Minimum inhibitory concentration-guided antimicrobial therapy - the Achilles heel in the antimicrobial stewardship agenda.

The global problem of resistance to antimicrobials has resulted in a co-ordinated drive to use antimicrobial agents more responsibly. At a clinical level this is promoted through antimicrobial stewardship which demands appropriate use through optimal drug selection. Many factors play a role in this process of selection, antimicrobial susceptibility and the pharmacodynamics of the drug being two key determinants. Yet the detail provided by current diagnostic antimicrobial susceptibility testing is suboptimal and does not allow for adequate dose optimisation. The minimum inhibitory concentration (MIC) which underlies all antimicrobial susceptibility testing is largely ignored in the decision-making process of optimal drug selection. Understanding and application of MIC-guided antimicrobial therapy is desperately needed if antimicrobial stewardship is to truly fulfil its mandate.