Recombinant Lysostaphin Protects Mice from Methicillin-Resistant Staphylococcus aureus Pneumonia
Histopathology of the lungs of untreated (PBS) and treated (VAN or rLys) animals (). (a)–(d) Gross histopathology of the lungs. (e)–(h) Histopathology of the lung tissues. (a) and (e) Control mice treated with PBS. Infection with MRSA showing typical necrotizing pneumonia with multifocal bacterial colonies, complete destruction of the alveolar architecture, hemorrhage, and perivascular growth of S. aureus. Presence of acute pneumonia with neutrophils in the distal bronchioles and alveolar spaces is also evident. Suppurative inflammation is present in the interstitium and at perivascular locations. (b) and (f) Lungs from mice infected with MRSA after treatment with VAN. This panel demonstrates the reduced acute inflammation, although it is still apparent as neutrophils and neutrophil debris throughout the lung interstitium, with congestion and intra-alveolar fluid. (c) and (g) Lungs from mice treated with 45 mg/kg rLys. This panel shows the reduced acute inflammation; the lung tissue is similar to normal lung tissue. (d) and (h) Lungs from mice treated with 1 mg/kg rLys. This panel shows the reduced acute inflammation, although inflammation is still evident as neutrophils and neutrophil debris. (e)–(h) Tissues were stained with hematoxylin and eosin (original magnification, ×400).