Yeast infections are an increasingly important problem and the recogni
tion of antifungal resistance stresses the need for improved susceptib
ility testing, Antifungal susceptibility testing has lacked reproducti
bility because of the absence of universally accepted guidelines. The
major sources of variation in susceptibility testing have been attribu
ted to the choice of medium and pH, inoculum preparation and size, inc
ubation temperature and time, and end-point criteria. These parameters
have been addressed by the National Commmittee for Clinical Laborator
y Standards (NCCLS) and proposed guidelines have recently been publish
ed (M27- P). Although major advances in fungal susceptibility testing
have been achieved, the results of studies to date do not support a co
rrelation between the results of in vitro susceptibility testing and i
n vivo response, Routine antifungal susceptibility testing of yeasts s
hould therefore be discouraged, Susceptibility testing of the filament
ous fungi is currently poorly developed.