In vitro studies of activities of the antifungal triazoles SCH56592 and itraconazole against Candida albicans, Cryptococcus neoformans, and other pathogenic yeasts.

1997 ◽  
Vol 41 (1) ◽  
pp. 180-183 ◽  
Author(s):  
J N Galgiani ◽  
M L Lewis
Keyword(s):  
Incubation Temperature ◽  
Clinical Laboratory ◽  
Synthetic Medium ◽  
Reference Method ◽  
Inoculum Size ◽  
Antifungal Drugs ◽  
Yeast Cells ◽  
National Committee ◽  
Broth Macrodilution

We investigated the effects of various assay conditions on the activities of two antifungal drugs, SCH56592 and itraconazole, against seven species of fungi by the broth macrodilution testing procedure proposed by the National Committee for Clinical Laboratory Standards (NCCLS). For both drugs, which are insoluble in water, the concentration and type of solubilizing agent produced differences in drug activity. Starting inoculum size differences from 10(2) to 10(5) yeast cells per ml resulted in approximately a fourfold effect on the MIC of both drugs, but other significant differences were not observed with variations in synthetic medium composition, pH, buffering reagent, or incubation temperature. Under standardized conditions of reference method M27-T with 1% polyethylene glycol as the solubilizing agent, median MICs of SCH56592 and itraconazole of 60 and 125 mg/ml, respectively, were demonstrated for 110 strains (12 to 23 strains for each of seven species). Broth microdilution results were typically severalfold higher than broth macrodilution results. We conclude that the NCCLS standard reference method can be applied without modification to the testing of SCH56592 and itraconazole, but particular attention to solubilizing the agents is critical to obtaining consistent results.

scholarly journals Comparison of the in vitro activities of the echinocandin LY303366, the pneumocandin MK-0991, and fluconazole against Candida species and Cryptococcus neoformans.

1997 ◽  
Vol 41 (9) ◽  
pp. 1957-1960 ◽  
Author(s):  
T V Krishnarao ◽  
J N Galgiani
Keyword(s):  
Cryptococcus Neoformans ◽  
Candida Species ◽  
Clinical Laboratory ◽  
Inoculum Size ◽  
National Committee ◽  
Broth Microdilution ◽  
Test Conditions ◽  
Broth Macrodilution ◽  
Glucan Synthesis

Two new glucan synthesis inhibitors, the echinocandin LY303366 and the pneumocandin MK-0991 (formerly L-743,872), were studied for their antifungal activities in vitro in relation to each other and in relation to the activity of the triazole fluconazole. Systematic analysis of broth macrodilution testing by varying the starting inoculum size, medium composition, medium pH, temperature of incubation, length of incubation, or selection of endpoints failed to identify significant differences in antifungal activity for either LY303366 or MK-0991 in comparison to the activity under standard test conditions specified for other antifungal agents in National Committee for Clinical Laboratory Standards (NCCLS) document M27A. Under standardized conditions, both drugs exhibited prominent activity against Candida species including Candida glabrata and Candida krusei but showed little activity against Cryptococcus neoformans. This spectrum of activity differed from that of fluconazole, which exhibited marginal activity against C. glabrata and C. krusei but prominent activity against other Candida species and C. neoformans. For individual strains, broth microdilution MICs of LY303366 and MK-0991 were similar to but frequently higher than broth macrodilution results. In contrast, fluconazole broth microdilution MICs were often lower than broth microdilution results. We conclude that the test conditions specified in NCCLS document M27A are applicable to these two new glucan synthesis inhibitors and that systematic differences between broth microdilution procedures and the broth macrodilution reference standard will need to be addressed before the two test methods can be used interchangeably.

scholarly journals In Vitro Testing of Susceptibilities of Filamentous Ascomycetes to Voriconazole, Itraconazole, and Amphotericin B, with Consideration of Phylogenetic Implications

