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PubMed2006

Characteristics of methicillin resistant Staphylococcus aureus isolated from chicken meat and hospitalized dogs in Korea and their epidemiological relatedness.

Methicillin resistant Staphylococcus aureus (MRSA) is one of the most important pathogens in human and veterinary hospitals. The isolation of MRSA from animals and foodstuffs has been reported with an increased incidence. However, methicillin (oxacillin) is not used in animal husbandry or in animal hospitals in Korea. In this study, three pre-MRSA and one silent mecA-carrying methicillin susceptible S. aureus (smMSSA) were isolated from retail chicken meat, and three MRSA were isolated from hospitalized dogs in Korea. The three pre-MRSA isolates were determined to have a staphylococcal cassette chromosome mec (SCCmec) type III, and the smMSSA isolate was not classified. The animal hospital isolates were found to contain SCCmec type II. Seven and 15 S. aureus isolated from hospitalized humans and bovine milk, respectively, were also examined in this study in order to determine the epidemiological origins of MRSA. Multilocus sequencing typing (MLST) revealed that the chicken meat and bovine milk isolates were closely related to the animal hospital isolates. The SCCmec characteristics and MLST analyses indicated the possibility of the human to animal transmission of MRSA. These results highlight the importance of identifying MRSA carriers as well as intercepting MRSA transmission because MRSA is becoming increasingly widespread without any plausible relationship with the use of methicillin (oxacillin).

Animals↗
PubMed2000

The molecular biology of pasteurella multocida.

Pasteurella multocida is an important veterinary and opportunistic human pathogen. The species is diverse and complex with respect to antigenic variation, host predeliction and pathogenesis. Certain serological types are the aetiologic agents of severe pasteurellosis, such as fowl cholera in domestic and wild birds, bovine haemorrhagic septicaemia and porcine atrophic rhinitis. The recent application of molecular methods such as the polymerase chain reaction, restriction endonuclease analysis, ribotyping, pulsed-field gel electrophoresis, gene cloning, characterisation and recombinant protein expression, mutagenesis, plasmid and bacteriophage analysis and genomic mapping, have greatly increased our understanding of P. multocida and has provided researchers with a number of molecular tools to study pathogenesis and epidemiology at a molecular level.

Animals↗
PubMed2005

Evidence of tick-borne organisms in mule deer (Odocoileus hemionus) from the western United States.

Free-ranging mule deer (MD; Odocoileus hemionus) from Arizona and California were tested for evidence of infection with several tick-borne pathogens, including species of Ehrlichia, Anaplasma, Babesia, and Borrelia. Of 125 mule deer tested from Arizona, 29 (23%) and 11 (9%) had antibodies reactive to E. chaffeensis and A. phagocytophilum by indirect immunofluorescent antibody testing, respectively; none of the six MD tested from California were seropositive. Using a commercial competitive ELISA kit, antibodies reactive to Anaplasma spp. were detected in 19 (15%) MD from Arizona and four of six (67%) MD from California. Polymerase chain reaction (PCR) testing for tick-borne pathogens was conducted on blood samples from 29 MD from Arizona and 11 MD from California. Twenty-two of 29 (75.9%) MD from Arizona had PCR evidence of infection with at least one tick-borne pathogen. We detected an Anaplasma sp. in 19 of 29 (65.5%) MD and a Babesia sp. in 10 of 29 (34%) MD. Sequencing of these amplicons indicated that the Anaplasma sp. was the same that had previously been detected in MD from California and the Babesia sp. was similar to one previously detected in a reindeer (Rangifer tarandus tarandus) from California. All of the California MD had evidence of infection with a tick-borne pathogen. Two different species of Anaplasma spp. were detected in MD from California, eight of of 11 MD were infected with an Anaplasma sp., and three of 11 MD were infected with A. ovis. This is the first report of a mule deer naturally infected with A. ovis. Ten of 11 MD from California were infected with a Babesia-like organism previously associated with human disease, and a single MD was PCR positive for Borrelia coriaceae, which has been associated with epizootic bovine abortion. Together, these data suggest that MD in northern Arizona and eastern California are exposed to several pathogens of human and veterinary importance.

