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J Surg Res. 2000 Apr;89(2):132-8.

Aggregation substance promotes colonic mucosal invasion of Enterococcus faecalis in an ex vivo model.

Author information

1
Department of General Surgery, University of Ulm, Ulm, 89075, Germany.

Abstract

BACKGROUND:

Bacterial translocation through the gastrointestinal tract is the crucial step in the pathogenesis of intraabdominal infections. We assessed whether aggregation substance (AS), a bacterial adhesin and virulence factor of Enterococcus faecalis, promotes bacterial translocation and colonic mucosal invasion in an ex vivo experiment.

METHODS:

Colonic mucosa of male Wistar rats was placed in a modified Ussing system. The mucosal side of the chamber was filled with a suspension of E. faecalis OG1X:pAM721 (AS-positive) or E. faecalis OG1X (AS-negative). The serosal side was filled with sterile Dulbecco's modified Eagle's medium. For assessment of colonic mucosal invasion the mucosal side was incubated for 2.5 h with a suspension of AS-positive or AS-negative enterococci. After being washed, a solution of gentamicin and penicillin G in tissue culture medium was added on both sides in order to kill extracellular bacteria. Subsequently, the mucosa was removed from the system, washed, lysed with Triton X-100, and homogenized. Viable intramural bacteria were quantified by plating serial dilutions of the homogenate on Todd-Hewitt broth agar plates. To quantify bacterial translocation samples which were taken at various time points from the serosal side were plated on Todd-Hewitt broth agar plates and colony forming units (CFU) were determined.

RESULTS:

Invasion of the AS-positive E. faecalis strain OG1X:pAM721 into the colonic mucosa was significantly higher than invasion rates of the AS-negative strain OG1X (2.88 log(10) CFU/ml vs 1.73 log(10) CFU/ml; P = 0.02). However, none of the tested strains was found to translocate from the mucosal to the serosal side within the incubation time of 4 h.

CONCLUSIONS:

The aggregation substance promotes invasion of E. faecalis into colonic mucosa.

PMID:
10729241
DOI:
10.1006/jsre.1999.5813
[Indexed for MEDLINE]

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