Rhodococcus equi in Advanced Antiretroviral Therapy-Naïve HIV-Positive Patients: Differential Diagnosis and Clinical Findings.

We present the case of a 47-year-old man living with HIV who had experienced fever, night sweats, cough and occasional haemoptysis for the previous two months. Computed tomography of the chest revealed a lesion measuring 57 mm in diameter with cavitation in the left lower superior segment. His CD4+ T cell count was 220 cells/mm³ and his HIV RNA level was 406,756 copies/ml. Acid-resistant coccobacilli were isolated from the transthoracic biopsy of the lesion and were initially identified as Mycobacterium lentiflavum. However, 16S rDNA sequence analysis identified it as Rhodococcus equi. A histopathological examination revealing malakoplakia with Michaelis-Gutmann bodies supported the diagnosis. The patient responded dramatically to a 3-month course of treatment with azithromycin and moxifloxacin. The most obvious epidemiological risk factor in this case was that the patient regularly took care of multiple stray cats. Rhodococcus equi should be considered in differential diagnosis of cavitary pneumonia in patients with cellular immunodeficiencies, especially when there is a contact history not only with horses, but with other herbivores.