PCR-based quantification of Pneumocystis carinii in in vitro systems

In many laboratories, PCR has become a routine method for the sensitive dia gnosis of Pneumocystis carinii in patient samples. In contrast, quantificat ion of fungal numbers in in vitro setups still largely relies on more conve ntional procedures such as histological stainings. These are rime consuming and their applications are limited when dealing with small fungal numbers contaminated with tissue and cellular debris. This study presents a sensiti ve and rapid method for P. carinii quantification based on PCR analysis tha t can be easily integrated into standard detection procedures without requi ring any major additional steps. P. carinii-specific PCR performed with tot al DNA extracted from both standard samples with known fungal numbers and e xperimental samples was quantified relative to PCR products of a standard c oncentration from a control plasmid added prior to DNA extraction. This mea sure controlled for variations in DNA extraction and PCR efficiency among t he samples to be compared. The correlation between analyzed P. carinii-spec ific DNA and the actual fungal numbers employed was highly significant. (C) 2000 Editions scientifiques ec medicales Elsevier SAS.