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PubMedDate not supplied

Monoclonal antibody and nucleic acid probes for the diagnosis of avian diseases.

Various properties of monoclonal antibody (MAB) and nucleic acid (NA) probes confer advantages over polyclonal antibodies in sera and permit the probes to be used to directly and rapidly detect small quantities of pathogens in body fluids, biopsy, or postmortem material. This makes it unnecessary to amplify the amount of pathogen by growth in vitro or to perform neutralization tests, procedures that are time-consuming. Even if pathogens are grown in vitro, highly specific MABs can be used in immunofluorescence tests to differentiate isolates to extents not possible using antisera. There has been much greater investment in the development of probes for the diagnosis of human disease than for veterinary disease, because of the greater commercial potential of the former. A number of factors work against the development and distribution of new probes, but most of these are only temporary impediments if demand is there. Even in human medicine, the application of new probes is in its infancy, and it is probable that it will be several years yet before probes achieve widespread use in avian diagnosis. However, the potential of some MAB and NA probes is too great to ignore.

Animals↗
PubMed2004

Application of a reverse line blot assay to the study of haemoparasites in cattle in Uganda.

Recent advances in genomic technology have focused many veterinary researchers on the possibility of producing one multivalent recombinant vaccine against all the haemoparasites that infect cattle in the tropics. Before such a vaccine is developed it is essential to define target cattle populations as well as the range of anti-pathogen vaccines required in order to control disease. To further this objective, we have evaluated a reverse line blot (RLB) assay, which simultaneously detects the principal tick transmitted protozoan and rickettsial cattle pathogens, in different epidemiological scenarios in Uganda. A critical question is the sensitivity, particularly in relation to detecting carrier animals. As Theileria parva is considered to be the most important pathogen in the region, we assessed the sensitivity of the RLB assay for T. parva and showed that 1-2 x 10(3) parasites per ml of blood could be detected-a level comparable with previously developed PCR methods and well below conventional microscopic detection. We applied the RLB assay to evaluate the differences in pathogen profiles between crossbred and indigenous cattle and show that there were different profiles, with a low prevalence of T. parva and Theileria taurotragi in the indigenous cattle compared to a high prevalence in the crossbred cattle. In contrast, we show higher prevalences of Theileria mutans and Theileria velifera in the indigenous compared to the crossbred cattle. Interestingly Anaplasma marginale, Babesia bovis and Babesia bigemina were of low prevalence but a high prevalence of Ehrlichia bovis was seen, raising the question of whether this rickettsial species could be pathogenic in cattle. Analysis of animals with clinical symptoms of East Coast Fever showed that, while T. parva is a major cause of these symptoms, T. mutans and possibly T. taurotragi and T. velifera, may also cause clinical disease. Overall, the results presented here highlight the complexity of tick-borne pathogen infections in cattle in Uganda.

Anaplasmosis↗
PubMed2002

Gram-positive bacterial resistance. A challenge for the next millennium.

Penicillin G was first used in 1941. Since then, the trend in bacterial infections has changed. New antibiotics have been developed and bacterial resistance has spread as a consequence. The spread of Gram positive resistant bacteria is related to an inappropriate use of antibiotics. Antibacterial agents are abused or overused in various fields: medicine itself, veterinary science and zootechnics. Now, at the beginning of the third millennium we have been forced to limit our therapeutic options in order to combat these insidious enemies. Selective antibiotic pressure on the microbial population, notably on enterococci and staphylococci, made these two pathogens recalcitrant to traditional chemotherapy. It is a matter of concern that today, vancomycin-resistant Enterococcus spp. (VRE) and vancomycin-intermediate and resistant Staphylococcus aureus (VISA and VRSA) are now being observed worldwide among emerging pathogens. Most pharmaceutical companies are today developing antimicrobial drugs that are active against Gram-positive bacteria. Quinupristin/dalfopristin and linezolid are the most promising drugs and are available only for serious infections; future agents being developed for multi-resistant Gram-positive infections include daptomycin and the glycyclines, although these are still in the development phase. Nevertheless, our group has had the opportunity to treat some serious infections with these drugs and the good results achieved are reported in this review.

