Interpretation of antibacterial susceptibility reports - In vitro versus clinical break-points

Currently, antibacterial activity is measured primarily via in vitro labora tory tests. Clinicians rely heavily upon the reported susceptibility gained via in vitro laboratory tests when choosing an antibacterial agent. An evo lving concept is to utilise pharmacodynamic and pharmacokinetic drug proper ties in addition to in vitro susceptibility reports to assess the potential effectiveness of an antibacterial agent against a specific pathogen. This article presents examples of the utility of these concepts in terms of opti mal clinical use of common antibacterials as well as more informed interpre tation of the in vitro literature.