Rhodococcus equi: An emerging zoonotic pathogen


In recent decades, many emerging zoonoses of diverse etiologies have attracted the attention of national and international organization as they caused significant morbidity and mortality in humans as well as animals. Among several zoonotic pathogens, Rhodococcus equi is emerging as an important opportunistic intracellular bacterial pathogen of immunosuppressed hosts such as human immunodeficiency virus infected patients. Infection due to R. equi has also been recorded in immunocompetent subjects. It is a well-recognized agent causing disease in animals mainly in equines. The natural habitat of R. equi is soil, particularly contaminated with animal manure. The exact mode of transmission of R. equi infection is not well established. The primary infection occurs in the lungs in approximately 80% of cases. Necrotizing pneumonia is the most common form of infection caused by R. equi in human, however, wound infections, and subcutaneous abscess like extrapulmonary infections have also been described. Microbiological, cytological, and molecular techniques are employed to confirm the diagnosis of disease. It is pertinent to differentiate R. equi from Nocardia, Mycobacterim, and diphteroids. Prognosis is grave as mortality may reach up to 50% in HIV patients. Combined antimicrobial agents could be used as therapeutics to reduce the chance of development of antibiotic resistant. Presently, no commercial vaccine is available for immunization. Further research on the pathogenesis, epidemiology, chemotherapy, and vaccinology to protect the equine and humans from rhodococcosis may be rewarding. In this review we focus on etiology, host, transmission, diagnosis and treatment of R. equi infection

Key words: Emerging pathogen, Horse, Immunocompromised host, Public health, Rhodococcus equi, Zoonosis