The polymerase chain reaction: a revolutionary new procedure for the laboratory diagnosis of infectious disease.

The polymerase chain reaction (PCR) is a revolutionary new means of amplifying, ie, replicating, selected DNA sequences in vitro. This procedure is rapid, requiring approximately 5 hours for completion, and exquisitely sensitive. Studies have shown that as few as one microorganism can be detected. Thus, it has the potential for revolutionizing the diagnosis of infections. Because of its expense, its immediate role will probably be restricted to infections where the causative organism cannot be cultured or is difficult to detect by conventional means. As further progress occurs, however, this technique may well become a major new tool for diagnosing infections.