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1.
CS31A is a K88-related non-fimbrial adhesin first described on Escherichia coli strains isolated from diarrhoeic and septicaemic calves. In this report, CS31A antigen was screened by immunological methods and confirmed by PCR among bovine E. coli isolates. In addition, CS31A-producing strains were characterized with respect to different fimbrial antigens, O-serogroup and other properties related to virulence. Faecal or tissue specimens of 100 diarrhoeic or septicaemic calves and 27 older cattle with different pathologies from 71 outbreaks or individual cases that occurred in Buenos Aires province, Argentina, were examined. CS31A + E. coli strains were isolated from 21 (21.0%) calves from 16 outbreaks or individual cases. No CS31A + E. coli was detected in samples from cattle more than 1 year old. Fimbriae F5, F41, F17a and F17b were not detected among the CS31A-producing strains. Three (14.3%) of the CS31A+ E. coli strains expressed the F17c fimbria. All of the 21 isolates exhibited at least one property of septicaemic strains (resistance to serum, production of aerobactin or colicins) but none of them demonstrated heat-stable enterotoxigenic activity. CS31A + E. coli isolates belonged to 10 serogroups, more commonly O8, O7, O17 and O21. The results obtained here confirm the worldwide distribution of CS31A antigen in bovine E. coli strains. However, CS31A + or CS31A + /F17c + E. coli were less frequently isolated than they were in North hemisphere countries.  相似文献   

2.
Verotoxin-producing Escherichia coli O111:NM were isolated from two five week old Holstein calves with dysentery. On necropsy both calves had pseudomembranous ileitis, mucohemorrhagic colitis and proctitis. Large numbers of E. coli O111:NM were isolated from the colon and lesions typical of attaching-and-effacing E. coli were evident. The isolates from both calves had identical biochemical reactions and antimicrobial resistance patterns. Oral inoculation of a four day old colostrum deprived calf with 1 x 10(10) organisms of E. coli O111:NM produced a mild, focal colitis with typical attachment and effacement lesions. We conclude that the strain of E. coli O111:NM isolated from the clinical cases has the ability to produce colitis characterized by attachment and effacement of the colonic mucosa.  相似文献   

3.
A new diarrhoeic syndrome was examined clinically in 19 one to two-week old Charolais calves. It differs from other digestive disorders in calves of this age in the discrete diarrhoeic signs, the absence of dehydration and the presence of signs of ataxia. The microbiological study carried out for three consecutive years in 58 sick calves and nine healthy control calves demonstrated the special role of E coli possessing virulence markers from septicaemic strains (CS31A, Col V). The clinical signs could be the result of bacteraemia with subacute E coli endotoxaemia.  相似文献   

4.
Dysentery lasting 4-8 days was produced in five 4-day-old colostrum-fed calves, after inoculation with an atypical strain of Escherichia coli S102-9; peak excretion of S102-9 occurred during the period of dysentery. Two calves were killed when clinical signs were most severe and bacteria were seen attached to the surfaces of enterocytes in the large intestine; microscopic lesions were seen in these areas. The lesions were identical to those previously reported in a natural outbreak of dysentery in calves, from which E. coli S102-9 was isolated, and to those seen in gnotobiotic calves experimentally infected with S102-9. Reinfection of the three surviving calves 16-20 days later with S102-9 and primary infection of two calves aged 24 and 51 days did not cause dysentery. Four of 659 coliforms isolated from field outbreaks of calf diarrhoea resembled the atypical strain S102-9. These four isolates and S102-9 did not produce heat-stable enterotoxin, but all produced a toxin cytopathic for Vero and HeLa cells. Two of the four isolates were inoculated alone into 4-day-old gnotobiotic calves deprived of colostrum; neither calf developed dysentery but microscopic lesions identical to those produced by S102-9 were detected in the large intestines of both animals.  相似文献   

