Review of methods for susceptibility testing of anaerobes.

In the USA, the National Committee for Clinical Laboratory Standards has studied and published a reference agar dilution method for the susceptibility testing of anaerobic bacteria. While numerous investigators both in Europe and the USA have evaluated a variety of methods with a variety of modifications, only the broth microdilution method appears to be appropriate for routine use. The problems of the choice of breakpoint, inoculum size, media, media additives, endpoint recognition and other parameters affecting test performance and interpretation, while troublesome for anaerobes, are not unique to this group of organisms. The increasing resistance of anaerobes and the ever existing need to provide therapeutic guidance, surveillance for resistance and susceptibility data on new drugs make the need for an accurate and reliable susceptibility test for anaerobes critical. The newer methods, while showing promise, need further evaluation with all agents that have a therapeutic indication for anaerobic infections.