Biased genotype distributions of Candida albicans strains associated with vulvovaginal candidosis and candidal balanoposthitis in China.

BACKGROUND: Vulvovaginal candidosis (VVC), which is most frequently caused by Candida albicans, is one of the most common vaginal infections and is a common problem worldwide. Despite the fact that extensive epidemiological studies have been performed, what triggers VVC, especially recurrence of the infection, is still uncertain.

METHODS: Genotypes of C. albicans strains associated with VVC and balanoposthitis and of strains isolated from samples from vaginas of asymptomatic women and from various extragenital sites were determined with use of C. albicans microsatellite locus I polymorphism analysis. Genetic similarity of representative strains with the same and different C. albicans microsatellite locus I genotypes were examined by sequence analysis of housekeeping genes CaADP1, CaSYA1, and CaVPS13.

RESULTS: The C. albicans microsatellite locus I genotypes of independent C. albicans strains isolated from samples from extragenital sites were mostly of individual specificity. In contrast, strains associated with VVC were mainly concentrated to a few genotypes, with genotypes 30-45 and 32-46 being the most common. The overall frequencies of the 2 genotypes among C. albicans strains from vaginal samples from patients with VVC and from asymptomatic women were 59.1% and 24.0%, respectively (P = .002); the frequencies among patients with complicated VVC and among patients with uncomplicated VVC were 69.2% and 35.7%, respectively (P = .003). A similar genotype distribution pattern of C. albicans strains associated with balanoposthitis was also revealed. The genetic similarity of strains with the dominant genotypes associated with both VVC and balanoposthitis was confirmed by sequence analysis of the 3 genes.

CONCLUSIONS: The results suggest the existence of vaginopathic C. albicans strains with enhanced virulence and tropism for the vagina and the high possibility of sexual transmission of genital C. albicans infection. Identification of specific genotypes that correlate with severity of VVC is also of diagnostic and therapeutic significance.