Effect of mesalazine, metronidazole and gentamicin on bacterial translocation in experimental colitis

In inflammatory bowel disease it has been established that enteric microorganisms are present in the final stage of the active inflammatory process. The purpose of the present study was to investigate the effects of mesalazine, and metronidazole-gentamicin combination, on bacterial translocation in an animal colitis model.

Fifty rats were stratified into five groups. The control group (group NC) was given only 2 mL saline enema and the remaining four groups were given 2 mL acetic acid enema. Group CC was the diseased control group. The treatment regimens started on the fifth day: mesalazine enema in group MesC, metronidazole-gentamicin in group MGC, and mesalazine + metronidazole + gentamicin in group MesMGC. After death on day 10, 2.5-cm colonic segments from all groups were weighed separately. In all rats, histopathological scoring was done, and samples from feces, blood, liver and spleen underwent microbiological analyses.

For all diseased rats, both mean weight loss and colonic segment weight/bodyweight ratio was significantly higher than that in the sham group. As compared with other groups, body and colonic segment changes as well as histopathological scoring in rats receiving mesalazine enema either solely or in combination with the antibiotics were lower. No bacterial growth was found in the blood, liver and spleen of the rats in the control group while enteric bacteria, mainly Escherichia coli (35%) were the most common bacteria translocated to that in the latter. Antibiotic combination, alone or in combination with mesalazine was effective in reducing the bacterial translocation while mesalazine administration did not properly influence its regression.

Gram-negative enteric bacteria, predominantly E. coli, was the most common bacteria isolated in bacterial translocation occurring in acetic acid-induced colitis. This trial showed that mesalazine alone did not incorporate the reduction of infectious events, despite its beneficial effect on inflammatory changes in experimental colitis. Metronidazole and gentamicin combination given intraperitoneally was more effective than topical mesalazine in decreasing bacterial translocation.