Effects of temperature on anti-Candida activities of antifungal antibiotics

Abstract

The relative growth (percentage of growth relative to control growth) of 767 Candida isolates representing five species was measured in microcultures at 25 and 37°C. In the presence of 10-4 M flucytosine, the distribution of relative yeast growth data indicated that Candida albicans isolates were less susceptible at 25°C than at 37°C, while the opposite was found with 4 x 10-s M amorolfine for most of the isolates tested.Repetition of the experiments at four different temperatures with 99 C. albicans isolates and five antifungal agents confirmed a direct relationship between growth inhibition and increasing temperature from 25 to 40°C with amphotericin B, flucytosine, and terconazole; a strong inverse relationship between inhibition and temperature with amorolfine; and a weak inverse relationship with terbinafine. However, these relationships were not always noted with other Candida spp.: in particular, the growth of C. glabrata and C. parapsilosis isolates tended to be greater at 37°C than at 25°C in the presence of the azole-derivative antifungal agents itraconazole and terconazole. These findings stress the species-specific individuality of yeast susceptibility to azole antifungal agents. The results with C. albicans and amorolfine and terbinafine accord with their known in vivo efficacy in mycoses involving low-temperature superficial sites and poor activity against mycoses involving deep body sites. The data also reinforce the need for control of experimental variables such as temperature in the design of standardized yeast susceptibility tests.

Antifungal susceptibility testing of yeasts: evaluation of technical variables for test automation

“…(107 C. albicans isolates, 41 C. glabrata isolates, 16 C. krusei isolates, 17 C. tropicalis isolates, and 16 isolates representing 7 other species). The arithmetic mean OD (SD) was 1.037 (0.160), the geometric mean was 1.020, the lowest reading was 0.257, and the highest reading was 1.445; these measurements generally matched previously published results (18 By contrast, the flucytosine susceptibility test outcome varied considerably with the initial yeast concentration. At least 10 of the 29 isolates tested showed inoculum size-dependent variations in ICs that exceeded 2 dilution steps.…”

Update on terbinafine with a focus on dermatophytoses

“…7 While the majority of clinical terbinafi ne use is observed with infections caused by dermatophytes, the susceptibility of numerous organisms including pathogenic yeast, dematiaceae, thermally dimorphic fungi and hyaline hyphomycetes has been evaluated. [8][9][10][11][12][13][14][15][16] Although the nature of the assays employed precludes direct comparison of minimum inhibitory concentrations (MICs) between studies (ie, some were performed prior to standardization of a reference method by the Clinical and Laboratory Standards Institute (CLSI), 17 some universal trends are repeated throughout. Namely, terbinafi ne demonstrates the greatest activity against species within the Trichophyton, Microsporum, and Epidermophyton genera followed by the dematiaceae, the fi lamentous fungi and a few selected pathogenic yeast.…”

Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada

“…We found that these two fungal pathogens exhibited increased susceptibility to KC at 37°C compared to 30°C. The temperature-related sensitivity to antimicrobial therapy has been reported previously (65,66).…”