[Rhodococcus equi--a newly recognized opportunistic pathogen in man]

Area of Science:

• Microbiology
• Infectious Diseases
• Veterinary Medicine

Context:

• Rhodococcus equi, a zoopathogenic actinomycete, is increasingly recognized as an opportunistic pathogen in humans.
• Found in soil and manure, R. equi primarily affects young foals but also poses risks to human health.
• Human infections are often chronic and recurrent, particularly in immunocompromised individuals, including those with AIDS.

Purpose:

• To review the significant features of Rhodococcus equi and analyze its isolation reports in humans.
• To highlight the importance of identifying R. equi as an opportunistic pathogen in clinical microbiology.
• To discuss the pathogenesis, clinical manifestations, and treatment of R. equi infections.

Summary:

• Rhodococcus equi is a gram-positive, encapsulated coccobacillus that thrives in soil and manure.
• It causes granulomatous pneumonia in foals and pneumonia, lung abscesses, and other infections in humans, especially those with weakened immunity.
• The pathogen's ability to persist in macrophages and the importance of cell-mediated immunity in resistance are key to its pathogenesis.
• Infection routes include inhalation, ingestion, or skin injury, with animal/manure contact reported in about a third of human cases.
• Standard treatment involves a combination of rifampin and erythromycin, and laboratory identification is generally straightforward.

Impact:

• Enhances understanding of R. equi as a significant opportunistic pathogen in human medicine.
• Provides guidance for microbiological laboratories on identifying and managing R. equi infections.
• Informs clinicians about the clinical spectrum, pathogenesis, and treatment of R. equi infections, especially in vulnerable populations.
• Contributes to improved diagnostic and therapeutic strategies for R. equi infections in both veterinary and human medicine.