Rhodococcus equi infection in HIV-positive patients: report of 5 cases and literature overview.

The importance of Rhodococcus equi infection, an uncommon human pathogen that almost exclusively affects immunocompromised hosts, has greatly increased following the advent of acquired immune deficiency syndrome (AIDS) epidemics. Until the present time, 38 cases of R. equi infection have been described in human immunodeficiency virus (HIV)-infected patients; we now report a further five personal cases. R. equi was acquired via respiratory exposure to animals in less than half of the patients, and caused invasive pulmonary infection (91%), bacteraemia and sometimes bloodstream dissemination. R. equi was easily cultured from sputum or blood, but its diagnosis was often difficult due to microbiological and clinical similarities with other pathogens. The persistence of the micro-organism inside macrophages and its high tissular load represent the major limitation to an effective treatment. Several antibiotics are active in vitro, but their efficacy in vivo depends on macrophage uptake and/or bactericidal activity. Treatment should start with at least two intravenous bactericidal antibiotics for 3-4 weeks, and then continue with oral therapy for a period of up to several months with at least two intracellularly active drugs. Surgical resection of the lesions may be beneficial in selected cases.