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Infectious Diseases and Microbiology: Vaginal Discharge / Vaginitis
Vaginal discharge may be physiologic or pathologic. Normal vaginal discharge, also referred to as leukorrhea, consists of cervical mucus and desquamated epithelial cells and is not associated with irritation, odor, or discomfort. In contrast, pathologic discharge is usually associated with infection and may present with abnormal color due to increased polymorphonuclear leukocytes, increased volume, malodor, vulvar pruritus, burning, dysuria, or dyspareunia. The three most common infectious causes of vaginitis are bacterial vaginosis, trichomoniasis, and candidiasis. Bacterial vaginosis represents a disruption of normal vaginal flora in which hydrogen-peroxide–producing lactobacilli are replaced by anaerobic organisms, mycoplasmas, and Gardnerella vaginalis.
Evaluation begins with a detailed history focusing on the characteristics of the discharge, associated symptoms, prior similar episodes, and a complete sexual history. Office-based diagnostic evaluation includes measurement of vaginal pH, performance of the amine (“whiff”) test by adding 10% potassium hydroxide to vaginal secretions, and microscopic examination of saline wet mount preparations to identify clue cells, motile trichomonads, and white blood cells. A potassium hydroxide preparation may reveal Candida pseudohyphae. In sexually active women, both endocervical and high vaginal swabs should be obtained. Chlamydial testing requires sampling of the squamocolumnar junction for culture or nucleic acid amplification testing. Screening cultures may include selective media for Neisseria gonorrhoeae, Candida species, and beta-hemolytic streptococci.
Bacterial vaginosis is the most common cause of vulvovaginal symptoms, followed by vulvovaginal candidiasis. Trichomoniasis is less common in developed countries. Risk factors for vaginal infections include unprotected sexual contact, multiple sexual partners, young age, and certain socioeconomic factors. Bacterial vaginosis is particularly associated with new or multiple sexual partners.
Clinically, vulvovaginal candidiasis often presents with vulvar pruritus and burning, dysuria at the urethral orifice, vaginal erythema, and occasionally thick, white, curd-like discharge. However, only a minority of patients exhibit the classic discharge. Trichomoniasis commonly presents with malodorous yellow discharge, vulvar erythema, itching, dysuria, urinary frequency, and dyspareunia, although symptoms are nonspecific. Bacterial vaginosis typically produces a thin, homogeneous discharge with a characteristic fishy odor that may be more noticeable after intercourse. In the absence of identifiable pathogens, vulvar inflammation may reflect noninfectious irritation or allergic reactions.
Diagnosis of trichomoniasis is commonly made by identifying motile organisms on saline wet mount, although sensitivity is moderate. Direct immunofluorescent testing and culture are more sensitive when available. Candidiasis is diagnosed by microscopic identification of budding yeast or pseudohyphae on saline or potassium hydroxide preparation. Vaginal pH in candidiasis is typically normal (≤4.5), and the amine test is negative. The presence of white blood cells without yeast or trichomonads suggests cervicitis. Absence of organisms on microscopy does not exclude infection, as culture or PCR may be required.
Treatment depends on the identified etiology. Trichomoniasis is treated with a single 2 g oral dose of metronidazole. Bacterial vaginosis is treated with oral metronidazole 500 mg twice daily for seven days or clindamycin 300 mg twice daily for seven days. Intravaginal metronidazole gel or clindamycin cream are effective alternatives. Symptomatic candidiasis is treated primarily with intravaginal azole antifungals such as clotrimazole, miconazole, butoconazole, or terconazole. Oral fluconazole as a single dose is an alternative but is more costly. In pregnancy, intravaginal azoles may be used after the first trimester.
Recurrent vulvovaginal candidiasis, defined as four or more episodes per year, may occur more frequently in women with diabetes mellitus or HIV infection. Vaginal trichomoniasis and bacterial vaginosis during pregnancy are associated with increased risk of preterm labor. Bacterial vaginosis is also associated with pelvic infections, postoperative endometritis, neonatal sepsis, increased risk of HIV acquisition and transmission, and increased susceptibility to other sexually transmitted infections.
