Confocal Laser Endomicroscopy for Live Visualization of GI Bacteria

A team of European researchers has developed an endoscopic microscope to visualize bacteria in the gut associated with inflammatory bowel disease. The researchers tagged bacteria with enhanced green fluorescent protein and used the Confocal Laser Endomicroscope (CLE) to image fluorescence in vivo in live mice.

(A) Fluorescent intramucosal bacteria within the lamina propria can readily be identified using fluorescein-aided endomicroscopy. Single crypts are shown with their characteristic round appearance (blue arrow). Single bacteria as well as clustered bacteria (orange arrow) can be identified within the lamina propria between two crypts (pericryptal space). (B) FISH testing confirmed the presence of intramucosal bacteria due to the bright red fluorescence. The nuclei and RNA are shown in blue.
From the study abstract in Gut:

Methods Initially, E coli strains expressing enhanced green fluorescent protein (pEGFP) were endomicroscopically imaged in mice. In addition, ex vivo and in vivo imaging of fluorescent human enteric bacteria was performed to specify the distinct endomicroscopic appearance of enteral bacteria. Targeted mucosal biopsies towards endomicroscopic identifiable intramucosal bacteria and negative mucosal areas were prospectively obtained during colonoscopy and correlated with bench-top fluorescence microscopy (FISH) to prove the endomicroscopic visualisation of intramucosal bacteria. Finally, a retrospective analysis as well as a prospective study was performed in patients with UC and CD to confirm the presence and distribution of intramucosal bacteria within the gut.
Results Confocal endomicroscopy was able to identify intramucosal pEGFP E coli in mice and strains of enteric microflora in the mucosa of humans. Using FISH as the gold standard, evaluation of 21 patients showed that CLE had a sensitivity of 89% and specificity of 100% to identify intramucosal bacteria. In a retrospective study, 113 patients with CD and UC had intramucosal bacteria significantly more often than 50 control patients (66% vs 60% vs 14%, p<0.001). This result was confirmed in a prospective study in which 10 patients with CD and 10 with UC had a significantly wider distribution of involvement with intramucosal bacteria in the colon and terminal ileum compared with 10 controls (85.2% vs 75.9% vs 16.8%, p<0.0001).

Paper in Gut: Confocal laser endomicroscopy is a new imaging modality for recognition of intramucosal bacteria in inflammatory bowel disease in vivo
East Anglia University press release: New tool in the early detection of bowel disease …