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Parasitic adaptation of pathogenic fungi to mammalian hosts.

Pathogenic fungi involved in medical and veterinary mycology can be classified in three different groups according to their level of adaptation to parasitism. Only a few species belonging to dermatophytes can be considered genuine parasites as opposed to molds or fungi involved in systemic mycoses. Ecological, ethological, biochemical, and immunological factors can play a role in preadaptation or adaptation to parasitic life and are discussed.

Adaptation, Physiological↗

Assessment of genetic management at three specific-pathogen-free rhesus macaque (Macaca mulatta) colonies.

Genetic management is required to maintain genetic diversity by minimizing inbreeding and genetic subdivision in colonies of animals bred for biomedical research. Polymorphic short tandem repeat (STR) loci are useful for genetic management because they facilitate parentage assignments, genetic characterization of individuals, and estimates of baseline population genetic parameters. Using highly informative STR loci, we estimated gene diversity and F-statistics to determine the level of genetic heterogeneity and genetic structure of three specific-pathogen-free (SPF) rhesus macaque (Macaca mulatta) colonies. Effective population sizes, variance in male reproductive success, and rate of decrease in genetic variability also were estimated for two of the three colonies. We documented the overall success of genetic management in maintaining genetic diversity in captive colonies. We report that even genetically managed SPF colonies, despite maintaining high and stable levels of gene diversity (over 0.75), are prone to genetic subdivision due to different management strategies, founder effects, genetic isolation, and drift. These processes are accelerated by the high variances in male reproductive success and low adult sex ratios that are typical of captive rhesus macaque breeding groups, both of which reduce the effective population sizes of these groups.

Animal Husbandry↗

Cutaneous acariasis in the African clawed frog (Xenopus laevis).

Increased mortality was observed in a single colony of 50 Xenopus laevis. The frogs were used as oocyte donors in developmental biology studies. Necropsy findings included dermal erythema and petechiation consistent with red leg syndrome; dermal ulcerations and white, filamentous growths on the skin were consistent with Saprolegnia sp. Microscopic evaluation of the skin and fungus revealed an astigmatid mite similar to those of the genus Rhizoglyphus. The mite was also found in the water and the biological filter of the tanks housing the frogs. This mite is considered not to be a parasite of X. laevis; instead, it feeds off moss, fungi, and detritus. Subsequent evaluation of the sphagnum moss used for shipping the frogs from the supplier revealed the same mite in the moss. Our hypothesis is that the mite was introduced into the tank with the shipment of new frogs in sphagnum moss. The mites lived within the biological filter, and were only found after the growth of Saprolegnia sp. attracted the mites to the frogs. Laboratory animal care and veterinary personnel should consider non-pathogenic species of mites in the differential diagnosis of acariasis in Xenopus frogs.

Acaridae↗

Encephalitis and chorioretinitis associated with neurotropic African horsesickness virus infection in laboratory workers. Part III. Virological and serological investigations.

Four cases of encephalitis with chorioretinitis occurred in the vaccine-packing section of a veterinary research institute: 1 in 1982, 1 in 1985 and 2 in 1989. No viruses were isolated from patients and serological tests failed to reveal significant antibodies to a range of viruses incorporated in veterinary vaccines or to other likely pathogens, except for low titres of complement-fixing antibody to African horsesickness (AHS) virus in all 4 patients. In confirmatory tests, high enzyme immunoassay titres of antibody to AHS virus occurred in the 4 patients and lower titres in 5/58 other workers at the institute. The 4 patients had significant plaque reduction neutralisation antibody titres to some of the strains of virus incorporated in AHS vaccine, particularly to serotypes 1 and 6, which had undergone neuro-adaptation through serial intracerebral passage in mice and which were known to be encephalitogenic following intranasal instillation in horses, guinea pigs and dogs. It is believed that the patients may have acquired aerosol infection with AHS virus as a result of accidental breakage of freeze-dried vaccine bottles.

Adult↗

Susceptibility of rats to corneal lesions after injectable anesthesia.

