDURES: Individual fecal samples from all cows in the study herds were tested for Escherichia coli with reduced ceftriaxone susceptibility. Herd antimicrobial use policy and antimicrobial treatment records were also obtained. Plasmid DNA from these isolates was tested for the presence of the AmpC beta-lactamase gene (blaCMY-2). Minimum inhibitory concentrations to a standard panel of 16 antimicrobial drugs were determined by use of a broth microdilution system. RESULTS: Herds for which ceftiofur use was reported were more likely to have cows from which reduced susceptibility E coli was isolated than herds that did not report ceftiofur use (odds ratio, 25.0). However, at the individual cow level, no association was found between recent ceftiofur treatment and isolation of reduced-susceptibility E coli (adjusted odds ratio, 1.01). No observed linear relationship was found between the percentage of cows from which E coli with reduced ceftriaxone susceptibility was isolated and the percentage of cows in the herd recently treated with ceftiofur. CONCLUSIONS AND CLINICAL RELEVANCE: Our observation of a herd-level but not an individual cow-level association between ceftiofur use and isolation of E coli with reduced ceftriaxone susceptibility from fecal samples suggests that interventions to reduce the spread of antimicrobial resistance genes in agricultural animals will be most effective at the herd level.  相似文献   

6.
A total of 1050 samples from apparently healthy cattle were examined bacteriologically with special regard to Pc. indolicus and Cb. pyogenes.Pc. indolicus was found in 58 % of 130 samples from tonsils (slaughterhouse material), in 23 % of 620 samples from the vagina of cows, in 22 % of 100 samples from the vagina of calves and heifers, in 5 % of 100 samples from the conjunctival sac of cows, and in 10 % of 100 samples from the nasal cavity of cows (Table 1). Cb. pyogenes was found in 51 %, 17 %, 19 %, 8 %, and 6 %, respectively. Both organisms were found in each of 9 herds examined, though with varying frequency (Tables 2, 3, and 4).Altogether Pc, indolicus was found in 254 (24 %) and Cb. pyogenes in 205 (20 %) of the samples examined (Table 1). In 127 samples both organisms were present. Eleven of the strains of Pc. indolicus were β-hemolytic, the rest non-hemolytic.By gel diffusion analysis the strains of Pc. indolicus as well as those of Gb. pyogenes could be identified with strains originating from pathological conditions in cattle. With Serotype B occurring most frequently, usually two or three different types of Pc. indolicus were found in each of the herds examined (Tables 5, 6, and 7).The investigation has shown that Pc. indolicus is widespread among healthy cattle, and given evidence to suggest that Pc. indolicus and Cb. pyogenes are natural cohabitants.  相似文献   

7.
A strain of Escherichia coli O157:H7 was isolated from goat faeces during a surveillance study on the prevalence of this serotype of E. coli in farm animals in Greece. Three hundred and fifty one faecal samples were collected from goat, sheep and cattle breeding farms in the area of Epirus, Northwestern Greece. The E. coli O157:H7 isolate was nonsorbitol-fermenter, produced only VT2 and showed a beta-glucuronidase positive activity, a rather unusual biochemical feature for the E. coli O157:H7 serotype. No other strain of E. coli O157:H7 was isolated from the faecal samples of the rest farm animals examined, thus the overall prevalence of animal carriage was found to be 0.2%. The findings also indicate that goats can be a reservoir of E. coli O157:H7 and goat milk, dairy products and meat may serve as a vehicle for the pathogen transmission to humans.  相似文献   

