Potential associations between fecal shedding of Salmonella in feedlot cattle treated for apparent respiratory disease and subsequent adverse health outcomes     

Alam MJ  Renter DG  Ives SE  Thomson DU  Sanderson MW  Hollis LC  Nagaraja TG 《Veterinary research》2009,40(1):2-Feb;40(1):02

A prospective cohort study was used to assess whether Salmonella fecal shedding in commercial feedlot cattle treated with antimicrobials for respiratory disease was associated with subsequent adverse health outcomes. Feces were collected per rectum from cattle that were examined for apparent respiratory disease, had a rectal temperature > or = 40 degrees C, and subsequently received antimicrobial treatment. Salmonella were recovered from 918 (73.7%) of 1 245 fecal samples and weekly prevalence estimates ranged from 49 to 100% over the 3-month study. Genotypic and phenotypic characteristics of Salmonella strains in the population were determined. Serogroup E Salmonella were most common (73.3%), followed by C1 (11.0%), C3 (8.6%), and B (1.1%). Predominant serotypes were Orion (46.5%), Anatum (19.8%), Kentucky (8.7%), Montevideo (7.5%), and Senftenberg (4.9%). Few isolates (36/918) were positive for antimicrobial resistance-associated integron gene intI1. Phenotypic susceptibility was associated with isolate intI1 status. Crude re-pull, re-treatment and case fatality risks were higher for cattle that were Salmonella-positive versus -negative at initial treatment, but not statistically different on multivariable analysis. However, case fatality risk was higher for cattle shedding Group B Salmonella than for cattle shedding other serogroups. Lots (groups) with a higher Salmonella prevalence at first treatment had a higher proportion of mortalities occur in a hospital pen, higher overall re-treatment risks, and were more likely to be sampled later in the study. Results indicate a high prevalence of Salmonella in this population of cattle treated for apparent respiratory disease, but that effects associated with clinical outcomes may depend on the Salmonella strain.  相似文献   

Role of Fatty Acids in Energy Provision During Oocyte Maturation and Early Embryo Development     

RG Sturmey  A Reis  HJ Leese  TG McEvoy 《Reproduction in domestic animals》2009,44(S3):50-58

While much is known about the metabolism of exogenous nutrients such as glucose, lactate, pyruvate, amino acids by oocytes and pre-implantation mammalian embryos, the role of endogenous stores, particularly lipid, has been largely overlooked. The presence of lipid within oocytes and early embryos has been long known, and comparisons between species indicate that the amounts and types of lipid present vary considerably. Large amounts of intracellular lipid can compromise the success of cryopreservation and the removal of such lipid has been the subject of considerable effort. In this review, we present evidence that strongly suggests a metabolic role for lipid, specifically with regard to energy provision, in the late-stage oocyte and the pre-implantation embryo. We focus initially on oxygen consumption as a global indicator of metabolic activity, before reviewing different approaches that either have been designed to investigate directly, or have revealed indirectly the role of endogenous lipid in energy generation. These fall under five headings: (i) fatty acid oxidation; (ii) inhibition of triglyceride oxidation; (iii) culture in the absence of exogenous substrates; (iv) cytoplasmic organization; and (v) delipidation. On the basis of the data derived from these studies, we conclude that there is strong evidence for the utilization of endogenous lipid as an energy substrate by oocytes and early embryos.  相似文献   

Kyasanur forest disease virus breaking the endemic barrier: An investigation into ecological effects on disease emergence and future outlook          下载免费PDF全文

K. Ajesh  B. K. Nagaraja  K. Sreejith 《Zoonoses and public health》2017,64(7):e73-e80

Kyasanur Forest disease (KFD) is found in a limited range of India, but is epidemiologically understudied. The seasonal patterns of KFD are well known; however, the significant concern is on the extent to which changes in epidemiology happen especially under the influence of ecological destructions and by the eventual effects of resulting climate change. Presently, a southward and northward spread of the Kyasanur Forest disease virus (KFDV) along the Western Ghats has been reported in the adjoining states of Kerala, Tamil Nadu, Goa and Maharashtra. In this review, we investigate the cascade of factors that might have facilitated the resurgence of KFDV among the endemic regions in higher frequency and its recent emergence in the area previously not reported. Utilizing published data, we additionally endeavour to exhibit a portion of the impediments of control systems and embody the powerful option strategies for developing KFDV control.  相似文献   

Identification of quantitative trait loci associated with resistance to foliar diseases in sorghum [<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench]     