Acetamides↗
PubMed1977

[Examination for infertility in cattle (author's transl)].

In order to evaluate clinically recognisable manifestations while undertaking examinations for fertility in cattle it is necessary to take cognizance of the physiological events taking place during the puerperium. The frequently incorrect diagnoses of cystic degeneration of the ovaries during this period can be avoided if the mechanisms controlling ovarian activity are properly understood. The close interaction between the ovaries, the hypothalamus, the hypophysis and adrenals as well as the luteolytic mechanism controlling ovarian activity is discussed. Attention is focussed on the effect of various pathogens on the endometrium, the influence of nutrition on the reproductive cycle and the consequent ovarian changes. The necessity to institute fertility examinations on a herd basis is stressed rather than attempts at treating the individual animal which, according to the owner, requires veterinary attention. By doing so a much more satisfactory service can be rendered. The existence of competent diagnostic centres, where the practitioner can obtain a metabolic or infection profile, is absolutely essential when fertility examinations on a herd basis are considered.

Animals↗
PubMed2005

Stakeholder position paper: food animal veterinarian.

Food animal veterinarians practice in a variety of settings with considerable differences between the settings. Due to variability, aggregate data from surveillance of antimicrobial use is not very useful to practitioners unless correlated information is provided, such as the relative disease status, ages of animals, and purpose of use. Of greater utility is use data as it relates to a specific farm or production system. Of greater importance to clinical practitioners is a meaningful surveillance system that tracks trends in antimicrobial resistance in common pathogens causing animal diseases.

Animal Feed↗
PubMed1993

Epitopes of glycoprotein G of equine herpesviruses 4 and 1 located near the C termini elicit type-specific antibody responses in the natural host.

Specific serological diagnosis of equine herpesvirus 4 (EHV4; equine rhinopneumonitis virus) and EHV1 (equine abortion virus) hitherto has not been possible because of extensive antigenic cross-reactivity between these two closely related but distinct viruses. Recently, we identified EHV4 glycoprotein G (gG) and characterized it as a type-specific, secreted glycoprotein (B. S. Crabb, H. S. Nagesha, and M. J. Studdert, Virology 190:143-154, 1992). This paper shows that EHV1 gG also possesses type-specific epitopes and describes the localization of strong, type-specific epitopes to the apparently corresponding and highly variable regions comprising amino acids 287 to 382 of EHV4 gG and 288 to 350 of EHV1 gG. Fusion proteins expressing these variable regions reacted strongly and type specifically with sera from four foals, three of which were colostrum-deprived, specific-pathogen-free foals, whose history with respect to exposure to EHV4 or EHV1 was well-defined. These antigens provided the basis for the development of a single-well diagnostic enzyme-linked immunosorbent assay to distinguish horses infected with EHV4, EHV1, or both. Such a type-specific test provides for the first time the opportunity to differentiate antibodies to these viruses, and it has, therefore, important implications for understanding the epidemiology of these equine pathogens. Evidence for the existence of EHV1 in Australia 10 years prior to the first confirmed case of EHV1 abortion is presented.

Abortion, Veterinary↗
PubMed1989

[The most frequent infectious causes of abortion in sheep in north Bavaria with special reference to Chlamydia and Salmonella infections].

Between 1980 and 1987 1153 ovine fetuses and placentas were examined after abortion. In 68.5% of the cases a cause of abortion could be diagnosed as follows: 43.5% Chlamydia psittaci var. ovis, 10.7% Salmonella abortus ovis, 3.7% Coxiella burnetii, 3.3% Listeria monocytogenes and 0.4% Campylobacter fetus intestinalis. Hemolyzing Escherichia coli and Streptococci, Yersinia pseudotuberculosis, Salmonella typhimurium, Salmonella enteritidis, Corynebacterium pyogenes and other facultative pathogens isolated in pure culture out of fetal organs as well as non-infectious reasons (fetal deformities) were the causes of abortion in only 7%.