5.
CS31A is a K88‐related non‐fimbrial adhesin first described on Escherichia coli strains isolated from diarrhoeic and septicaemic calves. In this report, CS31A antigen was screened by immunological methods and confirmed by PCR among bovine E. coli isolates. In addition, CS31A‐producing strains were characterized with respect to different fimbrial antigens, O‐serogroup and other properties related to virulence. Faecal or tissue specimens of 100 diarrhoeic or septicaemic calves and 27 older cattle with different pathologies from 71 outbreaks or individual cases that occurred in Buenos Aires province, Argentina, were examined. CS31A+ E. coli strains were isolated from 21 (21.0%) calves from 16 outbreaks or individual cases. No CS31A+ E. coli was detected in samples from cattle more than 1 year old. Fimbriae F5, F41, F17a and F17b were not detected among the CS31A‐producing strains. Three (14.3%) of the CS31A+ E. coli strains expressed the F17c fimbria. All of the 21 isolates exhibited at least one property of septicaemic strains (resistance to serum, production of aerobactin or colicins) but none of them demonstrated heat‐stable enterotoxigenic activity. CS31A+ E. coli isolates belonged to 10 serogroups, more commonly O8, O7, O17 and O21. The results obtained here confirm the worldwide distribution of CS31A antigen in bovine E. coli strains. However, CS31A+ or CS31A+/F17c+ E. coli were less frequently isolated than they were in North hemisphere countries.  相似文献   

6.
There exists experimental evidence that necrotoxigenic Escherichia coli (NTEC) strains producing the cytotoxic necrotising factor 1 cause intestinal and extra-intestinal disease in piglets. On the other hand, no experimental model has been developed with NTEC strains producing the cytotoxic necrotising factor 2. In all, 14 colostrum-restricted calves were orally challenged with two strains isolated from the faeces of a diarrheic calf (B20a) or from the heart blood of a septicaemic calf (1404). All calves had diarrhoea which lasted until euthanasia in eight of them. In those calves, diarrhoea was correlated with the faecal excretion of the challenge strains. At necropsy, vascular congestion of the intestinal mucosa, hypertrophy of the mesenteric lymph nodes (MLN) and some congestion of the lungs were observed. Bacteriology confirmed the colonisation of the intestine by the challenge strains which were also recovered from the heart blood, the lungs and/or the liver. Histological sections confirmed enterocolitis, lymphadenitis and limited bronchopneumonia. In the intestinal tissue sections, bacteria testing positive in an in situ DNA hybridisation assay with a CNF2 probe were observed. Those results were confirmed by immunohistochemistry with a polyclonal anti-O78 and a monoclonal anti-F17b antisera. Three of the five control calves receiving either saline or a CNF(-), F17a strain (25KH09) had no clinical signs or lesions. The other two presented a profuse liquid diarrhoea but those calves were positive for the presence of K99(+) E. coli. In this model, both NTEC2 strains were thus, able to colonise the intestine, to cause long-lasting diarrhoea and to invade the blood stream with localisation in various internal organs in colostrum-restricted conventional newborn calves.  相似文献   

7.
Comparison of colostrum-induced immunities in calves was made by challenge exposure with Escherichia coli. These calves were delivered of cows which were vaccinated intramuscularly or deep subcutaneously (in the region of the mammary lymph nodes) with strain B44 E coli bacterin during the last trimester of pregnancy. The calf of each cow was allowed to nurse colostrum naturally after birth. Cows vaccinated by either route of administration were capable of providing increased resistance to their calves, via the colostrum, when compared with nonvaccinated cows.  相似文献   

8.
Two experiments were conducted to evaluate detection of Escherichia coli heat-stable enterotoxin (ST) in the feces of calves as a method for implicating E coli in neonatal calf diarrhea. The first experiment evaluated the use of the infant mouse test for detection of ST in the feces of calves with naturally occurring diarrhea. Simultaneous identification of bovine enteropathogenic strains of E coli (EEC) and of other infective agents implicated in neonatal calf diarrhea was attempted in these samples. The ST was detected with certainty in only 7 of 41 samples from calves less than or equal to 3 weeks old. Enteropathogenic E coli, however, was detected in 27 samples. In 23 of these 27 samples, EEC was the only recognizable diarrheagenic agent. In a small percentage of the samples, Salmonella, rotavirus, coronavirus, and cryptosporidium were recognized alone, in combination with each other, or with EEC. In the second experiment, 6 calves were fed colostrum from cows inoculated with the bovine EEC strain B44; 6 were given colostrum from cows vaccinated with non-EEC strain 28F, and 4 were given milk from nonvaccinated heifers. Two of the calves that were given colostrum from cows inoculated with strain B44 were challenge exposed with the non-EEC strain 28F. The remaining calves were challenge exposed with the EEc strain B44. Fecal samples were taken from these calves at intervals and were examined for the presence of ST and of the challenge-exposure organism. The ST was detected in approximately one half of the fecal samples obtained, and it was most often detected in the early stages of the induced diarrhea. Calves were observed to shed the challenge-exposure EEC strain for long periods in the absence of diarrhea or detectable amounts of ST in the feces. The ST was detectable in fecal samples when the diarrhea was severe and when the dry matter content of the fecal samples was low.  相似文献   

