Disseminated nocardiosis caused by Nocardia abscessus in an HIV-infected patient: first reported case

Abstract

Members of the genus Nocardia are filamentous bacteria belonging to the order Actinomycetales. They are Gram-positive aerobes, partly acid fast, soil and water saprophytes [1]. Nocardiosis usually presents as cutaneous lesions in immunocompetent patients, and is generally caused by Nocardia brasiliensis. On the other hand, disseminated disease is often seen in immunocompromised patients, and Nocardia asteroides is the most common species [2]. Disseminated nocardiosis involving the central nervous system (CNS) has been described in immunocompromised patients, including patients with AIDS [2,3]. The taxonomy of these microorganisms has recently been revised and new phylogenetic groups have been described within the genus, one of them being Nocardia abscessus[4]. We describe the case of an AIDS patient with disseminated disease, including CNS involvement, caused by N. abscessus. Based on our MEDLINE and PubMed search, to the best of our knowledge, this is the first report of N. abscessus infection in an HIV-infected patient. Case report A 33-year-old man presented to his primary care physician with a suppurative nodule on his left gluteus and a 2-month history of asthenia, malaise, fever and weight loss. Three months before admission the patient was diagnosed with pneumonia, and a bronchoalveolar lavage revealed filamentous acid-fast bacteria compatible with Nocardia spp. At that time HIV infection was diagnosed. The patient was non-compliant with the treatment prescribed, ciprofloxacin plus trimethoprim–sulfamethoxazole (TMP–SMX). His past medical history was significant for severe smoking, alcoholism, sexual promiscuity and multiple episodes of herpes zoster. On admission, the physical examination was significant for a suppurative ulcer on his left gluteus. He also had multiple condylomas in the perineal region and oral thrush. His pulmonary examination was significant for rales in the right middle lobe. Neurological and funduscopic examinations were unremarkable. The chest radiograph demonstrated right perihilar opacities. The white blood cell count was 6900 cells/mm3 (N: 59%; L: 28%), haemoglobin 9.3 g/dl, platelets 250 000 cells/mm3, sedimentation rate 46 mm/h, CD4 T-cell count 11 cells/mm3. Liver function tests and metabolic profile were normal. Aspiration of the suppurative gluteal lesion also demonstrated acid-fast filamentous bacteria compatible with Nocardia spp. The case was interpreted as disseminated nocardiosis. A magnetic resonance imaging (MRI) scan performed to assess CNS involvement revealed multiple supratentorial lesions compatible with abscesses (Fig. 1a). The patient was placed on TMP–SMX plus ciprofloxacin for nocardiosis and pyrimethamine plus clindamycin for suspected cerebral toxoplasmosis.Fig. 1: Magnetic resonance images of the patient. (a) Baseline magnetic resonance image; (b) Two-month control magnetic resonance image.The pulmonary and skin lesions responded rapidly to the treatment. Blood cultures were positive for Cryptococcus neoformans, starting on amphotericin B. A one-month follow-up MRI scan showed no significant reduction in the size of the brain lesions. As a result of this poor response, antiobiotics were changed to TMP–SMX plus ceftriaxone, and a diagnostic surgical resection of a right temporal lobe lesion was performed. The culture of this lesion was positive for Nocardia spp. A 2-month MRI scan showed near-complete resolution of all brain lesions (Fig. 1b), so the same antibiotics were continued for an additional 15 days. The patient was discharged 3 months after admission and continued his outpatient treatment with TMP–SMX for nocardiosis and fluconazole for cryptococcosis. The final typing report from the National Institute of Infectious Diseases was N. abscessus. Disseminated nocardiosis is associated with several immunocompromising conditions such as organ transplant and prolonged corticosteroid therapy [5]. More recently, HIV infection has been described as a risk factor for disseminated nocardiosis [2,6]. Because of the low frequency of this co-infection, several points remain obscure regarding nocardiosis management in the HIV setting. Even when sulfonamides are indicated as first-line drugs, to date there are no widely accepted guidelines as to dosing, length of treatment or combination therapy. In the past few years, the importance of identifying the Nocardia species has been demonstrated, because the antimicrobial susceptibility pattern is not the same for the different species [2,7]. Finally, as there are no well-defined treatment response criteria for CNS involvement, it is difficult to establish criteria for surgical intervention. Some authors suggest that aggressive surgical intervention is needed to improve the outcome of these patients [8]. However, the present case highlights that knowing the Nocardia species and its antimicrobial susceptibility pattern may allow the clinician to optimize medical treatment and avoid unnecessary invasive procedures. N. abscessus is susceptible to third-generation cephalosporins and is resistant to ciprofloxacin in vitro, a fact that was verified clinically in the present report. This case also emphasizes the need for brain tissue sampling in patients with CNS involvement and inadequate response to medical treatment, in view of the multiple aetiologies of brain abscesses in HIV-infected patients, particularly those with severe immunosuppression.