Abortion, Veterinary↗
PubMed1986

[Automation: specter or aspiration for the large-animal practitioner?].

Automatic data processing in veterinary practices is rapidly progressing. Automation of the administration of practices was an important factor in starting these developments, and electronic processing of health and production data within the framework of a herd health and production service programme is enjoying considerable current interest. Information networks will be set up by agricultural branch organizations, the national and regional centres, the Stichting V-Data and commercial organizations. These will make the supply of information to and communication among animal owners, practitioners, advisers and other disciplines operational on a large scale. The data banks developed from information networks may be utilized, among other things, in epidemiological investigations and in taking well-founded decisions regarding management. The rapid advance of the technology of information in the animal production section will considerably affect the management of veterinary practices. The practitioner will have to be able to interpret his computer data and translate them into advice and measures to be adopted by animal owners. Epidemiological training will have to be an essential part of the activities of the veterinarian to enable him to interpret interactions of conditions and management on the one hand and the health status and state of production on the other. Establishing a merely clinical diagnosis in which interaction of host and pathogenic agent is central, will no longer suffice. Rather, an epidemiological diagnosis is required, in which the environment and its many vectors are also included. Apart from the variety of new possibilities to which entry is gained, the central co-ordinating position which can be occupied in the animal production section, will be considerably strengthened.

Animal Husbandry↗
PubMed2005

A survey for phosphoglucose isomerase with lysyl aminopeptidase activity in Vibrionaceae and non-Vibrio pathogens.

Phosphoglucose isomerase (PGI) with a novel lysyl aminopeptidase (LysAP) activity was recently purified and characterized from Vibrio vulnificus. We showed that it cleaves the amino-terminal lysyl residue from des-Arg(10)-kallidin to produce des-Arg(9)-bradykinin, suggesting that it plays a role in virulence. A survey was conducted to determine the presence of this potential virulence-enhancing enzyme among twenty-three halotolerant human and fish pathogens from eleven species within the Vibrionaceae family, including V. vulnificus, V. parahaemolyticus, V. cholerae, Aeromonas hydrophila, and Plesiomonas shigelloides. In addition, fourteen species of non-Vibrionaceae pathogens were screened for LysAP activity. Cell lysates were partially purified by anion exchange chromatography and fractions were screened for LysAP and isomerase activities. PGI-LysAP activity was detected in chromatographic fractions from all the Vibrio species tested, but was not detected in any of the non-Vibrionaceae pathogens. Levels of isomerase and LysAP activity correlated (R(2)=0.92) for nine strains of V. vulnificus. Since the Vibrionaceae represent an important family of human and fish pathogens, our identification of PGI-LysAP activity in a broad array of vibrios may lead to the development of improved analytical methods for their identification as well as interventions to reduce the high morbidity and mortality associated with some Vibrionaceae infections in clinical, veterinary, and aquaculture settings.

Aminopeptidases↗
PubMed1999

Spectrum and antimicrobial activity of alexomycin (PNU-82, 127), a peptide compound projected for use in animal health.

Alexomycin (PNU-82, 127) is a thiopeptide antimicrobial complex intended for veterinary practice that belongs to a series of cyclic peptides produced by Streptomyces arginensis. MICs against selected routine and fastidious clinical isolates of animal and human origin were determined by broth microdilution or agar dilution reference methods. Alexomycin was active against Gram-positive pathogens such as oxacillin-susceptible and -resistant Staphylococcus aureus and coagulase-negative staphylococci (260 strains; MIC90, 0.5 microgram/mL), as well as Enterococcus species (95 strains; MIC90, 0.25 to 0.5 microgram/mL), and generally inactive against Gram-negative aerobes. Alexomycin had more potent activity against Streptococcus bovis (MIC90, 0.12 microgram/mL), S. agalactiae (MIC90, 0.12 microgram/mL), Corynebacterium species (MIC90, 0.06-0.12 microgram/mL), and Listeria monocytogenes (MIC90, 0.5 microgram/mL). Alexomycin activity was limited against Bacillus species (MIC90, 1 microgram/mL), Neisseria meningiditis (MIC90, 2 micrograms/mL), Haemophilus influenzae (MIC90, 8 micrograms/mL), Moraxella catarrhalis (MIC90, 16 micrograms/mL), and Campylobacter jejuni (MIC90, 32 micrograms/mL). This thiopeptide complex was also found to be stable at low concentrations (0.015-32 micrograms/mL) in Mueller-Hinton broth for up to 24 h, possesses static antimicrobial activity and did not produce resistant mutants after multiple passages at subinhibitory drug concentrations. Alexomycin seems to have potential for use as a feed additive to increase feed efficiency and promote growth in poultry and swine as well as other applications against Gram-positive pathogens.

