Practical aspects of PCR application in microbiological diagnostic

Polymer chain reaction (PCR) is a very sensitive, rapid, and specific diagnostic method for identifying genotype markers of pathogenic and non-pathogenic micro-organisms. PCR-based assays are able to detect microbial nucleic acids in clinical samples and do not require time-consuming growth of the organisms in-vitro. Although these tests are rapid, sensitive, and specific they may have many limitations such as false positive or false negative results due to the presence of DNA polymer inhibitors in the sample tested. Several factors must be taken into account during the development and optimization of PCR assays, associated both with DNA templates and amplification reaction primers as well as with the components and parameters of the amplification test. PCR-based methods that are introduced for the first time into laboratory practice need an appropriate validation process with several positive and negative standard controls. New generation tests (with fluorogenic probes, e.g. TaqMan system or chip technology), which have proven to be a huge leap forward in the process of nucleic acid identification of pathogenic micro-organisms, are an important component of modern microbiological diagnosis and molecular epidemiology.