Antifungal Susceptibility Testing of Yeasts: A Brief Overview

Sheehan, Daniel J.; Espinel-Ingroff, Ana; Moore, Lynette; Webb, Chris

doi:10.1093/clinids/17.supplement_2.s494

Cited by 58 publications

(36 citation statements)

References 25 publications

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“…Investigating the patterns of resistance by antifungal susceptibility testing is one of the phenotypic methods and its role in epidemiological surveillance is limited 1 . But it is important to determine susceptibility patterns and resistance rates of the Candida isolates recovered from ICU patients as yeast species show discrepancies concerning virulence and resistance to antifungal agents 14–17 . Results of our antifungal susceptibility testing showed that MIC values of amphotericin B and fluconazole against the C. albicans , C. tropicalis , and C. glabrata isolates varied.…”

Section: Discussionmentioning

confidence: 98%

Molecular epidemiology of Candida species isolated from urine at an intensive care unit

Ergon¹,

Gülay²

2005

Mycoses

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Candida spp. has been the leading microorganism isolated from the urine specimens of patients hospitalized at the Anesthesiology and Reanimation intensive care unit (ICU) of Dokuz Eylul University Hospital, Izmir, since 1998. This study was undertaken to investigate the clonal relationship of Candida urine isolates in order to find the mode of spread among the patients. Epidemiological surveillance of 38 Candida albicans, 15 Candida tropicalis and 12 Candida glabrata recovered from the urine specimens of patients who were hospitalized in the ICU between June 11, 2000 and October 15, 2001 was carried out by antifungal susceptibility testing and randomly amplified polymorphic DNA (RAPD) analysis. Two short primers [Cnd3 (5'-CCAGATGCAC-3') and Cnd4 (5'-ACGGTACACT-3')] were used for RAPD. None of the isolates had high minimal inhibitory concentration (MIC) values (>1 microg ml(-1)) against amphotericin B with MIC50 values of 0.5 microg ml(-1), 0.5 microg ml(-1) and 0.125 microg ml(-1) for C. albicans, C. tropicalis and C. glabrata isolates, respectively. However, three C. glabrata isolates were resistant and one C. albicans and five C. glabrata isolates were dose-dependent susceptible (D-DS) to fluconazole. Among C. albicans isolates 19 and 20 patterns were detected with primers Cnd3 and Cnd4, respectively. When primers Cnd3 and Cnd4 were evaluated together, three and four genotypes were identified for C. tropicalis and C. glabrata isolates, respectively. Our results suggest that the source of C. albicans isolates was mostly endogenous. It is difficult to interpret the mode of spread of C. tropicalis and C. glabrata urine isolates as we obtained insufficient banding patterns for these species.

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Section: Discussionmentioning

confidence: 98%

Molecular epidemiology of Candida species isolated from urine at an intensive care unit

Ergon¹,

Gülay²

2005

Mycoses

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“…However, its antifungal activity is basically restricted to the genus Candida, C. neoformans isolates and dermatophytes. It is important to note that fluconazole has no antimycotic activity against Aspergillus spp and Fusarium spp, the agents which usually cause keratitis (15,25) . Regarding fluconazole MIC, we obtained a large variation of values against the tested ocular pathogens, including one C. albicans strain that exhibited a MIC value higher than the MIC-90 for the 8 tested samples (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…However, the capsule formulation available shows bioavailability limitations affecting its serum levels and tissular distribution. Therefore, in spite of its high tolerability and broad spectrum, its clinical ophthalmologic use is restricted (25)(26) . In the present study, MIC values for itraconazole were quite lower than those recorded for fluconazole when we evaluated Candida spp specimens.…”

Section: Discussionmentioning

confidence: 99%

Antifungal susceptibility testing of yeast isolated from corneal infections

Mascaro¹,

Hofling-Lima²,

Gompertz³

et al. 2003

Arq. Bras. Oftalmol.

