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1.
Three strains of Hemophilus somnus were infused into the posterior cervix of six pregnant cows. The organism persisted in the cervicovaginal region for eight to 87 days, and at parturition H. somnus was isolated from chorioallantois in four of six cows; placentitis developed, and fetal membranes were retained. All calves were born alive and no H. somnus was recovered from them. One cow died 14 days after parturition. The death was attributed to severe necrotizing metritis; H. somnus was not isolated from the uterus at death, but was isolated from the placenta at parturition and cervicovaginal mucus two days days later.  相似文献   

2.
Experimental bovine respiratory tract disease with Haemophilus somnus   总被引：1，自引：0，他引：1  
Eight calves were inoculated into the bronchus with H. somnus. Thirteen calves were inoculated with bovine respiratory syncytial virus (BRSV) and 8 days later with H. somnus. All calves developed necrotizing, suppurative, lobular bronchopneumonia and pleuritis. Clinical signs of disease and pneumonic lesions were significantly more severe in calves that were sequentially inoculated with BRSV followed by H. somnus. Pneumonic lesions in the inoculated calves were similar to those described for naturally occurring H. somnus-associated respiratory tract disease. Control calves inoculated with BRSV alone or sham-inoculated with medium did not develop clinical signs of respiratory tract disease. The BRSV-inoculated control calves developed minimal pneumonic lesions.  相似文献   

3.
Bovine respiratory syncytial virus (BRSV) and Haemophilus somnus are two bovine respiratory pathogens that cause disease singly or as part of a polymicrobial infection. BRSV infection is often associated with a predisposition towards production of a T helper type 2 (Th2) response and IgE production. In contrast, an IgG2 response to H. somnus has been shown to be most important for recovery. An experiment was performed to evaluate the hypothesis that infection with H. somnus on day 6 of experimental BRSV infection would result in disease enhancement and potentially an altered immune response when compared with single infection. Three groups of calves were either dually infected or singly infected with H. somnus or BRSV. Serum and bronchoalveolar lavage fluid (BALF) pathogen specific IgG1, IgG2, IgE, and IgA responses were evaluated by ELISA. TaqMan RT-PCR was used to examine cytokine gene expression by PBMC and BAL cells. Clinical signs were evaluated for 28 days after BRSV infection, followed by necropsy and histological examination of the lungs. In dually infected calves, disease was significantly more severe, H. somnus was isolated from the lungs at necropsy, and high IgE and IgG responses were detected to H. somnus antigens. Cytokine profiles on day 27 were elevated in dually infected calves, but did not reflect a skewed profile. These results contrasted with singly infected calves that were essentially normal by day 10 of infection and lacked both lung pathology and the presence of H. somnus in the lung at necropsy. The increase in IgE antibodies specific for antigens of H. somnus presents a possible mechanism for pathogenesis of the disease enhancement.  相似文献   

4.
Serial nasopharyngeal swab and bronchoalveolar lavage cultures were used to estimate changes in the bacterial flora of the respiratory tracts of calves during the first month after arrival in the feedlot. Bronchoalveolar lavage (BAL) differential cell counts served to evaluate pulmonary inflammatory changes during this period. Two groups of calves were studied, one consisting of clinically normal controls (n = 60), the other, of cases (n = 59) which received treatment for respiratory disease (penicillin +/- trimethoprimsulfadoxine). A variety of organisms, including Pasteurella multocida, Pasteurella haemolytica, Haemophilus somnus, Mycoplasma bovis and Mycoplasma bovirhinis, were present in the upper and lower airways of both groups during the postarrival period. With the exception of M. bovis, an overall decline in the prevalence of these organisms was observed during the course of the study. In cases, there was a marked decrease in the number of Pasteurella spp. and H. somnus isolates immediately following treatment. For the Pasteurella spp., however, this effect was shortlived as they often appeared to recolonize the respiratory tract within eight days of terminating antimicrobial therapy. Treatment did not appear to affect the frequency of isolating M. bovis. Its prevalence, in both groups of calves, increased to levels approaching 100% during the course of the study. All Pasteurella spp. isolates were tested for susceptibility to several commonly used antimicrobials. Resistance was only evident among P. haemolytica isolated from cases and in every instance this was to a combination of penicillin, ampicillin and tetracycline. Significantly more isolates were resistant after treatment than before. There were BAL differential cell count abnormalities indicative of inflammation in both cases and controls.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
A bacteriological examination of the pulmonary tissues of calves suffering from bronchopneumonia was complemented by a microaerophilic or anaerobic cultivation. Thirty-two strains (23.7%) of a microorganism hitherto not described in Czechoslovakia were isolated during the examination of 135 calves with disorders of the respiratory system. On the basis of the growth, morphological, biochemical and serological properties, the microorganism was identified as Haemophilus somnus. Chocolate agar supplemented with yeast extract, and blood agar were used for the cultivation. Incubation took place in a microaerophilic medium with 10% carbon dioxide or in an anaerobic medium. Serums against the collection strain of Haemophilus somnus were prepared in rabbits for the serological diagnosis. These antiserums reacted with all tested strains during test tube agglutination but did not enter cross reactions with other bacterial species. The coagglutination test, which was verified, did not provide reliable results.  相似文献   

