Table 4.
Determination and characterization of erythromycin and clindamycin MICs and molecular characterization of Brucella eryR mutants.
| Brucella ery R strains | ERY | ERY + PAβN | CL | CL + PAβN | Loci | Mutation | |
| B. suis | WT | 1.5 | 0.75 | 8 | 4 | NA | |
| a | 6 | 6 | 12 | 12 | - | ||
| b | 6 | 6 | 12 | 12 | ND | ||
| c | 4 | 6 | 8 | 8 | - | ||
| d | 6 | 6 | 12 | 12 | ND | ||
| e | 6 | 6 | 8 | 8 | ND | ||
| B. canis | WT | 0.5 | 0.094 | 8 | 0.5 | NA | |
| a | 2 | 0.32 | 8 | 1.0 | - | ||
| b | 2 | 0.047 | 6 | <0.016 | - | ||
| c | 3 | 0.047 | 8 | 0.38 | - | ||
| d | 3 | 0.047 | 4 | 0.125 | - | ||
| e | 2 | 0.19 | 8 | 3 | - | ||
| B. neotomae | WT | 0.75 | 0.047 | 3 | 0.75 | NA | |
| a | 4 | 0.125 | 8 | 0.75 | - | ||
| b | 3 | 0.125 | 6 | 2 | ND | ||
| c | 2 | 0.064 | 6 | 1.5 | - | ||
| d | 6 | 0.25 | 6 | 1.0 | L22 | 6 bp indel, β-loop | |
| e | 2 | 0.38 | 4 | 2 | - | ||
| Propoise | WT | 1.5 | 0.25 | 16 | 3 | NA | |
| a | 16 | 0.75 | 4 | 3 | L4 | G209A; Gly70Asp | |
| b | >256 | >256 | >256 | >256 | 23S | A2058G (Ec) | |
| c | 192 | 1.5 | 4 | 3 | L4 | Δ18aa (54–71) | |
| d | 48 | 0.38 | 6 | 3 | L4 | G209A; Gly70Asp | |
| e | 128 | 1.5 | 4 | 3 | L4 | Δ30aa (54–81) | |
| Seal | WT | 6 | 1.5 | >256 | 48 | NA | |
| a | 24 | 12 | 96 | 96 | - | ||
| b | 32 | 24 | >256 | >256 | - | ||
| c | >256 | >256 | 16 | 16 | L4 | C217A; Arg73Ser | |
| d | 128 | 16 | >256 | >256 | - | ||
| e | 128 | 24 | >256 | >256 | ND | ||
| Dolphin | WT | 3 | 0.38 | 2 | 0.75 | NA | |
| a | >256 | 128 | 1.0 | 1.5 | L4 | G209A; Gly70Asp | |
| b | >256 | 6 | 1.5 | 1.0 | L4 | C217T; Arg73Cys | |
| c | >256 | 192 | 1.5 | 1.5 | L4 | G209A; Gly70Asp | |
| d | >256 | 8 | 2.0 | 1.0 | L4 | C217T; Arg73Cys | |
| e | >256 | 8 | 1.5 | 1.0 | ND | ||
Mutants examined were isolates of B. suis biovar 1, B. canis, B. neotomae, and marine porpoise, seal and dolphin strains as per Table 1; WT, wild type; Ery, erythromycin; CL, clindamycin, PAβN, efflux inhibitor L-phenylalanine-L-arginine-β-naphthylamide; -, no mutation identified in any of three ribosomal loci examined; NA, not applicable; ND, sequence not determined.