FIGURE 3.

Increased drug concentration did not increase aPDT efficacy and dark toxicity was observed. Dual species biofilms of (A) M. catarrhalis (green) and NTHi (blue), (B) S. pneumoniae (red) and NTHi (blue), (C) S. pneumoniae (red) and M. catarrhalis (green), and triple species biofilms (D) were incubated for 30 min with 100 μM Ce6 followed by a 20 min 405 nm LED exposure. Surviving bacteria were quantitated by CFU enumeration. Bars represent the mean and standard deviation of three independent assays with a minimum of two technical replicates. Dashed lines indicate the limit of detection. ∅ indicates no detectable CFU were enumerated for the test condition. Statistically significant differences are denoted as *P < 0.05, **P < 0.01, ***P < 0.001.