Smear of vaginal discharge shows budding yeast cells. Causative agent is?
**Core Concept**
The question requires identification of a causative agent of vaginal discharge based on microscopic findings of budding yeast cells. This involves understanding the characteristics of fungal pathogens, particularly those that cause vaginal infections.
**Why the Correct Answer is Right**
Budding yeast cells are characteristic of Candida species, which are a common cause of vaginal yeast infections. Candida albicans is the most prevalent species responsible for these infections, particularly in women with altered vaginal pH, diabetes, or immunocompromised states. The presence of budding yeast cells in a vaginal discharge smear is a key diagnostic feature, often accompanied by pseudohyphae and blastoconidia.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because Trichomonas vaginalis causes a sexually transmitted infection characterized by a greenish-yellow discharge, not by budding yeast cells.
**Option B:** Incorrect because Gardnerella vaginalis is associated with bacterial vaginosis, which presents with a thin, white or gray discharge and a fishy odor, not with budding yeast cells.
**Option C:** Incorrect because Herpes simplex virus causes genital herpes, characterized by painful vesicles and ulcers, not by budding yeast cells.
**Clinical Pearl / High-Yield Fact**
The presence of a thick, white or yellowish discharge with a fishy odor, accompanied by pruritus and dysuria, should raise suspicion for bacterial vaginosis, while a greenish-yellow discharge with a strong fishy odor suggests trichomoniasis.
**Correct Answer: D. Candida albicans**