Corneal injury is not a commonly reported side effect after injectable or inhalation anesthesia in rats, but a number of surgery studies at our facility resulted in a high incidence of these injuries. To explore the potential association of various anesthetic protocols with the development of corneal lesions in rats, we retrospectively evaluated clinical records and sections of eyes from 215 male and 187 female Wistar rats used in eight intravenous infusion toxicology studies. None of the studied compounds was associated with eye toxicity. For placement of jugular vein vascular access ports, rats were anesthetized with enflurane, isoflurane, ketamine-xylazine, or Hypnorm-midazolam. Histologically, corneal changes were scored from 0 to 4 in light of degree of mineralization, leukocytic infiltrates, neovascularization, fibrosis, and ulceration. Prestudy (postsurgical) ophthalmic examination findings of corneal opacities were correlated with mineralization of the anterior limiting membrane and corneal ulceration. Corneal lesions were more severe in animals anesthetized with ketamine-xylazine, and minimal changes occurred after anesthesia with either enflurane or isoflurane. The results of further analysis suggest that corneal lesions can be observed within 24 h after injectable anesthetic administration and are not reversible. The severity of corneal changes was reduced when ketamine-xylazine anesthesia was reversed with yohimbine. Compared with Sprague-Dawley and Lewis rats, Wistar, Long-Evans, and Fischer 344 rats had increased incidence and severity of corneal lesions after anesthesia with ketamine-xylazine, suggesting that these three strains are at increased risk for developing postanesthetic corneal lesions with this regimen.

Anesthesia, Intravenous↗

Pyoderma caused by Peptostreptococcus tetradius in a pup.

Pyoderma caused by Peptostreptococcus tetradius in a pup was successfully treated with cefadroxil. Although this bacterium is rarely found in veterinary medicine, it is a known pathogen in human beings and should be considered as a potential causative agent in pyodermas in which anaerobes are suspected.

Animals↗

Veterinary surgeons as vectors of Salmonella dublin.

Salmonella dublin is an important bovine pathogen, causing dysentery, abortion, and death from septicaemia. S dublin dermatitis, a little-recognised occupational hazard for veterinary surgeons, does not cause serious disability or inconvenience. During a survey of brucellosis in south-west Wales four cases of S dublin dermatitis were seen in veterinary surgeons. One surgeon was reinfected three years later. On all five occasions the veterinary surgeons had not worn or had discarded polyethylene gloves. An apparently healthy cow may serve as a latent carrier of S dublin. Thus when disease starts in a closed, protected herd reactivation of infection within the herd is usually blamed and its introduction by extraneous agents considered to be unlikely. Veterinary surgeons should be regarded as potential vectors of S dublin.

Animals↗

Microbiologic evaluation of commercial probiotics.

OBJECTIVE: To evaluate contents of commercial probiotic products marketed for veterinary or human administration. DESIGN: Microbiologic culture assay. SAMPLE POPULATION: 8 veterinary probiotics and 5 human probiotics. PROCEDURE: Quantitative bacteriologic culture was performed on all products, and isolates were identified via biochemical characteristics. Comparison of actual contents versus label claims was performed. RESULTS: Label descriptions of organisms and concentrations accurately described the actual contents of only 2 of 13 products. Five veterinary products did not specifically list their contents. Most products contained low concentrations of viable organisms. Five products did not contain 1 or more of the stated organisms, and 3 products contained additional species. Some products contained organisms with no reported probiotic effects; some of these organisms could be pathogens. CONCLUSIONS AND CLINICAL RELEVANCE: Most commercial veterinary probiotic preparations are not accurately represented by label claims. Quality control appears to be poor for commercial veterinary probiotics.

Animals↗

Whole-Genome Analysis Reveals Antimicrobial Resistance and Population Structure of Environmental and Veterinary Acinetobacter baumannii.

Acinetobacter (A.) baumannii is an important multidrug-resistant pathogen increasingly recognized across animal and environmental settings, and carbapenem-resistant A. baumannii (CRAB) is classified as a critical-priority pathogen by the World Health Organization. This study investigated the antimicrobial resistance (AMR) and genomic characteristics of 122 A. baumannii isolates comprising 72 veterinary and 50 environmental isolates collected in Andhra Pradesh, India. Antimicrobial susceptibility testing, whole-genome sequencing (WGS), resistance and virulence gene profiling, multilocus sequence typing (MLST), core-genome analysis, single nucleotide polymorphism (SNP) phylogeny, and pan-genome analysis were performed. Overall, 58.2% of isolates were multidrug-resistant (MDR), and 41.8% were extensively drug-resistant (XDR). Sequence type (ST) 52 predominated among veterinary isolates, whereas ST2 was more frequent among environmental isolates. The presence of carbapenem-resistant isolates along with the ST2 lineage enhances the similarity to clinical A. baumannii. Several intrinsic resistance genes, including blaOXA-23, armA, aph(3″)-Ib, aph(6)-Id, tet(B), mph(E), and msr(E), were more prevalent in the ST2-associated population. Virulence-associated determinants were widely conserved. Core-genome MLST (cgMLST) and core-genome SNP (cgSNP) analyses identified highly related isolates within both lineages, while pairwise SNP differences were 0-7. Pan-genome analysis identified 4204 gene clusters and distinct accessory gene patterns between ST2 and ST52. These findings indicate that resistance gene distribution was closely associated with lineage structure and support integrated genomic surveillance of A. baumannii across animal and environmental reservoirs.