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Antifungal susceptibility testing of yeast isolated from corneal infections INTRODUTIONFungi are opportunistic agents which rarely infect healthy corneas of immunocompetent individuals. Systemic and local underlying diseases may render the corneal tissues susceptible to infections with these organisms (1) . Trauma, specially related to organic materials, topical use of steroids and antibiotics (2)(3) , contact lens wear, surgical procedures, contamination of eye solutions, inappropriate maintenance of contact lenses (4) , systemic infections as well as any disease associated with immunodeficiency are considered risk factors for fungal eye infections (5) . In Brazil, the incidence of fungal eye infections ranges from 3.8 to 10%, depending on the site of the infection, the diagnostic tools available for fungal infections in the medical center and the seasons related to the studied period (6)(7)(8)(9) . The occurrence of keratomycosis is of great importance, not only because of diagnostic problems but also due to the severity of clinical manifestations and poor outcome despite antifungal treatment. The severity and progression of the fungal infection usually depend on the existence of Purpose: To report the antifungal susceptibility profile of yeast isolates obtained from cases of keratitis. Methods: Susceptibility testing of 15 yeast strains isolated from corneal infections to amphotericin B, fluconazole, itraconazole and ketoconazole was performed using the NCCLS broth microdilution assay. Results: Most episodes of eye infections were caused by Candida albicans. The antifungal drugs tested showed the following minimal inhibitory concentration values against yeast isolates: 0.125-0.5 µg/ml for amphotericin B; 0.125->64.0 µg/ml for fluconazole; 0.015-1.0 µg/ml for itraconazole and 0.015-0.125 µg/ml for ketoconazole. Despite the fact that all Candida isolates were judged to be susceptible to azoles, one isolate showed a minimal inhibitory concentration value significantly higher than a 90% minimal inhibitory concentration of all tested isolates. Rhodotorula rubra was resistant to fluconazole and itraconazole. Conclusions: Despite the fact that most yeast isolates from corneal infections are usually susceptible to amphotericin B and azoles, they exhibit a wide range of minimal inhibitory concentration values for antifungal drugs. The identification of strains at species level and their susceptibility pattern to antifungal drugs should be considered before determining the concentration to be used in topical antifungal formulations in order to optimize therapeutic response in eye infections.ABSTRACT

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“…It has been observed that trailing growth is mainly associated to azoles, these drugs being fungistatic rather than fungicidal [8, 13]. In this context, the lack of a clear‐cut endpoint complicates the interpretation of the test.…”

Section: Discussionmentioning

confidence: 99%

Impact of endpoint definition on the outcome of antifungal susceptibility tests with Candida species: 24- versus 48-h incubation and 50 versus 80% reduction in growth

St-Germain¹

2001

Mycoses

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The growth inhibition patterns of 764 clinical yeast isolates, in response to amphotericin B, flucytosine, itraconazole and fluconazole, were studied in order to determine the frequency of trailing growth and any impact this, as well as 24- or 48-h incubation periods, may have on minimum inhibitory concentration (MIC) results. A broth microdilution method following National Committee for Clinical Laboratory Standard No. M27A recommendations was used. Trailing growth was observed mainly with azoles. Furthermore, over 98% of isolates exhibiting a trailing effect at 24 h with fluconazole and itraconazole were either Candida albicans or Candida tropicalis. When comparing 24- and 48-h IC50 values, discrepancies were observed with itraconazole and fluconazole, respectively, in 18 and 11% of C. albicans and 24 and 30% of C. tropicalis. When comparing IC50 and IC80 values at 24 h, discrepancies were again essentially seen with itraconazole and fluconazole, respectively, in 11 and 10% of C. albicans, and 17 and 27% of C. tropicalis. In susceptibility tests performed with a microdilution method and read spectrophotometrically, 48-h IC80 values result in an unlikely high number of resistant isolates, indicating that a 24-h incubation and a 50% reduction in optical density may correlate better with clinical outcome.

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Antifungal Susceptibility Testing of Yeasts: A Brief Overview

Cited by 58 publications

References 25 publications

Molecular epidemiology of Candida species isolated from urine at an intensive care unit

Molecular epidemiology of Candida species isolated from urine at an intensive care unit

Antifungal susceptibility testing of yeast isolated from corneal infections

Impact of endpoint definition on the outcome of antifungal susceptibility tests with Candida species: 24- versus 48-h incubation and 50 versus 80% reduction in growth

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