Anaplasma phagocytophilum↗
PubMedDate not supplied

Investigation of H7N2 avian influenza outbreaks in two broiler breeder flocks in Pennsylvania, 2001-02.

An avian influenza (AI) outbreak occurred in meat-type chickens in central Pennsylvania from December 2001 to January 2002. Two broiler breeder flocks were initially infected almost simultaneously in early December. Avian influenza virus (AIV), H7N2 subtype, was isolated from the two premises in our laboratory. The H7N2 isolates were characterized as a low pathogenic strain at the National Veterinary Services Laboratories based on molecular sequencing of the virus hemagglutinin cleavage site and virus challenge studies in specific-pathogen-free leghorn chickens. However, clinical observations and pathologic findings indicated that this H7N2 virus appeared to be significantly pathogenic in meat-type chickens under field conditions. Follow-up investigation indicated that this H7N2 virus spread rapidly within each flock. Within 7 days of the recognized start of the outbreak, over 90% seroconversion was observed in the birds by the hemagglutination inhibition test. A diagnosis of AI was made within 24 hr of bird submission during this outbreak using a combination of virus detection by a same-day dot-enzyme-linked immunosorbent assay and virus isolation in embryonating chicken eggs. Follow-up investigation revealed that heavy virus shedding (90%-100% of birds shedding AIV) occurred between 4 and 7 days after disease onset, and a few birds (15%) continued to shed virus at 13 days post-disease onset, as detected by virus isolation on tracheal and cloacal swabs. AIV was not detected in or on eggs laid by the breeders during the testing phase of the outbreak. The two flocks were depopulated at 14 days after disease onset, and AIV was not detected on the two premises 23 days after depopulation.

Animals↗
PubMed1999

Differentiation of hard-to-type bacterial strains by RNA mismatch cleavage.

Many bacteria are difficult to subtype due to high genetic relatedness. In the cases of pathogens of medical or veterinary importance, subtyping is an essential tool of epidemiologists. This report describes a method for molecular subtyping based on the detection of point mutations without DNA sequencing or specialized equipment. The method, known as RNA mismatch cleavage, hybridizes RNA transcripts derived from PCR-amplified DNA, with a control RNA transcript followed by RNase cleavage at point-mutation mismatches. The method was successful in distinguishing all six Brucella species tested and was able to distinguish 11 of the 18 biovars studied. Of the remaining seven biovars (all of which are Brucella abortus strains), three subgroups were identified. The method should be applicable to all hard-to-subtype bacterial strains.

Bacterial Typing Techniques↗
PubMed1999

Aedes albopictus in the United States: current status and prospects for further spread.

Since its initial discovery in the continental USA in 1985, the Asian tiger mosquito, Aedes albopictus, has spread rapidly throughout the eastern part of the country. Infestations of Ae. albopictus now have been reported to the Centers for Disease Control and Prevention from 919 counties in 26 states in the continental USA. This species is believed to be established in 911 counties in 25 states. Single individuals or small numbers of Ae. albopictus have been intercepted and destroyed in 3 additional states (California, New Mexico, and Washington). Five states (Florida, Georgia, North Carolina, South Carolina, and Tennessee) have reported infestations in all of their counties. The current reported distribution of Ae. albopictus was compared to ecoregions of the U.S. Environmental Protection Agency's Level III ecoregion map. Several areas are identified as probable candidates for extension of this species based on ecological characteristics of the landscape. In other areas, populations seem likely to become locally abundant in urban or suburban oases that do not reflect the native ecology of the region. The ability of Ae. albopictus to transmit a variety of pathogens of human and veterinary public health importance, coupled with its ability to colonize diverse ecological settings makes continued surveillance an important issue.

Aedes↗
PubMed2006

Development of a toxA gene knock-out mutant of Pasteurella multocida and evaluation of its protective effects.

Pasteurella multocida is an important veterinary and opportunistic human pathogen. In particular, strains of P. multocida serogroup D cause progressive atrophic rhinitis, and produce a potent, intracellular, mitogenic toxin known as P. multocida toxin (PMT), which is encoded by the toxA gene. To further investigate the toxigenic and pathogenic effects of PMT, a toxA-deleted mutant was developed by homologous gene recombination. When administrated to mice, the toxigenicity of the toxA mutant P. multocida was drastically reduced, suggesting that the PMT contributes the major part of the toxigenicity of P. multocida. Similar results were obtained in a subsequent experiment, while high mortalities were observed when toxA(+) P. multocida bacterial culture or culture lysate were administrated. Mice immunized with toxA(-) P. multocida were not protected (none survived) following challenge with toxA(+) P. multocida or bacterial culture lysate (toxin). These results suggest that the toxigenicity of P. multocida is mainly derived from PMT.

