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A Espinel-Ingroff

Publications and source records attributed to A Espinel-Ingroff.

At least 55 records · Page 3Linked to original sources
PubMed1998

In vitro activity of the new triazole voriconazole (UK-109,496) against opportunistic filamentous and dimorphic fungi and common and emerging yeast pathogens.

The in vitro antifungal activity of a new triazole derivative, voriconazole, was compared with those of itraconazole and amphotericin B against 67 isolates of Aspergillus flavus, Aspergillus fumigatus, Bipolaris spp., Fusarium oxysporum, Fusarium solani, Pseudallescheria boydii, Rhizopus arrhizus, Blastomyces dermatitidis, Histoplasma capsulatum, and Sporothrix schenckii. The in vitro activities of voriconazole were also compared with those of amphotericin B, fluconazole, and itraconazole against 189 isolates of emerging and common yeast pathogens of Blastoschizomyces capitatus, Candida (13 species), Cryptococcus neoformans, Hansenula anomala, Rhodotorula rubra, Saccharomyces cerevisiae, Sporobolomyces salmonicolor, and Trichosporon beigelii. MICs were determined according to a procedure under evaluation by the National Committee for Clinical Laboratory Standards (NCCLS) for broth microdilution testing of filamentous fungi and by the NCCLS M27-A broth microdilution method for yeasts. The in vitro activities of voriconazole were similar to or better than those of itraconazole and amphotericin B against Aspergillus spp., Fusarium spp., and P. boydii as well as against B. dermatitidis and H. capsulatum. The activities of voriconazole were also comparable to or better than those of amphotericin B, fluconazole, and itraconazole against most species of yeasts tested. Exceptions were certain isolates of R. rubra and S. salmonicolor. These results suggest that voriconazole has a wide spectrum of activity in vitro; its effectiveness in the treatment of human mycoses is under evaluation in clinical trials.

Antifungal Agents↗
PubMed1998

Comparison of In vitro activities of the new triazole SCH56592 and the echinocandins MK-0991 (L-743,872) and LY303366 against opportunistic filamentous and dimorphic fungi and yeasts.

The in vitro antifungal activities of SCH56592, MK-0991, and LY303366 against 83 isolates of Acremonium strictum, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Bipolaris spp., Blastomyces dermatitidis, Cladophialophora bantiana, Fusarium oxysporum, Fusarium solani, Histoplasma capsulatum, Phialophora spp., Pseudallescheria boydii, Rhizopus arrhizus, Scedosporium prolificans, and Sporothrix schenckii were compared. The in vitro activities of these agents against 104 isolates of yeast pathogens of Candida spp., Cryptococcus neoformans, and Trichosporon beigelii were also compared. MICs were determined by following a procedure under evaluation by the National Committee for Clinical Laboratory Standards (NCCLS) for broth microdilution testing of the filamentous fungi (visual MICs) and the NCCLS M27-A broth microdilution method for yeasts (both visual and turbidimetric MICs). The in vitro fungicidal activity of SCH56592 was superior (minimum fungicidal concentrations [MFCs], 0.25 to 4 microgram/ml for 7 of 18 species tested) to those of MK-0991 and LY303366 (MFCs, 8 to >16 microgram/ml for all species tested) for the molds tested, but the echinocandins had a broader spectrum of fungicidal activity (MFCs at which 90% of strains are inhibited [MFC90s], 0.5 to 4 microgram/ml for 6 of 9 species tested) than SCH56592 (MFC90s, 0.25 to 8 microgram/ml for 4 of 9 species tested) against most of the yeasts tested. Neither echinocandin had in vitro activity (MICs, >16 microgram/ml) against C. neoformans and T. beigelii, while the SCH56592 MICs ranged from 0.12 to 1.0 microgram/ml for these two species. The MICs of the three agents for the other species ranged from <0.03 to 4 microgram/ml. These results suggest that these new agents have broad-spectrum activities in vitro; their effectiveness in the treatment of human mycoses is to be determined.

Anidulafungin↗
PubMed1998

Comparison of RapID yeast plus system with API 20C system for identification of common, new, and emerging yeast pathogens.

