Vaginal yeast colonization in non-pregnant women: a longitudinal study

The relationship between yeast colonisation, symptoms and antifungal self-medication remains poorly understood. Previous studies have involved pregnant women or women using hormonal contraception, and many have been underpowered. This American cohort study aimed to determine the prevalence of yeast colonisation over a 1-year period in 18–30-year-old, sexually active, non-pregnant women. A total of 1248 women were recruited and more than 80% of the scheduled visits at baseline, 4, 8 and 12 months were attended. At each visit a questionnaire was used to enquire about symptoms, antifungal use, sexual/personal behaviour and contraception in the preceding 4 months. A swab of vaginal fluid was transferred to candida-selective culture media. Some 70% of women were colonised by vaginal yeast at one or more visits, but only 4% were colonised at all four visits. Factors associated with yeast colonisation included marijuana use [odds ratio (OR) 1.3, 95% CI 1.1–1.5], depot medroxyprogesterone acetate (DMPA) use (OR 1.4, 95% CI 1.1–1.7), sexual activity in past 5 days (OR 1.5, 95% CI 1.2–1.8) and concurrent colonisation with lactobacillus and group B streptococcus. Symptoms of pruritis and vulvovaginal burning were associated with yeast colonisation but antifungal use was not. The results support the concept that Candida albicans exists as part of the normal vaginal flora in many healthy asymptomatic women, and that host factors influence the development of symptoms. The authors suggest that the lack of an association with antifungal use casts doubt on the reliability of self-diagnosis and self-treatment of thrush symptoms. However, the study was limited by possible recall bias and the fact that most women were not examined at the time they had symptoms or used antifungal treatment. Moreover, the study population was relatively young (80% under 25 years) and from similar socioeconomic backgrounds, so may not be representative of the wider female population. The finding of an association with DMPA conflicts with previous studies showing a protective effect against yeast colonisation. Further research is therefore required to confirm an association between yeast colonisation and injectable progestogen-only contraceptives.