Acinetobacter baumannii↗

Molecular detection of pathogen DNA in ticks (Acari: Ixodidae): a review.

Ticks play an important role in human and veterinary medicine, in particular due to their ability to transmit a wide spectrum of pathogenic micro-organisms of protozoal, rickettsial, bacterial and viral origin. Pathogens in ticks can be identified by conventional methods such as indirect immunofluorescence, isolation in cell culture or by using histological staining techniques. However, the advent of the polymerase chain reaction (PCR) has resulted in tremendous improvements in the specific and sensitive detection of pathogen DNA in ticks. In this paper, literature on DNA extraction methods, PCR protocols, primers and probes, which are in use for the successful detection and identification of pathogens in ticks, are critically reviewed. Some recommendations are also given towards the end of this review.

Anaplasma↗

History of the scientific relationships of veterinary public health.

The origin of veterinary public health (VPH), as the term is understood today, dates back to the late 1940s and early 1950s with the creation of new responsibilities and a broader range of career openings for veterinarians within some public health agencies, especially in disease intelligence aspects of the newly developing science of epidemiology. Other well-established scientific relationships of veterinary medicine to human health (e.g. food safety, pathogenic microbiology, comparative pathology) experienced renewed vigour as a result of these innovations, the latter also in connection with VPH-facilitated development and support of a new veterinary clinical practice specialty of laboratory animal biology and medicine. Through these expanded interprofessional and intersectoral communication, liaison and cooperation channels, new academic programmes arose within veterinary schools. These programmes brought a number of innovations to the world of veterinary medicine, including newly developed methodologies. A variety of new biomedical research career roles for veterinarians within both veterinary and other medically oriented institutions were identified and filled during this overall process. Also related to these developments was the identification of new roles for veterinarians in environmental science research and practice, beyond those traditionally associated with veterinary food hygiene. Proposals have since been made for significant new intersectoral functions for agriculture-based governmental Veterinary Services in connection with these new aspects of environmental science and with the aims of recent primary health care programmes within public health.

Animals↗

Vaccines against protozoal diseases of veterinary importance.

Protozoan parasites are important animal and human pathogens. At present, most of these infections are controlled by chemotherapy. In addition, vaccines are available for some of these diseases. There is, however, still an urgent need for the development of vaccines against protozoal diseases, since the current array of available vaccines is very limited. This review describes the different approaches that have been taken to develop such vaccines and discusses the difficulties that hampered vaccine development. Many of the problems are related to the complex life cycle of these parasites and the virtual lack of mass in vitro culture systems. We also give an overview of the commercial and non-commercial vaccines that do exist at present. Finally, we describe the future directions of this interesting field. New techniques and strategies include parasite cultivation methods and recombinant-DNA techniques, such as vector vaccines and DNA-vaccines. Moreover, these approaches are complemented by the development of sophisticated adjuvants; the coupling of immunoprotective molecules to entities with adjuvant activity or the use of cytokines, e.g. IL-12. Through these innovations new vaccines against protozoal diseases will become available in the near future.

Animals↗

A novel generic dipstick-based technology for rapid and precise detection of tetracycline, streptogramin and macrolide antibiotics in food samples.

Excessive use of antibiotics in veterinary medicine and as growth promoters in stock farming has been associated with the dramatically increasing prevalence of multidrug-resistant human pathogenic bacteria. European community legislators have therefore restricted the veterinary use of antibiotics and banned them as growth-promoting food additives in stock breeding (1831/2003/EC). The monitoring of such legislation requires technology for precise and straightforward on-site quantification of antibiotics in farm samples and food products without the need for extensive laboratory equipment and trained personnel. Capitalizing on bacterial transcriptional regulators (TetR, PIP, E), which are dose-dependently released from their cognate operators (tetO, PIR, ETR) upon binding of specific classes of antibiotics (tetracycline, streptogramins, macrolides) we have designed an easy-to-handle dipstick-based assay for detection of antibiotic levels in serum, meat and milk whose detection limits are up to 40-fold below licensed threshold values. The generic dipstick consists of either nitrocellulose, nylon or polyvinylidenfluorid (PVDF) membrane strips coated with streptavidin and immobilized biotinylated operator DNA, which acts as capture DNA to bind hexa-histidine (His(6))-tagged bacterial biosensors. Antibiotics present in specific samples triggered the dose-dependent release of the capture DNA-biosensor interaction, which, after dipping into two different solutions, results in a correlated conversion of a chromogenic substrate by a standard His(6)-targeted enzyme complex. This can be quantified by comparison of the dipstick to a standardized color scale or by assessing the terminal solution at 450nm. As demonstrated using serum, meat and milk samples spiked with 14 different antibiotics, the dipstick technology provided sensitive detection in a rapid assay format, and could be employed to monitor non-authorized use of antibiotics and to discover novel antibiotics.

