EFFECTS OF INCUBATION-TEMPERATURE, INOCULUM SIZE, AND TIME OF READINGON BROTH MICRODILUTION SUSCEPTIBILITY TEST-RESULTS FOR AMPHOTERICIN-BAGAINST FUSARIUM

In vitro antifungal susceptibility testing for filamentous fungi remai ns unstandardized and is unreliable for determining adequate therapy, A study was performed to evaluate the effect of inoculum size (10(2), 10(3), 10(4), and 10(5) conidia/ml), incubation time (48 and 72 h), an d temperature (25, 30, and 35 degrees C) on MICs of amphotericin B for Fusarium spp, (20 strains), The inoculum size showed the dearest effe ct: when the inoculum was varied from 10(2) to 10(5) conidia/ml, the g eometric mean MICs showed increases of between 10- and 19-fold in all the combined conditions of temperature and incubation time assayed. Ti me of incubation had less effect (increases of between two- and threef old in approximately half of the geometric mean MICs), and temperature especially had little effect (the increases were no higher than twofo ld), The effects of interaction between inoculum size and temperature on MICs were not statistically significant, while the combined effects of inoculum size and time of reading and of time of reading and tempe rature produced systematic variation in MICs.