Antimicrobial susceptibility interpreted according to the cut-off levels proposed in Ref. (10) with strains considered resistant if inhibition zone diameters were equal to or smaller than 19 mm for penicillin G and ampicillin , 14 mm for vancomycin and tetracycline, and 13 mm for erythromycin. Equal to or smaller than 8 mm of inhibition zone diameters for streptomycin, sulfamethoxazole-trimethoprim and metronidazole were considered as resistant, according to the cut-off levels with minimal modifications of Ref. (11). All antibiotics were tested in duplicate.