8.
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   

9.
Cattle are a natural reservoir for Shiga toxigenic Escherichia coli (STEC), however, no data are available on the prevalence and their possible association with organic or conventional farming practices. We have therefore studied the prevalence of STEC and specifically O157:H7 in Swiss dairy cattle by collecting faeces from approximately 500 cows from 60 farms with organic production (OP) and 60 farms with integrated (conventional) production (IP). IP farms were matched to OP farms and were comparable in terms of community, agricultural zone, and number of cows per farm. E. coli were grown overnight in an enrichment medium, followed by DNA isolation and PCR analysis using specific TaqMan assays. STEC were detected in all farms and O157:H7 were present in 25% of OP farms and 17% of IP farms. STEC were detected in 58% and O157:H7 were evidenced in 4.6% of individual faeces. Multivariate statistical analyses of over 250 parameters revealed several risk-factors for the presence of STEC and O157:H7. Risk-factors were mainly related to the potential of cross-contamination of feeds and cross-infection of cows, and age of the animals. In general, no significant differences between the two farm types concerning prevalence or risk for carrying STEC or O157:H7 were observed. Because the incidence of human disease caused by STEC in Switzerland is low, the risk that people to get infected appears to be small despite a relatively high prevalence in cattle. Nevertheless, control and prevention practices are indicated to avoid contamination of animal products.  相似文献   

10.
To determine if Escherichia coli O157:H7 is capable of residing in the gall bladder of cattle, inoculation studies were conducted with O157:H7 strain 86-24 in weaned Holstein calves. Strain 86-24 was isolated from the gall bladders of five calves 36 days after inoculation. Two other calves contained the inoculation strain in the distal colon but the organism was absent in their gall bladders. A second trial in which the calves were euthanized 15 days after inoculation found strain 86-24 in six of seven inoculated calves but only in colon and/or rumen samples. In a third trial that inoculated eight calves with a four-strain cocktail of O157:H7 strains, the gall bladders from all eight animals were positive 9 days after inoculation. The colon and rumen samples from these calves were also positive. E. coli O157:H7 isolates recovered from bile samples and subtyped by pulsed field gel electrophoresis found that three of the four inoculation strains were present in one or more of the calves. Thus, residence in the gall bladder is not restricted to a single strain. Additional evidence of the ability to localize in the gall bladder of cattle was provided by testing the bile from 150 gall bladders (five collection dates, 30 samples each) obtained at an abbatoir and the isolation of E. coli O157:H7 from four samples (2.7%). This study establishes that E. coli O157:H7 can reside transiently or permanently at a low level in the gall bladder of cattle.  相似文献   

11.
The objective of this study was to compare the concentration and duration of fecal shedding of Escherichia coli O157:H7 between calves fed milk replacer with or without antibiotic (oxytetracycline and neomycin) supplementation. Eighteen 1-wk-old Holstein calves were orally inoculated with a strain of E. coli O157:H7 (3.6 x 10(8) cfu/calf) made resistant to nalidixic acid (NA). Rectal samples were obtained three times weekly for 8 wk following oral inoculation. Fecal shedding of NA-resistant E. coli O157:H7 was quantified by direct plating or detected by selective enrichment procedure. Eight weeks after inoculation, calves were killed, necropsied, and tissues (tonsils, retropharyngeal and mesenteric lymph nodes, and Peyer's patches) and gut contents (rumen, omasum, abomasum, ileum, cecum, colon, and rectum) were sampled to quantify or detect NA-resistant E. coli O157:H7. The percentage of calves shedding NA-resistant E. coli O157:H7 in the feces in the antibiotic-fed group was higher (P < 0.001) early in the study period (d 6 and 10) compared with the control group fed no antibiotics. There was no difference between treatment and control groups in the concentration of E. coli O157 in feces that were positive at quantifiable concentrations. A comparison of the duration of fecal shedding between treated and untreated calves showed no significant difference between groups. At necropsy, E. coli O157:H7 was recovered from the rumen and omasum of one calf in the control group and from retropharyngeal lymph node and Peyer's patch of two calves in the antibiotic group. Supplementation of milk replacer with antibiotics may increase the probability of E. coli O157:H7 shedding in dairy calves, but the effect seems to be of low magnitude and short duration.  相似文献   

