Figure 3. Photomicrograph of the gastric biopsy. Necrotic gastric mucosa (H&E stain), with fibrinous and purulent exudates. Abundant Sarcina organisms characterized by their organization in tetrads are seen (arrows). Focal clusters of smaller bacteria (cocci in clusters) are also noted (asterisk), as well as empty spaces suggestive of pneumatosis (arrowheads). Insets: A – Methenamine silver stain highlights the thick bacterial walls; B – H&E stain at higher magnification demonstrates Sarcina clusters resembling “packets tied by cords”.