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PubMed1997

The activity of a combination of penicillin and novobiocin against bovine mastitis pathogens: development of a disk diffusion test.

The combination of penicillin and novobiocin is currently available for the treatment of bovine mastitis, but methods are not available for susceptibility testing of the combination by veterinary diagnostic laboratories. The minimum inhibitory concentration (MIC) and disk diffusion data were determined for penicillin, novobiocin, and a combination of the two in a 1:2 ratio for 225 staphylococcal, streptococcal, and Gram-negative isolates from bovine intramammary infections. Based on the drug concentrations in milk following infusion, linear regression analysis, and error rate bounding, the interpretive zone diameters selected were < or = 16 mm for resistant isolates and > or 17 mm for susceptible isolates with a disk containing 10 U of penicillin and 30 micrograms of novobiocin. Additionally, MIC breakpoints of < or = 2 micrograms/ml of penicillin and 4 micrograms/ml of novobiocin were selected to categorize isolates as susceptible and > or = 4 micrograms/ml of penicillin and 8 micrograms/ml of novobiocin were selected to categorize isolates as resistant. The MIC and disk diffusion results, as well as studies to monitor bacterial killing by antimicrobial agents over time, indicated that the combination of penicillin and novobiocin in a 1:2 ratio was more active than were the individual drugs. Kinetics of the kill curves with the penicillin and novobiocin combination (1:2 ratio) showed that the combination was bactericidal for Staphylococcus aureus and Staphylococcus xylosus.

Animals↗
PubMed1997

Chlamydia psittaci infection in sheep: a paradigm for human reproductive tract infection.

Chlamydiae are important reproductive tract pathogens in a wide variety of animals. In humans, chronic or repeated infection of the female genital tract with Chlamydia trachomatis has been identified as a significant factor in the development of occlusive infertility or increased risk of ectopic pregnancy. The spectrum of reproductive disease recognized in sheep to be caused by Chlamydia psittaci has been primarily restricted to pregnant animals because the organism was clearly identified as a major cause of infectious abortion. However, following pregnancy failure, a chronic chlamydial infection can become established in the reproductive tracts of experimentally infected ewes. Persistent infection of the ewe's reproductive tract may eventually result in pathology, similar to that observed in women infected with C. trachomatis, thus decreasing the breeding life of affected ewes. Furthermore, ewes that experienced C. psittaci induced abortion provide a unique opportunity to study the host: parasite dynamic as it relates to persistent infection. This natural model of persistent infection may, in some ways, be superior to more contrived models in which the chlamydial isolate is not a normal reproductive pathogen of the study animal. Thus, the study of persistent chlamydial infection in sheep may be used for the benefit of both human and veterinary medicine.

Abortion, Veterinary↗
PubMed2003

Comparative sensitivity of different serological tests for seromonitoring and surveillance of Edwardsiella tarda infection of Indian major carps.

Different serological tests viz. indirect ELISA, indirect blocking ELISA, competitive ELISA and serum agglutination tests were evaluated to detect antibodies against Edwardsiella tarda in naturally infected fish sera for seromonitoring and epizootiological studies. Approximately 66.6, 62.5, 57.6 and 16.6% of the field sera samples were found to be positive by indirect ELISA, competitive ELISA, indirect blocking ELISA and serum agglutination test, respectively. The percentage of serum samples positive for E. tarda antibodies in serum agglutination, competitive ELISA and indirect blocking ELISA, when compared with indirect ELISA, were 33.3, 83.6 and 66.6%, respectively, but its use was restricted due to the requirement of several conjugates against different fish species and the difficulty in assaying large numbers of serum samples from different fish species in a limited time to enable seromonitoring of the disease prevalence. No significant difference (P<0.05) in the mean optical density value was found in indirect and competitive ELISA. Although the competitive ELISA was slightly less sensitive than the indirect ELISA, it could accommodate a large number of serum samples with one anti-rabbit conjugate, and the need for different fish conjugates as required in indirect ELISA was eliminated. As in medical and veterinary practices, these tests can now be used in aquaculture practices for seromonitoring and study of pre-exposure of Indian major carps to pathogens in enzootic areas.

