FIG 1.

Bactericidal effects of Ce6-aPDT on planktonic cultures (A) and established biofilms (B) of M. catarrhalis 7169 (Mcat), S. pneumoniae EF3030 (Spn), and NTHi 86-026NP (NTJi). Total light dosage was 12 J/cm² (100 mW/cm², 2 min) using 1 μM Ce6 for all planktonic assessments and 90 J/cm² (100 mW/cm², 15 min) using 10 μM Ce6 for biofilm assays. Control sets were exposed to Ce6 but not light (+PS–L), light in the absence of Ce6 (–PS+L), or were not treated (–PS–L). Survival of bacteria, both planktonic and biofilm-associated, was determined by viable plate counts. All bacteria exposed to aPDT treatment (+PS+L) were significantly decreased in viability compared to that of the controls (–PS–L) with a >99.9% kill rate. The dashed lines indicate the limit of detection. The data are presented as the means ± SDs, with individual data points shown. ns, not significant; *, P = 0.0327; ****, P < 0.0001.