- This pleomorphic, non-motile Gram-positive coccobacillus [Fig 1] has undergone several name changes.
- Formerly known as Corynebacterium equi, then Rhodococcus equi, and later on Rhodoccushoagii (due to the realization R. equi had an earlier heterotypic synonym in Corynebacterium hoagii).
- Ubiquitous in the environment.
- Variably acid-fast staining.
- Organism varies from coccoid to bacillary form depending on growth condition.
- Modes of acquisition: inhalation, local inoculation, or ingestion.
- A common cause of bronchopneumonia in foals, also swine and cattle.
- It can be overlooked as contaminant diphtheroids and be discarded.
- The lab should be aware if clinically suspected.
- It can also be confused with Micrococcus, Bacillus or Mycobacteria species.
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