Microscopy of bacterial translocation during small bowel obstruction and ischemia in vivo--a new animal model.
BACKGROUND
Existing animal models provide only indirect information about the pathogenesis of infections caused by indigenous gastrointestinal microflora and the kinetics of bacterial translocation. The aim of this study was to develop a novel animal model to assess bacterial translocation and intestinal barrier function in vivo.


METHODS
In anaesthetized male Wistar rats, 0.5 ml of a suspension of green fluorescent protein-transfected E. coli was administered by intraluminal injection in a model of small bowel obstruction. Animals were randomly subjected to non-ischemic or ischemic bowel obstruction. Ischemia was induced by selective clamping of the terminal mesenteric vessels feeding the obstructed bowel loop. Time intervals necessary for translocation of E. coli into the submucosal stroma and the muscularis propria was assessed using intravital microscopy.


RESULTS
Bacterial translocation into the submucosa and muscularis propria took a mean of 36 +/- 8 min and 80 +/- 10 min, respectively, in small bowel obstruction. Intestinal ischemia significantly accelerated bacterial translocation into the submucosa (11 +/- 5 min, p < 0.0001) and muscularis (66 +/- 7 min; p = 0.004). Green fluorescent protein-transfected E. coli were visible in frozen sections of small bowel, mesentery, liver and spleen taken two hours after E. coli administration.


CONCLUSIONS
Intravital microscopy of fluorescent bacteria is a novel approach to study bacterial translocation in vivo. We have applied this technique to define minimal bacterial transit time as a functional parameter of intestinal barrier function.
Samel
Stephan
S
Department of Surgery, University Hospital Mannheim, University of Heidelberg, Germany. stephan.samel@chir.ma.uni-heidelberg.de
Keese
Michael
M
Kleczka
Martha
M
Lanig
Sybille
S
Gretz
Norbert
N
Hafner
Mathias
M
Sturm
Jörg
J
Post
Stefan
S
D000818:Animals; D018988:Bacterial Translocation; D004926:Escherichia coli; D049452:Green Fluorescent Proteins; D007415:Intestinal Obstruction / Q000382:microbiology* / Q000473:pathology / Q000503:physiopathology; D007421:Intestine, Small / Q000098:blood supply* / Q000382:microbiology / Q000473:pathology; D007511:Ischemia / Q000382:microbiology* / Q000473:pathology / Q000503:physiopathology; D008164:Luminescent Proteins; D008297:Male; D008856:Microscopy, Fluorescence; D023421:Models, Animal; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins