Infection with Rhodococcus equi in a patient with sarcoidosis treated with corticosteroids

A 51-year-old female farmer was diagnosed as having sarcoidosis. During 4 years of observation, slow radiological progression was observed. Cough then developed, necessitating treatment with corticosteroids. After 28 months of continuous treatment with prednisolone in low doses (5-7.5 mg daily), she suffered fever episodes, recurrent haemoptyses, general malaise and loss of weight. A chest roentgenogram showed a left upper lobe infiltrate, which progressed and finally cavitated, and rib destruction. Despite efforts, including a thoracotomy, 22 months passed before a diagnosis could be made. Blood and sputum cultures and cultures from the destroyed rib showed growth of Rhodococcus equi, a common soil organism which can cause infections in foals and other animals. Treatment with rifampicin and erythromycin was successful. R. equi has been reported to cause infection in patients with neoplastic disease and/or immunosuppression, but the disease might be more common than is suggested by the sparse case reports in the literature, owing to lack of familiarity with the organism, which will tend to be overlooked as a contaminant.