The 1997 Garrod Lecture. The subtleties of antibiotic resistance.

Although the qualitative aspects of antibiotic resistance are increasingly well understood, our understanding of the quantitative aspects has always lagged. Deficiency of understanding or of investigation affects the methods used to characterize the phenotypes of organisms from clinical sources, delays acquisition of knowledge of the importance of quantitative diversity in patient management, and introduces error into epidemiological studies of the prevalence of resistance. This, in turn, gives rise to a devaluation of the work done in diagnostic laboratories in relation to the technology of sensitivity testing, to the interpretation of their results for clinicians, including those used in clinical trials, and to the statistical analyses of resistance trends used inter alia as a guide to empirical antibiotic therapy and to test the efficacy of methods of control. There is a need to bring about a shift of opinion of those who provide funds, in relation to the role of clinical microbiologists and infectious diseases clinicians in defining and solving these problems.