6.
Haemophilus somnus is an important cause of bovine respiratory disease and septicemia with all it's sequelae. The role of immune responses in protection and immunopathogenesis is not well understood. We showed that infection with bovine respiratory syncytial virus (BRSV) 6 days before H. somnus increased clinical scores and levels of IgE antibody to H. somnus over that of infection with H. somnus alone. To determine whether antigenic specificity of IgE responses differed from IgG responses, Western blots were done with sera from the infected calves, at 0 time and at 21 days post infection. Thus each calf was its own control. IgG antibodies recognized primarily a 40 kDa outer membrane protein (OMP) in whole cell H. somnus preparations and a 270 kDa immunoglobulin binding protein (IgBPs) in culture supernatants but generally not the 41 kDa major OMP (MOMP). IgE antibodies recognized primarily the 41 kDa MOMP in whole cell pellet preparations. Results were consistent among calves. With culture supernatants, IgE antibodies recognized both the 270 kDa IgBPs and the MOMP. Since some H. somnus strains from asymptomatic carriers (including strain 129Pt), do not have IgBPs and express a truncated MOMP (33 kDa rather than 41 kDa), reaction of strain 129Pt cells with serum from calves infected with H. somnus or BRSV and H. somnus was studied. IgE did not react with the truncated MOMP even at much lower (1:100) dilutions than in Western blots with virulent strain 2336 (serum dilution of 1:500). Reactions of IgE with the 40 and 78 kDa antigens in strain 129Pt were noted but since the major reactivities with the IgBPs and the MOMP were not detected, this strain may be useful for inducing protective rather than immunopathogenic responses.  相似文献   

7.
On the aetiopathogenesis of Mycoplasma pneumonia in calf   总被引：1，自引：0，他引：1  
A pure culture of Mycoplasma (M.) bovis was isolated from calves with respiratory disease, exhibiting the picture of lymphohistiocytic proliferative pneumonia with presence of eosinophil plasmatic cells. A mixed infection of M. bovis and Pasteurella (P.) multocida was demonstrated in calves with exudative pneumonia. Both M. bovis and Haemophilus (H.) somnus were recovered from calves with necrotic pneumonia. All 3 organisms--M. bovis, P. multocida, and H. somnus--were present in cases of exudative-necrotic pneumonia. It was also shown that M. bovis played a primary role in the aetiopathogenesis of respiratory diseases caused by mixed infections.  相似文献   

