The minimum inhibitory concentration (MIC) for amoxicillin, ciprofloxacin, clindamycin, erythromycin, metronidazole, moxifloxacin, tetracycline and vancomycin were determined by using the E-test (bioMérieux, Lyon, France) on Brucella blood agar (Oxoid, Basingstoke, UK) containing hemin (5 mg/mL) and vitamin K1 (10 mg/mL). The MIC breakpoints for metronidazole (2 mg/L), vancomycin (2 mg/L) and moxifloxacin (4 mg/L) were applied as recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST), [20 ]. The MIC breakpoints for amoxicillin (16 mg/L), ciprofloxacin (4 mg/L), clindamycin (8 mg/L), tetracycline (8 mg/L) and erythromycin (8 mg/L) were determined according to the Clinical and Laboratory Standards Institute guidelines (CLSI) breakpoints for the susceptibility testing of anaerobic bacteria [21 ].
The presence of known antimicrobial-resistance determinants for tetracycline (tetM, tetW, tetO, tetA/B, tet 0/32/0 and tet44), clindamycin/macrolides (ermB) and fluoroquinolones (gyrA mutations in the quinolone resistance-determining region (QRDR)) was investigated by PCR amplification and Sanger sequencing as previously described [17 (link),19 (link),22 (link),23 (link),24 (link)]. The primers used in the study are listed inSupplementary Table S2 .
The presence of known antimicrobial-resistance determinants for tetracycline (tetM, tetW, tetO, tetA/B, tet 0/32/0 and tet44), clindamycin/macrolides (ermB) and fluoroquinolones (gyrA mutations in the quinolone resistance-determining region (QRDR)) was investigated by PCR amplification and Sanger sequencing as previously described [17 (link),19 (link),22 (link),23 (link),24 (link)]. The primers used in the study are listed in