Colonic Bacteria (colonic + bacteria)

Distribution by Scientific Domains


Selected Abstracts


The effect of antibiotics and bismuth on fecal hydrogen sulfide and sulfate-reducing bacteria in the rat

FEMS MICROBIOLOGY LETTERS, Issue 1 2003
Hiroki Ohge
Abstract Colonic bacteria produce the highly toxic thiol, hydrogen sulfide. Despite speculation that this compound induces colonic mucosal injury, there is little information concerning manipulations that might reduce its production. We studied the effect of antibiotics and bismuth on the production of hydrogen sulfide in rats. Baseline fecal samples were analyzed for hydrogen sulfide concentration and release rate during incubation and numbers of sulfate-reducing bacteria. Groups of six rats received daily doses of ciprofloxacin, metronidazole, or sulfasalazine for one week, and feces were reanalyzed. Bismuth subnitrate was then added to the antibiotic regimens. While sulfide production and sulfate-reducing bacteria were resistant to treatment with ciprofloxacin or metronidazole, bismuth acted synergistically with ciprofloxacin to inhibit sulfate-reducing bacteria growth and to reduce sulfide production. Combination antibiotic,bismuth therapy could provide insights into the importance of sulfide and sulfate-reducing bacteria in both human and animal models of colitis and have clinical utility in the treatment of antibiotic-resistant enteric pathogens. [source]


Review article: nitric oxide from dysbiotic bacterial respiration of nitrate in the pathogenesis and as a target for therapy of ulcerative colitis

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2008
W. E. W. ROEDIGER
Summary Background, Factors initiating human ulcerative colitis (UC) are unknown. Dysbiosis of bacteria has been hypothesized to initiate UC but, to date, neither the nature of the dysbiosis nor mucosal breakdown has been explained. Aim, To assess whether a dysbiosis of anaerobic nitrate respiration could explain the microscopic, biochemical and functional changes observed in colonocytes of UC. Methods, Published results in the gastroenterological, biochemical and microbiological literature were reviewed concerning colonocytes, nitrate respiration and nitric oxide in the colon in health and UC. A best-fit explanation of results was made regarding the pathogenesis and new treatments of UC. Results, Anaerobic nitrate respiration yields nitrite, nitric oxide (NO) and nitrous oxide. Colonic bacteria produce NO and UC in remission has a higher lumenal NO level than control cases. NO with sulphide, but not NO alone, impairs ,-oxidation, lipid and protein synthesis explaining the membrane, tight junctional and ion channel changes observed in colonocytes of UC. The observations complement therapeutic mechanisms of those probiotics, prebiotics and antibiotics useful in treating UC. Conclusions, The prolonged production of bacterial NO with sulphide can explain the initiation and barrier breakdown, which is central to the pathogenesis of UC. Therapies to alter bacterial nitrate respiration and NO production need to evolve. The production of NO by colonic bacteria and that of the mucosa need to be separated to pinpoint the sequential nature of NO damage in UC. [source]


Organization of butyrate synthetic genes in human colonic bacteria: phylogenetic conservation and horizontal gene transfer

FEMS MICROBIOLOGY LETTERS, Issue 2 2007
Petra Louis
Abstract Butyrate producers constitute an important bacterial group in the human large intestine. Butyryl-CoA is formed from two molecules of acetyl-CoA in a process resembling ,-oxidation in reverse. Three different arrangements of the six genes coding for this pathway have been found in low mol% G+C-content Gram-positive human colonic bacteria using DNA sequencing and degenerate PCR. Gene arrangements were strongly conserved within phylogenetic groups defined by 16S rRNA gene sequence relationships. In the case of one of the genes, encoding ,-hydroxybutyryl-CoA dehydrogenase, however, sequence relationships were strongly suggestive of horizontal gene transfer between lineages. The newly identified gene for butyryl-CoA CoA-transferase, which performs the final step in butyrate formation in most known human colonic bacteria, was not closely linked to these central pathway genes. [source]


Influence of urease activity in the intestinal tract on the results of 13C-urea breath test

JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 4 2006
Yoshihisa Urita
Abstract Background and Aim:, A late rise in 13CO2 excretion in the 13C-urea breath test (UBT) should be found when the substrate passes rapidly through the stomach and makes contact with the colonic bacteria. The aim of this study was to evaluate the influence of intestinal urease activity on the results of the UBT. Method:, A total of 143 subjects who were diagnosed as Helicobacter pylori negative by serology, histology and rapid urease test were recruited. At the end of endoscopy, the tip of the endoscope was placed to the second part of the duodenum and 20 mL of water containing 100 mg of 13C-urea was sprayed into the duodenum. Breath samples were taken at baseline and at 5, 10, 20, 30 and 60 min after administration. Results:, Of 143 subjects, breath ,13CO2 values higher than 2.5, were detected in six (4.2%), four (2.8%) and five (3.5%) subjects at 20, 30 and 60 min, respectively. There was no subject with high ,13CO2 values at 5 and 10 min. Only one subject had an immediate rise at 60 min. Conclusion:, Variability derived from urease activity in the intestinal tract appears to be minimal up to 60 min after ingestion of the test urea. [source]


Review article: nitric oxide from dysbiotic bacterial respiration of nitrate in the pathogenesis and as a target for therapy of ulcerative colitis

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2008
W. E. W. ROEDIGER
Summary Background, Factors initiating human ulcerative colitis (UC) are unknown. Dysbiosis of bacteria has been hypothesized to initiate UC but, to date, neither the nature of the dysbiosis nor mucosal breakdown has been explained. Aim, To assess whether a dysbiosis of anaerobic nitrate respiration could explain the microscopic, biochemical and functional changes observed in colonocytes of UC. Methods, Published results in the gastroenterological, biochemical and microbiological literature were reviewed concerning colonocytes, nitrate respiration and nitric oxide in the colon in health and UC. A best-fit explanation of results was made regarding the pathogenesis and new treatments of UC. Results, Anaerobic nitrate respiration yields nitrite, nitric oxide (NO) and nitrous oxide. Colonic bacteria produce NO and UC in remission has a higher lumenal NO level than control cases. NO with sulphide, but not NO alone, impairs ,-oxidation, lipid and protein synthesis explaining the membrane, tight junctional and ion channel changes observed in colonocytes of UC. The observations complement therapeutic mechanisms of those probiotics, prebiotics and antibiotics useful in treating UC. Conclusions, The prolonged production of bacterial NO with sulphide can explain the initiation and barrier breakdown, which is central to the pathogenesis of UC. Therapies to alter bacterial nitrate respiration and NO production need to evolve. The production of NO by colonic bacteria and that of the mucosa need to be separated to pinpoint the sequential nature of NO damage in UC. [source]