Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi.
Abstract: Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described as properties of plasmids of Rhodococcus species other than R. equi. Tests included cadmium resistance, Congo red binding, resistance to 26 antibiotics, conventional clinical microbiological tests, utilization of 95 different carbon sources, enzymatic activities in API ZYM, fluorogenic assays for exo- and endopeptidase, glycosidase activities, and testosterone degradation. Apart from production of VapA by foal isolates, no phenotypic property was identified in the plasmid-positive isolates. Phenotypic characteristics of R. equi that have not been described before, and might be useful in identification were: metabolism of N-acetyl-beta D-glucopyranoside, alpha- and beta-hydroxybutyric, alpha-ketobutyric and N-acetyl-glutamic acids, of methylpyruvate, heptanoate, nonanoate and stearate esters; exopeptidase activity against alanine-alanine-tyrosine, alanine-phenylalanine-lysine, glycine-arginine, lysine-alanine, and valine-glycine-alanine; endopeptidase activity against arginine and methionine; and hydrolysis of bis-phosphate ester.
Publication Date: 1996-01-01 PubMed ID: 8825990PubMed Central: PMC1263796
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research attempted to find characteristics other than the virulence-associated protein (VapA) potentially linked to the virulence plasmid of Rhodococcus equi, a pathogen causing pneumonia in foals, through extensive examination of phenotypic properties. However, no such property could be identified among the plasmid-positive isolates, apart from the production of VapA.
Objective and Strategy
- The study aimed to find phenotypic markers that might be encoded by the virulence plasmid of Rhodococcus equi, other than the virulence-associated protein (VapA).
- This was an ambitious task that assessed 239 phenotypic properties of four R. equi isolates from pneumonic foals, a porcine isolate, and their plasmid cured derivatives.
- The researchers chose tests that included those that had previously given variable results for R. equi since such variability could be plasmid-related. The traits that have been described as properties of plasmids of Rhodococcus species other than R. equi were also included.
Methodology
- The study included a wide array of tests such as cadmium resistance, Congo red binding, antibiotic resistance, clinical microbiologic tests, the utilization of distinct carbon sources, enzymatic activities, peptidase, glycosidase activities, and testosterone degradation.
- The testing was conducted under standardized conditions with the organisms grown at 37 degrees celsius, the human body’s average internal temperature.
Findings
- No phenotypic property connected with the virulence plasmid was identified in the plasmid-positive isolates, except for the production of VapA.
- However, the researchers identified previously undescribed phenotypic characteristics of R. equi that could aid in its identification. These comprised the metabolism of various compounds and the activity of certain enzymes.
Impact
- This research deepens our understanding of Rhodococcus equi’s complexity and prepares the ground for more accurate identification and subsequent treatment strategies.
- The discovered phenotypic characteristics, although not linked with the virulence plasmid, may assist in distinguishing strains and potentially provide valuable markers for diagnosis.
- However, the absence of phenotypic markers other than VapA suggests that the virulence plasmid’s role is primarily in promoting virulence, narrowing down the focus of future investigations and interventions.
Cite This Article
APA
De La Peña-Moctezuma A, Prescott JF, Goodfellow M.
(1996).
Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi.
Can J Vet Res, 60(1), 29-33.
Publication
Researcher Affiliations
- Department of Veterinary Microbiology and Immunology, University of Guelph, Ontario.
MeSH Terms
- Amino Acids / metabolism
- Animals
- Anti-Bacterial Agents / pharmacology
- Cadmium / pharmacology
- Chloramphenicol / pharmacology
- Congo Red / metabolism
- Drug Resistance, Microbial
- Horses / microbiology
- Hydrolysis
- Hydroxybutyrates / metabolism
- Phenotype
- Plasmids / genetics
- Rhodococcus equi / drug effects
- Rhodococcus equi / genetics
- Rhodococcus equi / metabolism
- Swine
References
This article includes 20 references
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Citations
This article has been cited 7 times.- Sangal V, Goodfellow M, Jones AL, Schwalbe EC, Blom J, Hoskisson PA, Sutcliffe IC. Next-generation systematics: An innovative approach to resolve the structure of complex prokaryotic taxa. Sci Rep 2016 Dec 7;6:38392.
- Bidaud P, Hébert L, Barbey C, Appourchaux AC, Torelli R, Sanguinetti M, Laugier C, Petry S. Rhodococcus equi's extreme resistance to hydrogen peroxide is mainly conferred by one of its four catalase genes. PLoS One 2012;7(8):e42396.
- Lührmann A, Mauder N, Sydor T, Fernandez-Mora E, Schulze-Luehrmann J, Takai S, Haas A. Necrotic death of Rhodococcus equi-infected macrophages is regulated by virulence-associated plasmids. Infect Immun 2004 Feb;72(2):853-62.
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- Navas J, González-Zorn B, Ladrón N, Garrido P, Vázquez-Boland JA. Identification and mutagenesis by allelic exchange of choE, encoding a cholesterol oxidase from the intracellular pathogen Rhodococcus equi. J Bacteriol 2001 Aug;183(16):4796-805.
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