Polymerase chain reaction from bench to bedside. Applications for infectious disease.

The past decade has seen the rapid advancement of molecular biology and its application in the field of infectious diseases. The polymerase chain reaction (PCR) is a technique which allows for the in vitro amplification of DNA. The ability of this method to recognize and amplify small quantities of foreign genome from unpurified samples will revolutionize the diagnoses of microbial diseases which have previously been cumbersome or impossible. It has already been widely applied in this area, and clinical labs will soon be offering this test for selected pathogens. There are ongoing studies evaluating its use in CNS infections and for the identification of viruses in the immunocompromised host. The PCR is not without problems, particularly false positive results from contamination. Because it is so sensitive, the significance of a positive result in patients with latent or chronic infections is yet to be determined. As our knowledge and familiarity with PCR expands, it will become a powerful tool for the clinician to use to identify various infectious diseases.