Animals↗
PubMed2002

Antifungal effect of Australian tea tree oil on Malassezia pachydermatis isolated from canines suffering from cutaneous skin disease.

The lipophilic yeast Malassezia pachydermatis is part of the normal skin flora of most warm-blooded organisms. In a number of surveys it could be demonstrated that this yeast species might be involved in different skin diseases like seborrhoeic dermatitis, especially in dogs and cats. In order to look for an alternative therapeutic agent to the commonly used antimycotic and antiseptic synthetic substances the in vitro activity of Australian tea tree oil, the essential oil of Melaleuca alternifolia, against several strains of Malassezia pachydermatis was examined. All tested strains showed remarkably high susceptibility to tea tree oil. With these results the excellent antibacterial activity of tea tree oil is extended to a new group of fungal pathogens colonizing mainly mammals' skin. During the last ten years there was an increasing popularity of tea tree oil containing human health care products. The presented data open up new horizons for this essential oil as a promising alternative agent for topical use in veterinary medicine as well.

Animals↗
PubMed1999

Genetic comparison of Bacillus anthracis and its close relatives using amplified fragment length polymorphism and polymerase chain reaction analysis.

Amplified fragment length polymorphism (AFLP) analysis allows a rapid, relatively simple analysis of a large portion of a microbial genome, providing information about the species and its phylogenetic relationship to other microbes (Vos et al. 1995). The method simply surveys the genome for length and sequence polymorphisms. The AFLP pattern identified can be used for comparison to the genomes of other species. Unlike other methods, it does not rely on analysis of a single genetic locus that may bias the interpretation of results and does not require any prior knowledge of the targeted organism. Moreover, a standard set of reagents can be applied to any species without using species-specific information or molecular probes. We are using AFLP analysis to rapidly identify different bacterial species. A comparison of AFLP profiles generated from a large battery of Bacillus anthracis strains shows very little variability among different isolates (Keim et al. 1997). By contrast, there is a significant difference between AFLP profiles generated for any B. anthracis strain and even the most closely related Bacillus species. Sufficient variability is apparent among all known microbial species to allow phylogenetic analysis based on large numbers of genetically unlinked loci. These striking differences among AFLP profiles allow unambiguous identification of previously identified species and phylogenetic placement of newly characterized isolates relative to known species based on a large number of independent genetic loci. Data generated thus far show that the method provides phylogenetic analyses that are consistent with other widely accepted phylogenetic methods. However, AFLP analysis provides a more detailed analysis of the targets and samples a much larger portion of the genome. Consequently, it provides an inexpensive, rapid means of characterizing microbial isolates to further differentiate among strains and closely related microbial species. Such information cannot be rapidly generated by other means. AFLP sample analysis quickly generates a very large amount of molecular information about microbial genomes. However, this information cannot be analysed rapidly using manual methods. We are developing a large archive of electronic AFLP signatures that is being used to identify isolates collected from medical, veterinary, forensic and environmental samples. We are also developing the computational packages necessary to rapidly and unambiguously analyse the AFLP profiles and conduct a phylogenetic comparison of these data relative to information already in our database. We will use this archive and the associated algorithms to determine the species identity of previously uncharacterized isolates and place them phylogenetically relative to other microbes based on their AFLP signatures. This study provides significant new information about microbes with environmental, veterinary and medical significance. This information can be used in further studies to understand the relationships among these species and the factors that distinguish them from one another. It should also allow the identification of unique factors that contribute to important microbial traits, including pathogenicity and virulence. We are also using AFLP data to identify, isolate and sequence DNA fragments that are unique to particular microbial species and strains. The fragment patterns and sequence information provide insights into the complexity and organization of bacterial genomes relative to one another. They also provide the information necessary for the development of species-specific polymerase chain reaction primers that can be used to interrogate complex samples for the presence of B. anthracis, other microbial pathogens or their remnants.

