Nontuberculous mycobacteria in pleural fluid. Assessment of clinical significance.

We reviewed the case records of 22 patients from whose pleural fluid a nontuberculous Mycobacterium (NTM) was isolated. Three patients had pleural effusions definitely due to NTM infection, with evidence of NTM infection in other tissues; 16 had pleural effusions of known etiology unrelated to the isolated NTM and no other evidence of NTM infection; and three had pleural effusions of undetermined etiology and no other evidence of NTM infection. The case histories of the three patients with pleural effusions due to NTM are presented and the significance of the isolation of NTM from the remaining 19 patients is discussed. Criteria are proposed for evaluating the significance of NTM isolated from pleural fluid.