USEFULNESS OF PCR FOR DIAGNOSIS OF PNEUMOCYSTIS-CARINII PNEUMONIA IN DIFFERENT PATIENT GROUPS

Pneumocystis carinii pneumonia (PCP) is one of the most predominant op portunistic infectious diseases in patients with AIDS. Nested PCR has been described as a sensitive and specific tool for detecting P. carin ii DNA in clinical specimens. Little is known about the correlation of positive PCR results and clinical evidence of PCP in patients with di fferent forms of immunosuppression. One hundred and thirty-six sputum samples, 26 tracheal-bronchial aspirate samples, 35 bronchoalveolar la vage samples, and 11 lung biopsy samples from (i) human immunodeficien cy virus (HIV)-infected patients with AIDS, (ii) immunocompromised pat ients with leukemia or lymphoma, and (iii) immunocompetent control pat ients were investigated by a nested PCR amplifying DNA from the mitoch ondrial large subunit of P. carinii. All patients suffered from acute episodes of respiratory disease. The resulting data were correlated wi th clinical evidence of PCP. A high degree of association of positive P. carinii PCR results and clinical evidence of PCP in HIV-infected pa tients with AIDS was found. When calculated for bronchoalveolar lavage and lung biopsy samples, the positive and the negative predictive val ues of P. carinii PCR for PCP diagnosis in HIV-infected patients with AIDS were I and the specificity and the sensitivity were 100%. In cont rast, in the group of patients with leukemia or lymphoma, the positive predictive value of the nested PCR for these materials was found to b e as low as 0.09, the negative predictive value was 0.73, the specific ity was 44.4%, and the sensitivity was 25.0%. No P. carinii DNA could be detected in specimens from immunocompetent patients. In summary, in contrast to patients with leukemia and lymphoma, nested PCR seems to be a sensitive and specific tool for PCP diagnosis in HIV-infected pat ients with AIDS.