The ability to identify yeast isolates by the new enzymatic RapID Yeast Plus System was compared to the ability to identify yeast isolates by the API 20C system. A total of 447 yeast isolates representing Blastoschizomyces capitatus, 17 Candida spp., 5 Cryptococcus spp., Geotrichum spp., 2 Hanseniaspora spp., Hansenula anomala, Hansenula wingei, 3 Rhodotorula spp., Saccharomyces cerevisiae, Sporobolomyces salmonicolor, Trichosporon beigelii, and 2 Prototheca spp. were evaluated. Also, five quality control strains (Candida spp. and Cryptococcus laurentii) with well-documented reactivities by the RapID Yeast Plus System were used. Each isolate was evaluated by both methods with a 48-h culture grown at 30 degrees C on Sabouraud dextrose agar (Emmons modification) by following the recommendations of the manufacturers. The RapID Yeast Plus System enzymatic reactions were read after 4 h of incubation, and the API 20C carbohydrate assimilation identification profiles were obtained after 72 h of incubation. There was good (95.7%) agreement between the identifications obtained by the two methods with the eight common Candida spp. and with Cryptococcus neoformans. The agreement was lower when the emerging Candida spp. and other yeast-like pathogens were tested (79.1 and 75.2%, respectively). These preliminary data suggest the potential utility of the RapID Yeast Plus System for use in the clinical laboratory for the rapid identification of common yeast pathogens as well as certain new and emerging species.

Yeasts↗
PubMed1998

Standardization of antifungal susceptibility testing and clinical relevance.

Standardization of antifungal susceptibility testing became essential to overcome the problem of interlaboratory variability and to determine the clinical relevance of in vitro data. This evolving process began for the yeasts and consequently broth macrodilution and microdilution methods (NCCLS M27 document) have been developed. These tests may not be useful for testing all organism-drug combinations or be the most convenient techniques for routine use in the clinical laboratory. Different alternatives to the NCCLS methods are currently under investigation. The identification of standard guidelines for antifungal susceptibility testing has reduced interlaboratory variability and further progress has been achieved with the determination of tentative interpretive breakpoints for certain drug-yeast combinations. However, these breakpoints are not adequate for interpretations of MICs for fungi-drug combinations beyond the setting for which they were determined. The NCCLS Subcommittee has also generated data for proposed testing guidelines for the moulds.

Antifungal Agents↗
PubMed1997

Clinical relevance of antifungal resistance.

The availability of standard guidelines (NCCLS M27 document) for antifungal susceptibility testing has facilitated the establishment of tentative interpretive breakpoints for fluconazole and itraconazole by the NCCLS. Based on correlations of MIC values with the outcomes of patients with mostly Candida infections, fluconazole MICs of > or = 64 and itraconazole MICs of > or = 1.0 microgram/mL are considered resistant. Fluconazole MICs of 16 to 32 micrograms/mL and itraconazole MICs of 0.2 to 0.5 microgram/mL were categorized as "susceptible dependent upon dose" (S-DD), that is, clinical response may be obtained with increased doses. Susceptible breakpoints for fluconazole and itraconazole correspond to < or = 8 and < or = 0.12 microgram/mL, respectively. For flucytosine, resistant and susceptible breakpoints for Candida were set at > or = 32 micrograms/mL and 4 micrograms/mL, respectively, based on historical data and the drug's pharmacokinetics for Candida. Although no breakpoints have been established for amphotericin B, clinical failure has been associated with MICs > 1.0 microgram/mL.

Amphotericin B↗
PubMed1997

Development of interpretive breakpoints for antifungal susceptibility testing: conceptual framework and analysis of in vitro-in vivo correlation data for fluconazole, itraconazole, and candida infections. Subcommittee on Antifungal Susceptibility Testing of the National Committee for Clinical Laboratory Standards.

The availability of reproducible antifungal susceptibility testing methods now permits analysis of data correlating susceptibility in vitro with outcome in vivo in order to define interpretive breakpoints. In this paper, we have examined the conceptual framework underlying interpretation of antimicrobial susceptibility testing results and then used these ideas to drive analysis of data packages developed by the respective manufacturers that correlate fluconazole and itraconazole MICs with outcome of candidal infections. Tentative fluconazole interpretive breakpoints for MICs determined by the National Committee for Clinical Laboratory Standards' M27-T broth macrodilution methodology are proposed: isolates for which MICs are < or = 8 microg/mL are susceptible to fluconazole, whereas those for which MICs are > or = 64 microg/mL appear resistant. Isolates for which the MIC of fluconazole is 16-32 microg/mL are considered susceptible dependent upon dose (S-DD), on the basis of data indicating clinical response when > 100 mg of fluconazole per day is given. These breakpoints do not, however, apply to Candida krusei, as it is considered inherently resistant to fluconazole. Tentative interpretive MIC breakpoints for itraconazole apply only to mucosal candidal infections and are as follows: susceptible, < or = 0.125 microg/mL; S-DD, 0.25-0.5 microg/mL; and resistant, > or = 1.0 microg/mL. These tentative breakpoints are now open for public commentary.