S. Murali Mohan  R. Madhusudhana  K. Mathur  D. V. N. Chakravarthi  Sanjay Rathore  R. Nagaraja Reddy  K. Satish  G. Srinivas  N. Sarada Mani  N. Seetharama 《Euphytica》2010,176(2):199-211

Forage sorghum cultivars grown in India are susceptible to various foliar diseases, of which anthracnose, rust, zonate leaf spot, drechslera leaf blight and target leaf spot cause severe damage. We report here the quantitative trait loci (QTLs) conferring resistance to these foliar diseases. QTL analysis was undertaken using 168 F₇ recombinant inbred lines (RILs) of a cross between a female parental line 296B (resistant) and a germplasm accession IS18551 (susceptible). RILs and parents were evaluated in replicated field trials in two environments. A total of twelve QTLs for five foliar diseases on three sorghum linkage groups (SBI-03, SBI-04 and SBI-06) were detected, accounting for 6.9–44.9% phenotypic variance. The morphological marker Plant color (Plcor) was associated with most of the QTL across years and locations. The QTL information generated in this study will aid in the transfer of foliar disease resistance into elite susceptible sorghum breeding lines through marker-assisted selection.  相似文献   

Effect of cattle breed on innate resistance to inoculations of Babesia bigemina     

RE BOCK  TG KINGSTN  NF STANDFAST  AJ de  VOS 《Australian veterinary journal》1999,77(7):465-466

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Effect of lasalocid, monensin and thiopeptin on rumen protozoa   总被引：4，自引：0，他引：4  

S M Dennis  T G Nagaraja  A D Dayton 《Research in veterinary science》1986,41(2):251-256

The effects of lasalocid, monensin and thiopeptin on the total number and the generic composition of rumen protozoa were determined in vivo and in vitro. Feeding lasalocid or monensin to cattle on either high grain or high roughage diets reduced total protozoal counts. Addition of lasalocid or monensin (6 to 48 micrograms ml-1) to the in vitro rumen fermentation resulted in marked reduction in protozoal numbers. The inhibition was dose dependent. Thiopeptin had no effect on rumen protozoa either in vivo or in vitro. Among the protozoal types, holotrichs (Dasytricha, Isotricha and Charonina) were unaffected by either lasalocid or monensin. Among the entodiniomorphs, Entodinium, Diplodinium and Ophryoscolex were more sensitive than the other types. Ophryoscolex purkynei was more sensitive to monensin than to lasalocid. Protozoal inhibition by lasalocid and monensin was transient because prolonged antibiotic feeding resulted in the selection of a resistant population in the rumen of cattle.  相似文献   

Rapid coagglutination test for detection of rotaviruses in turkeys     

S Y Kang  K V Nagaraja  J A Newman 《Avian diseases》1985,29(3):640-648

Avian rotaviruses present in fecal samples were readily detected using a staphylococcal protein-A coagglutination test on a white porcelain plate. Staphylococci, which produced large amounts of protein-A, were coated with rabbit anti-avian rotavirus serum. The antibody-coated staphylococci were agglutinated specifically by rotavirus present in the fecal sample. The macroscopic agglutination reaction occurred within a few minutes. A total of 40 fecal samples were tested by the coagglutination test. The sensitivity and specificity of the coagglutination test were compared with those of electron microscopy, enzyme-linked immunosorbent assay, and tissue-culture virus-isolation methods. Of the 31 fecal samples positive for rotavirus on electron microscopy, 27 (87%) were positive on coagglutination test. Of the nine electron-microscopy-negative samples, seven (78%) were also negative on coagglutination test. It was concluded that the staphylococcal protein-A coagglutination test can be used as a simple, rapid screening test for avian rotavirus.  相似文献   

Fusobacterium necrophorum infections: Virulence factors,pathogenic mechanism and control measures     