9.
Rotavirus and enterotoxigenic Escherichia coli infections of calves were surveyed during 2 successive years on a closed Finnish dairy farm consisting of 90–105 milking cows. From a clinical standpoint, diarrhoea was of moderate to high severity during the first year, compared to the milder disease in the second year of the study. Diarrhoea or abnormal faeces were found only in calves less than 8 weeks old, with the peak occurring during the first 2 weeks of life.In the first year, rotavirus was detected throughout the calving season in diarrhoeic or abnormal faeces of calves aged 1 day to 7 weeks. In the second calving season, rotavirus was detected only during the 4 autumn months and in calves aged 11 days to 8 weeks. Rotavirus was detected in only 1 sample of normal faeces in both years. Electron microscopy revealed no enteropathogenic viruses other than rotaviruses. Enterotoxigenic K99 E. coli was found in about half of diarrhoeic or abnormal faeces in both years and throughout the calving seasons. K99 E. coli was also found in 5–10 % of normal faeces.In the second year of the study, 45 of 101 pregnant dams were vaccinated with 2 doses of E. coli antigen. The vaccination trial did not prevent or reduce altered faeces in calves whose dams had been vaccinated compared with calves whose dams had not been vaccinated in the same year. Comparing the 2 years, the earlier uptake of colostrum together with better cleaning and disinfection of the calf house, contributed to the later and rarer occurrence of rotavirus infection in the second year of the study. The earlier uptake of colostrum together with better cleaning and disinfection of the salf house, in the second year, could not prevent enterotoxigenic E. coli infections in calves but partly prevented and modified the disease.  相似文献   

10.
To compare the pathogenesis of calf and rabbit strains of E. coli, gnotobiotic pigs were infected with 10(10) colony forming units (cfu) of verotoxigenic strain RDEC-1 or S102-9, or a non-verotoxigenic E. coli (X114/83). Pigs were killed 4 days later, and intestinal tissue was fixed and examined by light, scanning, and transmission electron microscopy. Strains S102-9 and RDEC-1 caused diarrhea, attached to enterocytes, and effaced microvilli, confirming that the calf and rabbit strains possessed similar mechanisms of pathogenicity. Non-verotoxigenic strain X114/83 did not cause diarrhea, but in 5/5 piglets it was detected in histological sections adherent to enterocyte surfaces. Exfoliated enterocytes were seen in 4/5. Bacteria attached to enterocytes by "cups" and "pedestals," with effacement of microvilli, were seen by electron microscopy in 1/5 piglets. It was concluded that strain S102-9 appears to be an animal equivalent of human enterohemorrhagic E. coli, that verotoxin is not essential in the pathogenesis of attaching and effacing lesions, and that the lesions induced by S102-9 are more severe in gnotobiotic pigs than in gnotobiotic or conventional calves.  相似文献   

11.
It has been established that maternal leukocytes, conditioned by the mammary environment, cross the neonatal gut and circulate in the newborn calf. However, the impact of these cells on the development of neonatal immunity remains to be determined. This study examined the effects of maternal colostral leukocytes on development and maturation of neonatal adaptive immunity by examining the expression of surface markers on neonatal lymphocytes. At birth, neonatal calves were fed whole colostrum, or colostrum that had the maternal cells removed (cell-free colostrum), from their respective dams. Peripheral blood samples were collected at regular intervals over the first 4 weeks of life and lymphocytes were evaluated for surface expression of cellular markers. The results of these studies demonstrated that calves receiving whole colostrum had fewer CD11a positive lymphocytes in circulation during the first 2 weeks of life and this marker was expressed at a lower density than calves receiving cell-free colostrum. In addition, calves receiving whole colostrum also had a higher percentage of lymphocytes expressing the activation markers CD25 and CD26 by 7 days after birth. During the first week of life, lymphocytes from calves receiving whole colostrum had a higher density of MHC class I expression on their surfaces than cells from calves receiving cell-free colostrum. In general, these results indicate that transfer of maternal cells with colostrum allows for more rapid development of lymphocytes and maternal cells appeared to enhance their activation.  相似文献   

12.
Eight newborn calves were challenged orally with a known enteropathogenic strain of Escherichia coli 0101 K?(A) and two to six hours later each calf was fed a minimum of three pints colostrum. All calves suffered from acute diarrhoea of varying severity within 24 to 48 hours of infection. Immunofluorescent and histological examination of the small intestine demonstrated adherence of the challenge organism to the epithelium and the presence of pathological lesions similar to those seen in colostrum-deprived calves with enteric colibacillosis. It was concluded that in order to be effective prophylactically, colostrum must be fed prior to infection.  相似文献   

