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Rhodococcus equi in Horses: Distribution and Virulence Factors |
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Kelly A. Cunningham
Department of Dairy and Animal Science |
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Rhodococcus equi is
a soil-dwelling bacterium found on almost every mid- to large-scale
breeding farm in the world. Infection occurs in foals after inhalation
of bacteria and manifests as coughing, wheezing, and lung abscesses. A
high mortality rate makes this infectious organism a concern, as it has
a tendency to spread even under acknowledged disease management
practices. This summer’s work at Penn State investigated the current
distribution of R. equi in a model Quarter horse breeding herd. A
new R. equi-selective medium, developed by Dr. Gary Muscatello of
the University of Melbourne, was used to culture samples. Positive
results were obtained from a number of foals, and most were identified
as one of several species of Corynebacterium. R. equi reference
strains did not come up positive, however, raising questions about the
validity of tests used. Future investigation on the samples collected
from this farm will include a simple set of tests suggested by Dr.
Muscatello, while the study’s long-term goal is to speciate any strains
of R. equi present at the Penn State facility. This study was supported by an undergraduate student research grant from the College of Agricultural Sciences at Penn State. |
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