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Comparison of sampling techniques for measuring the antimicrobial susceptibility of enteric Escherichia coli recovered from feedlot cattle
2002
Wagner, Bruce A. | Dargatz, David A. | Salmān, Muḥammad | Morley, Paul S. | Wittum, Thomas E. | Keefe, Thomas J.
Objective - To evaluate the effectiveness of various sampling techniques for determining antimicrobial resistance patterns in Escherichia coli isolated from feces of feedlot cattle. Sample Population - Fecal samples obtained from 328 beef steers and 6 feedlot pens in which the cattle resided. Procedure - Single fecal samples were collected from the rectum of each steer and from floors of pens in which the cattle resided. Fecal material from each single sample was combined into pools containing 5 and 10 samples. Five isolates of Escherichia coli from each single sample and each pooled sample were tested for susceptibility to 17 antimicrobials. Results - Patterns of antimicrobial resistance for fecal samples obtained from the rectum of cattle did not differ from fecal samples obtained from pen floors. Resistance patterns from pooled samples differed from patterns observed for single fecal samples. Little pen-to-pen variation in resistance prevalence was observed. Clustering of resistance phenotypes within samples was detected. Conclusions and Clinical Relevance - Studies of antimicrobial resistance in feedlot cattle can rely on fecal samples obtained from pen floors, thus avoiding the cost and effort of obtaining fecal samples from the rectum of cattle. Pooled fecal samples yielded resistance patterns that were consistent with those of single fecal samples when the prevalence of resistance to an antimicrobial was > 2%. Pooling may be a practical alternative when investigating patterns of resistance that are not rare. Apparent clustering of resistance phenotypes within samples argues for examining fewer isolates per fecal sample and more fecal samples per pen.
Mostrar más [+] Menos [-]Comparison of serologic tests for detection of Brucella infections in cattle and water buffalo (Bubalus bubalis)
2002
Fosgate, Geoffrey T. | Adesiyun, Abiodun A. | Hird, David W. | Johnson, Wesley O. | Hietala, Sharon K. | Schurig, Gerhardt G. | Ryan, Joseph
Objective-To estimate sensitivity and specificity of 4 commonly used brucellosis screening tests in cattle and domestic water buffalo of Trinidad, and to compare test parameter estimates between cattle and water buffalo. Animals-391 cattle and 381 water buffalo. Procedure-4 Brucella-infected herds (2 cattle and 2 water buffalo) and 4 herds (2 of each species) considered to be brucellosis-free were selected. A minimum of 100 animals, or all animals > 1 year of age, were tested from each herd. Serum samples were evaluated for Brucella-specific antibodies by use of standard plate agglutination test (SPAT), card test (CT), buffered plate agglutination test (BPAT), and standard tube agglutination test (STAT). A Bayesian approach was used to estimate sensitivity and specificity of diagnostic tests without the use of a gold standard, assuming conditional independence of tests. Results-Sensitivity and specificity estimates in cattle, respectively, were SPAT, 66.7 and 98.9; CT, 72.7 and 99.6; BPAT, 88.1 and 98.1; and STAT, 80.2 and 99.3. Corresponding test estimates in water buffalo, respectively, were SPAT, 51.4 and 99.3; CT, 90.4 and 99.4; BPAT, 96.3 and 90.7; and STAT, 75.0 and 98.8. Sensitivity of the CT and specificity of the BPAT were different between cattle and water buffalo with at least 95% probability. Conclusions and Clinical Relevance-Brucellosis serologic test performance varied by species tested, but BPAT had the highest sensitivity for screening cattle and water buffalo. Sensitivity and specificity of more than 2 screening tests can be estimated simultaneously without a gold standard by use of Bayesian techniques.
Mostrar más [+] Menos [-]Effect of genistein on replication of bovine herpesvirus type 1
2002
Akula, Shaw M. | Hurley, David J. | Wixon, Regina L. | Wang, Chungyang | Chase, Christopher C.L.