Bacillus↗
PubMedDate not supplied

Quinolone resistance in Escherichia coli.

Escherichia coli is an important pathogen of animals and humans that causes great financial cost in food production by causing disease in food animals. The quinolones are a class of synthetic antimicrobial agents with excellent activity against Escherichia coli and other Gram-negative bacteria used in human and veterinary medicine. Different quinolones are used to treat various conditions in animals in different parts of the world. All members of this class of drug have the same mode of action: inhibition of topoisomerase enzymes, DNA Gyrase and Topoisomerase IV. Escherichia coli can become resistant to quinolones by altering the target enzymes, reducing permeability of the cell to inhibit their entry, or by actively pumping the drug out of the cell. All these resistance mechanisms can play a role in high-level fluoroquinolone resistance, however target site mutations appear to be most important. As all quinolones act in the same way resistance to one member of the class will also confer decreased susceptibility to all members of the family. Quinolone resistant Escherichia coli in animals have increased in numbers after quinolone introduction in a number of different case studies. The resistance mechanisms in these isolates are the same as those in resistant strains found in humans. Care needs to be taken to ensure that quinolones are used sparingly and appropriately as highly resistant strains of Escherichia coli can be selected and may pass into the food chain. As these drugs are of major therapeutic importance in human medicine, this is a public health concern. More information as to the numbers of quinolone resistant Escherichia coli and the relationship between resistance and quinolone use is needed to allow us to make better informed decisions about when and when not to use quinolones in the treatment of animals.

Animals↗
PubMed2005

Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus.

Coronaviruses are a family of enveloped, single-stranded, positive-strand RNA viruses classified within the Nidovirales order. This coronavirus family consists of pathogens of many animal species and of humans, including the recently isolated severe acute respiratory syndrome coronavirus (SARS-CoV). This review is divided into two main parts; the first concerns the animal coronaviruses and their pathogenesis, with an emphasis on the functions of individual viral genes, and the second discusses the newly described human emerging pathogen, SARS-CoV. The coronavirus part covers (i) a description of a group of coronaviruses and the diseases they cause, including the prototype coronavirus, murine hepatitis virus, which is one of the recognized animal models for multiple sclerosis, as well as viruses of veterinary importance that infect the pig, chicken, and cat and a summary of the human viruses; (ii) a short summary of the replication cycle of coronaviruses in cell culture; (iii) the development and application of reverse genetics systems; and (iv) the roles of individual coronavirus proteins in replication and pathogenesis. The SARS-CoV part covers the pathogenesis of SARS, the developing animal models for infection, and the progress in vaccine development and antiviral therapies. The data gathered on the animal coronaviruses continue to be helpful in understanding SARS-CoV.

Animals↗
PubMed1995

Examination of gills from salmonids with bacterial gill disease using monoclonal antibody probes for Flavobacterium branchiophilum and Cytophaga columnaris.

