Figure 4.

Staphylococcal communities at the center of abscess lesions. Kidney tissue from mice infected with S. aureus Newman (wild type), its isogenic sortase A mutant (ΔsrtA), or MRSA strain USA300 was sectioned, fixed, dehydrated, and sputter-coated with 80% Pt/20% Pd for scanning electron microscopy. A) Wild-type pathogen is organized as a tightly associated lawn, the SAC, at the abscess center that is contained within an amorphous pseudocapsule (arrowheads), separating SACs from the cuff of leukocytes. Red blood cells (R) are located among staphylococci. B) The sortase mutant, ΔsrtA (arrowheads) did not form SACs, and isolated staphylococci were found in healthy kidney tissue. C) Similar to S. aureus Newman, MRSA strain USA300 also formed SACs contained within a pseudocapsule (arrowheads).