Membrane Filtration Test for Rapid Presumptive Differentiation of Four Candida Species

AUTOR(ES)

Bauters, T. G.

FONTE

American Society for Microbiology

RESUMO

A rapid enzymatic two-step test for the presumptive differentiation of four Candida species commonly occurring in various clinical samples is described. The technique involves membrane filtration of a liquid sample, followed by preincubation of the membrane filter on Sabouraud glucose agar supplemented with ticarcillin-clavulanic acid to yield microcolonies. In a separate assay step, parts of the filter are placed on absorbent pads impregnated with fluorogenic 4-methylumbelliferyl (4-MU) enzyme substrates (4-MU-N-acetyl-β-d-galactosaminide, 4-MU-phosphate, 4-MU-pyrophosphate, and 4-MU-β-d-galactoside) in combination with 0.1% digitonin acting as a membrane permeabilizer. The membrane filter in contact with the assay medium is incubated to allow cleavage of the enzyme substrate, resulting in fluorescent microcolonies under long-wavelength UV light. This approach, tested on 301 clinical samples, is able to presumptively differentiate C. albicans, C. glabrata, C. krusei, and C. tropicalis and to distinguish them from other Candida spp. in about 9 to 11 h. Overall agreement with the conventional methods of 94.4% (one Candida species present in the sample) to 83.8% (multiple Candida spp. present) was obtained. The false-negative rates with reference to identification by traditional methods were 1.3% (single species) and 3.8% (multiple species).

Documentos Relacionados

• Comparison of Chromogenic and Fluorogenic Membrane Filtration Methods for Detection of Four Candida Species
• Rapid isolation and presumptive diagnosis of uropathogens by using membrane filtration and differential media.
• Rapid selective urease test for presumptive identification of Cryptococcus neoformans.
• Rapid sodium chloride tolerance test for presumptive identification of enterococci.
• Improved rapid slide agglutination test for presumptive diagnosis of canine brucellosis.