Fig 1.

CC17 GBS strains are more phagocytosed by monocytes and macrophages than non-CC17 GBS strains. (A–D) Phagocytosis level of GBS strains was assessed by CFU count after infection at MOI 10 followed by antibiotic treatment to kill extracellular bacteria using (A) THP-1 macrophages, (B) hMDM primary cells, (C) THP-1 monocytes, or (D) human primary monocytes. (A) Phagocytes were infected with CC17 and non-CC17 GBS clinical isolates from invasive infections, each dot representing a clinical strain. Triangles correspond to BM110 strain (CC17) and NEM316 (non-CC17). Results are expressed as the percentage of phagocytosis relative to BM110 strain phagocytosis, with horizontal lines indicating the median value. (B–D) Phagocytes were infected with GBS strains BM110 and NEM316. Results are expressed as the percentage of phagocytosed bacteria normalized to (B, C) the initial inoculum or (D) to BM110 strain phagocytosis. Statistical analysis: data shown are (A) median or (B–D) mean ± scanning electron microscopy (SEM) of at least four independent experiments. (A–C) t test or (D) Mann Whitney test was performed with *P < 0.05; **P < 0.01; ****P < 0.0001.