Animals↗
PubMed2005

Low-level detection of viral pathogens by a surface-enhanced Raman scattering based immunoassay.

The need for rapid, highly sensitive, and versatile diagnostic tests for viral pathogens spans from human and veterinary medicine to bioterrorism prevention. As an approach to meet these demands, a diagnostic test employing monoclonal antibodies (mAbs) for the selective extraction of viral pathogens from a sample in a chip-scale, sandwich immunoassay format has been developed using surface-enhanced Raman scattering (SERS) as a readout method. The strengths of SERS-based detection include its inherent high sensitivity and facility for multiplexing. The capability of this approach is demonstrated by the capture of feline calicivirus (FCV) from cell culture media that is exposed to a gold substrate modified with a covalently immobilized layer of anti-FCV mAbs. The surface-bound FCVs are subsequently coupled with an extrinsic Raman label (ERL) for identification and quantification. The ERLs consist of 60-nm gold nanoparticles coated first with a layer of Raman reporter molecules and then a layer of mAbs. The Raman reporter molecule is strategically designed to chemisorb as a thiolate adlayer on the gold nanoparticle, to provide a strong and unique spectral signature, and to covalently link a layer of mAbs to the gold nanoparticle. The last feature provides a means to selectively tag substrate-bound FCV. This paper describes the development of the assay, which uses cell culture media as a sample matrix and has a linear dynamic range of 1 x 10(6)-2.5 x 10(8) viruses/mL and a limit of detection of 1 x 10(6) viruses/mL. These results reflect the findings from a detailed series of investigations on the effects of several experimental parameters (e.g., salt concentration, ERL binding buffer, and sample agitation), all of which were aimed at minimizing nonspecific binding and maximizing FCV binding efficiency. The performance of the assay is correlated with the number of captured FCV, determined by atomic force microscopy, as a means of method validation.

Buffers↗
PubMed2005

Human granulocytic anaplasmosis and Anaplasma phagocytophilum.

Human granulocytic anaplasmosis is a tickborne rickettsial infection of neutrophils caused by Anaplasma phagocytophilum. The human disease was first identified in 1990, although the pathogen was defined as a veterinary agent in 1932. Since 1990, US cases have markedly increased, and infections are now recognized in Europe. A high international seroprevalence suggests infection is widespread but unrecognized. The niche for A. phagocytophilum, the neutrophil, indicates that the pathogen has unique adaptations and pathogenetic mechanisms. Intensive study has demonstrated interactions with host-cell signal transduction and possibly eukaryotic transcription. This interaction leads to permutations of neutrophil function and could permit immunopathologic changes, severe disease, and opportunistic infections. More study is needed to define the immunology and pathogenetic mechanisms and to understand why severe disease develops in some persons and why some animals become long-term permissive reservoir hosts.

Anaplasma phagocytophilum↗
PubMed1990

[Veterinary drugs and good veterinary practice].

The following definition of 'Good Veterinary Practice' in relation to pharmacotherapy is presented: 'The selective use (in accordance with directions for users) of veterinary drugs registered by the authorities in those indications in which they are permitted when the diagnosis has been established and in which the problem of residues in foods of animal origin on using these agents has been taken into account'. The following recommendations are made with reference to 'Good Principles of Veterinary Practice': (1) Current training and supplementary training in the fields of pharmacy and pharmacotherapy should be adjusted in the light of recent developments in society. (2) The development of simple, rapid and reliable tests for the detection of pathogenic agents and residues of veterinary drugs should stimulated. (3) The development of conveniently arranged and standardised data sheets in generally comprehensible terms should receive sufficient attention. (4) Quality control, particularly of generic products, deserves adequate attention. (5) The institution of a Side-Effects of Veterinary Drugs Office, in which the authorities, manufacturers and other parties concerned co-operate closely, is eminently desirable. (6) The establishment of a Veterinary Drugs Committee in which all interested parties are represented, is of the utmost importance within the framework of recommendations on policy to the authorities.