8.
Three field trials were conducted in a large commercial feedlot in Saskatchewan to determine the prevalence of Haemophilus somnus in calves and to evaluate the efficacy of prophylactic mass medication with long-acting oxytetracycline on day 17 (1990, n = 1336), day 11 (1991, n = 4372), or day 8 (1992, n = 5632) postarrival. Hemophilosis accounted for > 40% of the mortality in feedlot calves each year. Haemophilus somnus was cultured from the blood of one febrile calf on day 1 (0.1%, n = 895), but it was not cultured from nasal swabs on day 1 or day 11 (n = 881) or from blood samples on day 11 (n = 883). Similarly, it was not cultured from nasal swabs or blood samples from sick calves first treated for bovine respiratory disease (BRD) (n = 219). Serological titers to H. somnus increased (p < 0.05) in unvaccinated calves from day 1 (Geometric mean titer = 11,846) to day 96 (Geometric mean titer = 63,712), indicating natural infection following feedlot entry. Calves that relapsed twice with BRD or died from BRD +/- hemophilosis had significantly (p < 0.06) lower titers to H. somnus on days 1 and 96 than those that did not relapse twice or die. Postarrival mass medication with long-acting oxytetracycline did not reduce (p > 0.05) the risk of hemophilosis mortality. However, it reduced (p < 0.05) the risk of BRD treatment by 14% and the risk of BRD mortality by 71%. Additional epidemiological studies of H. somnus are needed so that we can develop strategic medication and vaccination programs to reduce losses from hemophilosis.  相似文献   

9.
Respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. Haemophilus somnus (recently reclassified as Histophilus somni) is associated with respiratory disease in American bison, domestic sheep, and cattle. It is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. Therefore, reproductive tract and lung samples from bighorn sheep were evaluated for the presence of this organism. Organisms identified as H. somnus were isolated from 6 of 62 vaginal but none of 12 preputial swab samples. Antigen specific to H. somnus was detected by immunohistochemical study in 4 of 12 formalin-fixed lung tissue samples of bighorn sheep that died with evidence of pneumonia. Notably, H. somnus was found in alveolar debris in areas of inflammation. The 6 vaginal isolates and 2 H. somnus isolates previously cultured from pneumonic lungs of bighorn sheep were compared with 3 representative isolates from domestic sheep and 2 from cattle. The profiles of major outer membrane proteins and antigens for all of the isolates were predominantly similar, although differences that may be associated with the host-parasite relationship and virulence were detected. The DNA restriction fragment length profiles of the bighorn-sheep isolates had similarities not shared with the other isolates, suggesting distinct phylogenetic lines. All of the isolates had similar antimicrobial profiles, but the isolates from the bighorn sheep produced less pigment than those from the domestic livestock, and growth of the former was not enhanced by CO2. Wildlife biologists and diagnosticians should be aware of the potential of these organisms to cause disease in bighorn sheep and of growth characteristics that may hinder laboratory detection.  相似文献   

10.
Serum samples were obtained from 602 calves (from 19 groups in four feedlots: three in Ontario, and one in Alberta) upon arrival at the feedlot and 28 d later. Of these calves, 202 developed bovine respiratory disease (BRD) and 400 did not develop BRD. Based on high antibody titers noted upon arrival, we infer that most calves were exposed to Haemophilus somnus prior to arrival at the feedlot. Within a group, calves with high titers on arrival had a reduced risk of developing BRD later. Most calves did not experience titer increases after arrival; however, calves that had stable or increasing titers had a relatively low risk of contracting BRD. The calves at greatest risk of BRD were those with titers on arrival of less than 6.8 units and subsequent titer decreases of more than 1 unit. The effects of both the titer on arrival and the titer change after arrival were stable when the serologic effects of a number of viruses and Mycoplasma agents were considered. Neither antibody titer on arrival nor titer change was related to weight gain differences among calves. Calves with BRD or calves with lower weight on arrival had decreased weight gains in the first 28-day feeding period. The high titers on arrival may have protected most calves against further infection with H. somnus. However, since the calves that developed BRD had large titer increases to a number of viruses and to Pasteurella haemolytica, while having decreased antibody titers to H. somnus, we infer that the existing antibodies were "used up" in combatting the agents, including H. somnus, which may have "caused" the BRD. Calves which were able to increase their antibody levels to H. somnus tended to have a reduced risk of BRD.  相似文献   

11.
Pneumonia was induced in four month old Holstein calves by intratracheal inoculation of 1 x 10(9) colony forming units of Haemophilus somnus. Twenty calves were divided into four groups of five and challenged with a pneumonic strain (Group 1), an encephalitic strain (Group 2), a preputial strain (Group 3), or a placebo (Group 4). The clinical score, neutrophil count, respiratory rate, and temperature were significantly increased in group 1 by day 1 postinoculation (P less than 0.05) and maintained until day 6 postinoculation (P less than 0.05). The macroscopic pathological changes were significantly greater in group 1 (P less than 0.05). Haemophilus somnus was consistently isolated from pneumonic tissue of group 1 only. Groups 2 and 3 had mild transient increases in all parameters measured and macroscopically only small focal lesions were present. It is concluded that virulence differences exist between H. somnus strains following intratracheal challenge of bovine lungs.  相似文献   

