Snapshot A 23-year-old woman presents to her gynecologist for a wellness exam. She reports that she has been having a “fishy” vaginal odor for the past 3 days. She endorses to recently being sexually active with a new partner and does not use barrier contraception. Physical examination is notable for gray vaginal discharge that has a fishy odor. Nucleic acid amplification testing for gonorrhea and chlamydia is negative. An amine whiff test enhances the fishy odor. Vaginal fluid pH is > 4.5. There are clue cells with a stippled appearance on the outer margins on microscopic testing of the vaginal fluid. She is started on metronidazole. (Bacterial vaginosis) Introduction Mechanism of action free radical formation that damages bacterial DNA is bactericidal and has antiprotozoal activity Clinical use protozoal infections Giardia Entamoeba Trichomonas anaerobic bacteria (below the diaphragm) Bacteroides Clostridium difficile Gardnerella vaginalis Helicobacter pylori as part of triple therapy in patients who are penicillin allergic Adverse reaction disulfiram-like reaction when consuming alcohol, patients can experience severe flushing, hypotension, and tachycardia metallic taste