1998 ◽  
Vol 36 (8) ◽  
pp. 2353-2355 ◽  
Author(s):  
Michael R. McGinnis ◽  
Lester Pasarell
Keyword(s):  
Amphotericin B ◽  
Clinical Laboratory ◽  
Reference Method ◽  
Antifungal Drugs ◽  
National Committee ◽  
In Vitro Testing ◽  
Phylogenetic Relatedness ◽  
Phylogenetic Implications ◽  
The Family

The in vitro susceptibilities of three hundred eighty-one isolates representing two classes, five orders, nine families, 30 genera, and 51 species of ascomycetous fungi to voriconazole, itraconazole, and amphotericin B were tested by using a modification of the National Committee for Clinical Laboratory Standards M27-A reference method. For those fungi of known phylogenetic relatedness, drug MICs were consistently low for isolates among all clades, except for members of the family Microascaceae. The highest MICs of all drugs tested were consistently for the Microascaceae, supporting the observation of fungal phylogeny and corresponding susceptibility to antifungal drugs. Itraconazole and voriconazole have a broad range of activity against phylogenetically similar agents of hyalohyphomycosis, phaeohyphomycosis, chromoblastomycosis, and mycetoma.

scholarly journals Evaluation of a flow cytofluorometric method for rapid determination of amphotericin B susceptibility of yeast isolates.

1997 ◽  
Vol 41 (7) ◽  
pp. 1537-1540 ◽  
Author(s):  
F Peyron ◽  
A Favel ◽  
H Guiraud-Dauriac ◽  
M El Mzibri ◽  
C Chastin ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Fluorescence Intensity ◽  
Clinical Laboratory ◽  
Rapid Determination ◽  
Reference Method ◽  
National Committee ◽  
Candida Spp ◽  
Broth Macrodilution

A rapid-flow cytofluorometric susceptibility test for in vitro amphotericin B testing of yeasts was evaluated and compared to the National Committee for Clinical Laboratory Standards (NCCLS) M27-T reference broth macrodilution method. The flow cytofluorometric method is based on the detection of decreased green fluorescence intensity of cells stained with DiOC5(3), a membrane potential-sensitive cationic dye, after drug treatment. Testing was performed on 134 clinical isolates (Candida spp. and Torulopsis glabrata). From the dose-response curve obtained for each isolate, three endpoints were calculated by computer analysis (the concentrations at which the fluorescence intensity was reduced by 50, 80, and 90%, i.e., 50% inhibitory concentration [IC50], IC80, and IC90, respectively). A regression analysis correlating these endpoints with the M27-T MICs showed that the best agreement was obtained with IC80. The flow cytofluorometric method showed good reproducibility with control strains. These initial results suggest that the flow cytofluorometric method is a valid alternative to the NCCLS reference method.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

scholarly journals Comparison of NCCLS and 3-(4,5-Dimethyl-2-Thiazyl)-2,5-Diphenyl-2H-Tetrazolium Bromide (MTT) Methods of In Vitro Susceptibility Testing of Filamentous Fungi and Development of a New Simplified Method

2000 ◽  
Vol 38 (8) ◽  
pp. 2949-2954 ◽  
Author(s):  
Joseph Meletiadis ◽  
Jacques F. G. M. Meis ◽  
Johan W. Mouton ◽  
J. Peter Donnelly ◽  
Paul E. Verweij
Keyword(s):  
Filamentous Fungi ◽  
Clinical Laboratory ◽  
Colorimetric Method ◽  
Antifungal Drugs ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Initial Inoculum ◽  
Tetrazolium Bromide ◽  
Mtt Method

