FREQUENCY OF PULMONARY TUBERCULOSIS IN PATIENTS UNDERGOING SPUTUM INDUCTION FOR DIAGNOSIS OF SUSPECTED PNEUMOCYSTIS-CARINII PNEUMONIA

Objective: To determine the frequency of pulmonary tuberculosis (TB) i n patients with suspected Pneumocystis carinii pneumonia (PCP). Design : Prospective study of sputum specimens from subjects undergoing diagn ostic sputum induction for PCP and medical chart review. Setting: Univ ersity hospital in the Bronx, New York City. Patients: A total of 373 consecutive adults with induced sputum specimens adequate for acid-fas t smear and mycobacterial culture. Main outcome measures: Direct immun ofluorescence for PCP, acid-fast stain, and mycobacterial culture of a ll induced sputum specimens. Determination of demographic characterist ics, HIV risk factors, and HIV serological status. Clinical and radiog raphic findings of patients with TB. Results: Proven symptomatic HIV i nfection was present in 251 of the 373 (67%) patients prior to sputum induction. PCP was detected in 136 out of 519 (26%) specimens, Mycobac terium tuberculosis in 10 (1.9%) specimens from nine patients. Smear w as positive for acid-fast bacilli in nine (1.7%), of which seven (78%) grew M. tuberculosis and two (22%) M. avium complex. Pulmonary TB was found in nine of the 373 (2.4%) patients [95% confidence intervals (C I), 1.1-4.61. Smears were positive for acid-fast bacilli in seven out of 10 (70%) specimens with M. tuberculosis compared with two out of 65 (3%) with other mycobacteria (P<0.0001). Of 66 specimens that grew my cobacteria despite negative acid-fast smears, three (4.5%) were M. tub erculosis (95% CI, 0-13.3). Of the nine patients with TB, six had prio r known TB, chest radiographs atypical for PCP, or both; two others ha d positive acid-fast smears. Only a single patient (0.27%; 95% CI, 0-0 .79) had pulmonary TB, which remained unsuspected after acid-fast smea r of induced sputum. Conclusions: Pulmonary TB occasionally occurs in patients with suspected PCP and in most cases is suggested by medical history, clinical findings, or acid-fast stain of induced sputum.