FIG 2 .

Antimicrobial-mediated killing is growth phase and agr specific. Cells were grown in serum for 2, 4, 6, or 24 h as indicated and treated with 15 μg/ml of gentamicin for 60 min (A). To determine whether the observed difference in killing was due to agr, wild-type (WT; BS12), Δagr mutant (BS13), and complemented Δagr mutant (BS519) cells were treated with 15 μg/ml of gentamicin (B) or 2.5 μg/ml of ciprofloxacin (C) for 60 min. Survival was determined as described in the legend to Fig. 1. Significance was examined by unpaired two-tailed t test (P < 0.05). ***, P < 0.01; ****, P < 0.001. Data represent the means from biological replicates ± standard deviations (n = 3).