12.
OBJECTIVE: To serotype an enterotoxin gene from Escherichia coli isolated from cows, pigs, and chickens in Korea. SAMPLE POPULATION: Isolates from 37 cows with mastitis, 51 diarrheic pigs, and 5 diarrheic chickens. PROCEDURE: Serogroups and serotypes were identified by slide agglutination testing, using pathogenic E coli sera. Detection of E coli enterotoxins by use of reversed passive latex agglutination and ELISA was compared by proving existence of the gene by polymerase chain reaction (PCR) analysis. RESULTS AND CONCLUSIONS: Detection of E. coli enterotoxin by either method was positive for 1 strain (O20:H10; heat-labile enterotoxin [LT+], heat-stable enterotoxin [STa+]; isolation rate, 2%) and 3 other strains (O111:H10, O119:H9, and O125:H6, STa+; isolation rate, 5.9%) isolated from fecal specimens obtained from diarrheic pigs. The E coli enterotoxin genes were identified by use of PCR analysis in 1 strain containing the 417- and 163-base pair (bp) genes (LT+, Sta+; O20:H10) and in 3 strains containing only the 163-bp gene (STa+; O111:H10, O119:H9, and O125:H6). CLINICAL RELEVANCE: Serotyping of E coli enterotoxin may be used to analyze patterns of transmission among species of domestic animals.  相似文献   

13.
There has been strong debate as to whether feeding cattle hay prior to slaughter will reduce the number and/or virulence of Escherichia coli O157:H7 in the bovine gastrointestinal tract (GIT). This study addressed this issue by comparing numbers, persistence, and acid resistance of generic coliforms and E. coli O157:H7 from various gastrointestinal tract sites of cattle fed grain or hay. Mature Angus steers, doubly cannulated into the rumen and duodenum were inoculated with E. coli O157:H7. Aliquots of digesta from the rumen, duodenum, and rectum were cultured directly or acid shocked (pH 2.0) and then cultured to determine acid resistance. The culture technique used was as sensitive as standard immunomagnetic bead separation protocols. E. coli O157:H7 from hay-fed or grain-fed cattle were similarly acid resistant in all GIT locations. In contrast, generic coliforms from the rumen and rectum of hay-fed animals were more sensitive to an acid shock than coliforms from those GIT locations in grain-fed animals. E. coli O157:H7 colonized the most distal region of the GIT and was not consistently cultured from the rumen or the duodenum. Numbers in the upper GIT did not predict numbers or persistence of E. coli O157:H7 in rectal samples. Grain-feeding or hay-feeding did not affect survival of E. coli O157:H7 in the rumen, nor its passage through the abomasum (pH 2.0) to the duodenum. These data show that generic coliforms behave differently in the bovine host than E. coli O157:H7 and that E. coli O157:H7 acid resistance was independent of animal diet.  相似文献   

14.
In cattle, the lymphoid rich regions of the rectal-anal mucosa at the terminal rectum are the preferred site for Escherichia coli O157:H7 colonisation. All cattle infected by rectal swab administration demonstrate long-term E. coli O157:H7 colonisation, whereas orally challenged cattle do not demonstrate long-term E. coli O157:H7 colonisation in all animals. Oral, but not rectal challenge of sheep with E. coli O157:H7 has been reported, but an exact site for colonisation in sheep is unknown. To determine if E. coli O157:H7 can effectively colonise the ovine terminal rectum, in vitro organ culture (IVOC) was initiated. Albeit sparsely, large, densely packed E. coli O157:H7 micro-colonies were observed on the mucosa of ovine and control bovine terminal rectum explants. After necropsy of orally inoculated lambs, bacterial enumeration of the proximal and distal gastrointestinal tract did suggest a preference for E. coli O157:H7 colonisation at the ovine terminal rectum, albeit for both lymphoid rich and non-lymphoid sites. As reported for cattle, rectal inoculation studies were then conducted to determine if all lambs would demonstrate persistent colonisation at the terminal rectum. After necropsy of E. coli O157:H7 rectally inoculated lambs, most animals were not colonised at gastrointestinal sites proximal to the rectum, however, large densely packed micro-colonies of E. coli O157:H7 were observed on the ovine terminal rectum mucosa. Nevertheless, at the end point of the study (day 14), only one lamb had E. coli O157:H7 micro-colonies associated with the terminal rectum mucosa. A comparison of E. coli O157:H7 shedding yielded a similar pattern of persistence between rectally and orally inoculated lambs. The inability of E. coli O157:H7 to effectively colonise the terminal rectum mucosa of all rectally inoculated sheep in the long term, suggests that E. coli O157:H7 may colonise this site, but less effectively than reported previously for cattle.  相似文献   

