Comparison study of broth macrodilution and microdilution antifungal susceptibility tests for the filamentous fungi

Abstract

An evaluation of broth dilution antifungal susceptibility tests was performed by determining both the microand macrodilution MICs of amphotericin B, fluconazole, ketoconazole, 5-fluorocytosine, miconazole, and itraconazole against representative species of opportunistic hyphomycetes (Fusarium spp. and Cladosporium [Cladophialophora] spp.) and ascomycetes (Chaetomium spp.). A total of 78 strains were tested, the majority of them twice and some three times on different days. Both methods were performed according to the recommendations of the National Committee for Clinical Laboratory Standards (Document M27-P), with the exception of the temperature of incubation, which was 25؇C in our case. A spectrophotometric method for inoculum preparation, RPMI 1640 medium buffered with morpholinepropanesulfonic acid (pH 7.0), and an additive drug dilution procedure were used. The MICs obtained by the two methods were read after 48, 72, and 96 h of incubation for Fusarium spp. and after 72, 96, and 120 h for the remaining isolates. The kappa test was used to calculate the degree of agreement. Considering the three fungal groups together, a good agreement between the results of both tests was observed with almost all the drugs at the different incubation times. There were no cases of poor agreement. The highest level (kappa index ‫؍‬ 1) was observed with ketoconazole at the second-day reading. These results support the further evaluation of the broth microdilution test as an alternative to the reference broth macrodilution susceptibility test.

Molecular characterization of drug-resistant and drug-sensitive Aspergillus isolates causing infectious keratitis

“…As resistance to antifungal drugs continues to expand, and antifungal sensitivity testing of filamentous fungi is time-consuming and needs standardization of many variables,[312] elucidation of a good marker for resistance becomes increasingly important. In our previous study we hypothesized that proteinase production was a good phenotypic characteristic of amphotericin B resistance amongst fungi in mycotic keratitis.…”

“…[1] Empiric therapy, without knowing the antifungal susceptibility pattern, often gives rise to complications, if the causative fungal agent is unresponsive to the drug. [2] In view of the increasing resistance amongst mycelial fungi to one or more antifungal agents,[3] it is often advisable to conduct the antifungal drug susceptibility testing before administering the drug. Not infrequently, amphotericin B in its topical form (0.15% drops) is used for the treatment of suspected cases of fungal keratitis in our setup,though natamycin is the preferred first line polyene antifungal.…”

Determination of susceptibility/resistance to antifungal drugs ofTrichophyton mentagrophytesisolates by a macrodilution method

“…The isolates were cultured on Mycosel™ (BD Difco, Detroit, Michigan) for identification. These isolates were subcultured on Sabouraud dextrose agar (BD Difco) at 28°C and were maintained as a suspension in sterile distilled water (Gupta and Kohli 2003) at 4°C (Pujol et al 1996) until testing was performed.…”

Trypanocidal and antifungal activities of p-hydroxyacetophenone derivatives from Calea uniflora (Heliantheae, Asteraceae)

“…Antifungal activity was measured using a modified agarwell diffusion method according to Matar et al (2003), Okeke et al (2001), Pujol et al (1996), Espinel-Ingroff et al (1995) and Grove and Randall (1955). The test fungi strains were inoculated into RPMI-1640 Medium (Sigma) with MOPS (USB) buffer solutions in agar glucosed plates, containing an inoculum size of 10 6 cfu mL ¡1 (0.5 McFarland scale).…”