Drug of choice for infection by Gardnerella vaginatis is
**Core Concept**
Gardnerella vaginalis is a bacterium that causes bacterial vaginosis (BV), a common vaginal infection in women of reproductive age. The treatment of BV involves restoring the normal vaginal flora, which is disrupted by the overgrowth of this bacterium.
**Why the Correct Answer is Right**
The first-line treatment for bacterial vaginosis is metronidazole, a nitroimidazole antibiotic that works by inhibiting DNA synthesis in anaerobic bacteria such as Gardnerella vaginalis. This is achieved through the reduction of the nitro group to a highly reactive intermediate by the bacterial enzyme pyruvate:ferredoxin oxidoreductase (PFOR), which ultimately leads to DNA strand breaks and cell death. Metronidazole is effective against a wide range of anaerobic bacteria, including Gardnerella vaginalis.
**Why Each Wrong Option is Incorrect**
**Option A:** Clindamycin is an alternative treatment for bacterial vaginosis, but it is not the first-line choice due to its potential for resistance and side effects.
**Option B:** Fluconazole is an antifungal medication used to treat vaginal yeast infections, not bacterial vaginosis.
**Option C:** Ciprofloxacin is a fluoroquinolone antibiotic that is not typically used to treat bacterial vaginosis.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the treatment of bacterial vaginosis should be repeated after 7 days to ensure complete eradication of the infection.
**Correct Answer: D. Metronidazole**