The susceptibility of 30 clinical isolates belonging to six different species of filamentous fungi (Aspergillus fumigatus, Aspergillus flavus, Scedosporium prolificans, Scedosporium apiospermum, Fusarium solani, and Fusarium oxysporum) was tested against six antifungal drugs (miconazole, voriconazole, itraconazole, UR9825, terbinafine, and amphotericin B) with the microdilution method recommended by the National Committee for Clinical Laboratory Standards (NCCLS) (M38-P). The MICs were compared with the MICs obtained by a colorimetric method measuring the reduction of the dye 3-(4,5-dimethyl-2-thiazyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan by viable fungi. The levels of agreement between the two methods were 96 and 92% for MIC-0 (clear wells) and MIC-1 (75% growth reduction), respectively. The levels of agreement were always higher for Aspergillus spp. (97% ± 2.5%), followed byScedosporium spp. (87% ± 10.3%) and Fusariumspp. (78% ± 7.8%). The NCCLS method was more reproducible than the MTT method: 98 versus 95% for MIC-0 and 97 versus 90% for MIC-1. However, the percentage of hyphal growth as determined visually by the NCCLS method showed several discrepancies when they were compared with the percentages of MTT reduction. A new simplified assay that incorporates the dye MTT with the initial inoculum and in which the fungi are incubated with the dye for 48 h or more was developed, showing comparable levels of agreement and reproducibility with the other two methods. Furthermore, the new assay was easier to perform and more sensitive than the MTT method.

scholarly journals Antifungal susceptibility testing.

1993 ◽  
Vol 6 (4) ◽  
pp. 367-381 ◽  
Author(s):  
J H Rex ◽  
M A Pfaller ◽  
M G Rinaldi ◽  
A Polak ◽  
J N Galgiani
Keyword(s):  
Susceptibility Testing ◽  
Incubation Temperature ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Inoculum Size ◽  
Antifungal Susceptibility Testing ◽  
National Committee ◽  
Candida Spp ◽  
Interlaboratory Variability ◽  
Future Work

Unlike antibacterial susceptibility testing, reliable antifungal susceptibility testing is still largely in its infancy. Many methods have been described, but they produce widely discrepant results unless such factors as pH, inoculum size, medium formulation, incubation time, and incubation temperature are carefully controlled. Even when laboratories agree upon a common method, interlaboratory agreement may be poor. As a result of numerous collaborative projects carried out both independently and under the aegis of the Subcommittee on Antifungal Susceptibility Testing of the National Committee for Clinical Laboratory Standards, the effects of varying these factors have been extensively studied and a standard method which minimizes interlaboratory variability during the testing of Candida spp. and Cryptococcus neoformans has been proposed. This review summarizes this work, reviews the strengths and weaknesses of the proposed susceptibility testing standard, and identifies directions for future work.

scholarly journals In Vitro Activities of Free and Lipid Formulations of Amphotericin B and Nystatin against Clinical Isolates of Coccidioides immitis at Various Saprobic Stages

2002 ◽  
Vol 46 (5) ◽  
pp. 1583-1585 ◽  
Author(s):  
Gloria M. González ◽  
Rolando Tijerina ◽  
Deanna A. Sutton ◽  
John R. Graybill ◽  
Michael G. Rinaldi
Keyword(s):  
Amphotericin B ◽  
Clinical Laboratory ◽  
National Committee ◽  
Growth Stages ◽  
Coccidioides Immitis ◽  
In Vitro Susceptibility ◽  
Broth Macrodilution ◽  
Lipid Formulations ◽  
Different Growth Stages

ABSTRACT We investigated the susceptibilities of hyphal, mixed hyphal, ungerminated arthroconidial, and germinated arthroconidial populations of Coccidioides immitis to lipid formulations of amphotericin B and nystatin and their conventional preparations, utilizing the National Committee for Clinical Laboratory Standards M38-P broth macrodilution method. The differences in effects of the three different growth stages of the saprobic phase of C. immitis on the MIC/minimum lethal concentration (MLC) ratio were not statistically significant for any of the antifungal agents tested. These results suggest that either inocula could be used for in vitro susceptibility studies with C. immitis.

scholarly journals Determination of Antifungal MICs by a Rapid Susceptibility Assay

2000 ◽  
Vol 38 (1) ◽  
pp. 333-340
Author(s):  
Marcia H. Riesselman ◽  
Kevin C. Hazen ◽  
Jim E. Cutler
Keyword(s):  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Colorimetric Method ◽  
Inoculum Size ◽  
Antifungal Drugs ◽  
Therapeutic Drug ◽  
National Committee ◽  
Substrate Uptake ◽  
Microtiter Assay ◽  
Susceptibility Assay

