Fig 6.

F2 decreases bacterial resistance to antibiotics. (A) Survival of wild-type B. anthracis Sterne after 24 h of incubation with vehicle control, 40 μM F2, and/or 5 mg/ml penicillin (PEN), as indicated. (B) Survival of MRSA Sanger 252 with vehicle control, 40 μM F2, and/or 1 mg/ml daptomycin (DAP), as indicated. Two daptomycin-susceptible S. aureus parent strains and daptomycin-nonsusceptible strains, 0616/0701 (C) and 32/32D (D), were incubated with the indicated concentration of daptomycin. F2 at 15 to 20 μM was added to 0701 or 32D, as shown, and the surviving numbers of CFU were enumerated 24 h later. #, a synergistic interaction (P < 0.05) by two-way ANOVA; *, P < 0.05 compared to daptomycin-nonsusceptible S. aureus (0701 or 32D) by one-way ANOVA, followed by Tukey's post hoc analysis; $, no CFU recovered.