Use of a rapid differential stain for identifying Pneumocystis carinii in bronchoalveolar lavage fluid. Diagnostic efficacy in patients with AIDS.

Identification of Pneumocystis carinii involves silver stains which require several hours for processing. Diff Quik, a differential stain similar to Wright-Giemsa, requires less than 1 min and reproducibly stains trophozoites and intracystic bodies of P carinii. To determine the utility of DQ for rapid detection of P carinii in BAL fluid, we reviewed DQ-stained slides of 50 BAL samples from 36 patients seropositive for HIV+ who had undergone bronchoscopy with BAL for evaluation of interstitial pulmonary infiltrates. A comparison group of immunocompromised patients with P carinii pneumonia also were reviewed. For HIV+ samples, sensitivity of DQ was 93 and 100 percent for cytopathologists and 75 and 89 percent for pulmonologists. Specificity was 95 percent for each cytopathologist and 100 percent for pulmonologists. For non-HIV+ patients, sensitivity ranged from 22 to 55 percent. Thus, DQ may be useful as a rapid, reliable method to identify P carinii in BAL fluid from HIV+ patients.