Orocecal transit time and bacterial overgrowth in patients with Crohn's disease

Small intestinal bacterial overgrowth: roles of antibiotics, prebiotics, and probiotics

Small intestinal bacterial overgrowth is common in intestinal failure. Its occurrence relates to alterations in intestinal anatomy, motility, and gastric acid secretion. Its presence may contribute to symptoms, mucosal injury, and malnutrition. Relationships between bacterial overgrowth and systemic sepsis are of potential importance in the intestinal failure patient because the direct translocation of bacteria across the intestinal epithelium may contribute to systemic sepsis: a phenomenon that has been well established in experimental animal models. The accurate diagnosis of bacterial overgrowth continues to present a number of challenges in clinical practice and especially so among patients with intestinal failure. The management of patients with bacterial overgrowth remains, for the most part, primarily empiric and comprises antibiotic therapy and correction of any associated nutritional deficiencies. Although evidence from experimental animal studies consistently indicates that probiotics exert barrier-enhancing, antibacterial, immune-modulating, and anti-inflammatory effects, which all could be benefits in small intestinal bacterial overgrowth and intestinal failure, their role in human beings remains to be evaluated adequately.

Irritable bowel syndrome and inflammatory bowel disease: interrelated diseases?

In the past inflammatory bowel disease (IBD), celiac disease and irritable bowel syndrome (IBS) were regarded as completely separate disorders. Now, with the description of inflammation, albeit low-grade, in IBS, and of symptom overlap between IBS and celiac disease, this contention has come under question. Is there true overlap between these disorders? Despite the limitations of available data one cannot but be struck by some areas of apparent convergence: IBD and celiac disease in remission, lymphocytic colitis and microscopic inflammation in IBS, in general, and, especially, in the post-infectious IBS category. The convergence between latent celiac disease and sub-clinical IBD, on the one hand, and IBS, on the other, appears, based on available evidence, to be somewhat spurious and may largely relate to misdiagnosis, a phenomenon which may also explain the apparent evolution of IBS into IBD in some studies. Similarities between IBS and lymphocytic colitis are more striking and less readily dismissed; as for IBS, well documented instances of progression of lymphocytic colitis to full-blown IBD are infrequent, suggesting a true separation between this disorder and classical IBD. Do IBS and lymphocytic colitis represent different responses to similar triggers? Will some of the 'inflamed' IBS subgroup be reclassified as part of the spectrum of lymphocytic colitis in the future? Will inflammation emerge as a common underlying factor in the pathogenesis of IBS? The answer to these and many questions must await further study of this fascinating area.

Fasting breath hydrogen concentration in short bowel syndrome patients with colon incontinuity before and after antibiotic therapy

OBJECTIVE

Nutrition success in short bowel syndrome (SBS) depends on the intake nutrients and the intestinal absorption capacity. An evaluation of energy expenditure and oxidation of substrate can be obtained with indirect calorimetry by measuring O(2) and CO(2) in the respiration. Elevated colonic fermentation can occur in SBS, producing H(2) and CO(2), which can also be eliminated through respiration and as a consequence affect the results from indirect calorimetry. The objective of this study was to determine the fasting breath H(2) concentration and alterations before and after antibiotic therapy in patients with severe SBS with colon in continuity.

METHODS

The study was conducted in two phases. In phase 1, the fasting breath H(2) concentrations were measured in 10 patients with severe SBS with colon incontinuity and a control group of 10 healthy volunteers. In phase 2, the fasting breath H(2) concentrations were re-evaluated after treatment for 7 d with antibiotics in six patients with high rates of H(2). The analyses were performed with a gas chromatograph (microanalyzer DP; Quintron Instruments, Milwaukee, WI, USA), with results of breath hydrogen and methane concentration expressed in parts per million (ppm).

RESULTS

In phase 1, the levels of fasting breath H(2) were higher in the patients with severe SBS with colon incontinuity than in the healthy controls (32.00 +/- 17.77 versus 5.30 +/- 3.31 ppm; P < 0.001), with 7 of 10 patients presenting levels of H(2) above the normal rate (12 ppm). The presence of an ileocecal valve did not modify the results significantly. In phase 2, all six patients treated with antibiotics presented normalization in the levels of fasting breath H(2) (from 43.50 +/- 6.90 ppm to 1.33 +/- 1.03 ppm; P < 0.001) and concomitant improvement in the gastrointestinal symptoms.

CONCLUSIONS

In relation to the healthy controls, patients with SBS with colon incontinuity presented higher levels of fasting breath H(2). Antibiotic therapy normalized the levels of fasting breath H(2) and improved the gastrointestinal symptoms. We suggest that the breath H(2) test may be performed routinely in patients with SBS to diagnose elevated intestinal fermentation, prevent errors in the interpretation of the indirect calorimetry, and treat eventual associated gastrointestinal symptoms.

