Candida albicans strain delineation

Abstract

Candida albicans is a major opportunistic pathogen causing a wide spectrum of disease in human beings. Methods for strain delineation of this species to assess or predict virulence or to conduct epidemiologic or pathogenetic investigations have been developed. Although factors associated with virulence have been identified, there is no rapid system to quantitate them in a clinical laboratory. Therefore, many typing methods are based on variable phenotypic characteristics within this species including morphotyping, serotyping, antibiogram, resistogram typing, biotyping, biotyping based on commercial carbon assimilation patterns, enzyme profiles, sensitivity to yeast killer toxins, and typing based on protein variability. Phenotypically defined strains generally do not correlate with the pathogenic potential of a strain with the exception of morphotyping. However, these methods can be useful in epidemiologic investigations; for example, they have revealed that most individuals harbor one strain and that infections are frequently due to an endogenous strain. Problems with these methods usually relate to their discriminatory power. When this is maximized, reproducibility (especially between laboratories) suffers. Recently, methods based on differences in DNA structure (genotyping) for strain delineation have been developed, including electrophoretic karyotyping and restriction enzyme fragment length polymorphisms. The development of a computer-assisted data bank and analysis for these genotypic strain delineators will open investigations into the pathogenesis of this infection and permit epidemiologic studies previously not possible with this important human pathogen.

Multiple chromosomal and phenotypic changes in spontaneous mutants of Candida albicans

“…A distinct feature of C. albicans is that different clinical isolates have various electrophoretic karyotypes, as described by Merz et al (1988) and others (for a rewiew, see Merz, 1990), and investigated in detail for the four clinical isolates, 3153A, 199 1). In addition to having varied electrophoretic karyotypes, these four clinical isolates also had distinct colonial morphologies, consistent with the result with spontaneous morphological mutants.…”

“…Initially, such variation was considered to offer reasonable grounds for establishing strain differences that might be used in epidemiological work (Merz, 1990). However, it has become clear that single strains, either fresh isolates or stock cultures, may give rise to mutants with single and multiple alterations in their electrophoretic karyotypes and that the frequency of such spontaneous mutations may be high (Suzuki et al, 1989;Rustchenko-Bulgac et al, 1990 ;Rustchenko-Bulgac, 1991).…”

Clonal variation of chromosome size derived from the rDNA cluster region in Candida albicans

“…This karyotyping method should be useful in clinical applications for strain identification (Merz, 1990). It has been reported that a change in karyotype appears to be correlated with a change in colony morphology (Rustchenko-Bulgac et al, 1990; Suzuki et al, 1989) although a definitive relationship between phenotype and karyotype has yet to be determined.…”

Electrophoretic Karyotypes of Candida Yeasts Recurrently Isolated from Single Patients

“…With the advent of molecular genetics, the methods based on genotype (DNA) or variations in DNA structure have been applied to elucidate.the differences both among and within the species of medically important yeasts. These approaches are to detect differences between strains (i) in the restriction fragment length polymorphism of DNA (RFLP), occasionally in combination with Southern hybridization with specific DNA probes and (ii) in the electrophoretic karyotype (9,13).…”