Use of molecular techniques for the detection of antibiotic resistance in bacteria.

The introduction of antibiotics in the 1930s revolutionized the treatment of previously fatal infections. Unfortunately, bacteria adapted quickly to this threat and antibiotic resistance soon developed. Both penicillin and methicillin resistance in Staphylococcus aureus were noted almost immediately following the introduction of penicillin and the penicillinase-resistant penicillins respectively. Antibiotic susceptibility testing rapidly became an integral part of the management of patients with infectious disease and remains the basis for clinical decision-making and antibiotic selection. However, the fundamental principles underlying antibiotic susceptibility testing methods have remained largely unchanged over the last few decades. Due to the inherent time delay imposed by bacterial growth rates, culture-based systems have traditionally provided results several hours to days after initial isolation. Better understanding of the genetic basis of resistance has resulted in the development of molecular methods to detect the genetic changes or mutations present in resistant bacterial phenotypes. Microbiologists and clinicians are faced with increasing options for the use of genotypic or phenotypic methods. This review provides an insight into the current molecular methods available for the detection of antibiotic resistance and to provide a basis for evaluating the choice of testing method to be used.