VARIABLE EFFICIENCY OF 3 PRIMER PAIRS FOR THE DIAGNOSIS OF PNEUMOCYSTIS-CARINII PNEUMONIA BY THE POLYMERASE CHAIN-REACTION

The efficiency of three different primer pairs, complementary to diffe rent Pneumocystis carinii DNA regions, was compared in the polymerase chain reaction (PCR) for the diagnosis of Pneumocystis carinii pneumon ia (PCP) on bronchoalveolar fluid (BALF) from patients with AIDS. PCR coupled with dot-blot hybridization (BLOT) using primers and probe fro m the mitochondrial 23SrDNA region showed the highest sensitivity, wit h a lower detection limit of 0.5-1 organisms mu l(-1). When testing 47 BALF, PCR plus BLOT of the mitochondrial 23SrDNA region showed also t he best diagnostic efficiency (97% sensitivity, 100% specificity). Sen sitivity was significantly higher than with PCR and BLOT of the 5SrDNA region (81.5% sensitivity; P=0.025, McNemar test); and of the dehydro folate reductase (DHFR) gene region (75.6% sensitivity; P=0.019). Sens itivity was also significantly higher than indirect immunofluorescence (75.8% sensitivity; P=0.008). Using DHFR primers and probe, specifici ty was also reduced. The diagnostic sensitivity in clinical specimens paralleled the detection limit in the standard dilutions. The use of r epeated DNA sequences of proven specificity as target of PCR amplifica tion favourably influences sensitivity and specificity. This comparati ve study demonstrates that primer selection plays a significant role i n the diagnosis of PCP by PCR. (C) 1995 Academic Press Limited