Preparing for a Revolution in Antimicrobial Susceptibility Testing

Abstract

Our understanding of the pharmacology of antimicrobials has taken major leaps in the past few years, as has the science of antimicrobial susceptibility testing. In addition, the pathogenic bacteria vying for existence have started to regain the edge they had before the introduction of antimicrobials. The result is that we need to revise our vision of how to use antimicrobials. Antimicrobial therapy should be viewed like cardiac therapy: tailored to the animal, drug and disease. The days of one drug/one dose/all diseases are over.

But how can you as practitioners prepare for these changes? As with any diagnostic test, an understanding of how susceptibility testing works is critical for you to make reasonable decisions based on the results. This is not meant to be a discussion of microbiology, but rather the application of microbiology to pharmacology. Most veterinarians are familiar with the disc diffusion (KirbyBauer, BIOMIC system) and tube or plate dilution (e.g., Sensititre system) methods of susceptibility testing, but a quick review is in order.