Biofilm formation testing by one clinical isolates of Gardnerella vaginalis (isolate nos. G1 and G2) against metronidazole. Clinical Gardnerella vaginalis (isolate nos. G1 and G2) was evaluated for antimicrobial susceptibilities in vitro to metronidazole targeting the biofilm. To develop the biofilm model, a starting inoculum of approximately 106 CFU/mL of prepared bacterial suspension in the BHI broth with 0.4% (w/v) glucose was added to different concentrations of metronidazole and inoculated into a 96-well microplate for 48 h at 37°C, 5% CO2. Crystal violet staining was used to quantify the total amount of biofilm biomass. Light blue wells with red box were considered as wells without growth, the minimum biofilm eradication concentration (MBEC), defined as the lowest concentration of an antibiotic that completely inhibited the growth of microorganisms, indicating complete biofilm eradication (No. G1 : MBEC = 16 μg/mL; No. G2 : MBEC > 128 μg/mL).