A 24-year-old sexually active woman who uses an oral contraceptive recently underwent a successful course of antibiotic treatment for a gonococcal infection. For the past two days, she has been experiencing intense vulvar and vaginal pruritus, along with a thick "cheesy" vaginal discharge. The symptoms are sufficiently irritating that she seeks medical advice. Her vital signs are normal. On physical examination, the vulva is found to be swollen and erythematous. There are a number of adherent, dry, white, curd-like patches of material attached to the vaginal mucosa. There is no noticeable odor associated with the infection, and there are no other remarkable findings.

Question 3.1: What is your preliminary diagnosis?

The symptoms imply a classic case of fungal vulvovaginitis, also known as vaginal candidiasis.

Question 3.2: What tests should you perform?

If a fungal infection is suspected, a 10% KOH preparation of a vaginal smear can be performed, to look for yeast cells, hyphae, or budding spores. A culture for yeast can be ordered as well.

Test Results

Budding yeasts and pseudohyphae are visible in the KOH preparation. The lab is able to culture a yeast from the vaginal smear sample.

Question 3.3: What is the most likely causative agent?

Candida albicans causes 80-95% of fungal vulvovaginitis cases in the U. S. Other species that may cause this disease include Candida tropicalis, Candida dubliniensis, Candida parapsilosis, Candida guilliermondii, Candida krusei, and Candida glabrata (formerly Torulopsis glabrata). Some of these Candida species are former C. albicans strains that were recently designated new species.

Question 3.4: What is the differential diagnosis and how are the most similar conditions differentiated from this one?

The differential includes bacterial vaginosis and Trichomonas vulvovaginitis. Bacterial vaginosis is caused by overgrowth of a variety of bacteria (Gardnerella vaginalis, Prevotella, Mobiluncus, Peptostreptococcus, Mycoplasma hominis, etc.) in the vagina. It differs from fungal vulvovaginitis in that (1) there is usually a rather unpleasant and quite noticeable "fishy" odor; (2) the vaginal discharge is homogenous, lower in viscosity, and uniformly coats the vaginal walls; and (3) the vaginal pH is usually >4.5, whereas it remains < 4.5 during fungal vulvovaginitis. Bacterial vaginosis can be diagnosed by the observation of clue cells with adherent bacilli in a vaginal smear.

Trichomonas vulvovaginitis is caused by the protozoan Trhicomonas vaginalis. It differs from fungal vulvovaginitis in that there is a profuse, homogenous vaginal discharge that usually has a yellow or greenish-yellow color. Vaginal pH is usually > 5.0, and the "fishy" odor may or may not be present. Trichomonas vulvovaginitis is diagnosed by observation of motile trichomonads and large numbers of PMNs in a vaginal smear.

Question 3.5: How prevalent is this disease?

Fungal vulvovaginitis is the second most common cause of vaginal infections in the U.S. (Bacterial vaginosis is the most frequent cause.) Approximately 13 million women are infected each year. 75% of women will have at least one episode during their child bearing years, and 40-50% of these will experience a second attack.

Question 3.6: Did antibiotic treatment play a role in this disease?

It could have. By killing off bacteria that normally inhabit the vagina the drug might have eliminated competition that usually keeps the yeast in check. However, vaginal candidiasis frequently occurs in the absence of antibiotic therapy. Unlike some forms of candidiasis (such as thrush in adults), vaginal candidiasis frequently occurs in the absence of immunosuppression. The use of oral contraceptives that raise estrogen levels is a significant predisposing factor for fungal vulvovaginitis, and this may have played a role in the present case. Another predisposing factor is the wearing of tight, poorly ventilated underwear (e.g., nylon), which increases local perineal moisture and temperature, thus encouraging the growth of fungi.

Question 3.7: How should this case be treated?

Cure rates for the various azole derivatives are 85%-90%, with little evidence for superiority of one agent over another. Choices include miconazole, clotrimazole, butoconazole, terconazole, and tioconazole. For resistant or recurrent infections, these treatments can be continued for 14-21 days, or drugs like fluconazole or ketoconazole can be administered.