Unusual Presentation: Chronic Gastritis Caused by Sarcina ventriculi Identified via Helicobacter pylori Immunohistochemistry.

This case report presents a rare occurrence of Sarcina ventriculi in a 15-year-old male patient with a clinical history of renal failure due to chronic rejection status post kidney transplantation, with persistent symptoms of diarrhea, nausea, vomiting, and fatigue. Despite exhibiting normal gastrointestinal mucosa upon endoscopy, biopsy analysis revealed chronic gastritis accompanied by the presence of Sarcina ventriculi in a tetrad arrangement across the stomach, duodenum, and distal esophagus. Interestingly, immunohistochemistry (IHC) staining targeting the Helicobacter pylori organism (H. pylori) also highlighted the presence of Sarcina ventriculi, suggesting a potential cross-reactivity between the two pathogens. Further investigation into the protein sequences and three-dimensional structures of H. pylori and Sarcina ventriculi revealed significant similarities, with a 65% protein sequence alignment and nearly identical configurations in the urease subunit. This finding suggests the possibility of cross-reactivity in diagnostic testing, particularly in IHC staining for H. pylori. This case highlights the importance of clinical awareness regarding Sarcina infections, particularly in symptomatic patients with seemingly normal endoscopic findings. The potential for cross-reactivity in IHC staining for H. pylori may offer valuable insights into the detection of Sarcina ventriculi, underscoring the significance of thorough diagnostic evaluation in such cases.