Sensitivity and specificity of indirect immunofluorescence and Grocott-technique in comparison with immunocytology (alkaline phosphatase anti alkaline phosphatase = APAAP) for the diagnosis of Pneumocystis carinii in broncho-alveolar lavage (BAL).

The purpose of the study was to compare the sensitivity and specificity of the indirect method of immunofluorescence with the immunocytological technique of alkaline phosphatase anti alkaline phosphatase complex (APAAP) for the detection of Pneumocystis carinii by bronchoalveolar lavage (BAL) in HIV-1 positive patients. - 83 HIV-1 positive patients with clinical presentations suggestive of Pneumocystis carinii pneumonia (PcP) were included in the study. 28 samples were found Pc-positive by immunofluorescence (IFT), 26 by Grocott and 29 by APAAP. In comparison to the lab results 33 patients were diagnosed as PcP according to the clinical course (i.e. therapeutic outcome, drugs used, and therapy changes). Compared to the clinical diagnoses, the following lab tests proved to be false positive and false negative: false positive: IF = 1, Grocott = 0, APAAP = 4 (3F6). false negative: IF = 5, Grocott = 7, APAAP = 4 (3F6). - Grocott stain shows insufficient correlation to the clinical diagnoses (p = 0.0156, McNemar-Test, two-tailed). - The two different detection methods (IFT and APAAP) showed no significant statistical difference with regard to their sensitivity (p = 0.3438, McNemar-Test, two tailed) and specificity. Considering cost and time the immunofluorescence technique seems to be the most suitable for the diagnosis of PcP in HIV-1 positive patients.