The article "Antimicrobial Susceptibility Testing: A Review of General Principles and Contemporary Practices" by James H. Jorgensen and Mary Jane Ferraro discusses the importance of antimicrobial susceptibility testing (AST) in clinical microbiology laboratories. The primary goals of AST are to detect drug resistance in common pathogens and ensure susceptibility to the chosen drugs for specific infections. Various testing methods, including broth microdilution, rapid automated instruments, disk diffusion, and gradient diffusion, are described, each with its strengths and weaknesses. Broth microdilution provides quantitative results (minimum inhibitory concentration, MIC) but is labor-intensive, while disk diffusion and gradient diffusion offer qualitative assessments (susceptible, intermediate, or resistant) and are more cost-effective and user-friendly. The article also highlights the emergence of new resistance mechanisms and the need for constant vigilance in testing methods. It emphasizes the importance of selecting appropriate drugs for routine testing based on the isolated organism, infection site, and institutional formulary. Interpretation of test results must be done by the laboratory using current criteria from sources like the Clinical and Laboratory Standards Institute (CLSI). The accuracy of AST methods is crucial, with the FDA requiring very major errors to be less than 1.5% and major errors not exceeding 3%. The article concludes by discussing the future directions for AST, including the need for faster and more accurate methods to detect bacterial resistance.The article "Antimicrobial Susceptibility Testing: A Review of General Principles and Contemporary Practices" by James H. Jorgensen and Mary Jane Ferraro discusses the importance of antimicrobial susceptibility testing (AST) in clinical microbiology laboratories. The primary goals of AST are to detect drug resistance in common pathogens and ensure susceptibility to the chosen drugs for specific infections. Various testing methods, including broth microdilution, rapid automated instruments, disk diffusion, and gradient diffusion, are described, each with its strengths and weaknesses. Broth microdilution provides quantitative results (minimum inhibitory concentration, MIC) but is labor-intensive, while disk diffusion and gradient diffusion offer qualitative assessments (susceptible, intermediate, or resistant) and are more cost-effective and user-friendly. The article also highlights the emergence of new resistance mechanisms and the need for constant vigilance in testing methods. It emphasizes the importance of selecting appropriate drugs for routine testing based on the isolated organism, infection site, and institutional formulary. Interpretation of test results must be done by the laboratory using current criteria from sources like the Clinical and Laboratory Standards Institute (CLSI). The accuracy of AST methods is crucial, with the FDA requiring very major errors to be less than 1.5% and major errors not exceeding 3%. The article concludes by discussing the future directions for AST, including the need for faster and more accurate methods to detect bacterial resistance.