Molecular Methods in Clinical Microbiology Introduction

Extract

One of the greatest challenges a clinical microbiologist encounters is identifying and reporting out pathogenic organisms in a timely manner. Physicians want results “stat” in order to prescribe the appropriate antimicrobial and prevent systemic spread of the infectious agent. Although the advent of automation and rapid methods has reduced turn-around times considerably, there are still fastidious organisms that may not grow well on conventional media making identification virtually impossible. These organisms can be extremely pathogenic and unless identified quickly can spread rapidly from person to person. Examples include patients infected with Mycobacterium tuberculosis (MTB), methicillin resistant Staph aureus (MRSA) and vancomycin resistant enterococcus (VRE). Fortunately, molecular diagnostic assays decrease turn around times and provide accurate and sensitive results in the identification of infectious agents. This in turn has allowed for prompt and accurate identification of pathogens, which ultimately improves patient outcomes and patient care.

Since the discovery of the DNA molecule in 1953 by James Watson and Francis Crick, the field of molecular biology has accelerated significantly, especially in the last two decades. The reason for this astonishing growth was the contribution of Dr. Kary Banks Mullis. In 1983 while driving one evening through northern California, Dr. Mullis thought of a way to amplify DNA so that billions of copies could be generated in a matter of hours.¹ Dr. Mullis, who was working at Cetus Corporation in Emeryville, California at the time invented the technique called the polymerase chain reaction (PCR). PCR has revolutionized the field of molecular biology, biochemistry,…

ABBREVIATIONS: bDNA = Branched DNA; DNA = Deoxyribonucleic Acid; dNTP = Deoxyribonucleotides; dATP = Deoxyadenosine Triphosphate; dCTP = Deoxycytidine Triphosphate; dGTP = Deoxyguanosine Triphosphate; dTTP = Deoxythymidine Triphosphate; FDA = Food and Drug Administration; FRET = Fluorescence Resonance Energy Transfer; MRSA = Methicillin Resistant Staph aureus; MTB = Mycobacterium tuberculosis; NASBA = Nucleic Acid Sequence Based Amplification; PCR = Polymerase Chain Reaction; PFGE = Pulsed-Field Gel Electrophoresis; RT-PCR = Reverse Transcription Polymerase Chain Reaction; Taq = Thermus aquaticus; TMA = Transcription-Mediated Amplification; VRE = Vancomycin Resistant Enterococcus.