Background: Pulmonary nocardiosis is a dangerous chronic infection caused by implantation of aerobic actinomycetes called nocardia in respiratory system. The disease is more commonly found in patients with chronic infectious disorders, which may be treated by prolonged courses of antibiotics or corticosteroids, and in immunosuppressed patients. While pulmonary and systemic nocardiosis has no pathognomonic clinical or radiographic features it has the same clinical symptoms as tuberculosis, with a treatment much more different. The aim of this study was evaluation of nocardiosis among suspected pulmonary patients being confined or referred to Isfahan T.B center, in 2005.

Materials and Methods: In this descriptive study 200 reliable samples, including 90 BAL (Bronchoalveolar lavage) and 110 sputum specimens, were collected during a period of 12 months from patients with diverse bronchopulmonary diseases, whether confined or referred to the center. %53.5 of patients were male and the rest were female. The data were statistically analyzed by SPSS Software using Fisher Exact Test.

Results: The results obtained through direct smears (KOH, BM, Kynion), culture and diagnostically - identical methods revealed eight positive cases (4%) of Nocardia Asteroids. Of 107 males, 6 (5.6%) and of 93 females, two (2.2%) were infected by Nocardia. There was no significant difference concerning age, sex, occupation, and nocardiosis.�

Conclusion: Because of high incidence of nocardiosis found in this study, paying attention to nocardiosis in patients suffering from pulmonary diseases is highly recommended. Nocardiosis can become a severe infection which profoundly affects immunocompromised patients. Differential diagnosis often delays the time of diagnosis, which worsens the out come.