Vaginal discharge may be physiologic or pathologic. Normal vaginal discharge, also referred to as leukorrhea, consists of cervical mucus and desquamated epithelial cells and is not associated with irritation, odor, or discomfort. In contrast, pathologic discharge is usually associated with infection and may present with abnormal color due to increased polymorphonuclear leukocytes, increased volume, malodor, vulvar pruritus, burning, dysuria, or dyspareunia. The three most common infectious causes of vaginitis are bacterial vaginosis, trichomoniasis, and candidiasis. Bacterial vaginosis represents a disruption of normal vaginal flora in which hydrogen-peroxide–producing lactobacilli are replaced by anaerobic organisms, mycoplasmas, and Gardnerella vaginalis.
Evaluation begins with a detailed history focusing on the characteristics of the discharge, associated symptoms, prior similar episodes, and a complete sexual history. Office-based diagnostic evaluation includes measurement of vaginal pH, performance of the amine (“whiff”) test by adding 10% potassium hydroxide to vaginal secretions, and microscopic examination of saline wet mount preparations to identify clue cells, motile trichomonads, and white blood cells. A potassium hydroxide preparation may reveal Candida pseudohyphae. In sexually active women, both endocervical and high vaginal swabs should be obtained. Chlamydial testing requires sampling of the squamocolumnar junction for culture or nucleic acid amplification testing. Screening cultures may include selective media for Neisseria gonorrhoeae, Candida species, and beta-hemolytic streptococci.
Bacterial vaginosis is the most common cause of vulvovaginal symptoms, followed by vulvovaginal candidiasis. Trichomoniasis is less common in developed countries. Risk factors for vaginal infections include unprotected sexual contact, multiple sexual partners, young age, and certain socioeconomic factors. Bacterial vaginosis is particularly associated with new or multiple sexual partners.
Clinically, vulvovaginal candidiasis often presents with vulvar pruritus and burning, dysuria at the urethral orifice, vaginal erythema, and occasionally thick, white, curd-like discharge. However, only a minority of patients exhibit the classic discharge. Trichomoniasis commonly presents with malodorous yellow discharge, vulvar erythema, itching, dysuria, urinary frequency, and dyspareunia, although symptoms are nonspecific. Bacterial vaginosis typically produces a thin, homogeneous discharge with a characteristic fishy odor that may be more noticeable after intercourse. In the absence of identifiable pathogens, vulvar inflammation may reflect noninfectious irritation or allergic reactions.
Diagnosis of trichomoniasis is commonly made by identifying motile organisms on saline wet mount, although sensitivity is moderate. Direct immunofluorescent testing and culture are more sensitive when available. Candidiasis is diagnosed by microscopic identification of budding yeast or pseudohyphae on saline or potassium hydroxide preparation. Vaginal pH in candidiasis is typically normal (≤4.5), and the amine test is negative. The presence of white blood cells without yeast or trichomonads suggests cervicitis. Absence of organisms on microscopy does not exclude infection, as culture or PCR may be required.
Treatment depends on the identified etiology. Trichomoniasis is treated with a single 2 g oral dose of metronidazole. Bacterial vaginosis is treated with oral metronidazole 500 mg twice daily for seven days or clindamycin 300 mg twice daily for seven days. Intravaginal metronidazole gel or clindamycin cream are effective alternatives. Symptomatic candidiasis is treated primarily with intravaginal azole antifungals such as clotrimazole, miconazole, butoconazole, or terconazole. Oral fluconazole as a single dose is an alternative but is more costly. In pregnancy, intravaginal azoles may be used after the first trimester.
Recurrent vulvovaginal candidiasis, defined as four or more episodes per year, may occur more frequently in women with diabetes mellitus or HIV infection. Vaginal trichomoniasis and bacterial vaginosis during pregnancy are associated with increased risk of preterm labor. Bacterial vaginosis is also associated with pelvic infections, postoperative endometritis, neonatal sepsis, increased risk of HIV acquisition and transmission, and increased susceptibility to other sexually transmitted infections.
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