Animals↗

Chloramphenicol 1. Hazards of use and the current regulatory environment.

Chloramphenicol is a broad-spectrum antibiotic which has enjoyed extensive use in both medical and veterinary practice. Shortly after its introduction in the late 1940s, the use of chloramphenicol was associated with the induction of an idiosyncratic form of aplastic anaemia in man. This rare and unpredictable adverse effect has since been associated not only with systemic use but with topical applications, as well as occupational exposure. Recognition of the small risk of a potentially fatal adverse reaction, together with the risk of selection of chloramphenicol-resistant pathogens, has led to restrictions on the veterinary uses of chloramphenicol. In Australia at present, the use of chloramphenicol is only permitted in small animals. Its use is specifically prohibited in food-producing animals, including horses.

Agricultural Workers' Diseases↗

Influence of febrile disease on the pharmacokinetics of veterinary drugs.

In mammals, tissue damage, inflammation or invasion of pathogenic microorganisms induces systemic changes, collectively known as the 'acute phase response'. Among the varied alterations, which together produce this response, are: fever, inappetence, inhibition of gastric function, synthesis of hepatic acute phase proteins and changes in blood flow to various organs. The intensity of these different reactions may vary depending upon the type of invading microorganism or bacterial toxin given. Considerable attention has been paid to the involvement of pyrogenic cytokines derived from reticuloendothelial cells and phagocytes in the host responses to infection. These cytokines include interleukins, interferons and tumor necrosis factor. In the present paper, attention has been focused on the role of cytokines and the effects of the acute phase response on drug disposition in disease states (including the effect of anorexia on medicated feed intake and drug bioavailability). From the disease-induced changes in pharmacokinetics, it follows that more attention should be paid to drug disposition in patients in relation to efficacy, side effects and drug residues in food products. In relation to good veterinary practice, it is also recommended that the route of administration, dosage and withdrawal time be adjusted according to the severity of the disease.

Acute-Phase Reaction↗

An outbreak of lymphadenitis associated with Stenotrophomonas (Xanthomonas) maltophilia in Omani goats.

Stenotrophomonas maltophilia is a commonly isolated organism from human clinical specimens and is gaining significance as a pathogen in immunocompromised patients and nosocomial infections. In most cases it is difficult to establish the source of human infections. In veterinary medicine, S. maltophilia is not generally considered a primary pathogen. In the present study, we report the occurrence of 16 cases of caprine abscess from which S. maltophilia was isolated in pure culture from 15 animals. In six animals, the abscesses were confined to the pre-scapular lymph nodes but in the remaining nine, the cutaneous abscesses were multiple and extended from the neck to the inguinal area. The possibility is suggested that goats in Oman, which often live in close proximity to humans, might potentially serve as a reservoir of infection.

Animals↗

The mandatory CAM testing of cells and scaffolds for tissue engineering: benefits for the three Rs of cooperation with the vaccine industry.

In cooperation with BAXTER Vaccine AG, which supplies incubated special pathogen-free chicken eggs (including a full veterinary record), a permanent hen's egg chorio-allantoic membrane test (HET-CAM) unit has been established, where angiogenesis testing, cell culture, and digital and histological analyses are performed. At the Core Unit for Biomedical Research, the location of the animal testing facility of the Medical University Vienna, cell-scaffold constructs must be evaluated in vitro and in ovo prior to eventual in vivo tissue engineering experiments. The animal testing advisory committee requires that new test proposals are first evaluated by using cell culture and HET-CAM models. Approvals for in vivo experiments are postponed and not issued prior to in vitro/in ovo evaluation. Examples are presented of protocols planned for in vivo studies on cell seeded scaffolds, which were refined after in vitro/in ovo evaluations.

Animal Testing Alternatives↗