Biology Reference
In-Depth Information
Clinical manifestations
Transmission
As AIEC strains are detected in a portion of the healthy population (
Darfeuille-
Michaud et al., 1998
;
Martinez-Medina et al., 2009
), it is believed that in the
absence of predisposing human host genetic factors, they are not able to trigger
abnormal inflammatory responses and rather behave as commensal bacteria, not
posing a risk for humans. However, truly adherent and invasive
E. coli
strains
are found in dogs, cats, and swine; therefore, a putative zoonotic risk has been
assigned in the infection with AIEC for the development of CD (
Simpson et al.,
2006
;
Martinez-Medina et al., 2011
).
Complications
Although the exact role of AIEC strains needs to be further elucidated, the fea-
tures of the CD lesions seem to be the result of a microbial process in the gut,
including the onset of lymphoid aggregates, ulceration, micro-abscesses, fis-
sures, fistulas, granulomas, and lymphangitis (
Barnich and Darfeuille-Michaud,
2007
). The exposure of the distal ileum to luminal contents after curative resec-
tion in patients with CD is associated with the onset of endoscopic lesions and
increased inflammation (
Rutgeerts et al., 1991
). In severe CD cases, deeper
and larger ulcers can develop, leading to bowel obstruction and holes in the
intestinal wall, which could result in a disseminated infection (
Barnich and
Darfeuille-Michaud, 2007
).
Diagnosis
Adhesion and invasion patterns of
E. coli
strains isolated from CD patients have
been used to identify AIEC strains (
Baumgart et al., 2007
;
Martinez-Medina
et al., 2009
). However, the identification of AIEC strains in a subset of healthy
individuals and several AIEC-negative CD cases reflects the involvement of
host genetic determinants as well as the possibility of different microbial prim-
ing in CD patients (
Sartor, 2005
). All these factors suggest that rendering solely
on AIEC identification is an unreliable indicator of the disease status.
Treatment
The control of AIEC infection as a proposed method to treat CD has under-
gone two main directions, antibiotic treatment and feeding of probiotics as a
maintenance therapy. Broad-spectrum antibiotics are clinically used to treat
CD. Metronidazole administered alone or in combination with cotrimoxazole
or ciprofloxacin has been shown to improve colonic but not ileal CD and
to be effective at reducing post-operative recurrence (
Rutgeerts et al., 1995
;
Gionchetti et al., 2006
). Also, rifamycin derivatives induce remission in active
CD (
Khan et al., 2011
). Although good results are obtained at maintaining UC
remission with probiotics, more modest results are obtained in CD. Rifamixin
Search WWH ::
Custom Search