Before we explain what bacterial vaginosis is, let’s talk about the normal bacterial flora in the vagina. The normal flora in the vagina includes Lactobacillus, Corynebacterium, non-hemolytic Streptococcus, Enterococcus, Gardnerella, Escherichia coli, Peptococcus, Actinomyces, etc., as well as Mycoplasma and Mycobacterium. The reason why so many pathogens in the vagina do not cause vaginitis is that they are all in a state of ecological balance, and in maintaining this ecological balance, lactobacilli, estrogen and vaginal pH play a very important role. When the ecological balance in the vagina is disturbed, lactobacilli decrease, their production of lactic acid and hydrogen peroxide (H2O2) decreases accordingly, and vaginal pH increases, leading to a proliferation of other microorganisms, which can lead to bacterial vaginosis. When bacterial vaginosis occurs, 10% to 40% of patients may be asymptomatic, while those with symptoms may have increased leucorrhea with a fishy odor, and some patients may have mild vulvar itching or burning sensation.