What causes vaginitis?

Updated: Dec 04, 2018
  • Author: Hetal B Gor, MD, FACOG; Chief Editor: Michel E Rivlin, MD  more...
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Approximately 90% of all cases of vaginitis are thought to be attributable to 3 causes: bacterial vaginosis, vaginal candidiasis (or vulvovaginal candidiasis [VVC]), and Trichomonas vaginalis infection (trichomoniasis).

Bacterial vaginosis is the most common cause of vaginitis, accounting for 50% of cases. As previously mentioned, bacterial vaginosis is caused by an overgrowth of organisms such as Gardnerella vaginalis (a gram-variable coccobacillus), Mobiluncus species, Mycoplasma hominis, and Peptostreptococcus species. Risk factors include pregnancy, intrauterine device (IUD) use, and frequent douching.

Candida species (including C albicans, C tropicalis, and C glabrata) are airborne fungi that are natural inhabitants of the vagina in as many as 50% of women. Vaginal candidiasis is the second most common cause of vaginitis. In 85-90% of cases, it is caused by C albicans, and in 5-10%, it is caused by C glabrata or C parapsilosis. Risk factors include oral contraceptive use, IUD use, young age at first intercourse, increased frequency of intercourse, receptive cunnilingus, diabetes, HIV or other immunocompromised states, long-term antibiotic use, and pregnancy.

T vaginalis infection, the third most common cause of vaginitis, is caused by trichomonads. T vaginalis is an oval-shaped or fusiform-shaped flagellated protozoan that is 15 μm long (the size of a leukocyte). These organisms primarily infect vaginal epithelium; less commonly, they infect the endocervix, urethra, and Bartholin and Skene glands. Trichomonads are transmitted sexually and can be identified in as many as 80% of male partners of infected women. Risk factors include tobacco use, unprotected intercourse with multiple sexual partners, and the use of an IUD.

A study by Mercer et al suggested that symbionts, commensals, and concomitant infections impact the adaptive immune response to T vaginalis, finding that the presence of M hominis in vitro led to greater diversity in the inflammatory cytokine secretion response to T vaginalis. [2]

Noninfectious vaginitis is usually due to allergic reaction or irritation. Another common cause is atrophic vaginitis due to estrogen deficiency.

Common preventable causes of candidal vaginitis or bacterial vaginosis include damp or tight-fitting clothing, scented detergents and soaps, feminine sprays, and poor hygiene.

For related information, see the Women’s Sexual Health Resource Center.

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