Prospects for standardisation of methods and guidelines for disc susceptibility testing.

The disc diffusion method of susceptibility testing is widely used in diagnostic laboratories throughout the world. It is simple to perform and very suited to the clinical laboratory where a single isolate can be tested with a series of antibiotics in one experiment. For these two reasons the test is by far the commonest type of susceptibility method used. Other methods such as determination of the minimum inhibitory concentration or "breakpoint" methods are used in only a small number of laboratories. If standardisation of methods is to be achieved in order to agree on uniform reporting and guidelines, methods using disc tests are of the highest priority.