FIG. 5.

M. catarrhalis inhibited S. pyogenes and S. agalactiae invasion of human epithelial cells. Human cell lines 16HBE14o⁻ (polarized bronchial epithelial cells) and A549 (lung epithelial cells) were incubated with S. pyogenes, S. aureus, or S. agalactiae alone (light gray bar) or with M. catarrhalis (∼2 × 10⁷ CFU/ml, dark bar). M. catarrhalis inhibited S. pyogenes (25- to 28-fold) and S. agalactiae (10-fold) invasion but not S. aureus invasion. None of the bacteria tested had a significant effect on the adherence or invasion of M. catarrhalis. Bar height is the mean of two or three independent experiments, each done in duplicate. Error bars represent the standard deviation.