Figure 4.

Lack of effect of induced hemolysis on clindamycin susceptibility in P. acnes. Aerolysin, a potent hemolysin from Aeromonas hydrophila bacteria, was used to induce hemolysis on agars not permissive for P. acnes hemolysis. (A) P. acnes strain 77 on TSA + 5% sheep’s blood, testing the clindamycin MIC in the absence (left) or presence (right) of aerolysin. (B) The same plate photographed via transmitted light on a light box shows the hemolysis induced by the aerolysin. Bacterial growth is not well seen in transmitted light conditions in (B). (C) Lack of effect of aerolysin on the clindamycin MIC of a moderately resistant P. acnes strain. Arrows indicate the MIC of 6 µg/mL.