Resistance as a cause of treatment failure

Clinicians and microbiologists both vary in their views on the usefulness of in-vitro antibacterial sensitivity tests, and on the significance of in-vitro resistance. This seems to relate to the fact that conditions in most in-vitro tests are remote from those in the patient, and that at best the designation 'resistant' depends on a pragmatic consensus. Furthermore, results of treatment are difficult to assess in infected patients because of the many variables that affect outcome. Well-designed clinical trials, when they are feasible, and the results of animal experiments, strongly suggest that, when it can be assessed, there is a good correlation between in-vitro and in-vivo results. There is a need to improve the content of clinical reports on the subject sent by microbiologists to clinicians.