Introduction: Nocardiosis is an infectious disease that frequently involves to the respiratory tract. Nocardia asteroides is the predominant human pathogen. Nocardiosis is difficult to diagnose and that's why its incidence is not well established.
Cases: Three cases diagnosed in a Pneumology Section are reported. None of them was affected by AIDS and all of them were initially diagnosed from bronchopneumonia. Empirical antibiotherapy was initiated and because of the unsatisfactory progress, bronchoscopy was performed in all cases and in one case a transthoracic puncture was made. Nocardia spp. was then isolated and this let to began with a specific treatment. All the patients progress satisfactorily in their respiratory infection.
Discussion: Although there are usually factors that predispose to nocardiosis, it can also occur in absence of these, as it happened in one of report patients. The clinical and radiological manifestations are not, in many cases enough to reach the diagnosis. Thus germ isolation is very important, and invasive procedures are often essential to obtain a quality samples to cultivate. Sulfonamides were considered drugs of choice, but nowadays, many authors propose trimethoprim-sulfamethoxazole. Imipenem, amikacin have also proved to be effective.