Laboratory issues in the detection and reporting of antibacterial resistance

The emergence of antimicrobial resistance among several common bacterial pathogens requires that clinical microbiology laboratories have the ability to promptly and accurately recognize resistance in patients' isolates. Laboratories have several options for performing routine susceptibility testing including the broth microdilution procedure (with or without instrumentation for test reading), automated instrument systems that provide rapid results, antibiotic gradient diffusion, and disk diffusion procedures. In addition, there are definitive screening tests capable of recognizing resistance to drugs of choice among several common bacterial species based on single drug concentration tests or rapid spot tests. The likely emergence of still newer resistance mechanisms will provide a challenge to clinical microbiologists to devise accurate, yet cost-effective strategies for use in the future.