Gardnerella vaginalis
Treatment for gardnerella vaginalis
Gardnerella vaginalis is a facultative, anaerobic, pleomorphic, non-motile, Gram-variable bacillus or coccobacillus. Characteristically on Gram stain, they tend to be arranged at angles or parallel to one another. Morphologically, when grown on appropriate media, the colonies appear as minute, convex, circular, translucent ‘dew drops’ measuring about 0.1–0.8 mm in diameter. Gram-negativity is characteristic of the organisms from early, 6 to 36 hour-old cultures. After 72 to 96 hours, the organism may stain Gram-positive. Gardnerella vaginalis is one of the most important regulators of the abnormal vaginal flora. Only two bacteria, Lactobacillus species and G. vaginalis have been shown to be recoverable as sole isolates from the female genital tract. What is implied by this finding is that they can individually function as ultimate regulators of the female genital tract’s bacterial flora. In vivo analysis of microbiological data has shown the absence of aerobic lactobacilli when G. vaginalis is present at high multiplicity.
Diagnosis
The clinical diagnosis of vaginal bacteriosis necessitates the presence of 3 of the 4 following criteria: (1) presence of milky discharge; (2) vaginal pH?4.7; (3) presence of ‘clue cells’; and (4) amine odor after the addition of KOH.
Vaginal Gram smear can infer the diagnosis by demonstration of: (1) relative absence of lactobacilli; (2) presence of an abnormal bacterial flora;
a. qualitatively
b. quantitatively; and
(3) presence of ‘clue cells’.
The presence of ‘clue cells’ is the best single diagnostic indicator of vaginal bacteriosis. Since the bacterial constituents producing disease can vary significantly, vaginal cultures are difficult to interpret. The discharge of vaginal bacteriosis may be present on the perineum. It usually involves the anterior and lateral walls of the vagina. The characteristic ‘fishy’ vaginal odor is a clue to increased amine production by anaerobic bacteria. Intensification of this odor by adding 10% KOH to vaginal secretions is due to conversion of amines to a more volatile state. Amine odor is the most specific indicator of disease but lacks sensitivity.
Treatment of gardnerella vaginalis
A number of therapeutic regimens have been effective for type II disease (vaginal bacteriosis): (1) oral metronidazole: 500 mg bid for 7 days (efficacy=85%); (2) oral clindamycin: 300 mg bid for 7 days (efficacy=85%);
(3) intravaginal 2% clindamycin cream: 5 ml applied intravaginally at night for seven days (efficacy=85%); (4) metronidazole gel: 5 ml of 0.75% gel inserted intravaginally twice daily for 5 days; and (5) amoxycillin 500 mg tid x 5–7 days.
When dealing with type I disease, good results have been achieved with: (1) amoxycillin 500 mg tid x 5–7 days; (2) doxycycline 100 mg bid x 4 days; or (3) clindamycin 300 mg bid for 7 days.
Most therapies for BV achieve an initial 75–85% clinical success; however microbiological success a month or so post therapy is between 50 and 60%, if that. The reasons for both therapeutic failures and extented microbiological failures have not been well delineated. Individual strains of G. vaginalis are not susceptable to metronidazole. A second important therapeutic variable is the presence of Mobiluncus species within the BV flora. Mobiluncus species are resistant to metronidazole. Depending on whether M. curtisii or M. mulieris is present, clindamycin may not afford optimal coverage. To address these possibilities, the European use combine metronidazole and erythromycin therapy. All women with BV need a comprehensive evaluation for co-infections, particularly the major STDs. While most male sexual partners are colonized with BV-type flora, studies to date have yet to conclusively demonstrate increased efficacy when sexual partners are treated. Gardner and Duke isolated G. vaginalis from the urethra of 54 (96%) of 57 husbands of women with G. vaginitis, but not from the urethra of 20 medical students. The urethra of 77–91% of the sexual consorts of infected women can be demonstrated to harbor the bacteria. These male carriers rarely have clinical evidence of disease. Women whose sexual consorts are not treated tend to become reinfected. If reinfection occurs, ampicillin or amoxycillin is superior to bolus metronidazole in the treatment of the sexual consort.
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Tags: coccobacillus, Gardnerella vaginalis, Gram-variable bacillus
