FIG. 1.

Triple-disk test performed with the iMLS-B strain iB1 (A) and the iMLS-C strain iC1 (B). In each plate, the erythromycin disk (30 μg) is at the center, with the clindamycin disk (10 μg) on the right and the josamycin disk (30 μg) on the left. Normal test medium was used with both strains in the plates on the left side, whereas the same medium supplemented with CCCP (12.5 μM) was used in the plates on the right side. While the difference between the iMLS-B and the iMLS-C phenotypes is clearly apparent in normal test medium, no difference can be appreciated in the test medium supplemented with the efflux pump inhibitor, both strains exhibiting an iMLS-C phenotype under the latter condition.