15.
Surgical embryo recovery and transfer methods were applied to 25 cows and heifers with chronic reproductive problems. In 16 of the 25 animals, abnormalities could not be detected by palpation per rectum and, at laparotomy, the probable cause of low fertility was found to be oviductal obstructions or periovarian adhesions in 6 of them. Four pregnancies were obtained from 3 of these 6 animals. A definitive diagnosis was not obtained through laparotomy in the other 10 animals in this group; however, an abnormal uterine environment associated with senescence may have been responsible for low fertility in the older cows. Eighteen calves were obtained by embryo transfer from 8 of these 10 donor animals. The remaining 9 heifers and cows had lesions detectable by palpation per rectum. Chronic, purulent metritis was found in 2 cows, one of which produced 7 calves by embryo transfer. The other 7 had periovarian adhesions, and 8 calves were obtained from 2 of them. The adhesions in 6 of these 7 cows were attributable to cesarean section. Laparotomy was valuable for defining the extent of the adhesions and establishing a reliable prognosis in some cases.  相似文献   

16.
An antigen capture or sandwich ELISA (sELISA) was evaluated for the diagnosis of Hypoderma lineatum in cattle under field conditions in northwestern Spain. The kinetics of circulating hypodermin C (HyC) and specific antibodies during the course of natural infestation were determined in a group of 10 Frisian calves. In addition, oesophagi and blood samples were taken from 105 cows at a slaughterhouse in order to compare three methods for the diagnosis of H. lineatum: sandwich ELISA for the detection of the antigen HyC (sELISA), indirect ELISA for the detection of antibodies anti-HyC (iELISA) and the detection of first instars (L1) in the oesophagus. In naturally infested cattle, HyC was present in circulation at low levels during the early and late phases of the infestation. However, in the middle phase, coinciding with the presence of L1 in the oesophagus, two peaks of increased HyC concentration were observed. Specific antibodies increased progressively until the first appearance of larvae in warbles on the back. There was no correlation between antigen or antibody levels and the number of grubs in the back. Prevalence of first instars in the oesophagi of slaughtered cows was 21.9% (23/105). The percentage of cattle that were positive for circulating antigen was slightly higher (24.8%), suggesting the recent destruction of migrating larvae in some animals. However, there was no correlation between the number of L1 and HyC levels. With the iELISA, 79% of the animals were positive to Hypoderma, which means that a high percentage of those animals have been exposed to the parasite but they had no apparent current infestation. The sELISA is a good tool to follow larval development within the host; however, the episodic elevation of HyC levels limits the usefulness of this test for the early diagnosis of Hypoderma under field conditions.  相似文献   

17.
The number of animals that die during transport to a slaughterhouse or shortly after being delivered to a slaughterhouse may serve as an indicator of animal welfare during transport. The aim of this study was to determine the mortality rate in cattle resulting from transport to slaughter in the Czech Republic in the period from 2009 to 2014, and to investigate the effect of travel distance and season of the year. Transport‐related mortality rates were recorded for all categories of cattle for the following travel distances: up to 50 km, 51–100 km, 101–200 km and over 200 km. Higher mortality rates occurred with shorter travel distances (<50 km and 51–100 km) when compared to longer travel distances (101–200 km and > 200 km), with a significant difference (P < 0.01) between short and long travel distances being found in feeders and dairy cows. Also, the season of the year had a significant impact on the mortality rate among transported cattle. The highest mortality rate in all categories was observed in spring months. The lowest mortality rate was found in autumn months for fat cattle and dairy cows and in winter months for feeders and calves.  相似文献   

