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Clinical features, diagnosis, therapy, and prevention of Rhodococcus equi infections

Camille N Kotton, MD
Section Editor
Stephen B Calderwood, MD
Deputy Editor
Jennifer Mitty, MD, MPH


The first case of infection caused by Rhodococcus equi was reported in 1967 [1], and only 12 additional cases were recorded in the next 15 years [2]. While still not commonplace, a dramatic increase occurred early in the HIV pandemic and R. equi has increasingly been appreciated, especially as an opportunistic pathogen. Increasing recognition of R. equi as a pathogen has subsequently led to improved laboratory identification of infections in both immunocompromised and normal humans.

The clinical manifestations, diagnosis, treatment, and prevention of R. equi infections will be reviewed here. The microbiology, epidemiology, and pathogenesis of R. equi infections are discussed separately. (See "Microbiology, epidemiology, and pathogenesis of Rhodococcus equi infections".)


R. equi has increasingly been appreciated as a cause of infection in patients with immune system dysfunction [3-13]. The majority of R. equi infections occur in adults, but infection in children and infants (including preterm infants) has also been reported [14]. Although such patients often have epidemiologic risk factors for disease (eg, contact with horses), disease has been reported even in those without a known exposure [13]. (See "Microbiology, epidemiology, and pathogenesis of Rhodococcus equi infections".)

Pulmonary infections are the most common form of human disease caused by R. equi. Extrapulmonary disease, with or without a concurrent pulmonary infection, can also occur. In one large review of 72 cases, pneumonia occurred in 76 percent of patients, and the lung was the sole site of infection in 82 percent [7]. Pneumonia was accompanied by extrapulmonary infection in 18 percent of cases, while infection at extrapulmonary sites occurred without evidence of pulmonary involvement in 24 percent.

Immunocompromised hosts

Pulmonary infection — Most published cases of pneumonia have occurred in immunocompromised hosts, including transplant recipients (both solid organ and hematopoietic stem cell recipients) [13,15,16]. In such patients, infection is typically subacute in onset but results in high fever, cough (which may or may not be productive), and prominent fatigue [3-11]. Chest pain and weight loss are also common [17].

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Literature review current through: Dec 2017. | This topic last updated: Jun 20, 2017.
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