Influence of intestinal flora on the development of fibrosis and cirrhosis in a rat model.
OBJECTIVE
The gut flora play a significant role in the disposition of many foreign substances, as well as producing nutrients and toxins that may be absorbed and reach the liver. This study examines the influence of antibiotic-induced alterations in gut flora on the development of hepatic fibrosis in a rat model.


METHODS
Thirty-six male Porton rats were fed alcohol (3.9 g/kg per day) in the drinking water and exposed to carbon tetrachloride (CCl4) vapor (80 p.p.m.) for 6 h each night, five nights per week. Half were also given neomycin (330 mg/kg per day) and polymyxin B (105 mg/kg per day) in the drinking water. Fecal cultures were carried out at 0, 3, 8 and 13 weeks; rats were killed at 14 weeks. Coded liver section were assessed for fibrosis using a graded scale (0, no abnormal fibrosis to 4, early or established cirrhosis).


RESULTS
Rats that received antibiotics had significantly higher fibrosis scores than those that did not (mean score 2.4 vs 1.4, P < 0.01, ordinal logistic regression). Three rats, all of which were in the antibiotic group, were cirrhotic. Rats that had received antibiotics fell into three groups. Four had overgrowth of Proteus mirabilis; in these the fibrosis scores (mean 1.5) were similar to those in the rats that did not receive antibiotic. In six, no organisms could be cultured; fibrosis scores of these (mean 2.3) were slightly elevated (P = 0.03), but this was mainly because of a single rat in this subgroup being cirrhotic. The remaining eight had overgrowth of Morganella morganii; these had significantly (P < 0.001) elevated fibrosis scores. Furthermore, in this subgroup, fibrosis scores were significantly correlated (Spearman's r = 0.82, P = 0.01) with the number of weeks of Morganella colonization.


CONCLUSIONS
Antibiotic treatment exacerbated fibrosis in the alcohol/CCl4 rat model; this effect appeared to be related to the type of gut flora and may be endotoxin-mediated.
Plummer
J L
JL
Department of Anesthesia, Flinders Medical Centre and The Flinders University of South Australia, Australia. john.plummer@flinders.edu.au
Ossowicz
C J
CJ
Whibley
C
C
Ilsley
A H
AH
Hall
P D
PD
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002251:Carbon Tetrachloride; D000431:Ethanol; D007422:Intestines / Q000382:microbiology*; D008103:Liver Cirrhosis / Q000382:microbiology* / Q000473:pathology*; D008297:Male; D023421:Models, Animal; D009355:Neomycin / Q000494:pharmacology; D011112:Polymyxin B / Q000494:pharmacology; D051381:Rats
D000900:Anti-Bacterial Agents; D000431:Ethanol; D002251:Carbon Tetrachloride; D009355:Neomycin; D011112:Polymyxin B