This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Established Infection, Subject name: Surgery
[{'content': 'Drug of choice for infection by Gardnerella vaginatis is \nSelect and explain. \nA. Ampicillin, B. Metronidazole, C. Vancomycin, D. Cephalosporin', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans is 'b' ie Metronidazole (Ref. Harrisons, 16/e, p 767 (15/e, p 843))Gardnerella vaginalis causes Bacterial vaginosis*.Bacterial vaginosis can be differentiated from other vaginitis and diagnosed by Amsel criteria :White homogenous vaginal discharge*Vaginal discharges pH > 4.5*Liberation of distinct fishy odour* on mixing vaginal discharge with 10% solution of KOH.Microscopic demonstration of clue cells* (Vaginal epithelial cells coated with coccobacillary organisms)", 'role': 'assistant'}]