RESUMEN
Advances in molecular technology have helped in better understanding of mechanisms and diagnosis of diseases in many medical fields.Several molecular techniques are available for determining the genotypic drug-resistance and monitoring epidemic spread of a particular antimicrobial resistance gene in a hospital or patient population.The molecular [genotypic] testing has several advantages over conventional [phenotypic] testing in being faster and unambiguous, more accurate, able to detect masked resistance and can serve as a "gold" or "reference" test for detecting antibiotic resistance genes. This article addresses these molecular tests with their application and limitations and provide examples of their use especially in Mycobacterium tuberculosis and methicillin resistant Staphylococcus aureus