Review for 10.1186/1471-230X-13-61 (2013)

Reviewer's report
Title:Studies on a possible role of Escherichia coli in propagation and
perpetuation of the gut chronic inflamation in ulcerative colitis.
Version: 1Date:10 December 2012
Reviewer: Serena Schippa
Reviewer's report:
The manuscript:”Studies on a possible role of Escherichia coli in propagation and
perpetuation of the gut chronic inflammation in ulcerative colitis” by Magdalena
Pilarczyk-Zurek and colleagues is a study of importance in its field. Detailed
studies on the E.coli role in ulcerative colitis are very few, but are needed. Infact,
even if an increased load of mucosa associate E.coli in UC and CD patients has
been found, it is likely that their role in UC is different from that played in MC
patients. However I’m unable to decide on acceptance or rejection until the
authors have responded to the major compulsory revisions.
Major compulsory revisions
1) The patients age ranged between 18 to 72 hears. The authors should take in
considerations that the gut microbiota composition change in age relations, and
after age of 50 years old it is reported to be different from the ones in young
people. Age-related physiological changes in the gastrointestinal tract, inevitably
affect the gut microbiota The biological processes of aging may involve a role for
the gut microbiota (Elena Biagi et al. Plos One 2012).
This leads inevitably to an heterogeneous group ruled in the study. This should
be considered when the authors put together comparisons and analysis data, at
list by comparing subjects matching by age and sex.
2) On lines 123,124 and 125 are reported the exclusion criteria (diabetes,
autoimmune disorders, severe systemic diseases, alcohol abuse, cow’s milk
allergy as well as non-steroidal anti inflammatory drugs intake). Nothing is
reported about antibiotic treatments, which is known to have a strong impact on
intestinal microbiota composition. Usually in the recruitment of patients and
control subjects are excluded those which have undergone antibiotic treatments,
in the three months prior to the biopsy.
3) Usually the biopsy specimens dedicated to bacterial culture, by traditional
methods, undergo treatment useful to remove the flora not strictly adhered to the
intestinal mucosa, such as washing with the biopic sample with dithioerythritol
DDT ( Conte MP et al. GUT.2006). Briefly for the bacteriological study,
specimens should be immediately processed and first washed in 500 ml of
physiological saline with 0.016% dithioerythritol to remove the mucus and then
washed three times in 500 ml of physiological saline by shaking for 30 seach
time. Nothing is mentioned to this methodic. I wonder if such treatment was not
carried out, what kind of bacterial has been cultivated? The adherent or the
luminal ones, or both? Maybe this could explain the results discrepancy obtained
by authors, between cultural and molecular methods.
4) Another point that remain vague is in relation to the number of E.coli strains
collected from each biotic sample. For the results interpretation it is important to
find out if the study was referred to a E.coli population colonizing each subject (
meaning to have collected at list 50-100 E.coli strains for each biopic samples),
or to a few E.coli strains, randomly collected. Since the interspecies variability,
study on E.coli population will give results with stronger impact. If not the authors
should discuss the limit imposed by a study conducted on few, randomly
collected, E.coli strains.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I declare that I have no competing interests'