Detection of Resistance to Amphotericin B among
            <i>Cryptococcus neoformans</i>
            Clinical Isolates: Performances of Three Different Media Assessed by Using E-Test and National Committee for Clinical Laboratory Standards M27-A Methodologies

Lozano-Chiu, Mario; Paetznick, Victor L.; Ghannoum, Mahmoud A.; Rex, John H.

doi:10.1128/jcm.36.10.2817-2822.1998

Cited by 99 publications

(40 citation statements)

References 35 publications

(35 reference statements)

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“…Briefly, for amphotericin B, it has been shown in several studies that Etest was able to better detect the decreased susceptibility of some yeasts than reference methods [30,31,36,[90][91][92][93]. Etest was better than the CLSI in recognizing non-WT isolates among C. neoformans [92] and Candida lusitaniae [90,93]. For the filamentous fungi, one study compared Etest and CLSI methods for some A. flavus isolates [94] and the Etest results better correlated with the data from an experimental model of systemic aspergillosis.…”

Section: Ability To Detect Acquired Resistancementioning

confidence: 99%

Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review

Dannaoui

Espinel-Ingroff

2019

JoF

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Antifungal susceptibility testing is an important tool for managing patients with invasive fungal infections, as well as for epidemiological surveillance of emerging resistance. For routine testing in clinical microbiology laboratories, ready-to-use commercial methods are more practical than homemade reference techniques. Among commercially available methods, the concentration gradient Etest strip technique is widely used. It combines an agar-based diffusion method with a dilution method that determinates a minimal inhibitory concentration (MIC) in µg/mL. Many studies have evaluated the agreement between the gradient strip method and the reference methods for both yeasts and filamentous fungi. This agreement has been variable depending on the antifungal, the species, and the incubation time. It has also been shown that the gradient strip method could be a valuable alternative for detection of emerging resistance (non-wild-type isolates) as Etest epidemiological cutoff values have been recently defined for several drug-species combinations. Furthermore, the Etest could be useful for direct antifungal susceptibility testing on blood samples and basic research studies (e.g., the evaluation of the in vitro activity of antifungal combinations). This review summarizes the available data on the performance and potential use of the gradient strip method.

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Section: Ability To Detect Acquired Resistancementioning

confidence: 99%

Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review

Dannaoui

Espinel-Ingroff

2019

JoF

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“…Just one patient (53) had five isolates and one patient (57) had four.Repartition of the 56 major molecular types for the 363 studied isolates. Twenty-four patients(2,3,14,16,21,23,29,30,32,33,34, 35, 38, 42, 45, 47, 48, 51, 52, 54, 58, 59, 60, 61) exhibited Cryptococcus species with 2 to 4 different major molecular types in the same sample. The patient 19 was infected with two isolates with high flucytosine MICs (16 μg mL −1 ).…”

mentioning

confidence: 98%

Molecular epidemiology reveals genetic diversity among 363 isolates of the Cryptococcus neoformans and Cryptococcus gattii species complex in 61 Ivorian HIV‐positive patients

Kassi

Drakulovski

Bellet

et al. 2016

Mycoses

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Cryptococcal meningitis is a severe opportunistic infection in HIV-infected patients. In Ivory Coast, despite the availability of antiretroviral treatment (ART), this infection is still prevalent. The study investigates the genetic diversity of 363 clinical isolates of Cryptococcus from 61 Ivorian HIV-positive patients, the occurrence of mixed infections and the in vitro antifungal susceptibility of the isolates. Serotyping was performed via LAC1 and CAP64 gene amplification. Genotyping was performed using the phage M13 core (GACA) and (GTG) primers and restriction fragment length polymorphism analysis of the URA5 gene. By PCR fingerprinting, the presence of the three serotypes were demonstrated among the 363 isolates in the population studied: A (n=318; 87.6%), AD (n=40; 11%) and B (n=4; 1.1%). Using PCR fingerprinting with primers M13 (GACA) and (GTG) , we grouped the isolates into 56 molecular subtypes. We observed a high frequency (39.3%) of mixed infections, with up to two different genotypes per sample. None of the isolates were resistant to amphotericin B. Only 0.3% and 1.1% of the isolates were resistant to fluconazole and flucytosine respectively. This study revealed the high genetic diversity among Cryptococcus isolates, the occurrence of mixed infections and a high antifungal susceptibility for the majority of Ivorian cryptococcal isolates.

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“…Current reports suggest that testing with Antibiotic Medium 3 (AM3) instead of RPMI permits us to enhance the ability to detect it [31]. However, the reproducibility of this method is still under study, owing to lot-to-lot variability of AM3 [32].…”

Section: Nccls Reference Guidelines Antifungal Susceptibility Testingmentioning

confidence: 99%

“…The M27 methodology does not permit consistent detection of isolates resistant to amphotericin B. Several works suggest that testing with AM3 supplemented with 2% glucose permits more reliable detection of these isolates, but AM3 is not standardized and substantial lot-to-lot variabibty has been observed [31,32]. Variabihty is a basic limitation for reproducibility.…”

Section: Alternative Media Inoculum Size and Incubation Timementioning

confidence: 99%

Present status of the detection of antifungal resistance: the perspective from both sides of the ocean

Cuenca-Estrella

Rodríguez-Tudela

2001

Clinical Microbiology and Infection

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The NCCLS reference methodology for antifungal susceptibility testing is a new milestone of the evolution of medical mycology. The use of this methodology however, is not problem-free. At present, major limitations are a trailing phenomenon with azoles, unreliable detection of resistance to amphotericin B, poor growth of some organisms and unpractical procedures for the clinical laboratory. Herein a overview of NCCLS guidelines for yeasts and filamentous fungi is presented. Likewise, a review of studies conducted trying to overcome the limitations of reference procedures is also included. Several alternative approaches are reviewed as alternative media, inoculum size and incubation time. Modifications of reading procedure and endpoint determination are also evaluated. Agar diffusion methods and other methods for susceptibility testing are cited. Finally, we discuss the data on correlation of the in vitro results with the in vivo activity.

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Detection of Resistance to Amphotericin B among Cryptococcus neoformans Clinical Isolates: Performances of Three Different Media Assessed by Using E-Test and National Committee for Clinical Laboratory Standards M27-A Methodologies

Cited by 99 publications

References 35 publications

Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review

Antifungal Susceptibly Testing by Concentration Gradient Strip Etest Method for Fungal Isolates: A Review

Molecular epidemiology reveals genetic diversity among 363 isolates of the Cryptococcus neoformans and Cryptococcus gattii species complex in 61 Ivorian HIV‐positive patients

Present status of the detection of antifungal resistance: the perspective from both sides of the ocean

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