What is Rhodococcus equi? A bacterium found in soil worldwide, Rhodococcus equi (R. equi) is a common cause of bronchopneumonia in foals between 3 weeks and 5 months of age. While the survival rate of R equi pneumonia is upwards of 70% with appropriate therapy, the case fatality rate without therapy is a staggering 80%. A leading cause of premature …