Comparison of the minimum fungicidal concentration of amphotericin B determined in filamentous fungi by macrodilution and microdilution methods.
Minimum fungicidal concentration (MFC) determination could be useful in severe fungal infections in immunocompromised patients. No reference tests to determine the MFC are available, and both macro- and microdilution methods are commonly used. In this study, discrepancies between minimum inhibitory concentrations (MICs) and MFCs of amphotericin B against 58 isolates of filamentous fungi other than Aspergillus (46 Fusarium spp., six Paecilomyces spp. and six Scopulariopsis spp.), obtained with macro- and microdilution methods, were evaluated. Additionally, the agreement between MFCs obtained by both methods were analyzed. In general MFCs were higher than the corresponding MICs overall using the macrodilution method. MFCs were more than one dilution higher than MICs in 52.3% of the cases in the macrodilution test and in 20.5% of the cases in microdilution test. The degree of agreement between MFCs obtained with the two methods was of 70.4% (Kappa coefficient of 0.5). In general, the macrodilution method showed higher MFC values than the microdilution method. Differences of up to six drug dilutions were observed between MFCs obtained by both methods.
Pujol
I
I
Laboratori de Microbiologia, Hospital Universitari de Sant Joan de Reus, Tarragona, Spain.
Aguilar
C
C
Fernández-Ballart
J
J
Guarro
J
J
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008826:Microbial Sensitivity Tests / Q000379:methods*; D003904:Mitosporic Fungi / Q000187:drug effects*
D000935:Antifungal Agents; D000666:Amphotericin B