Animals↗
PubMed2002

Detection of Chlamydophila (Chlamydia) abortus and Toxoplasma gondii in smears from cases of ovine and caprine abortion by the streptavidin-biotin method.

Fetal membranes from 59 cases of ovine and six of caprine abortion from a total of 52 flocks or herds were collected. Immunohistochemical examination of cotyledons fixed in formalin and embedded in paraffin wax detected Chlamydophila abortus in 44 (68%) cases. Immunocytochemical examination of smears made from the surface of fetal membranes detected the organism in 37 (57%) cases. Light microscopical examination of such smears stained by Stamp's method detected C. abortus in 26 (40%) cases. The streptavidin-biotin method described proved to have 100% specificity and 84% sensitivity in the detection of C. abortus in cotyledon smears. Sensitivity could probably be increased still further by the simultaneous examination of smears made from the cut surface of several cotyledons. In five cases Toxoplasma gondii was detected in the cotyledons by immunohistochemical examination. In three of these cases the presence of T. gondii was revealed also by immunocytological examination. In four cases, simultaneous C. abortus and T. gondii infection of the cotyledons was observed. The two pathogens and the lesions caused by them occurred in separate locations.

Abortion, Veterinary↗
PubMed2006

Development and daily management of an explicit strategy of nonuse of antimicrobial drugs in twelve Danish organic dairy herds.

Promotion of animal health and well-being at the individual animal and herd level is an important goal in organic farming. At the same time, chemical products affecting the natural balance among living organisms are prohibited in all areas of the organic farm. From an animal welfare point of view, however, no animal must suffer. Therefore, veterinary drugs are allowed under the European Union's regulations for organic farming, despite the fact that they are powerful cell toxins affecting both pathogenic and necessary bacteria, and as such in organic terminology, are regarded as "chemical" or "artificial" products. In this article, we present and discuss interviews with 12 Danish organic dairy producers who claim that minimized use or nonuse of antimicrobial drugs is an explicit goal. The dairy producers were at different levels with regard to reduced antimicrobial treatment. An explicit strategy of no antimicrobial treatments is based primarily on a long-term effort to improve herd health, and secondarily, on finding alternative treatments for diseased animals. Improved hygiene, outdoor access, use of nursing cows, and blinding of chronic mastitis quarters were the main techniques in developing a strategy of not using antimicrobial treatments in the herd by dairy producers. Producers' perception of disease changed from something unavoidable to a disturbing break in the daily rhythm that often could have been avoided. Change toward a nonantimicrobial strategy was gradual and stepwise. All dairy producers in this study desired to preserve the possibility of using antimicrobial drugs in emergencies.

Animal Husbandry↗
PubMed1980

Yersinia pseudotuberculosis infection in a group of Macaca fascicularis.

Diarrheal disease associated with abortions and stillbirths occurred in a group of 42 Macaca fascicularis. The group was composed of wild-caught adults and their colony-born offspring housed in a half-acre cage. Thirteen adult females and 1 infant male were affected. All 14 monkeys had diarrhea and all 9 pregnant females either aborted or had a stillbirth. Yersinia pseudotuberculosis was isolated from 7 animals. In addition, Y enterocolitica was isolated from 1 monkey and Shigella flexneri type IV was isolated from 5 monkeys. One adult female had a mixed infection of both Y pseudotuberculosis and S flexneri. Every pregnant monkey from which Y pseudotuberculosis was isolated aborted or had a stillbirth. Five animals died, and Y pseudotuberculosis was the only pathogen isolated from these 5 monkeys.

Abortion, Veterinary↗
PubMed1982

Ascending intrauterine infections in rhesus monkeys.

Seventeen cases of abortions and stillbirths from a harem breeding colony of rhesus monkeys (Macaca mulatta) were studied to determine the role of aerobic bacteria in their etiology. Using histopathologic criteria correlated with bacterial cultures, the cause in 11 of 17 cases was found to be ascending infection with normal vaginal flora, most commonly gram-positive cocci, especially an alpha-hemolytic streptococcus (Streptococcus viridans). Actively breeding animals in the colony were screened for Str viridans, and it was determined to be a normal vaginal inhabitant that had the potential of becoming an opportunistic pathogen.

