Rhodococcus equi and Nocardia brasiliensis infection of the brain and liver in a patient with acute nonlymphoblastic leukemia

Pyogenic liver abscess due to Rhodococcus equi in an immunocompetent host

A case of pyogenic liver abscess (PLA) due to Rhodococcus equi in an immunocompetent individual was successfully treated by combining surgery and antibiotics. The R. equi-targeted antimicrobial agents erythromycin and rifampin were used only after surgical resection of the lesion and identification of the infective organism.

Rhodococcus equi brain abscess in a patient without HIV

Rhodococcus equi, a Gram positive organism, is a cause of infections in immunocompromised individuals. In humans, it mainly causes disease in those infected with human immunodeficiency virus (HIV), and generally presents as chronic pulmonary infection. It may also cause intracranial infections, which manifest as brain abscesses. This report describes a case of rhodococcus brain and pulmonary infection in a patient who did not have HIV or another disorder of cell mediated immunity. He was treated with intravenous imipenem, vancomycin, and rifampin for eight weeks and recovered from the infection.

Pathogenic Nocardia, Rhodococcus, and related organisms are highly susceptible to imidazole antifungals

Rhodococcus equi and species of Nocardia and Gordonia may be human opportunistic pathogens. We find that these, as well as several isolates from closely related genera, are highly susceptible to the imidazoles bifonazole, clotrimazole, econazole, and miconazole, whose MICs are </=1 micro g/ml. In liquid cultures 1 micro g of the drug/ml was bacteriostatic and 10 micro g/ml was bactericidal. On solid media at 10 micro g of azole/ml no resistant mutants could be isolated. An MIC of 1 to 15 micro g/ml was observed with ketoconazole, whereas none of these organisms was inhibited by the triazoles fluconazole and voriconazole (100 micro g/ml). Imidazoles may offer the prospect of treatment of nocardioform mycetomas and may provide the basis for the development of additional antimicrobial agents to combat these pathogens.

Nocardiosis in cancer patients

Nocardiosis (NOC) is an important cause of infection in immunocompromised patients. However, large series in patients with cancer have not been described. We review the records of patients with cancer and NOC who were evaluated at The University of Texas M. D. Anderson Cancer Center, Houston, Texas, between 1988 and 2001, and we describe the incidence, microbiologic and clinical characteristics, treatment, and outcome of NOC in this population. Forty-two patients with a total of 43 episodes of NOC were identified (incidence of 60 cases of NOC per 100,000 admissions). Twenty-seven patients (64%) had hematologic malignancies. In 13 patients, NOC complicated bone marrow transplantation. Neutropenia was observed in 4 (10%) of 40 episodes with information available, and lymphopenia in 20 (50%) of 40 episodes. Patients had received steroids for 25 episodes (58%) and had received chemotherapy for 10 episodes (23%) within 30 days before the onset of NOC. Nine episodes of breakthrough NOC were identified in 7 (23%) of the 40 patients with information available. Pulmonary NOC was seen in 30 (70%) of 43 cases; soft-tissue NOC in 7 (16%); central venous catheter-related nocardemia in 3 (7%); and disseminated NOC, central nervous system NOC, and a perinephric abscess each in 1 (2%). Twenty-three percent of patients with pulmonary NOC had an acute presentation. complex was the most common causative species (77%). Therapy for NOC was mainly concurrent trimethoprim/ sulfamethoxazole and either a tetracycline or a beta-lactam. The median duration of treatment was 113 days (range, 10-600 d). Nine (60%) of 15 patients with outcome data died from NOC. NOC, although infrequent, is an important cause of morbidity and mortality in patients with cancer. It has pleomorphic manifestations, and it can be seen as a breakthrough infection. The present study confirms that timely diagnosis, the site of NOC, the type of, the presence of comorbidities, and cytomegalovirus coinfection influence the outcome of patients with cancer and NOC.

Rhodococcus equi: an emerging pathogen

More than 100 cases of Rhodococcus equi infection have been reported since the first description of human disease caused by this organism. The vast majority of patients infected with R. equi are immunocompromised, and two-thirds have human immunodeficiency virus infection. The clinical manifestations of R. equi infection are diverse, although 80% of patients have some pulmonary involvement. The organism is easily cultured from specimens of infected tissue or body fluid, but it may be misdiagnosed as a contaminant. Treatment is often prolonged, and relapses at distant sites are common. This article summarizes the history, diagnosis, clinical features, and treatment of infection with this emerging pathogen.

Unusual infections and novel therapy in the immunocompromised host

Many of the reports of infection in immunocompromised patients over the past year have been caused by unusual bacterial pathogens or fungi, which are often multiresistant and difficult to treat. Although many difficulties still remain some progress has been made over the past year in the development of new antimicrobial agents and alternative therapies.