A Comparison of Induced and Expectorated Sputum for the Diagnosis of Pneumocystis carinii Pneumonia

Abstract

To compare the sensitivities of expectorated and induced sputum for the diagnosis of Pneumocystis carinii pneumonia (PCP). Retrospective review. Academic medical center. Forty-five patients diagnosed as having PCP who had direct fluorescent antibody testing for P carinii on either expectorated or induced sputum. Patients were stratified according to the method of sputum production (induced vs expectorated). The two groups were similar with respect to demographic characteristics, use of prophylaxis with aerosolized pentamidine, serum lactate dehydrogenase level, and arterial oxygen level. When only the initial sputum for each patient was analyzed, there was a similar sensitivity of induced sputum, positive in 10 of 18 samples (56%), and expectorated sputum, positive in 14 of 27 samples (52%) (p>0.05). There was no significant difference in the sensitivity of induced and expectorated sputum for the diagnosis of PCP when the direct fluorescent antibody method of staining was used.