Development of a PCR assay for diagnosis of Pneumocystis carinii pneumoniabased on amplification of the multicopy major surface glycoprotein gene family

We have evaluate a PCR technique using primers based on Pneumocystis carini i major surface glycoprotein (MSG) genes, a multicopy gene family, for util ity in detection of P. carinii in BAL and oropharyngeal samples obtained fr om immunosuppressed patients. These primers were able to detect P. carinii DNA in as little as 16 fg of genomic DNA. PCR using MSG primers detected P. carinii DNA in 7 smear-positive BAL samples (100% sensitivity, and found n o P. carinii DNA in 12 smear-negative BAL samples (100% specificity. Mitoch ondrial ribosomal RNA (mrRNA)primers, commonly used in PCR studies of PCP, defected P. carinii in six of seven positive samples (85.7% sensitivity) an d none of 12 were negative samples (100% specificity). Diagnosis of PCP by amplification of 81 oropharyngeal samples using MSG primers had a 50% sensi tivity (4/8) and 96% specificity (70/73). PCR with mrRNA primers was 37.5% sensitive (3/8) and 100% specific (73/73). All three false positive MSG res ults showed a very low intensity on Southern hybridization. PCR using MSG g ene primers should prove valuable in the diagnosis of PCP. (C) 1999 Elsevie r Science Inc.