Evaluation of real-time quantitative PCR for identification and quantification of Chlamydia pneumoniae by comparison with immunohistochemistry

Chlamydia pneumoniae is a common cause of community-acquired pneumonia and it has been associated with atherosclerosis, C. pneumoniae has usually been diagnosed by serology using a microimmunofluorescence test. but more recen tly polymerase chain reaction (PCR) has been viewed as an advantageous alte rnative. We developed a quantitative real-time PCR for detection of C. pneu moniae. Primers were targeted for the pmp4 gene, and the PCR fragment was d etected real-time with a fluorescence resonance energy transfer probe set u sing a LightCycler instrument. The PCR was used on DNA released from 50 mum sections of paraffin-embedded formalin-fixed lung tissue from experimental ly infected mice. Thereby, the number of C. pneumoniae genomes was determin ed. To our knowledge this is the first rime quantification of C. pneumoniae DNA has: been attempted on paraffin-embedded formalin-fixed tissue. C. pne umoniae-specific immunohistochemistry (IHC) was done on 5 mum sections adja cent to the sections used in PCR, and the number of inclusions were counted in each section. Good correlation was found when comparing results from PC R and IHC, which is in contrast to many previous studies. (C) 2001 Elsevier Science B.V. All rights reserved.