Discussion
Our results revealed that G. vaginalis is more resistant to metronidazole than clindamycin and neither metronidazole nor clindamycin are able to effectively eradicate vaginal biofilms. Thus, the role of antibiotics and biofilms in BV requires further investigation.
Methods
Subgroups were identified by clade-specific polymerase chain reaction (PCR). Biofilm formation was measured by crystal violet staining, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The inhibition and eradication of biofilm formation were measured by XTT and broth recovery-based methods.
Results
Of the 24 samples of G. vaginalis, 11 samples and American Type Culture Collection (ATCC) 14018 formed biofilms; the remainder did not. The positive rates of detection for the sialidase A and vly genes in the 24 G. vaginalis samples were 100% and 79.2%, respectively. Moreover, 21 samples (87.5%) showed resistance to metronidazole and 16 (66.7%) presented with sensitivity towards clindamycin. The biofilm MIC80 (BMIC80) of metronidazole for ATCC14018 was 16 μg/ml while that of clindamycin was 0.125 μg/ml. The minimum biofilm eradication concentration (MBEC) of metronidazole was > 256 μg/ml while that of clindamycin was > 2 μg/ml.