subject: Nocardiosis clinical features and management [print this page] Nocardiosis clinical features and management
Nocardiosis is a systemic infection caused by species of Nocardia (N. asteroides and, less often, N. brasiliensis andN. caviae). N. brasiliensis is the common cause of actinomycetomain the tropics and subtropics. Nocardia arehigher bacteria which exist in a filamentous and coccobacillaryform, depending on culture conditions.
Aetiology, pathogenesis and epidemiology Nocardia are aerobic, filamentous branching Gram-positivebacteria and grow well on standard culture media. Theorganisms are found in rotting vegetation and infection isacquired by inhalation in most cases, although inoculationvia the skin occurs. Initial pulmonary lesions may lead todissemination of infection by the bloodstream. Necrosis andsuppuration are the typical pathological changes.Adults are most often affected. Infection occurs mainlyin immunosuppressed individuals.
Clinical features Acute and sometimes fulminant or chronic suppurativepulmonary disease occurs in nocardiosis. Fever, cough withviscid sputum, night sweats and weight loss are usual features.Pleural thickening and empyema may develop, andthe affected lung may cavitate. Haematogenous dissemination to cause brain abscess, kidney lesions, bone lesionsand subcutaneous sepsis is reported.Actinomycetoma due to Nocardia presents with longstanding swelling of the extremity, most often the foot orankle, and sinuses discharging on to the skin.
Diagnosis Diagnosis depends on finding the organism in discharges,exudates, bronchial washing or biopsy sections. Nocardiagrow well on media used for growing tubercle bacilli andon Sabouraud's medium. Serological tests are helpful indiagnosis and can give information about the response totreatment. An adequate deep biopsy will give the bestchance of isolating the organism concerned.
Management Co-trimoxazole is effective (two double-strength tabletsevery 8 hours). Prolonged treatment is the rule, withrelapse being less common after 3 months, medication.Minocycline (100-200 mg twice daily) is also effective.