ABSTRACT A novel microtiter assay for antifungal susceptibility testing was developed. This method has several potential advantages over the M27-A assay of the National Committee for Clinical Laboratory Standards. These include provision of MIC results within 6 to 19 h, graphical display of data, and the availability of objective quantitative endpoints. We refer to the method as the rapid susceptibility assay (RSA). RSA is based on substrate utilization by fungi in the presence of antifungal drugs. Substrate uptake is determined by a colorimetric method, which can be scored by analysis of data obtained from a microplate reader. Variables evaluated in the development of the RSA included inoculum size, incubation period, and efficacy with different classes of antifungal drugs and different yeast isolates. With the rapidly available and quantitative endpoints of the RSA, correlation of MICs and therapeutic drug doses can be evaluated more successfully than they can be evaluated by existing assays.

scholarly journals In vitro susceptibilities of clinical and environmental isolates of Cryptococcus neoformans to five antifungal drugs.

1996 ◽  
Vol 40 (3) ◽  
pp. 822-824 ◽  
Author(s):  
S P Franzot ◽  
J S Hamdan
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Clinical Laboratory ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
National Committee ◽  
Environmental Isolates ◽  
Susceptibility Data

A total of 53 Cryptococcus neoformans strains, including clinical and environmental Brazilian isolates, were tested for their susceptibilities to amphotericin B, 5-flucytosine, ketoconazole, fluconazole, and itraconazole. The tests were performed according to the National Committee of Clinical Laboratory Standards recommendations (document M27-P). In general, there was a remarkable homogeneity of results for all strains, and comparable MICs were found for environmental and clinical isolates. This paper represents the first contribution in which susceptibility data for Brazilian C. neoformans isolates are provided.

scholarly journals In Vitro Activity of a New Oral Triazole, BMS-207147 (ER-30346)

1998 ◽  
Vol 42 (2) ◽  
pp. 313-318 ◽  
Author(s):  
Joan C. Fung-Tomc ◽  
Elizabeth Huczko ◽  
Beatrice Minassian ◽  
Daniel P. Bonner
Keyword(s):  
Filamentous Fungi ◽  
Clinical Laboratory ◽  
Sporothrix Schenckii ◽  
Fungal Species ◽  
National Committee ◽  
Microsporum Gypseum ◽  
Dematiaceous Fungi ◽  
Pseudallescheria Boydii ◽  
Broth Macrodilution

ABSTRACT The antifungal activity of BMS-207147 (also known as ER-30346) was compared to those of itraconazole and fluconazole against 250 strains of fungi representing 44 fungal species. MICs were determined by using the National Committee for Clinical Laboratory Standards (NCCLS)-recommended broth macrodilution method for yeasts, which was modified for filamentous fungi. BMS-207147 was about two- to fourfold more potent than itraconazole and about 40-fold more active than fluconazole against yeasts. With the NCCLS-recommended resistant MIC breakpoints of ≥1 μg/ml for itraconazole and of ≥64 μg/ml for fluconazole against Candida spp., itraconazole and fluconazole were inactive against strains of Candida kruseiand Candida tropicalis. In contrast, all but 9 (allC. tropicalis) of the 116 Candida strains tested had BMS-207147 MICs of <1 μg/ml. The three triazoles were active against about half of the Candida glabrata strains and against all of the Cryptococcus neoformans strains tested. The three triazoles were fungistatic to most yeast species, except for BMS-207147 and itraconazole, which were fungicidal to cryptococci. BMS-207147 and itraconazole were inhibitory to most aspergilli, and against half of the isolates, the activity was cidal. BMS-207147 and itraconazole were active, though not cidal, against most hyaline Hyphomycetes (with the exception ofFusarium spp. and Pseudallescheria boydii), dermatophytes, and the dematiaceous fungi and inactive againstSporothrix schenckii and zygomycetes. Fluconazole, on the other hand, was inactive against most filamentous fungi with the exception of dermatophytes other than Microsporum gypseum. Thus, the spectrum and potency of BMS-207147 indicate that it should be a candidate for clinical development.

Sign in / Sign up

Export Citation Format

Share Document