12.
The population under study included young calves with pneumonia (group A, n = 13) and their controls (group B, n = 9), as well as older calves from which the lungs with (group C, n = 90) or without (group D, n = 10) lesions were collected after slaughter. Arcanobacterium pyogenes was the organism most commonly isolated from calves in group A (46%), followed by Haemophilus somnus (23%), Mannheimia haemolytica (15%), Streptococcus suis and Pasteurella multocida (7.7% each). Only S. suis (22%) and P. multocida (11%) were found in group B. P. multocida was isolated from 32% group C calves, H. somnus from 11%, A. pyogenes from 7.8%, M. haemolytica from 2.2% and S. suis from 1.1%. No specific pathogens were isolated in group D. Prevalence of Mycoplasma bovis infection was 69% in group A and 37% in group C. Ninety-eight strains were tested for resistAnce to antibiotics. Resistance to penicillin and ampicillin was present only in M. haemolytica (46%). High percentages of resistant strains were observed for streptomycin (48-100%), tetracycline (15-43%), sulfonamides alone (14-100%) or in combination with trimethoprim (0-100%). Therapeutic approaches to bacterial calf pneumonia in the area under study should be modified according to the isolated bacterial population, the observed antimicrobial resistances and the growing importance of Mycoplasma bovis.  相似文献   

13.
Nasal swabs of 293 calves were examined for Mycoplasma. The samples were collected from calves affected with respiratory diseases on 71 farms in various parts of Japan between 1996 and 1997. Mycoplasma bovirhinis was isolated from 47 of 293 calves (16.0%). Mycoplasma alkalescens, M. bovis, M. arginini, M. bovigenitalium and Acholeplasma spp. were isolated from 19 (6.5%), seven (2.4%), four (1.4%), four (1.4%) and 18 (6.1%) calves, respectively. Pasteurella multocida and P. haemolytica were isolated from 60% of Mycoplasma-positive calves. However, other bacteria were not isolated from calves. To evaluate the antimicrobial susceptibility of their isolates, 68 M. bovirhinis, 21 M. alkalescens and 10 M. bovis strains were examined for 12 antimicrobial agents. All isolates showed higher susceptibility to tiamulin than to the other drugs used in the study. However, erythromycin had no effect on any of the Mycoplasma strains studied. The field isolates were less susceptible than the type strains to some drugs, such as spiramycin, oxytetracycline and tylosin.  相似文献   

14.
Ten Haemophilus somnus isolates were grown on blood agar plates under a 5% CO2 atmosphere for 48 h. Harvested whole cells were washed and evaluated for the presence of histamine by ELISA. All H. somnus isolates had cell-associated histamine concentrations of between 18.5 and 200 ng/ml. In a separate study, the ability of H. somnus to secrete histamine into BHI growth medium was evaluated using H. somnus strains 8025 and 156A as well as a recent 156A respiratory isolate. Each strain or isolate was grown under various concentrations of CO2 to approximate the CO2 concentration in the bronchi. The histamine content of washed whole cells and medium supernatant were determined at various stages of incubation. Highest histamine concentrations were detected in the recent respiratory isolate; whole cells (225 ng/ml) after 120 h incubation in 15% CO2 and supernatant (1721 ng/ml) after incubation for 41 h in 25% CO2. This study indicates that different H. somnus isolates can produce and secrete histamine which may be enhanced by CO2 concentrations which approximate those in the bronchial tree. Results of this study may partially explain some of the post-vaccination reactions occasionally observed with H. somnus bacterins. Additional studies are needed to determine the actual role of H. somnus-derived histamine in the pathogenesis of bovine respiratory disease and airway hyperresponsiveness.  相似文献   

