High-frequency switching in Candida strains isolated from vaginitis patients.

High-frequency switching and strain variability at the site of infection was assessed in 11 patients with acute Candida albicans vaginitis. By cloning cells directly from the site of infection, it was demonstrated that 4 of the 11 isolates contained multiple-switch phenotypes at the site of infection and that 9 of the 11 isolates were in a high-frequency mode of switching (10(-2) to 10(-3)). Isolates could be separated into four general categories of switching repertoires. To demonstrate that multiple phenotypes at the site of a single infection represented the same strain, EcoRI digests of total cell DNA were separated on agarose gels, and Southern hybridization patterns with two cloned midrepeat sequences were compared.