Animals↗
PubMed1997

Multicenter evaluation of proposed standardized procedure for antifungal susceptibility testing of filamentous fungi.

A multicenter study was conducted to expand the generation and analysis of data that supports the proposal of a reference method for the antifungal susceptibility testing of filamentous fungi. Broth microdilution MICs of amphotericin B and itraconazole were determined in 11 centers against 30 coded duplicate pairs of Aspergillus spp., Fusarium spp., Pseudallescheria boydii, and Rhizopus arrhizus. The effect of inoculum density (approximately 10(3) and 10(4) CFU/ml), incubation time (24, 48, and 72 h), and procedure of MIC determination (conventional and colorimetric [Alamar Blue] evaluation of growth inhibition) on intra- and interlaboratory agreement was analyzed. Based on intra- (97 to 100%) and interlaboratory (94 to 95%) agreement for both drugs, the overall optimal testing conditions identified were determination of colorimetric MICs after 48 to 72 h of incubation with an inoculum density of approximately 10(4) CFU/ml. These testing conditions are proposed as guidelines for a reference broth microdilution method.

Antifungal Agents↗
PubMed1996

Microdilution antifungal susceptibility testing of Candida albicans and Cryptococcus neoformans with and without agitation: an eight-center collaborative study.

The growth patterns observed in the trailing wells when fluconazole is being tested may give rise to readings that suggest resistance or increased MICs for known susceptible strains. We conducted a multicenter study to evaluate the intralaboratory and interlaboratory reproducibilities of a method that uses agitation to disperse these types of growth. Ten strains of Candida albicans and five strains of Cryptococcus neoformans were tested against fluconazole, flucytosine, and amphotericin B by using a microdilution adaptation of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (M27-T). The endpoint criterion used before agitation was consistent with the M27-T recommendation, while a criterion of 50% or more reduction of growth compared with the control was used after agitation. The results of this study showed that use of agitation and the modified endpoint criterion both improved intralaboratory and inter-laboratory agreement and increased the frequency of interpretable MICs. The MICs obtained by this method were comparable to those obtained by the broth macrodilution M27-T method. Like M27-T, this method was not able to definitely distinguish amphotericin B-susceptible from -resistant strains, although the MICs for the resistant strains were consistently higher than those for the susceptible ones. The findings imply that agitation should be seriously considered when antifungal agents, particularly fluconazole, are tested in a microdilution format.

Amphotericin B↗
PubMed1996

Interlaboratory evaluation of Etest method for testing antifungal susceptibilities of pathogenic yeasts to five antifungal agents by using Casitone agar and solidified RPMI 1640 medium with 2% glucose.

An interlaboratory evaluation (two centers) of the Etest method was conducted for testing the antifungal susceptibilities of yeasts. The MICs of amphotericin B, fluconazole, flucytosine, itraconazole, and ketoconazole were determined for 83 isolates of Candida spp., Cryptococcus neoformans, and Torulopsis glabrata. Two buffered (phosphate buffer) culture media were evaluated: solidified RPMI 1640 medium with 2% glucose and Casitone agar. MIC endpoints were determined after both 24 and 48 h of incubation at 35 degrees C. Analysis of 3,420 MICs demonstrated higher interlaboratory agreement (percentage of MIC pairs within a 2-dilution range) with Casitone medium than with RPMI 1640 medium when testing amphotericin B (84 to 90% versus 1 to 4%), itraconazole (87% versus 63 to 74%), and ketoconazole (94 to 96% versus 88 to 90%). In contrast, better interlaboratory reproducibility was determined between fluconazole MIC pairs when RPMI 1640 medium rather than Casitone medium was used (96 to 98% versus 77 to 90%). Comparison of the flucytosine MICs obtained with RPMI 1640 medium revealed greater than 80% reproducibility. The study suggests the potential value of the Etest as a convenient alternative method for testing the susceptibilities of yeasts. It also indicates the need for further optimization of medium formulations and MIC endpoint criteria to improve interlaboratory agreement.

Agar↗
PubMed1996

Multicenter evaluation of broth microdilution method for susceptibility testing of Cryptococcus neoformans against fluconazole.