Abortion, Veterinary↗
PubMedDate not supplied

[Inventory of the parasites of domestic animals in French Polynesia. 1st list].

After a parasitological survey in French Polynesia a first list of parasites of domestic animals has been drawn up. 42 helminthes and 23 protozoan parasites have been found in seven species of domestic animals. The pathogenicity and economic importance is discussed. The parasitic fauna is rather poor in spite of favourable environmental conditions for the evolution of parasites; therefore veterinary services must increase their surveillance to avoid any introduction of new parasite.

Animals↗
PubMed1993

Responsible use of antimicrobials in veterinary medicine: perspectives in France.

In France a survey of the use of antimicrobials in veterinary medicine was set up in connection with the Committee for the Marketing Authorization of Veterinary Medicinal Products. This survey has emphasized the importance of antimicrobials in veterinary medicine and the reality of antibiotic resistance in both man and animals. Certain epidemiological data tend to demonstrate that the use of antibiotics in animals increases the risk of antibiotic resistance in man, through selection in animals of resistant pathogenic bacteria or of a non-pathogenic resistant bacteria carrying resistance plasmids. Four proposals are put forward for the control of these different risks: reserve certain antibiotics (life-saving antibiotics) for human medicine, conform to a code of good practices for antibiotic use in animals, strengthen and connect up existing networks for the epidemiosurveillance of antibiotic resistance, provide for studies on the ecological impact of antibiotics in the registration dossiers for veterinary medicinal products. These evolutive measures, based on scientific progress in microbiology, epidemiology and clinical studies should respond satisfactorily to the expectations of all concerned.

Animals↗
PubMed2005

Electrospray[+] tandem quadrupole mass spectrometry in the elucidation of ergot alkaloids chromatographed by HPLC: screening of grass or forage samples for novel toxic compounds.

Ergot alkaloids are mycotoxins generated by grass and grain pathogens such as Claviceps, for example. Ergot alkaloid-poisoning syndromes, such as tall fescue toxicosis from endophyte-infected tall fescue grass, are important veterinary problems for cattle, horses, sheep, pigs and chickens, with consequent impact on food, meat and dairy industries. Damage to livestock is of the order of a billion dollars a year in the United States alone. HPLC with UV and fluorescence detection are the predominant means of ergot alkaloid determination, with focus on quantitation of the marker compound ergovaline, although ELISA methods are undergoing investigation. These techniques are excellent for rapid detection, but of poor specificity in defining new or poorly characterized ergot alkaloids and related compounds. This paper demonstrates the facility of using electrospray(+) mass spectrometry with multiple reaction monitoring (MRM) detection during chromatographic examination of ergot alkaloid standards of lysergic acid, lysergol, ergonovine, ergovaline, ergotamine, ergocornine, ergocryptine and ergocrystine by HPLC. Ergoline-8 position epimers could be separated on the gradient HPLC system for ergocornine, ergocrystine and ergonovine and appeared as shoulders for ergotamine and ergovaline; epimers generally showed different patterns of relative intensity for specific MRM transitions. There was reasonable correspondence between retention of standards on the 2-mm ESI(+)MS phenyl-hexyl-based reverse phase column and those on the 4-mm C18-based column. Since up to 10% of clinical cases involving toxin exposure display unidentified chromatographic peaks, 11 samples of feed components associated with such cases were studied with developed MRM methods to attempt elucidation of crucial components if possible. Ergotamine appeared in all, ergovaline appeared in five and ergocornine appeared in six; ergonovine, ergocryptine, ergocrystine and lysergol also appeared in several. In addition, molecular weights of compounds newly revealed by mass spectrometry suggested ergosine, ergostine and ergoptine in four samples, for which standards were not available. Dehydrated products of ergotamine, ergocrystine and ergocornine were discovered, along with dihydrogenated ergocrystine and ergocryptine in seven of the samples, and the issue was raised as to whether dehydration was strictly an instrument-derived artifact. Finally, five of the samples, along with fescue seed standard, evidenced one or more of 14 new ergot alkaloids ranging in size from 381 to 611 molecular weight and with key mass spectral characteristics of ergot alkaloids, specifically the pair of peaks m/z 223 and 208, corresponding to the ergoline ring system and its demethylated variant, respectively. It is anticipated that findings such as these will provide impetus to future development of analytical methodology for these heretofore relatively rare ergot alkaloid species.

