Prevalence of Vulvovaginal Candidiasis and Susceptibility to Fluconazole in Women

Abstract

In this study a new method of membrane filtration using a panel of florigenic enzyme substrates to identify and differentiate four major Candida species within 9 to 12 hours was tested for its ability to diagnose vulvovaginal candidiasis. The study subjects were 612 women who were recruited from consecutive patients who attended a gynecological clinic at Ghent University Hospital during a 14-week period. Some subjects had symptoms of vaginitis, but others did not. Each subject underwent a clinical examination including a wet vaginal smear and a vaginal swab, which was placed in transport gel for delivery to the laboratory. The florigenic process involves the formation of a microcolony on a membrane filter over a 9- to 11-hour incubation period. The membrane is cut into five segments, which are impregnated with a buffered solution of a florigenic 4-methylumbilliferyl substrate. After a further incubation period of 30 minutes, during which cleavage of enzyme substrates takes place, the microcolonies are examined under long-wavelength ultraviolet light resulting in blue or orange fluorescence. A positive yeast culture was obtained from the vaginal swabs of 123 of the 612 women (20.1%). Sixty-five of the patients had symptoms of vaginitis (vulvar pruritus and vaginal discharge), and 547 were asymptomatic. Of the 65 symptomatic women, 60% (39 of 65) had a positive KOH wet smear, and 40% (26/65) had a negative KOH result. More than two thirds of the isolated species were C. albicans (68.3%); C. glabrata was found in 16.3%, C. parapsilosis was isolated in 8.9%, and C. humicola, C. krusei, and C. lusitaniae were found in 1.6%, 0.8%, and 0.8%, respectively. The florigenic technique agreed 100% of the time with chromogenic analysis performed as a comparative standard. The highest number of isolated yeasts was found in women with clinical symptoms of candidiasis and a positive KOH test (29 of 35 >1000 CFU/ml). Conversely, women with clinical symptoms and negative KOH test had low numbers of isolated yeasts. When the subjects were divided into subgroups, pregnant women were the most likely, and postmenopausal women with no hormonal replacement therapy were the least likely, to have a positive yeast culture (33 of 103, 32%, P =.045; 15 of 119, 12.6%, P =.003, respectively). Yeast was found in 26.9% of postmenopausal women not taking oral contraceptives (22 of 114), and 14.4% and 14.0% of premenopausal women taking oral contraceptives (16 of 111) or with an intrauterine device (8 of 57), respectively. The rate of yeast colonization was significantly related to the amount of estrogen in oral contraceptives, with the higher concentrations more likely to have positive yeast growth (P =.05). Similarly, yeast colonization in pregnant women grew significantly as pregnancy progressed (P =.05). Twenty-six of the 123 yeast isolates were resistant to fluconazole when subjected to in vitro sensitivity testing.