18.
With the DNA-DNA colony hybridization technique using specific gene probes for Verotoxin 1 (VT 1) and Verotoxin 2 (VT 2) 2100 E. coli strains from healthy animals were tested. Ten out of 82 milk cows (21.2%), 20 out of 212 beef cattle (9.4%) and five out of 75 pigs (6.7%) were found to carry genes for VT 1, VT 2 or both toxins, respectively. Among these strains the biotypes 5 and 6 were predominant. Some of the serotyped isolates have been described to be pathogenic for humans, like O157:H7, 082:H8, 0116, 0113, 0126 and 091, respectively. The unexpected high incidence of VTEC positive healthy animals possibly indicates a health hazard for human beings. Further investigations on the incidence of VTEC in food are necessary.  相似文献   

19.
Grazing-fed cattle were previously demonstrated to be reservoir of non-O157 Shigatoxigenic Escherichia coli (STEC) serotypes in Argentina. The acid-resistance of some STEC strains makes it reasonable to assume the presence in feedlot of particular STEC serotypes. Fifty-nine animals were sampled every 2 weeks during 6 months by rectal swabs. Twenty-seven of 59 animals (45.8%) were shown to be Stx2(+); 3/59 (5.1%) carried Stx1(+) and 7/59 (11.9%) were Stx1(+) Stx2(+). Among 44 STEC isolates, 31 isolates were associated to 10 O serogroups (O2, O15, O25, O103, O145, O146, O157, O171, O174, O175) and 13 were considered non-typable (NT). Six H antigens (H2, H7, H8, H19, H21, H25) were distributed in 21 isolates whereas 23 were non-mobile (H-). Seventeen of 44 strains (38.6%) were eaeA(+) and 14 (31.8%) harbored the 60MDa plasmid. The megaplasmid (Mp) and eaeA gene were simultaneously found in a limited number of serotypes belonging to the enterohaemorrhagic E. coli (EHEC). E. coli O157:H7 strains, isolated from four (6.8%) animals, corresponded to the Stx2(+), eaeA(+), Mp(+) pattern. Three O157:H7 strains belonged to phage type 4 and the other strain was atypical. Many serotypes isolated from grain-fed cattle (O2:H25, O15:H21, O25:H19, O145:H-, O146:H-, O146:H21, O157:H7, O175:H8) also differed from those isolated by us previously from grazing animals. The serotypes O15:H21, O25:H19 and O175:H8 had not been identified at present as belonging to STEC. This work provides new data for the understanding of the ecology of STEC in grain-fed cattle and confirms that cattle are an important reservoir of STEC.  相似文献   

20.
The objective of the present study was to compare the concentrations of 17 beta-estradiol, progesterone, cyclic adenosine monophosphate and cyclic quinosine monophosphate in the largest follicles of cows that persist for seven days after insemination following the preceding synchronization of oestrus and superovulation and in follicles of the luteal phase of cycle (5th-10th days). Animals included in the experiment were selected on the basis of rectal examination. Synchronization of oestrus was achieved in 24 crossbreds of Slovak Pied x Lowland Black Pied breeds (SS x Nc) using two doses of cloprostenol of Czechoslovak provenience Oestrophan Spofa, 500 micrograms in each, within 11 days. Serum gonadotrophin at the amount of 2500 I. U. was administered forty-eight hours before administration of the second dose PGF2 alpha. Experimental animals were inseminated after 72 hours. On the 7th day after mating the cows were killed at a slaughterhouse. Evaluated were only the ovaries of the 14 cows in which the persistent large follicles occurred. Ovaries of the 13 control cows in the luteal phase between the 5th-10th days were obtained at the slaughterhouse by the method after Ireland et al. (1980). Correct determination of the phase of sexual cycle was substantiated by determination of progesterone concentrations in blood serum. Follicular fluid was obtained from the largest follicles by aspiration and centrifuged in a cooled centrifuge at 3000 G. The concentrations of 17 beta-estradiol and progesterone in follicular fluid were determined using kits from URVJT at Kosice, designated RIA-test-ESTRA (SI-125-9) or RIA-test-Prog (SI-125-6).2+ persistent follicles (9.15 +/- 5.47 nmol.l-1).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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