13.
Twenty Holstein-Friesian male calves were obtained within 4 hours after bith (colostrum deprived) and allotted to 1 of 4 groups, each given a different feeding: colostrum, milk replacer, polyvinylpyrrolidone (PVP), and saline solution (0.85% NaCl). Each calf was fed 2 L of the respective diets every 12 hours. Rectal temperatures were recorded and blood samples were collected immediately before each feeding. At approximately 27 hours of age, all calves were inoculated orally with 1.5 X 10(10) viable organisms of a septicemia-producing Escherichia coli serotype O26: K60:NM. Within 8 hours, all calves had diarrhea. Coli-septicemia (E coli cultured from liver, spleen, and cardiac blood) was present in 1 of the 5 calves fed colostrum, in 5 or the 5 calves fed milk replacer, in 5 of the 5 calves fed PVP, and in 4 of the 5 calves fed saline solution. At necropsy of the calves (12 to 48 hours after oral inoculation), the same organism was isolated by cultural technique from small intestines of 19 of the 20 calves. Serum immunoglobulin G concentrations increased (P less than 0.01) in calves fed the colostrum diet in sharp contrast to the agammaglobulinemia occurring in calves fed the milk replacer, PVP, or saline solution. Results indicate that colostrum fed to the calf soon after birth provides protection from colisepticemia, but does not prevent the diarrhea of colibacillosis.  相似文献   

14.
[目的]为了分析河西走廊地区犊牛腹泻致病性大肠杆菌携带毒力基因和耐药性情况,[方法]2020—2021年在河西走廊地区采集患腹泻病犊牛的粪便、肛拭子及肝脏等病料组织279份,采用人工感染试验动物、PCR方法和K-B药敏纸片法分别检测犊牛腹泻性大肠杆菌致病性、毒力因子和耐药性。[结果]结果表明,分离得到了126株大肠杆菌,其中79株犊牛腹泻性大肠杆菌能引起小鼠死亡;分离的79株致病性大肠杆菌的毒力基因crl、irp2、fimH、papC、K88、K99、stx1、stx2检测率在40.5%～100%之间,其他毒力基因检测率在15.2%～34.2%之间;分离的79株致病性大肠杆菌对氨苄西林、阿莫西林、新霉素等8种药物的耐药率在49.4%～96.2%之间,对其他药物的耐药率在5.1%～32.9%之间。[结论]从河西走廊地区患腹泻病犊牛病料组织中分离得到79株致病性大肠杆菌,这些菌株携带多种毒力基因,对临床中常用的抗菌药物产生了耐药性。  相似文献   

15.
Oral inoculation of approximately 1.2 x 10(9) viable Escherichia coli to pregnant cows resulted in increased blood serum and colostral whey titers to the "O" antigen. The antibody titers were more pronounced in colostral whey and were correlated with the inoculum strain of Escherichia coli. There was no correlation between antibody titers of the colostrum ingested and the resulting serum antibody titers of the calves. The incidence of diarrhea in calves did not correlate with the antibody titer in the colostrum. The occurrence of diarrhea was significantly greater in calves that did not ingest colostrum until they were 12 hours old, compared with calves that had free access to their dams and suckled within an hour of birth.  相似文献   

16.
A modified, double-antibody, enzyme-linked immunosorbent assay (ELISA) was developed to detect the K99 pilus antigen of enterotoxic Escherichia coli (ETEC) in feces of calves. Extremely high positive to negative ratios (greater than 200) were obtained by using monoclonal antisera as the primary antibody. Strong positive reactions were obtained with strains of E coli known to produce the K99 antigen; however, non-enteropathogenic E coli (strains not producing the K99 antigen), Salmonella, Proteus, Klebsiella, Pseudomonas, Staphylococcus, Streptococcus, and rotavirus produced negative results. Seventy-five fecal samples, 8 from healthy calves and 67 from calves with neonatal calf diarrhea were examined with the K99 ELISA for the presence of ETEC. Rotavirus test and fecal culture results were available on feces from calves with diarrhea and were used with the K99 ELISA results to determine the specific cause of the disease. Enterotoxic E coli was the predominant agent detected in the feces of 29 diarrheal calves less than 5 days of age. Mixed infections of rotavirus and ETEC were also common in these calves, but rotavirus infections alone were not detected. In 38 calves greater than or equal to 5 days, rotavirus was detected without ETEC. Of these calves, only 2 produced positive tests with the K99 ELISA. Salmonella sp and Proteus sp were detected from 5 of 67 calves with diarrhea.  相似文献   

