FIG. 4.

SEM reveals GAS biofilms embedded within the macroscopic structures recovered from MGAS5005-infected middle ears. (A) GAS biofilm grown in an in vitro continuous-flow cell. Chains of cocci coated in a matrix material are visible. (B and C) White arrows demonstrate chains of cocci that are consistent in size and length with the presence of GAS. Note the seemingly complex matrix, three-dimensional community structure, and other cellular features present. Images were taken at 2 dpi (B) and 7 dpi (C). (D and E) Only isolated chains of cocci were identified in MGAS5005 Δsrv-infected samples at 2 (D) and 7 (E) dpi. Scale bars, 10 μm.