Z. L. Tan  T. G. Nagaraja  M. M. Chengappa 《Veterinary research communications》1996,20(2):113-140

Fusobacterium necrophorum, a Gram-negative, non-spore-forming anaerobe, is a normal inhabitant of the alimentary tract of animals and humans. Two types of F. necrophorum, subspecies necrophorum (biotype A) and funduliforme (biotype B), have been recognized, which differ morphologically, biochemically, and biologically. The organism is an opportunistic pathogen that causes numerous necrotic conditions (necrobacillosis) such as bovine hepatic abscesses, ruminant foot abscesses and human oral infections. The pathogenic mechanism of F. necrophorum is complex and not well defined. Several toxins, such as leukotoxin, endotoxin, haemolysin, haemagglutinin and adhesin, have been implicated as virulence factors. Among these, leukotoxin and endotoxin are believed to be more important than other toxins in overcoming the host's defence mechanisms to establish the infection. F. necrophorum is encountered frequently in mixed infections and, therefore, synergisms between F. necrophorum and other pathogens may play an important role in infection. Several investigators have attempted to induce protective immunity against F. necrophorum using bacterins, toxoids, and other cytoplasmic components. Generally, none of the immunogens has afforded statisfactory protection against Fusobacterium infections. Because of the unavailability of suitable immunoprophylaxis, the control of F. necrophorum infection has depended mainly on the use of antimicrobial compounds.Abbreviations CFU colony-forming units - DNA deoxyribonucleic acid - DNase deoxyribonuclease - Eh redox potential - ELISA enzyme-linked immunosorbance assay - LPS lipopolysaccharide - MPN most-probable number - PMN polymorphonuclear cells - rRNA ribosoma ribonucleic acid - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - subsp. subspecies  相似文献   

Applicability of a multiplex PCR to detect O26, O45, O103, O111, O121, O145, and O157 serogroups of Escherichia coli in cattle feces     

Paddock Z  Shi X  Bai J  Nagaraja TG 《Veterinary microbiology》2012,156(3-4):381-388

Shiga toxin-producing Escherichia coli (STEC), particularly O157, are major food borne pathogens. Non-O157 STEC, particularly O26, O45, O103, O111, O121, and O145, have also been recognized as a major public health concern. Unlike O157, detection procedures for non-O157 have not been fully developed. Our objective was to develop a multiplex PCR to distinguish O157 and the 'top six' non-O157 serogroups (O26, O45, O103, O111, O121, and O145) and evaluate the applicability of the multiplex PCR to detect the seven serogroups of E. coli in cattle feces. Published sequences of O-specific antigen coding genes, rfbE (O157) and wzx and wbqE-F (non-O157), were analyzed to design serogroup-specific primers. The specificity of amplifications was confirmed with 138 known STEC strains and the reaction yielded the expected amplicons for each serogroup. In feces spiked with pooled 7 STEC strains, the sensitivity of the detection was 4.1 × 10(5)CFU/g before enrichment and 2.3 × 10(2) after 6h enrichment in E. coli broth. Additionally, 216 fecal samples from cattle were collected and tested by multiplex PCR and cultural methods. The multiplex PCR revealed a high prevalence of all seven serogroups (178 [O26], 108 [O45], 149 [O103], 30 [O111], 103 [O121], 5 [O145], and 160 [O157]) of 216 samples in fecal samples. Cultural procedures identified 33.1% (53/160) and 35.5% (11/31) of PCR-positive samples for E. coli O157 and non-O157 serogroups, respectively. Samples that were culture-positive were all positive by the multiplex PCR. The multiplex PCR can be used to identify serogroups of putative STEC isolates.  相似文献   

Comparison of methods for differentiation of Salmonella enterica serovar Enteritidis phage type 4 isolates     

Lopes VC  Velayudhan BT  Halvorson DA  Lauer DC  Gast RK  Nagaraja KV 《American journal of veterinary research》2004,65(5):538-543

OBJECTIVE: To compare molecular typing methods for the differentiation of Salmonella enterica serovar Enteritidis phage type (PT) 4 isolates that allowed for the determination of their genetic relatedness. SAMPLE POPULATION: 27 Salmonella Enteritidis PT 4 strains isolated in the United States and Europe. PROCEDURE: Several molecular typing methods were performed to assess their ability to genetically differentiate among Salmonella Enteritidis PT 4 isolates. Results of pulse-field gel electrophoresis (PFGE), repetitive polymerase chain reaction (PCR) assay, 16S rRNA gene sequencing, random amplification of polymorphic DNA (RAPD), PCR-restriction fragment length polymorphism of 16S rRNA, and antimicrobial susceptibility were evaluated. RESULTS: Compared with results for other techniques, results for the RAPD typing method with the RAPD1 primer reveal that it was the most discriminatory fingerprinting technique, and it allowed us to cluster Salmonella Enteritidis PT 4 isolates on the basis of their genetic similarity. CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed the value of RAPD with the RAPD1 primer as a tool for epidemiologic investigations of Salmonella Enteritidis PT 4. It can be used in conjunction with PFGE and phage typing to determine the genetic relatedness of Salmonella Enteritidis isolates involved in outbreaks of disease. A reliable and highly discriminatory method for epidemiologic investigations is critical to allow investigators to identify the source of infections and consequently prevent the spread of Salmonella Enteritidis PT 4.  相似文献