17.
The influence of colostral leukocytes on the bactericidity of whole blood of calves against a strain of E. coli and on the activities of haemolytic complement and interferon-alpha (the antiviral activity of sera resisting an acidic treatment at pH 2 for 6 h) in the serum was investigated during a period of 4 weeks using 4 experimental groups. The calves received either complete colostrum (COL+, n = 16), cell-depleted colostrum (COL-, n = 16), cell-supplemented milk substitute (MS+, n = 7) or pure milk substitute (MS-, n = 6) during their first three days of life. The bactericidity of whole blood of the COL+ group was significantly higher on the second and third days of life while the activity of haemolytic complement was lower after the first week as compared to the COL- group. No interferon-alpha was detectable in the sera of both COL groups. The bactericidity of the MS groups was significantly lower than that of the COL groups after the first day of life. It was significantly lower in the MS+ group after one week of life while the activity of haemolytic complement was higher than that of the MS- group. Three out of 5 MS- and only one out of 7 MS+ calves had low titres of interferon-alpha in their sera on the third day. Three out of 6 MS- calves died and 5 out of 7 MS+ animals. The mean day of death was 4.0 in the MS- and 8.4 in the MS+ group. Based on the in vitro results of this and the previous three communications it can be concluded that leukocytes which are an integral part of normal bovine colostrum, influence immunological reactions of the calf and that they may enhance its defence against infection. Colostral leukocytes in the absence of humoral components of the colostrum are not able to prevent fatal losses in the calves due to natural infection, although their influence on immune responses of the calves was detectable in vitro.  相似文献   

18.
Septicemic colibacillosis is a highly fatal disease that occurs in calves less than 2 weeks of age. The disease occurs when a calf that fails to absorb protective levels of immunoglobulin from colostrum is exposed to an invasive serotype of E. coli. Management to ensure good passive transfer of colostral immunoglobulin will prevent this disease and reduce calf mortality caused by other infectious diseases as well.  相似文献   

19.
Gnotobiotic calves (24 hours old) were monoinfected with calf rotavirus (CRV) strain NCDV, an enterotoxigenic Escherichia coli (ETEC) strain B44 (K99+), or a nonenterotoxigenic E coli (NETEC) strain 123 (K99-). Calves also were dually infected with CRV and either ETEC or NETEC. Eighteen calves equally allotted between 6 treatment groups were used in these studies: Noninfected controls--group A; CRV--group B; ETEC--group C; NETEC--group D; CRV + ETEC--group E; and CRV + NETEC--group F. Severe diarrhea and villous atrophy were observed in calves of treatment groups B, C, E, and F. Mortality was present only in treatment groups C and E as result of ETEC infection. There were no significant differences in the clinical responses or enteric lesions between treatments B and F, although a significant increase in the concentrations of NETEC was demonstrated in calves dually infected with CRV + NETEC (group F) as compared with calves monoinfected with NETEC (group D). Calves inoculated with ETEC (group C) had severe villous atrophy, neutrophilic infiltration of intestinal lumen, and moderate enterocyte necrosis. Calves dually inoculated with CRV + ETEC (group E) had the most extensive and severe lesions, similar to those in group C, plus a pronounced necrotic fibrino-hemorrhagic enteritis. Infection of enterocytes by CRV did not affect in any way the adherence of ETEC to the intestinal mucosa. Dual viral and bacterial infections of the same enterocytes were evident.  相似文献   

20.
The P fimbriae F11 and F165 that have been demonstrated on Escherichia coli septicaemic strains in poultry and calves, respectively, possess a nearly identical major subunit that demonstrates a serological cross-reaction. A polyclonal antibody-based sandwich ELISA (sELISA) that was specific for both F11 and F165 fimbriated strains was compared with a PCR method to detect F11/F165 fimbriated strains, in a collection of E. coli strains isolated from diseased animals. Of 298 isolates tested, 36 were positive by PCR of which only 14 were sELISA positive. There were no sELISA positive but PCR negative results. The 36 PCR positive isolates comprised 11 avian strains of which 10 were sELISA positive, 20 bovine strains of which 4 were sELISA positive and 3 ovine strains, 1 porcine strain and 1 equine strain all of which were sELISA negative. The F11/F165 incidence of 10.7% in 103 poultry and 18.3% in 109 bovine isolates demonstrates a moderate level of these factors in E. coli septicaemic cases in Northern Ireland.  相似文献   

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