PCR and its variations

The polymerase chain reaction (PCR) is an in vitro technique used to replicate, or amplify, a specific region of DNA billions-fold in a few hours or less [1-3]. The amplification is primer directed; oligonucleotide primers anneal to and flank the DNA region to be amplified. PCR is utilized in diagnostic and research laboratories to generate sufficient quantities of DNA to be adequately tested, analyzed, or manipulated. Because of the exquisite sensitivity it offers, PCR has rapidly become a standard method in diagnostic microbiology. More recently, reagent kits and various instrument platforms have added speed, flexibility, and simplicity [4-10]. How significant is the contribution of PCR to the field of biomedicine? A PubMed search in 2005 for the first edition of this book using the key word PCR produced 214,352 hits [11]. A search conducted in June 2011 using the same key word produced 259,042 hits.