Infections due to Rhodococcus equi in three HIV-infected patients: microbiological findings and antibiotic susceptibility.

Infections of Rhodococcus equi, a well-known pathogen in animals which causes cavitated pneumonia similar to that caused by mycobacteria, were studied in three HIV-infected patients. This microorganism was isolated in the bronchoalveolar washings of two patients and in the sputum of the third. In two patients, Rh. equi represented the first clinical opportunistic manifestation of HIV disease. One patient died of concomitant Pneumocystis infection. The eradication of the microorganism occurred in two out of three patients. It was found that no isolates were resistant to erythromycin, claritromycin, rifampin, vancomycin, teicoplanin, imipenem, gentamycin or azithromycin (MIC values < or = 0.1 microgram/ml). Moreover, the quinolones (ciprofloxacin and ofloxacin) were found to be less effective, whereas neither the beta-lactam antibiotics nor chloramphenicol were effective therapy for this microrganism. At least two antimicrobial agents should be given contemporaneously to treat these infections for a period of up to several months. Our results suggest that the combinations erythromycin + rifampin or imipenem + teicoplanin are the most effective treatments in Rh. equi infections.