Animals↗
PubMed2001

Population biology of multihost pathogens.

The majority of pathogens, including many of medical and veterinary importance, can infect more than one species of host. Population biology has yet to explain why perceived evolutionary advantages of pathogen specialization are, in practice, outweighed by those of generalization. Factors that predispose pathogens to generalism include high levels of genetic diversity and abundant opportunities for cross-species transmission, and the taxonomic distributions of generalists and specialists appear to reflect these factors. Generalism also has consequences for the evolution of virulence and for pathogen epidemiology, making both much less predictable. The evolutionary advantages and disadvantages of generalism are so finely balanced that even closely related pathogens can have very different host range sizes.

Animals↗
PubMed1993

Bacterial resistance monitoring in animals: the French national experiences of surveillance schemes.

In France, bacterial resistance monitoring in animals is based on a national network of local veterinary laboratories organised by CNEVA following two methodologies. As part of the epidemiological surveillance of Salmonella, LCHA in Paris has been receiving since 1969 most of the strains isolated from animals (sick and healthy carriers) but also from food, feed and environment. For many years sensitivity tests have been carried out on strains collected: animal ones, mainly from cattle and poultry, show multiple antibiotic resistance more frequently than those of food or environment. Taking into account of the importance of antibiotic resistance in E. coli and Salmonella isolated from sick calves, LPB in Lyon has set up since 1982 a national system for collecting and analysing antimicrobial sensitivity patterns of main bovine pathogens determined routinely by local veterinary laboratories. In order to ensure comparability and coherency of data from different laboratories it was necessary to introduce standard techniques and reference reagents. The major bacterial species being tested concern enteric, respiratory and mammary flora. This network is useful to detect new resistances. The resistant strains collected are useful to carry out studies on the mechanism of resistance and the efficacy of new molecules. Results constitute the basis of a real predictive epidemiology necessary to lay down a policy for rational use of antimicrobials in animal breeding and veterinary medicine.

Age Factors↗
PubMed1988

Cryptosporidiosis in veterinary students.

Cryptosporidiosis was diagnosed in 10 veterinary students. Exposure to the pathogen was associated with direct contact with infected calves and contact with contaminated materials. Affected students had fever (50%), headache (50%), nausea (70%), diarrhea (80%), and vomiting (40%). Clinical signs persisted for 30 hours to 16 days after the onset of clinical signs of disease. Although one student required hospitalization, the remaining students recovered without treatment.

Animals↗
PubMed1999

Observed differences in virulence-associated phenotypes between a human clinical isolate and a veterinary isolate of Mycobacterium avium.

Mycobacterium avium, the most common opportunistic pathogen in patients with AIDS, is frequently isolated from a variety of environmental sources, but rarely can these environmental isolates be epidemiologically linked with isolates known to cause human disease. Using a number of in vitro tissue culture assays, we found significant pathogenic differences between a serotype 4 human clinical M. avium isolate and a serotype 2 veterinary isolate. Cell association of the patient strain with a human intestinal cell line was 1.7 times that of the veterinary strain. Growth of this clinical strain in human peripheral blood mononuclear cell-derived macrophages increased from 12-fold higher than that of the veterinary isolate after 2 days to 200-fold higher after 4 days. By the conclusion of each experiment, lysis of all examined host cell types and accumulation of cell debris were observed in infections with the human isolate, but monolayers remained relatively intact in the presence of the animal isolate. The two strains also differed in the ability to stimulate human immunodeficiency virus replication in coinfected host cells, with p24 antigen levels after 6 days threefold higher in the cells coinfected with the clinical strain than in those infected with the veterinary strain. If the genetic differences responsible for the phenotypes observed in these assays can be identified and characterized, it may be possible to determine which M. avium strains in the environment are potential human pathogens.

Animals↗
PubMed1983

[Pharmacological, toxicological, microbiological and pathohistological studies of gentamycin complex II].

