Comparison of the E-test with the NCCLS M38-P Method for Antifungal Susceptibility Testing of Common and Emerging Pathogenic Filamentous Fungi

Abstract

The National Committee for Clinical Laboratory Standards (NCCLS) M38-P method describes standard parameters for testing the fungistatic antifungal activities (MICs) of established agents against filamentous fungi (molds). The present study evaluated the in vitro fungistatic activities of itraconazole and amphotericin B by the E-test and the NCCLS M38-P microdilution method against 186 common and emerging pathogenic molds (123 isolates of Aspergillus spp. [five species], 16 isolates of Fusarium spp. [two species], 4 Paecilomyces lilacinus isolates, 5 Rhizopus arrhizus isolates, 15 Scedosporium spp., 18 dematiaceous fungi, and 5 Trichoderma longibrachiatum isolates). The agreement between the methods for amphotericin B MICs ranged from 70% for Fusarium solani to >90% for most of the other species after the first reading; agreement was dependent on both the incubation time and the species being evaluated. Major discrepancies between the amphotericin B MICs determined by the E-test and the NCCLS M38-P method were demonstrated for three of the five species of Aspergillus tested and the two species of Fusarium tested. This discrepancy was more marked after 48 h of incubation; the geometric mean MICs determined by the E-test increased between 24 and 48 h from between 1.39 and 3.3 g/ml to between 5.2 and >8 g/ml for Aspergillus flavus, Aspergillus fumigatus, and Aspergillus nidulans. The agreement between the itraconazole MICs determined by the E-test and the NCCLS M38-P method ranged from 83.3% for A. nidulans to >90% for all the other species tested; the overall agreement was higher (92.7%) than that for amphotericin B (87.9%). The agreement was less dependent on the incubation time. Clinical trials need to be conducted to establish the role of the results of either the E-test or the NCCLS M38-P method in vitro for molds with the two agents as predictors of clinical outcome.

Chemical composition, antioxidant and antimicrobial activities of essential oil of Thymus algeriensis wild-growing in Libya

“…The micromycetes were maintained on malt agar and the cultures stored at 4°C and sub-cultured once a month [25]. In order to investigate the antifungal activity of the essential oil, a modified microdilution technique was used [22][23][24]. The fungal spores were washed from the surface of agar plates with sterile 0.85% saline containing 0.1% Tween 80 (v/v).…”

“…The following Gram-negative bacteria were used: [22][23][24]. The bacterial suspensions were adjusted with sterile saline to a concentration of 1.0x10…”

Antimicrobial and cytotoxic activities of Alnus rugosa L. aerial parts and identification of the bioactive components

“…The micromycetes were maintained on malt agar and the cultures were stored at 4 • C and sub-cultured once a month. The antifungal assay was carried out by modified microdilution technique (Hanel and Raether, 1988;Espinel-Ingroff, 2001). The fungal spores were washed from the surface of agar plates with sterile 0.85% saline containing 0.1% Tween 80 (v/v).…”

Can Suillus granulatus (L.) Roussel be classified as a functional food?

“…15 Briefly, a fresh overnight culture of bacteria was adjusted by the spectrophotometer to a concentration of 1×10 5 CFU/mL. The requested CFU/mL corresponded to a bacterial suspension determined in a spectrophotometer at 625 nm (OD625).…”