Animal Feed↗
PubMed2005

Lower respiratory tract infection due to Capnocytophaga cynodegmi in a cat with pulmonary carcinoma.

A 10-year-old male castrated domestic shorthair cat was evaluated for coughing and lethargy. Thoracic radiographs revealed a soft tissue lung mass and diffuse peribronchial infiltrates. Bronchoscopy was performed and Capnocytophaga cynodegmi was cultured from bilateral bronchoalveolar lavage samples. Clinical signs and bacterial colonization resolved following treatment with enrofloxacin. A lung lobectomy was performed to remove the lung mass, which was diagnosed as pulmonary carcinoma. C cynodegmi is most frequently isolated from localized wound and corneal infections in humans. Specialized growth characteristics of C cynodegmi may result in low sensitivity for bacterial culture. To the authors' knowledge, this case represents the first report of C cynodegmi infection in a veterinary patient and only the second case in human or veterinary medicine where the organism has been isolated from a bronchoalveolar lavage sample. Based on this report, Capnocytophaga species should be considered as potential opportunistic pathogens.

Animals↗
PubMed2004

Resistance in the environment.

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Anti-Bacterial Agents↗
PubMed2002

Development of an antibiotic resistance monitoring system in Hungary.

Because of the rapid development and spread of antimicrobial resistance it is important that a system be established to monitor antimicrobial resistance in pathogenic zoonotic and commensal bacteria of animal origin. Susceptibility testing of bacteria from carcasses and different samples of animal origin has been carried out in veterinary institutes for a long time but by an inconsistent methodology. The disc diffusion method proposed by the National Committee for Clinical Laboratory Standards (NCCLS) was introduced in all institutes in 1997. In order to obtain a coherent view of the antimicrobial resistance of bacteria a computer system was consulted, consisting of a central computer to store all data and some local computers attached to it through the network. At these local measuring stations computers are connected to a video camera, which displays the picture of Petri dishes on the monitor, and inhibition zone diameters of bacteria can be drawn with the mouse by the inspector. The software measures the diameters, evaluates whether or not the bacteria are sensitive, and stores the data. The evaluation is based upon the data of the NCCLS. The central computer can be connected to as many local computers with measuring stations as we wish, so it is suitable for an integrated system for monitoring trends in antimicrobial resistance of bacteria from animals, food and humans, facilitating comparison of the occurrence of resistance for each circumstance in the chain. It depends on the examiners which antibiotics they want to examine. Thirty-two different antibiotic panels were compiled, taking into consideration the active ingredients of medicinal products permitted for veterinary use in Hungary, natural resistance and cross-resistance, the mechanism of resistance and the animal species, i.e. which drugs were recommended for treatment in the given animal species, and the recommendations of the OIE Expert Group on Antimicrobial Resistance. The members of the panels can be changed any time, even during the measuring process. In addition to the inhibition zone diameters of bacteria the database also includes information about bacterial and animal species, the age of animals and the sample or organ where the bacteria are from. Since January 2001 the antibiotic susceptibility of E. coli, Salmonella, Campylobacter and Enterococcus strains isolated from the colons of slaughter cows, pigs and broiler chickens has also been examined. Each of the 19 counties of Hungary submits to the laboratory three tied colon samples from a herd of the above-mentioned animals every month.

Animals↗
PubMed1997

Attenuation and vaccine potential of aroQ mutants of Corynebacterium pseudotuberculosis.

