Most cases of infectious gastritis unrelated to Helicobacter pylori occur in individuals with immune deficiencies, such as those with acquired immunodeficiency virus (HIV) infection, those receiving high doses of glucocorticoids or immunosuppressants, those undergoing or recovering from chemotherapy, or those in critical conditions.
Bacterial Infections
Suppurative inflammation is often caused by Staphylococcus, α-hemolytic Streptococcus, or Escherichia coli. Gastric surgery and chemotherapy are common predisposing factors. Clinical manifestations include sudden onset of epigastric pain, nausea, vomiting, and purulent vomitus containing necrotic mucosa. Gastric dilation, marked tenderness, localized muscle rigidity, and fever may also occur. Extensive necrosis of the gastric mucosa, which may extend to the gastric wall, is frequently accompanied by sepsis. Severe necrosis or perforation can lead to suppurative peritonitis. Due to underlying diseases often causing systemic failure and malnutrition, the mortality rate is high. Other bacterial infections, such as tuberculosis and syphilis, may also occur.
Viral Infections
Cytomegalovirus (CMV) infections can involve the stomach or duodenum. Endoscopic findings may reveal localized or diffuse thickening of the gastric mucosal folds. Histological examination shows infected cells enlarged by 3–4 times, with eosinophilic intranuclear inclusions resembling "owl's eyes," which are highly characteristic.