Clinical Review

Candidiasis: The essentials of diagnosis and treatment

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Vulvovaginal candidiasis is commonplace and may be caused by species other than Candida albicans. Serious complications may occur when infection occurs during pregnancy.


 

References

CASE Woman with vulvar itch and white vaginal discharge

A 26-year-old sexually active nulligravid woman requests evaluation for moderately intense “itching in the vagina and on the vulva.” She uses combination oral contraceptives and has 2 current sexual partners. On physical examination, you note a thick, white, curd-like discharge that is adherent to the vaginal epithelium. The vulva is erythematous, and small “satellite lesions” are evident in the intertriginous folds.

  • What is the most likely diagnosis?
  • How should you treat this patient?

Approximately 75% of all women will have at least 1 episode of vulvovaginal candidiasis (VVC) in their lifetime.1 Candida albicans, the most commonly identified organism in these infections, colonizes the vagina of many individuals commensally; higher rates of colonization occur in women with diabetes, obesity, recent use of broad-spectrum antibiotics, steroid use and immunosuppression, and in women who are pregnant. Of special interest, pregnant women have an increased risk of symptomatic infection, and they respond less favorably to conventional treatment regimens.1

Deconstructing C albicans and other species

Historically, in more than 90% of cases, C albicans is the principal cause of VVC. While it remains the most prevalent Candida species in the United States, over the last 15 years studies have demonstrated that in some countries, such as India and Nigeria, C albicans constitutes less than half of the cultured species in women with VVC. This observation may be due to the widespread availability and use of common antifungal medications, which leads to resistance and selection for resistant species.1,2

In asymptomatic women, vaginal colonies of C albicans grow in the yeast form. This condition is usually well tolerated by the host and does not cause a major immune response. In periods of stress for the host micro- and mycobiomes, however (dysbiosis, immune suppression, trauma), C albicans is induced into morphogenesis, proliferating and forming hyphae that are thought to activate the host immune response. The vaginal epithelium becomes sensitized to the presence of C albicans and recruits large numbers of neutrophils that, in turn, drive the pathophysiology of VVC.3

There is a theory that the separation of the urethra and anus by the vagina has exerted evolutionary pressure to maintain the presence of commensal C albicans yeast colonies in the vagina. C albicans exerts an antagonistic effect on many bacteria and, therefore, may act as a “microbiologic barrier” between the anus and the urethra to prevent urinary tract infections that, before the modern antibiotic era, may have caused serious morbidity and even mortality.3

Other organisms that cause VVC include C glabrata, C parapsilosis, and C tropicalis. Ex vivo experiments have shown that co-infection of C albicans with C glabrata enhances the ability of C glabrata to invade tissue.2 C glabrata is more frequently resistant to commonly used antifungal compounds than C albicans,2,4 which suggests that identifying the specific fungal pathogen is becoming increasingly important in planning targeted therapy.

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