Table 1.

Gardnerella species biofilm formation and minimum inhibitory concentration (MIC) of metronidazole and clindamycin against the planktonic and biofilm forms.

Strains	Biofilm formation at 24 h	Biofilm formation at 48 h	Metronidazole			Clindamycin
			MIC (mg/L)	Ratio of MBIC/MICat 24 h	Ratio of MBIC/MICat 48 h	MIC (mg/L)	Ratio of MBIC/MICat 24 h	Ratio of MBIC/MICat 48 h
XB-06	0.39 ± 0.03 (N)	1.65 ± 0.17 (M)	128	2 (256/128)	2 (256/128)	0.0625	2 (0.125/0.0625)	2048 (128/0.0625)
XB-05	0.34 ± 0.04 (N)	1.73 ± 0.18 (M)	1	4 (4/1)	16 (16/1)	0.0625	2 (0.125/0.0625)	2 (0.125/0.0625)
XB-04	0.61 ± 0.07 (W)	3.23 ± 0.61 (S)	16	8 (128/16)	16 (256/16)	0.0625	4 (0.25/0.0625)	2048 (128/0.0625)
XB-03	0.35 ± 0.04 (N)	1.81 ± 0.33 (M)	0.125	8 (2/0.125)	8 (2/0.125)	0.0625	2 (0.125/0.0625)	2 (0.125/0.0625)
XB-02	0.34 ± 0.03 (N)	2.20 ± 0.60 (M)	0.125	1 (0.125/0.125)	8 (1/0.125)	0.0625	2 (0.125/0.0625)	2 (0.125/0.0625)
XB-01	0.37 ± 0.03 (N)	2.50 ± 0.40 (M)	2	4 (8/2)	4 (8/2)	0.0625	2 (0.125/0.0625)	2 (0.125/0.0625)
ATCC14018	0.97 ± 0.13 (M)	2.32 ± 0.19 (M)	16	4 (64/16)	4 (64/16)	0.0625	16 (1/0.0625)	512 (32/0.0625)

N, no biofilm producer; W, weak biofilm producer; M, moderate biofilm producer; S strong biofilm producer. The biofilm formation capacity at 48 h positively correlated with both ratios of MBIC/MIC in metronidazole (correlation coefficient = 0.601, p = 0.018) and the ratio of MBIC/MIC in clindamycin (correlation coefficient = 0.318, p = 0.000) at 48 h. The biofilm formation capacity at 24 h positively correlated with the ratio of MBIC/MIC in clindamycin at 24 h (correlation coefficient = 0.949, p = 0.000). No correlation was observed between the biofilm formation capacity at 24 h and the ratio of MBIC/MIC in metronidazole at 24 h (correlation coefficient = 0.350, p > 0.05).