FIG 4.

Oxygen is required for effective motility and clearance of adherent S. aureus. (A) Maximum growth rate of S. aureus was not different between 20% oxygen and pooled 0% or 2% oxygen conditions; n = 17 fields of view from 8 independent experiments and n = 12 fields of view from 6 independent experiments for normal oxygen and low oxygen, respectively. (B and C) Neutrophils traverse less distance and a higher fraction of neutrophils are stationary in the last ∼5 min of an experiment in an environment with reduced oxygen tension; n = 32 from 5 independent experiments and n = 37 from 5 independent experiments for normal and low oxygen, respectively. (D and E) Net change in S. aureus bacterial area after 4 h under normal conditions (n = 32 from 8 independent experiments) or low-oxygen conditions (n = 33 from 3 independent experiments at 2% O₂ and 3 at 0% O₂). Error bars represent standard deviations of the samples. ***, P < 0.001; ****, P < 0.0001 by unpaired t tests.