Strain differentiation ofCandida albicansby morphotyping

Abstract

Strains of Candida albicans can be differentiated by the morphological features of streak colonies developed on malt agar. A morphotyping system is proposed, where numerical codes are assigned primarily on the basis of the nature and extent of marginal fringing and the surface topography of the streak colony. The system allows ready differentiation to be made of morphotypes, requires no specialized equipment or expertise and provides a simple and reproducible means for epidemiological studies of candida and candidosis.

Morphotype markers of virulence in human candidal infections

“…It is not yet known if phenotypic switching will affect morphotyping results, particularly as the morphotyping streak is seeded by many thousand colony forming units. The in-vitro reproducibility over 2 years for this morphotyping scheme, relying ng an identical morphotype, and 96% for those giving a morphotype differing by one or less adjacent characters (Phongpaichit et al, 1987). In a further study (Hunter and Fraser, unpublished data) of 15 cases of candidal vaginitis, in which five colonies from each of the original cultures were morphotyped, we found that there was 100% in-vivo reproducibility.…”

“…Identification was by germ-tube formation in serum. One colony, chosen at random, was further sub-cultured on to Bacto YM Agar (0712-01-8 Difco, Detroit, MI, USA), from which a suspension in distilled water was made for inoculation on to morphotyping agar as described by Phongpaichit et al, (1987).…”

“…After incubation for 10 days, each strain was examined and assigned a morphotype code (Phongpaichit et al, 1987) of two pairs of three numbers, with an occasional additional number being added in parenthesis. To simplify analysis, a limited code was used in this study.…”

“…A new typing scheme for C. albicans, which is based on colonial morphology (morphotyping), has recently been described (Phongpaichit et al, 1987). We undertook this study of a collection of clinical isolates to determine the variety and distribution of morphotypes of C. albicans and also to determine whether the method is able to detect strains of proven virulence.…”

The Ins and Outs of DNA Fingerprinting the Infectious Fungi

“…The conclusion of the authors of this latter study was that although this biotyping method was effective for research applications, it probably would not prove effective for clinical use. In addition to serotyping and the Odds and Abbott biotyping method, a number of other biotyping methods have been used to discriminate C. albicans strains, including morphotyping (145,270,293), resistotyping (144,215), killer yeast typing (278,279), enzyme typing (66,424,425), sugar assimilation typing (50,105,113,120) and drug susceptibility typing (294). Isoenzyme biotyping has also been successfully applied to Candida species (52,180,288).…”