Corynebacterium pseudotuberculosis, a gram-positive intracellular bacterial pathogen, is the etiological agent of the disease caseous lymphadenitis (CLA) in both sheep and goats. Attenuated mutants of C. pseudotuberculosis have the potential to act as novel live veterinary vaccine vectors. We have cloned and sequenced the aroB and aroQ genes from C. pseudotuberculosis C231. By allelic exchange, aroQ mutants of both C231, designated CS100, and a pld mutant strain TB521, designated CS200, were constructed. Infection of BALB/c mice indicated that introduction of the aroQ mutation into C231 and TB521 attenuated both strains. In sublethally infected BALB/c mice, both CS100 and CS200 were cleared from spleens and livers by day 8 postinfection. The in vivo persistence of these strains was increased when the intact aroQ gene was supplied on a plasmid in trans. Mice infected with TB521 harbored bacteria in organs at least till day 8 postinfection without ill effect. When used as a vaccine, only the maximum tolerated dose of CS100 had the capacity to protect mice from homologous challenge. Vaccination with TB521 also elicited protective immunity, and this was associated with gamma interferon (IFN-gamma) production from splenocytes stimulated 7 days postvaccination. The role of IFN-gamma in controlling primary infections with C. pseudotuberculosis was examined in mice deficient for the IFN-gamma receptor (IFN-gammaR(-/-) mice). IFN-gammaR(-/-) mice cleared an infection with CS100 but were significantly more susceptible than control littermates to infection with C231 or TB521. These studies support an important role for IFN-gamma in control of primary C. pseudotuberculosis infections and indicate that aroQ mutants remain attenuated even in immunocompromised animals. This is the first report of an aroQ mutant of a bacterial pathogen, and the results may have implications for the construction of aromatic mutants of Mycobacterium tuberculosis for use as vaccines.

Amino Acid Sequence↗
PubMed2000

Identification of Pasteurella multocida virulence genes in a septicemic mouse model using signature-tagged mutagenesis.

P. multocida is the causative agent of several economically significant veterinary diseases occurring in numerous species worldwide. Signature-tagged mutagenesis (STM) is a powerful genetic technique used to simultaneously screen multiple transposon mutants of a pathogen for their inability to survive in vivo. We have designed an STM system based on a mini-Tn10 transposon, chemiluminescent detection and semi-quantitative analysis and have identified transposon insertions into genes of Pasteurella multocida that attenuate virulence in a septicemic mouse model. A bank of 96 transposons containing strongly-hybridizing tags was used to create 19 pools of P. multocida transposon mutants containing approximately 70-90 mutants/pool. A total of 62 mutants were attenuated when checked individually, and 25 unique single transposon insertion mutations were identified from this group. The sequence of the disrupted ORF for each attenuated mutant was determined by either cloning or PCR-amplifying and sequencing the flanking regions. The attenuated mutants contained transposon insertions in genes encoding biosynthetic enzymes, virulence factors, regulatory components and unknown functions. This study should contribute to an understanding of the pathogenic mechanisms by which P. multocida and other pathogens in the Pasteurellaceae family cause disease and identify novel live vaccine candidates and new potential antibiotic targets.

Animals↗
PubMed2006

Genotypic diversity and antimicrobial resistance in asymptomatic Salmonella enterica serotype Typhimurium DT104.

The recent emergence of multidrug-resistant Salmonella enterica subspecies enterica serotype Typhimurium phage-type DT104 represents a challenge to health workers from both human and veterinary medicine. In an effort to develop effective control strategies, it is vital to characterize accurately the extent of genetic and phenotypic variation present in the pathogen population. While previous studies have focused on disease-associated populations, we report the genetic diversity and the diversity in antimicrobial resistance associated with asymptomatic Salmonella Typhimurium DT104 isolates found in pigs. Using pulsed-field gel electrophoresis (XbaI and SpeI), we identified 62 different genotypes associated to 13 different antimicrobial resistant phenotypes among 80 asymptomatic DT104 isolates collected from the Canadian swine industry. When rarefaction curves of a subsample the asymptomatic isolates were compared to that of disease-associated isolates from a similar spatial and temporal scale, we identified significantly more genotypes among the asymptomatic populations with 27 PFGE patterns against 23.0+/-1.4 (95% confidence intervals) in the latter. Also, using Simpson's diversity index, we observed considerably higher genetic and phenotypic diversity in the asymptomatic isolates within herds and detected possible patterns of periodic selection within the disease-associated population. We thus concluded that an important aspect of Salmonella population structure and ecology is overlooked in investigations of disease-associated isolates.

Animals↗
PubMed1999

Diagnostic sampling of amphibians.

This article discusses basic restraint, sample collection, and guidelines for interpretation. Common pathogens are mentioned throughout the article. Staff safety and involvement are emphasized. Clinicians are encouraged to record all results and contribute to this growing area of veterinary medicine.

Amphibians↗