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Author (up) Muscatello, G.; Anderson, G.A.; Gilkerson, J.R.; Browning, G.F.
Title Associations between the ecology of virulent Rhodococcus equi and the epidemiology of R. equi pneumonia on Australian thoroughbred farms Type Journal Article
Year 2006 Publication Applied and Environmental Microbiology Abbreviated Journal Appl Environ Microbiol
Volume 72 Issue 9 Pages 6152-6160
Keywords Actinomycetales Infections/epidemiology/microbiology/*veterinary; Air Microbiology; Animal Husbandry; Animals; Animals, Newborn; Australia/epidemiology; Colony Count, Microbial; DNA, Bacterial/genetics; Ecosystem; Horse Diseases/epidemiology/*microbiology; Horses; Pneumonia, Bacterial/epidemiology/microbiology/*veterinary; Rhodococcus equi/genetics/isolation & purification/*pathogenicity; Soil Microbiology; Virulence
Abstract The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associated with the airborne burden of virulent R. equi (both the concentration and the proportion of R. equi bacteria that were virulent) but was not associated with the burden of virulent R. equi in the soil. Univariable screening and multivariable model building were used to evaluate the effect of environmental and management factors on virulent R. equi burdens. Lower soil moisture concentrations and lower pasture heights were significantly associated with elevated airborne concentrations of virulent R. equi, as were the holding pens and lanes, which typically were sandy, dry, and devoid of pasture cover. Few variables appeared to influence concentrations of virulent R. equi in soil. Acidic soil conditions may have contributed to an elevated proportion of virulent strains within the R. equi population. Environmental management strategies that aim to reduce the level of exposure of susceptible foals to airborne virulent R. equi are most likely to reduce the impact of R. equi pneumonia on endemically affected farms.
Address School of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia. mug@unimelb.edu.au
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0099-2240 ISBN Medium
Area Expedition Conference
Notes PMID:16957241 Approved no
Call Number Equine Behaviour @ team @ Serial 2622
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