Duodenal tropism of SARS-CoV-2 and clinical findings in critically ill COVID-19 patients

PURPOSE: Duodenal involvement in COVID-19 is poorly studied. Aim was to describe clinical and histopathological characteristics of critically ill COVID-19 patients suffering from severe duodenitis that causes a significant bleeding and/or gastrointestinal dysmotility. METHODS: In 51 critically ill patients suffering from SARS-CoV-2 pneumonia, severe upper intestinal bleeding and/or gastric feeding intolerance were indications for upper gastrointestinal endoscopy. Duodenitis was diagnosed according to macroscopic signs and mucosal biopsies. Immunohistochemistry was performed to detect viral specific protein and ACE2. In situ hybridization was applied to confirm viral replication. RESULTS: Nine of 51 critically ill patients (18%) suffering from SARS-CoV-2 pneumonia had developed upper GI bleeding complications and/or high gastric reflux. Five of them presented with minor and four (44%) with severe duodenitis. In two patients, erosions had caused severe gastrointestinal bleeding requiring PRBC transfusions. Immunohistochemical staining for SARS-CoV-2 spike protein was positive inside duodenal enterocytes in three of four patients suffering from severe duodenitis. Viral replication could be confirmed by in situ hybridization. CONCLUSION: Our data suggest that about 8% of critically ill COVID-19 patients may develop a severe duodenitis presumably associated with a direct infection of the duodenal enterocytes by SARS-CoV-2. Clinical consequences from severe bleeding and/or upper gastrointestinal dysmotility seem to be underestimated. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s15010-022-01769-z.