15.
Aerosol challenge of calves with Haemophilus somnus and Mycoplasma dispar   总被引：2，自引：0，他引：2  
The aim of the study was to examine the ability of Haemophilus somnus and Mycoplasma dispar to induce pneumonia in healthy calves under conditions closely resembling the supposed natural way of infection, viz. by inhalation of aerosol droplets containing the microorganisms. The infections were investigated by recording clinical data, cytokine expression of peripheral blood cells and pathology. Twelve calves were included in the study: Three animals were exposed to H. somnus only, and two to M. dispar only, whereas five were challenged to M. dispar followed by exposure to H. somnus 11-14 days later. Also, one calf was exposed to M. dispar followed by exposure to a sterile saline solution 11 days later, and one calf was only exposed to a sterile saline solution. Just one animal, only challenged with H. somnus, developed a focal necrotizing pneumonia, from which H. somnus was isolated. Thus, the ability of H. somnus and M. dispar to act as primary pathogens under these conditions were minimal and inconsistent.However, a transient rise in body temperature, a marked granulocytosis and increased levels of interleukin-8 in peripheral blood after inoculation with H. somnus indicated a clear systemic response, probably as a consequence of the natural non-specific local and systemic defence mechanisms acting in healthy calves.  相似文献   

16.
The prevalence of Haemophilus somnus in the genital tract of slaughtered and live cows in southern Ontario was investigated. The vagina and uterus of slaughtered cows were swabbed separately. Live cows were examined and sampled in two field surveys: Centre A and Centre B. In the former, aspirated mucus secretions and in the latter, specimens obtained by guarded swabbing were examined bacteriologically. Haemophilus somnus was isolated from 28 genital tracts of 461 slaughtered (6.1%), and seven of 199 live (3.5%) cows during the centre B survey. The isolates were recovered from both normal and diseased reproductive tracts. Fourteen strains isolated from genital organs were examined for pathogenicity in vivo to test the occurrence of pathogenic isolates. In the initial stage of the in vivo study on pathogenicity, each of the fourteen isolates was examined on one calf using an intracisternal inoculation. Subsequently, one pathogenic and one nonpathogenic strain were inoculated into five calves each to statistically confirm their pathogenic potential. Of 14 genital isolates of H. somnus examined in an intracisternal calf assay, six (43%) caused a fatal peracute neurological disease, while eight were nonpathogenic. A comparative pathological study of pathogenic and nonpathogenic isolates showed that the former caused a severe fatal suppurative meningoencephalitis whereas the latter caused no lesions whatsoever or a mild leukocytic leptomeningitis. The salient data obtained in this study indicate that there are pathogenic strains of H. somnus in the genital tract of apparently normal cows as well as of those with inflammatory disease.  相似文献   

17.
The commercially available API ZYM microbiological identification system was evaluated for the rapid identification of Haemophilus somnus. Eighty-seven isolates of the organism had API ZYM profiles which were characteristic. The API ZYM profiles demonstrate clear differences between H. somnus and other genera but suggest a close association to three related organisms. Enzyme activity of H. somnus isolates were similar to organisms identified as Histophilus ovis, Haemophilus agni and strains UQV of Actinobacillus actinoides and Actinobacillus seminis but was clearly different from isolates of Pasteurella haemolytica, Pasteurella multocida, Bordetella bronchiseptica and group EF4. The API ZYM system allowed more rapid identification of H. somnus than conventional biochemical tests and may be a useful adjunct to conventional methods used for identification of H. somnus isolates. The test did not reveal obvious differences between isolates from various anatomic locations.  相似文献   

