Antimicrobial susceptibility testing is a critical task in clinical microbiology laboratories to detect drug resistance in pathogens and ensure appropriate antibiotic treatment. Common methods include broth microdilution, disk diffusion, and gradient diffusion. Broth microdilution is widely used, with microdilution trays offering convenience and cost savings. Disk diffusion is simple and standardized, providing categorical results. The Etest uses a gradient strip to determine MICs but has limitations in accuracy for certain organisms. Automated systems like the MicroScan WalkAway, BD Phoenix, Vitek 2, and Sensititre ARIS 2X offer rapid results and improved accuracy, though they may not be as fast as manual methods. Interpretation of results relies on CLSI guidelines, which define susceptible, intermediate, and resistant categories. Accuracy is crucial, with FDA requirements for error rates. New resistance mechanisms require ongoing evaluation of testing methods. While phenotypic testing remains clinically relevant, molecular techniques have limited utility due to the complexity of resistance mechanisms. Future directions include developing faster, more accurate automated systems and improving resistance detection methods. Current methods are reliable when used according to established standards, but there is a need for continued improvement in rapid and accurate resistance detection.Antimicrobial susceptibility testing is a critical task in clinical microbiology laboratories to detect drug resistance in pathogens and ensure appropriate antibiotic treatment. Common methods include broth microdilution, disk diffusion, and gradient diffusion. Broth microdilution is widely used, with microdilution trays offering convenience and cost savings. Disk diffusion is simple and standardized, providing categorical results. The Etest uses a gradient strip to determine MICs but has limitations in accuracy for certain organisms. Automated systems like the MicroScan WalkAway, BD Phoenix, Vitek 2, and Sensititre ARIS 2X offer rapid results and improved accuracy, though they may not be as fast as manual methods. Interpretation of results relies on CLSI guidelines, which define susceptible, intermediate, and resistant categories. Accuracy is crucial, with FDA requirements for error rates. New resistance mechanisms require ongoing evaluation of testing methods. While phenotypic testing remains clinically relevant, molecular techniques have limited utility due to the complexity of resistance mechanisms. Future directions include developing faster, more accurate automated systems and improving resistance detection methods. Current methods are reliable when used according to established standards, but there is a need for continued improvement in rapid and accurate resistance detection.