We have developed a microdilution method for measuring the susceptibility of Cryptococcus neoformans to fluconazole. The present study evaluated the interlaboratory agreement of the results for the microdilution method obtained at three different sites and compared this method with the National Committee for Clinical Laboratory Standards M27-P reference method. Excellent interlaboratory agreement among the results obtained at the three sites was achieved with this method (83 and 96% agreement within 1 and 2 log2 dilutions, respectively). An overall agreement of 90% between the microdilution method and the M27-P method was observed, demonstrating the comparability of the two methods. However, there are inherent problems with the M27-P method in relation to measuring C. neoformans susceptibility, including suboptimal growth of the organism in RPMI 1640, a longer incubation period, and a narrow range of MICs. On the basis of these data, the microdilution method tested in this study is recommended for inclusion in the National Committee for Laboratory Standards method for testing the antifungal susceptibility of C. neoformans.

AIDS-Related Opportunistic Infections↗
PubMed1995

Ketoconazole and itraconazole susceptibility of Candida albicans isolated from patients infected with HIV.

Two hundred and fifty-five isolates of Candida albicans were collected from 93 patients infected with HIV during the course of a clinical trial comparing ketoconazole with itraconazole for the treatment of oropharyngeal or oesophageal candidosis. The susceptibility of the isolates to both drugs was determined by incubating 0.5-2.0 x 10(4) CFU/mL yeast in 0.25-16 mg/L drug in RPMI1640 buffered with MOPS for 24 h at 35 degrees C in 5%CO2 in microtitre trays. Each plate was agitated before reading the optical density. The IC90, IC80 and IC50 were defined as the lowest drug concentration to reduce the optical density to > or = 90%, 80% and 50% of the growth control respectively. IC90S > 0.25 mg/L of ketoconazole and/or itraconazole were found for 42 isolates recovered from 21 patients, 12 of whom had responded to treatment. IC80S > 0.25 mg/L were found for only six of these isolates which had been recovered from three patients, two of whom responded well to treatment. These results indicate that neither the IC90 nor the IC80 are useful in predicting clinical resistance. None of the isolates exhibited IC50 > 0.25 mg/L to either drug which is consistent with the low incidence of resistance reported for these antifungal agents.

AIDS-Related Opportunistic Infections↗
PubMed1995

Comparative and collaborative evaluation of standardization of antifungal susceptibility testing for filamentous fungi.

The purpose of the study was to evaluate the interlaboratory agreement of broth dilution susceptibility methods for five species of conidium-forming (size range, 2 to 7 microns) filamentous fungi. The methods used included both macro- and microdilution methods that were adaptations of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (m27-P). The MICs of amphotericin B, fluconazole, itraconazole, miconazole, and ketoconazole were determined in six centers by both macro- and microdilution tests for 25 isolates of Aspergillus flavus, Aspergillus fumigatus, Pseudallescheria boydii, Rhizopus arrhizus, and Sporothrix schenckii. All isolates produced clearly detectable growth within 1 to 4 days at 35 degrees C in the RPMI 1640 medium. Colony counts of 0.4 x 10(6) to 3.3 x 10(6) CFU/ml (mean, 1.4 x 10(6) CFU/ml) were demonstrated in 90% of the 148 inoculum preparations. Overall, good intralaboratory agreement was demonstrated with amphotericin B, fluconazole, and ketoconazole MICs (90 to 97%). The agreement was lower with itraconazole MICs (59 to 79% median). Interlaboratory reproducibility demonstrated similar results: 90 to 100% agreement with amphotericin B, fluconazole, miconazole, and ketoconazole MICs and 59 to 91% with itraconazole MICs. Among the species tested, the MICs for S. schenckii showed the highest variability. The results of the study imply that it may be possible to develop a reference method for antifungal susceptibility testing of filamentous fungi.

Aspergillus↗
PubMed1995

Comparison of two alternative microdilution procedures with the National Committee for Clinical Laboratory Standards reference macrodilution method M27-P for in vitro testing of fluconazole-resistant and -susceptible isolates of Candida albicans.

The National Committee for Clinical Laboratory Standards has proposed a reference broth macrodilution method for in vitro antifungal susceptibility testing of yeasts (the M27-P method). This method is cumbersome and time-consuming and includes MIC endpoint determination by the visual and subjective inspection of growth inhibition after 48 h of incubation. Two alternative microdilution procedures for MIC endpoint determination, a spectrophotometric MIC endpoint test that evaluates 80% growth inhibition by the drug and a colorimetric method with an oxidation-reduction indicator (Alamar Blue), were compared with the M27-P method for fluconazole susceptibility testing of 45 susceptible and resistant isolates of Candida albicans. The spectrophotometric method was performed with RPMI 1640 medium with 2% glucose, and the other two tests were performed with plain RPMI 1640 medium. All tests were incubated at 35 degrees C. Excellent agreement was demonstrated between the M27-P method and both 24-h microdilution tests (97.7%) as well as between the two microdilution tests (95.5%). Also, there was agreement in the detection in vivo of fluconazole resistance by the three methods. These preliminary data indicate that both microdilution methods may serve as less subjective alternatives to the M27-P method for the determination of fluconazole MIC endpoints.