Objective-To study the antiviral activity of genistein, a soya isoflavone, on in vitro replication of bovine herpesvirus type 1 (BHV-1). Sample Population-Madin-Darby bovine kidney (MDBK) cells. Procedure-Effects of genistein on the magnitude and kinetics of inhibition of BHV-1 phosphorylation of glycoprotein E (gE) and in vitro replication of BHV-1 in MDBK cells were evaluated. Antiviral activity of genistein was compared with 2 compounds, estradiol-17β (EST) and tamoxifen (TAM), that have estrogenic and antiestrogenic activity, respectively. High-performance liquid chromatography (HPLC) was used to determine the concentration of genistein in medium from infected and uninfected MDBK cultures. Results-Genistein reduced BHV-1, but not gE-deleted BHV-1 (BHV-1gEΔ3.1), replication by 90% at 18 hours after inoculation. This inhibition was not sustained through 24 hours after inoculation. The genistein concentration in media from MDBK cells was decreased by 40% during BHV-1 infection, compared with 16% for uninfected cells, at 24 hours after inoculation. Genistein inhibited gE phosphorylation and BHV- 1 replication in a dose-dependent manner. Dosing with 25 µMgenistein at 0 and 12 hours after inoculation of BHV-1 was optimal for decreasing BHV-1 replication. Estradiol-17β EST and TAM did not affect BHV-1 replication. Conclusions and Clinical Relevance-The decrease in genistein concentration was a viral infection-dependent event. Genistein is an inhibitor of BHV-1 replication because of its ability to inhibit tyrosine kinase activity. A possible application may be for the control of BHV-1 infection in cattle by feeding soya products rich in genistein prior to or during periods of stress.
Mostrar más [+] Menos [-]Seroprevalence and molecular evidence for the presence of bovine immunodeficiency virus in Brazilian cattle
2002
Meas, S. (Hokkaido Univ., Sapporo (Japan)) | Ruas, F.J. | Usui, T. | Teraoka, Y. | Mulenga, A. | Chang, K.S. | Masuda, A. | Madruga, C.R. | Ohashi, K. | Onuma, M.
Data on the worldwide distribution of bovine immunodeficiency virus (BIV) and bovine leukemia virus (BLV) is limited. A prevalence study of antibodies to BIV and BLV was conducted in six different cattle herds in Brazil. Out of a total of 238 sera analyzed, 11.7% were found positive for anti-BIV p26 antibodies as determined by Western blot analysis, 2.1% were positive for anti-BLV gp51 antibodies as detected by immunodiffusion test. Peripheral blood mononuclear cells from BIV seropositive cattle were found to have BIV-provirus DNA, as detected by nested polymerase chain reaction. A nucleotide sequence corresponding to a 298 bp fragment of the BIV pol gene was also analyzed. Amino acid sequences of these Brazilian pol gene products showed 98.0 to 100% homology to the American strain BIV R29, 97.0 to 99.0% to Japanese BIV isolates, and divergence ranged from 0 to 4.0% among Brazilian BIV isolates. This evidence of the presence of BIV and BLV infections in Brazil should be considered a health risk to Brazilian cattle populations and a potential causative agent of chronic disease in cattle.
Mostrar más [+] Menos [-]Occurrence of concurrent trypanosomosis, theileriosis, anaplasmosis and helminthosis in Friesian, Zebu and Sahiwal cattle in Uganda
2002
Magona, J.W. | Mayende, J.S.P. (Livestock Health Research Inst., Tororo (Uganda))
The prevalence and economic importance of bovine fasciolosis in Kenya - an analysis of abbattoir data
2002
Kithuka, J.M. (Nairobi Univ. (Kenya). Veterinary Public Health Dept.) | Maingi, N. | Njeruh, F.M. | Ombui, J.N.
Seasonal abundance of adult ixodid ticks infesting cattle belonging to resource-limited farmers in the north-eastern Free State Province of South Africa
2002
Hlatshwayo, M. | Mbati, P.A. | Dipeolu, O.O. (Northern Univ., Phuthaditjhaba (South Africa). Parasitology Research Programme)
Validation of an indirect enzyme-linked immunosorbent assay for the detection of antibody against Brucella abortus in cattle sera using an automated ELISA workstation
2002
Paweska, J.T. (Agricultural Research Council, Onderstepoort (South Africa). Onderstepoort Veterinary Inst.) | Potts, A.D. | Harris, H.J. | Smith, S.J. | Viljoen, G.J. | Dungu, B. | Brett, O.L. | Bubb, M. | Prozesky, L.
Seasonal availability of gastrointestinal nematode larvae to cattle on pasture in the central highlands of Kenya
2002
Waruiru, R.M. | Weda, E.H. | Otieno, R.O. | Ngotho, J.W. (Nairobi Univ., Kabete (Kenya). Veterinary Pathology, Microbiology and Parasitology Dept.)
Non-immune control of trypanosomosis: In vitro oxidative burst of PMA- and trypanosome-stimulated neutrophils of Boran and N'Dama cattle
2002
Taiwo, V.O. (Ibadan Univ. (Nigeria). Veterinary Pathology Dept.) | Adejinmi, J.O. | Oluwaniyi, J.O.