18.
Barbour, E.K., Nabbut, N.H., Hamadeh, S.K. and Al-Nakhli, H.M., 1997. Bacterial identity and characteristics in healthy and unhealthy respiratory tracts of sheep and calves. Veterinary Research Communications, 21 (6), 421-430The aim of this study was to compare different bacteriological aspects of the respiratory systems of healthy (H) versus unhealthy (UH) animals with respiratory signs. The prevalence of different bacterial species was determined in the upper and lower respiratory tract of H and UH Najdi sheep, Somali sheep and Holstein calves. The characteristics of Pasteurella spp. isolates, and the biotype of Pasteurella haemolytica were identified in H and UH animals. Eighteen out of 28 (64.3%) of the identified bacterial species in the upper respiratory tract were more prevalent in the nasal cavities of UH Najdi and Somali sheep and Holstein calves with respiratory signs than in apparently healthy animals; four of the most prevalent bacteria in the upper respiratory system of UH sheep were Moraxella spp., Pseudomonas pseudomallei, Erysipelothrix spp., and Pasteurella multocida, while three of the most prevalent bacteria in UH calves were Pasturella haemolytica, Actinomyces spp., and Pseudomonas aeruginosa. The prevalence of six different bacterial species was greater in the lungs of UH animals, namely Actinomyces pyogenes, Erysipelothrix spp., P. haemolytica, Pasteurella ureae, Staphylococcus aureus, and Staphylococcus epidermidis, which could be risk factors in the complexity of the prevalent respiratory diseases of the animals surveyed.Of the biochemical, cytological and colonial characteristics studied in the identified P. haemolytica and P. multocida, two characters were significantly different (p < 0.05) in organisms isolated from UH as compared to those from H animals. These were the higher loss of haemolytic power by the strains of P. haemolytica and the decreased fermentation of trehalose by all the strains of P. multocida recovered from healthy animals.The only biotype of P. haemolytica isolated from H animals was biotype A, while both biotypes A (88.0% of the isolates) and T (12.0% of the isolates) were recovered from UH animals.  相似文献   

19.
The ability of commercially available Haemophilus somnus bacterins to elicit an immunoglobulin E (IgE) response was examined in healthy calves using enzyme-linked immunosorbent assay (ELISA) and western blotting techniques. Thirty five calves were utilized in this study. Calves in Group 1 (n=7) did not receive any H. somnus vaccination and served as negative controls. Calves in each of Groups 2-5 (n=7 each) were vaccinated on days 0 (primary) and 14 (booster) with one of four commercially available H. somnus bacterins. Sera were harvested on days 0 and 14 and at weekly intervals for a total of 45 days. Sera were tested for the presence of IgE antibodies using a bovine IgE-specific ELISA.Low levels of H. somnus-specific IgE were detected by ELISA in all animals prior to the initiation of the study. All bacterins induced IgE levels that were significantly higher than control levels. Two bacterins elicited higher IgE levels at all time points. Sera were adsorbed against washed whole cells of either Salmonella typhimurium, P. multocida, or H. somnus or extracts of H. somnus. ELISA absorbance values were significantly decreased by adsorption with washed whole cells or extracts of H. somnus, whereas adsorption with other gram-negative bacteria only minimally decreased ELISA absorbance values. These results indicate that commercially available H. somnus bacterins can induce IgE antibody as early as 14 days post-vaccination. This IgE can be detected 45 days after the primary vaccination. Results also indicate that H. somnus-specific IgE antibodies can be found in serum of some cattle, possibly induced by existing or previous sensitization.  相似文献   

20.
Faecal samples from 76 diarrhoeic calves belonging to 36 farms located in the Pampas plain, Argentina, were examined for Shiga toxin-producing Escherichia coli (STEC). A total of 15 STEC strains were isolated from 12 (15.8%) calves which came from six different farms. All stx positive strains assayed by PCR were also positives in the Vero cell cytotoxicity test. The majority (60.0%) of the STEC strains carried the stx(1) gene. Twelve (80.0%) of the STEC isolates which belonged to serotypes O5:H- (n = 4), O26:H11 (n = 4), O26:H- (n = 1), O111:H- (n = 2), and O123:H38 (n = 1) were also enterohaemolysin (EHly) positive and carried the gene encoding for intimin (eae). All the stx positive strains were negative for the bfpA gene. Localized adherence to HEp-2 cells were observed in 83.3% of the eae+ STEC strains. STEC belonging to serotype O5:H- showed atypical biochemical properties, including urease production. Urease was also produced by two strains belonging to serotypes O153:H? and non-typeable, respectively. Resistance to three or more antibiotics was observed in 12 (80.0%) of the STEC isolates. Most of the serotypes of STEC recovered in this survey carried virulence traits that are associated with increased human and bovine pathogenicity. The present study shows that highly virulent STEC strains are being shed by diarrhoeic calves from farms located in a high incidence area of human STEC infections.  相似文献   

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