Scintigraphic visualization of bacterial translocation in experimental strangulated intestinal obstruction

Purpose: The purpose of this study was to obtain scintigraphic images depicting translocation of ^99mTc-labelled Escherichia coli bacteria through the intestinal barrier and to quantify this process using methods of nuclear medicine. Methods: Thirty male Wistar rats (including 20 rats with modelled strangulated intestinal obstruction and 10 healthy rats) were used for bacterial scintigraphy. ^99mTc-labelled E. coli bacteria ( ^99mTc-E. coli) with an activity of 7.4-11.1 MBq were administered into a section of the small intestine. Scintigraphic visualization of bacterial translocation into organs and tissues of laboratory animals was recorded in dynamic (240 min) and static (15 min) modes. The number of labelled bacteria, which migrated through the intestinal barrier, was quantified by calculating the translocation index (TI). Results: Control indicated no translocation of ^99mTc-E. coli administered into the intestine through the parietes of the small intestine's distal part in healthy animals. Animals with strangulated obstruction demonstrated different migration strength and routes of labelled bacteria from strangulated and superior to strangulation sections of the small intestine. ^99mTc-E. coli migrated from the strangulated loop into the peritoneal cavity later causing systemic bacteraemia through peritoneal resorption. The section of the small intestine, which was superior to the strangulation, demonstrated migration of labelled bacteria first into the portal and then into the systemic circulation. The strangulated section of the small intestine was the main source of bacteria dissemination since the number of labelled bacteria, which migrated from this section significantly, exceeded that of the area superior to the strangulation section of the small intestine (p = 0.0003). Conclusion: Bacterial scintigraphy demonstrated the possibility of visualizing migration routes of labelled bacteria and quantifying their translocation through the intestinal barrier. This approach to study bacterial translocation may be successfully applied not only in strangulated intestinal obstruction, but also in other modelled pathological conditions.