Trailing or paradoxical growth of Candida albicans when exposed to caspofungin is not associated with microsatellite genotypes

Abstract

Multilocus microsatellite polymorphisms in 27 clinical Candida albicans isolates were found to be clearly unrelated to in vitro paradoxical growth or trailing effect with caspofungin. These findings suggest that such in vitro phenotypes are either gained or lost too rapidly to be predicted by more stable genomic markers.

FIG. 1.

Elevated caspofungin concentration phenotypes in two Candida albicans isolates, as evidenced by the Etest agar diffusion test. Numbers on the Etest strip refer to caspofungin concentrations in micrograms per milliliter. The black arrows indicate the MIC. (A) Paradoxical growth; the white arrow indicates the concentration (mg/ml) above the MIC where growth resumes. (B) Trailing effect.

FIG. 2.

Factorial analysis correspondence graph illustrating the lack of significant population structure (Fst = 0.003, P = 0.10) and population differentiation (taking into account the within-population genotype structure; G test P = 0.21) with respect to clear endpoint and trailing or paradoxical growth phenotypes in C. albicans when exposed in vitro to caspofungin. In this two-dimensional graphical representation of genetic similarity between individuals, the information for all loci is condensed into a smaller dimension (two factors, axis I and axis II) with a minimum loss of information. A graphical proximity between two individuals indicates a genetic similarity. This graph shows that the phenotypes are clearly not clustered.