Rhodococcus equi: the many facets of a pathogenic actinomycete

José A. Vázquez-Boland*, Steeve Giguère, Alexia Hapeshi, Iain MacArthur, Elisa Anastasi, Ana Valero-Rello

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

87 Citations (Scopus)


Rhodococcus equi is a soil-dwelling pathogenic actinomycete that causes pulmonary and extrapulmonary pyogranulomatous infections in a variety of animal species and people. Young foals are particularly susceptible and develop a life-threatening pneumonic disease that is endemic at many horse-breeding farms worldwide. R. equi is a facultative intracellular parasite of macrophages that replicates within a modified phagocytic vacuole. Its pathogenicity depends on a virulence plasmid that promotes intracellular survival by preventing phagosome-lysosome fusion. Species-specific tropism of R. equi for horses, pigs and cattle appears to be determined by host-adapted virulence plasmid types. Molecular epidemiological studies of these plasmids suggest that human R. equi infection is zoonotic. Analysis of the recently determined R. equi genome sequence has identified additional virulence determinants on the bacterial chromosome. This review summarizes our current understanding of the clinical aspects, biology, pathogenesis and immunity of this fascinating microbe with plasmid-governed infectivity.

Original languageEnglish
Pages (from-to)9-33
Number of pages25
JournalVeterinary Microbiology
Issue number1-2
Publication statusPublished - 29 Nov 2013
Externally publishedYes

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