Rhodococcus equi infections in kidney transplant patients: Three case reports and a review of the literature.

Rhodococcus equi is an aerobic actinomycete initially identified in foal pneumonia and later recognized as an opportunistic human pathogen, particularly affecting immunocompromised individuals. Its incidence increased during the AIDS pandemic and with the rise of organ transplantation. Both cellular and humoral immunity contribute to host defense against R. equi, which is typically acquired through inhalation or ingestion of contaminated materials. The bacterium causes pneumonia that frequently progresses to lung cavitation, bacteremia, and potential dissemination to other organs. We report three cases of R. equi infection in renal transplant patients and review 35 previously published cases. The median age was 49 years, with a male predominance. Most patients presented with necrotizing pneumonia, often associated with bacteremia and soft tissue involvement. Treatment involved reducing immunosuppressive therapy, using bactericidal and intracellularly active antibiotics, and considering surgery when necessary. Prolonged antibiotic therapy and secondary prophylaxis are recommended. Mortality associated with this infection remains high, highlighting the need for early diagnosis and comprehensive treatment strategies. This report emphasizes the importance of considering infectious causes, such as R. equi, in the differential diagnosis of pulmonary masses in immunocompromised patients. Early diagnosis and combined antibiotic therapy are crucial. Lobectomy, though high-risk, may be required for durable infection control when antibiotic therapy is insufficient.