Bacterial diseases of the gills of commercially reared salmonids in freshwater are common problems. They accounted for 18% of all diagnostic submissions to the Atlantic Veterinary College from commercial fish hatcheries. Definitive diagnosis is difficult because of the growth characteristics of the putative bacteria in culture. Research into the pathogenesis of these diseases has also been similarly limited. Monoclonal antibodies (MAbs) were developed to 2 globally significant gill bacterial pathogens, Flavobacterium branchiophilum, the causative agent of bacterial gill disease, and Cytophaga columnaris, the causative agent of columnaris disease of salmonids. These MAbs were then used as the basis for an indirect fluorescent antibody test to assess archived cases of gill disease in our study region. Of the cases tentatively diagnosed based on histopathology as bacterial gill disease, 76.2% tested positively with the MAbs to F. branchiophilum. Also present within 18.7% of these cases were bacteria which reacted positively to the MAbs for C. columnaris. We conclude that the MAbs produced are valuable diagnostic and research probes for common bacterial disease of the gills of salmon and trout in Atlantic Canada. This study also adds further proof that F. branchiophilum acting alone can be sufficient cause for bacterial gill disease.

Animals↗
PubMed2003

Results of milk samples submitted for microbiological examination in Wisconsin from 1994 to 2001.

The objective of this study was to examine the characteristics of milk samples submitted for microbiological examination at the Wisconsin Veterinary Diagnostic Laboratory between 1994 and 2001. Results (n = 83,650) of microbiological testing of milk samples (n = 77,172) submitted to the Wisconsin Veterinary Diagnostic Laboratory from January 1994 until June 2001 were analyzed. Submissions included milk samples obtained from cases of clinical and subclinical mastitis as well as samples obtained for mastitis surveillance programs. Results were recorded as no growth, contaminated, or identified as specific bacterial pathogens. Statistical analysis was performed to determine trends in the isolation of mastitis pathogens. The proportion of samples identified as contaminated decreased from 20.6 (1997) to 9.5% (2001). The proportion of samples coded as no growth increased from 22.6 (1994) to 49.7% (2001). Isolation of Staphylococcus aureus decreased from 17.7% (1994) of isolates to 9.7% (2001), while isolation of Streptococcus agalactiae decreased from 8.1 (1994) to 3.0% (2001). Coagulase-negative Staphylococcus spp. were isolated from 12.7 to 17.5%, environmental Streptococcus spp. were isolated from 11.6 to 20.1%, and Escherichia coli were isolated from 3.1 to 6.7% of all isolates. No growth and contaminated samples comprised almost 50% of total submissions, and it is important that producers have proper expectations when submitting milk samples. The proportion of isolates identified as Staph. aureus and Strep. agalactiae decreased, suggesting the proportion of contagious bacteria causing mastitis has decreased. Environmental and contagious pathogens demonstrated characteristic differences by season.

Animals↗
PubMed2006

Contamination of multiple-dose vials in a veterinary hospital.

Bacterial contamination of multiple-dose saline bottles and medication vials in a veterinary teaching hospital was evaluated. Bacterial contamination was identified in 16/88 (18%) containers, with no difference in contamination between the large animal clinic, small animal clinic, and ruminant ambulatory clinic. Contamination of multiple-dose containers containing substances for injection was common, and potential pathogens were present in many situations. While the clinical significance is not resolved at this point, infection control practices should address this potential source of nosocomial infection.

Animals↗
PubMed1994

Association af changes in the bacterial ecology of bovine mastitis with changes in the use of milking machines and antibacterial drugs.

The results of mastitis bacteriology made by the National Veterinary and Food Research Institute in Finland during the past 50 years (1.15 million samples) are viewed in relation to simultaneous changes in dairy cow management. Although intensive preventive measures have been applied for decades, the prevalence of bovine mastitis has not decreased. Instead, pathogenic bacteria are becoming progressively less susceptible to the available therapy. In part this must be due to the emergence of antibiotic resistant strains of bacteria, but it seems that the bacterial spectrum has also changed. The incidence of Streptococcus agalactiae (group B streptococci) has decreased, while in contrast, the incidence of staphylococci, initially Staphylococcus aureus and later coagulase-negative staphylococci, has increased. Results suggest that external pressure, like changes in animal husbandry, including antimicrobial treatments and introduction of modern milking machines, act as selective forces on the bacterial species which cause bovine mastitis.

Animals↗