Diagnosis of Pneumocystis carinii pneumonia by bronchoalveolar lavage in AIDS patients. Comparison of Diff-Quik, fungifluor stain, direct immunofluorescence test and polymerase chain reaction.

OBJECTIVE: To assess the sensitivity, specificity and accuracy of Diff-Quik, fungifluor stain, the direct immunofluorescence test (DIFT) and the polymerase chain reaction (PCR) in the diagnosis of Pneumocystis carinii pneumonia (PCP) in human immunodeficiency virus (HIV)-infected patients. STUDY
DESIGN: From December 1992 through November 1993, 112 bronchoalveolar lavage fluid (BALF) samples were obtained from 80 HIV-infected patients. BALF samples were processed for cytologic and microbiologic analysis and for PCR. Cytologic examination was carried out on Diff-Quik-stained cytocentrifuge preparations and with May-Grünwald-Giemsa staining and fungifluor staining. For diagnosis of PC infection, DIFT and PCR were used.
RESULTS: Thirty-two of 112 acute episodes were caused by P carinii. Diff-Quik had the highest sensitivity (84.8%) as compared to fungifluor stain (60.0%), DIFT (59.4%) and PCR (65.6%). The specificity was 98.7% with Diff-Quik, 100% with fungifluor stain, and 98.6% and 97.3% with DIFT and PCR, respectively. Accuracy was high with every method (94.4% with Diff-Quik, 88.3% with fungifluor stain, 86.7% with DIFT and 87.6% with PCR).
CONCLUSION: Diff-Quik is a good diagnostic tool in the diagnosis of PCP. The combination of Diff-Quik and fungifluor stain is recommended because of its cost-effectiveness and because of its rapid diagnosis of severe PCP. PCR and DIFT should be used only on patients judged clinically to have PCP with discrepant results in Diff-Quik and fungifluor stain in BALF samples.