Figure 2. Lesions associated with swine vegetative endocarditis, United States, 2015–2020. A) Macroscopic findings of vegetative growth on the left atrioventricular heart valve leaflets. B) Histopathologic findings of inflammation characterized by necrotic leukocytes (N), fibrin (F), mineralization (M), and myriad bacterial colonization (yellow outline) along the surface of the heart valve (hematoxylin and eosin staining); original magnification ×40. Higher magnification image (inset) shows cocci bacteria in clusters and long chains; original magnification ×1,000. C) Streptococcus gallolyticus directly detected (red) on the surface of the heart valve by RNA in situ hybridization with a probe targeting the helix-hairpin helix domain–containing protein, ComEC/Rec2, and DNA pol III subunit delta genes specific to S. gallolyticus; original magnification ×40. Higher magnification image (inset) shows the bacteria labeled by the in situ hybridization probe; original magnification ×1,000.