AIDS-Related Opportunistic Infections↗
PubMed1995

Quality control guidelines for National Committee for Clinical Laboratory Standards recommended broth macrodilution testing of amphotericin B, fluconazole, and flucytosine.

Amphotericin B, fluconazole, and flucytosine (5FC) were tested in a multilaboratory study to establish quality control (QC) guidelines for yeast antifungal susceptibility testing. Ten candidate QC strains were tested in accordance with National Committee for Clinical Laboratory Standards M27-P guidelines against the three antifungal agents in each of six laboratories. Each laboratory was assigned a unique lot of RPMI 1640 broth medium as well as a lot of RPMI 1640 common to all of the laboratories. The candidate QC strains were tested 20 times each against the three antifungal agents in both unique and common lots of RPMI 1640. A minimum of 220 MICs per drug per organism were generated during the study. Overall, 95% of the MICs of amphotericin B, fluconazole, and 5FC fell within the desired 3 log2-dilution range (mode +/- 1 log2 dilution). Excellent performance with all three drugs was observed for Candida parapsilosis ATCC 22019 and C. krusei ATCC 6258. With these strains, on-scale 3 log2-dilution ranges encompassing 96 to 99% of the MICs of all three drugs were established. These two strains are recommended for QC testing of amphotericin B, fluconazole, and 5FC. Reference ranges were also established for an additional four strains for use in method development and for training. Four strains failed to perform adequately for recommendation as either QC or reference strains.

Amphotericin B↗
PubMed1994

Etest for antifungal susceptibility testing of yeasts.

Comparison [+/- 1 dilution between minimum inhibitory concentrations (MICs)] of fluconazole and flucytosine Etest MICs of 10 candidate quality control yeast isolates and 78 clinical isolates demonstrated good agreement (> or = 90%) with the reference method (National Committee for Clinical Laboratory Standards document M27-P). This study suggests that the Etest is a promising alternative method for antifungal susceptibility testing in the clinical laboratory, but that further evaluations are needed.

Fluconazole↗
PubMed1994

Multicenter comparison of a colorimetric microdilution broth method with the reference macrodilution method for in vitro susceptibility testing of yeast isolates.

This multicenter study was performed to compare a colorimetric microdilution method with the NCCLS M27-P reference macrodilution method for the testing of yeast isolates against amphotericin B, fluconazole, and 5-fluorocytosine (5FC). Testing was performed on ten yeast isolates in five independent laboratories. All sites tested each isolate a total of 20 times with both methods. MICs were read after 48 h incubation. The macrodilution MIC reference range was defined as the modal MIC +/- 1-log2 dilution for each organism-antifungal agent combination. Agreement between the M27-P reference range results and the microdilution MICs was 86% with amphotericin B, 90% with fluconazole, and 93% with 5FC. Based on these data, it is apparent that new approaches, such as the colorimetric microdilution method, will provide MIC values comparable to the M27-P macrodilution method in a format that is more practical for use in a busy clinical laboratory.

Amphotericin B↗
PubMed1994

Evaluation of 80% inhibition standards for the determination of fluconazole minimum inhibitory concentrations in three laboratories.

The purpose of this study was to evaluate 1:5 growth control dilutions (80% inhibition standards) to determine fluconazole minimum inhibitory concentration (MIC) end points in three laboratories. We tested 39 selected Candida species (in vitro susceptible: fluconazole MIC of < or = 1 microgram/ml, and resistant: fluconazole MIC of > or = 8 micrograms/ml) and Cryptococcus neoformans isolates by broth macro- and microdilution procedures following the National Committee for Clinical Laboratory Standards proposed reference method for yeasts (M27-P). Macrodilution MIC80% were the lowest drug concentrations with turbidity (growth) less than or equal to that of specific 1:5 dilutions of the growth control. Microdilution MICs-2 were the lowest drug concentrations in which there was prominent decrease of growth. A total of 1608 MICs were evaluated. C. krusei, C. parapsilosis, and C. tropicalis strains had reproducible fluconazole MICs by both tests (24 and 48 h). Fluconazole MIC80% and MIC-2 end points were consistent at 24 h (with C. albicans) and more variable at 48 h. MICs of C. neoformans were more reproducible at 72 h than at 48 h by both tests. This study suggests that the determination of fluconazole MICs is dependent on the length of incubation and the yeast being tested, and that antifungal testing of the yeasts may be performed by either test.

Candida↗