The acute toxicity was determined of the gentamycin complex II (GMC-II) for albino mice, containing gentamycin components in a varying ratio. The LD50 at intraperitoneal application was 347.7 mg/kg body mass, while at oral application it was 5,180 mg (4933 divided by 5439) mg/kg body mass. Histopathologically, (mice killed with high doses of GMC-II, given orally) there were diffuse hyperemia of the liver, parenchymal degeneration of the kidney tubuli epithelium, and edema and emphysema of the lungs. The local tolerance with regard to a 5 per cent solution of GMC-II applied to the conjunctiva of rabbits at twofold treatment proved to be good. Determined were the minimal inhibiting concentrations of 14 species of pathogenic organisms of great interest to veterinary medicine (Bacillus anthracis, Erysipelothrix insidiosa, Salmonella gallinarum, Escherichia coli, etc.). The antibacterial spectrum of GMC-II was similar to that of gentamycin sulphate, however, for some pathogenic organisms higher concentrations were required to produce and antimicrobial effect. Similarly to gentamycin sulphate GMC-II had limited absorbtion in the alimentary canal of clinically normal newborn pigs and of birds. At a high rate (0.05 g/kg body mass) GMC-II applied via the crop to birds it was found to maintain the lowest therapeutic concentration in the serum. At the rate of 0.012 (equal to 12000 IU) per kg of body mass for 24 hours GMC-II produced therapeutic effects in newborn pigs affected with colibacteriosis.

Animals↗
PubMed1990

Detection of DNA from infectious laryngotracheitis virus by colourimetric analyses of polymerase chain reactions.

A combination of the polymerase chain reaction and a novel ELISA-type DNA colourimetric assay (developed from studies with a retrovirus from man) was used in a preliminary study to detect DNA from avian infectious laryngotracheitis virus. The method is sensitive, specific and easy to perform. Since it can be readily adapted for the detection of DNA from other sources it could be useful for the identification of a variety of pathogens from other species of veterinary importance.

Animals↗
PubMed1993

Cellular biology of Cryptosporidium parvum.

With the emergence of Cryptosporidium parvum as a major pathogen encountered in human and veterinary clinical practice, a need for increased knowledge of the cellular- and immuno-biology of this Apicomplexan parasite has developed. Initial work has used paradigms taken from other Apicomplexans, especially Plasmodium, Toxoplasma and Eimeria, as a starting point. In this article, Carolyn Petersen discusses the observation that in these organisms, molecular targets of antibodies (which have protective value, in vivo, against disease) have frequently been located in the apical complex or on the surface of the invasive stages of the parasite and appear to mediate biologically crucial processes including motility, attachment to the host cell, modification of the host membrane, and entry into the host cell. Molecular-biology approaches to the study of enzymes and of structural proteins which mediate motility are also considered. Invasion mechanisms, biochemical pathways and motility may involve molecules that will prove susceptible to immunotherapeutic or chemotherapeutic interruption of cryptosporidiosis.

Journal Article↗
PubMed2001

Cysteine protease isoforms from Trypanosoma cruzi, cruzipain 2 and cruzain, present different substrate preference and susceptibility to inhibitors.

Cysteine-proteinases from parasitic protozoa have been recently characterized as factors of virulence and pathogenicity in several human and veterinary diseases. In Chagas' disease, the chronic infection caused by Trypanosoma cruzi, structure-functional studies on cysteine proteases were thus far limited to the parasite's major isoform, a cathepsin L-like lysosomal protease designated as cruzipain, cruzain or GP57/51. Encoded by a large gene family, cruzipain is efficiently targeted by synthetic inhibitors, which prevent parasite intracellular growth and differentiation. We have previously demonstrated that the multicopy cruzipain gene family includes polymorphic sequences, which could encode functionally different isoforms. We report here a comparative kinetic study between cruzain, the archetype of the cruzipain family, and an isoform, termed cruzipain 2, which is expressed preferentially by the mammalian stages of T. cruzi. Heterologous expression of the catalytic domain of cruzipain 2 in Saccharomyces cerevisae yielded an enzyme that differs markedly from cruzain with respect to pH stability, substrate specificity and sensitivity to inhibition by natural and synthetic inhibitors of cysteine proteases. We suggest that the structural-functional diversification imparted by genetic polymorphism of cruzipain genes may have contributed to T. cruzi adaptation to vertebrate hosts.

Amino Acid Sequence↗