Therapeutic manipulation of the enteric microflora in inflammatory bowel diseases: antibiotics, probiotics, and prebiotics

Crohn's disease, ulcerative colitis, and pouchitis are caused by overly aggressive immune responses to a subset of commensal (nonpathogenic) enteric bacteria in genetically predisposed individuals. Clinical and experimental studies suggest that the relative balance of aggressive and protective bacterial species is altered in these disorders. Antibiotics can selectively decrease tissue invasion and eliminate aggressive bacterial species or globally decrease luminal and mucosal bacterial concentrations, depending on their spectrum of activity. Alternatively, administration of beneficial bacterial species (probiotics), poorly absorbed dietary oligosaccharides (prebiotics), or combined probiotics and prebiotics (synbiotics) can restore a predominance of beneficial Lactobacillus and Bifidobacterium species. Current clinical trials do not fulfill evidence-based criteria for using these agents in inflammatory bowel diseases (IBD), but multiple nonrigorous studies and widespread clinical experience suggest that metronidazole and/or ciprofloxacin can treat Crohn's colitis and ileocolitis (but not isolated ileal disease), perianal fistulae and pouchitis, whereas selected probiotic preparations prevent relapse of quiescent ulcerative colitis and relapsing pouchitis. These physiologic approaches offer considerable promise for treating IBD, but must be supported by rigorous controlled therapeutic trials that consider clinical disease before their widespread clinical acceptance. These agents likely will become an integral component of treating IBD in combination with traditional anti-inflammatory and immunosuppressive agents.

Antibiotic treatment of small bowel bacterial overgrowth in patients with Crohn's disease

BACKGROUND

Small bowel bacterial overgrowth is common in Crohn's disease but its treatment is not clearly defined. Metronidazole and ciprofloxacin are effective antibiotics in active Crohn's disease.

AIM

To investigate the efficacy of metronidazole and ciprofloxacin in the treatment of bacterial overgrowth in patients with Crohn's disease.

PATIENTS AND METHODS

We performed the lactulose breath test in 145 consecutive patients affected by Crohn's disease. Patients positive to the lactulose breath test underwent a glucose breath test to confirm the overgrowth. These patients were randomized in two treatment groups: metronidazole 250 mg t.d.s. (Group A) and ciprofloxacin 500 mg b.d. (Group B), both orally for 10 days. The glucose breath test was repeated at the end of treatment. The clinical outcome after therapy was also recorded.

RESULTS

Bacterial overgrowth was present in 29 patients (20%). Breath test normalization occurred in 13 out of 15 patients treated by metronidazole and in all 14 patients treated by ciprofloxacin (P = ns). In both groups antibiotic treatment induced an improvement of intestinal symptoms: bloating (Group A 85% and Group B 83%), stool softness (44% and 50%), and abdominal pain (50% and 43%).

CONCLUSIONS

Small bowel bacterial overgrowth is a frequent condition in Crohn's disease which can be effectively treated by metronidazole or ciprofloxacin.

Normalization of lactulose breath testing correlates with symptom improvement in irritable bowel syndrome. a double-blind, randomized, placebo-controlled study

OBJECTIVE

We have recently found an association between abnormal lactulose breath test (LBT) findings and irritable bowel syndrome (IBS). The current study was designed to test the effect of antibiotic treatment for IBS in a double-blind fashion.

METHODS

Consecutive IBS subjects underwent an LBT with the results blinded. All subjects were subsequently randomized into two treatment groups (neomycin or placebo). The prevalence of abnormal LBT was compared with a gender-matched control group. Seven days after completion of treatment, subjects returned for repeat LBT. A symptom questionnaire was administered on both days.

RESULTS

After exclusion criteria were met, 111 IBS subjects (55 neomycin, 56 placebo) entered the study, with 84% having an abnormal LBT, compared with 20% in healthy controls (p < 0.01). In an intention-to-treat analysis of all 111 subjects, neomycin resulted in a 35.0% improvement in a composite score, compared with 11.4% for placebo (p < 0.05). Additionally, patients reported a percent bowel normalization of 35.3% after neomycin, compared with 13.9% for placebo (p < 0.001). There was a graded response to treatment, such that the best outcome was observed if neomycin was successful in normalizing the LBT (75% improvement) (one-way ANOVA, p < 0.0001). LBT gas production was associated with IBS subgroup, such that methane excretion was 100% associated with constipation-predominant IBS. Methane excretors had a mean constipation severity of 4.1, compared with 2.3 in all other subjects (p < 0.001).

CONCLUSIONS

An abnormal LBT is common in subjects with IBS. Normalization of LBT with neomycin leads to a significant reduction in IBS symptoms. The type of gas seen on LBT is also associated with IBS subgroup.

Assessment of orocaecal transit time in different localization of Crohn's disease and its possible influence on clinical response to therapy

BACKGROUND

A study on orocaecal transit time (OCTT) in patients with different localizations of Crohn's disease (CD) is not available. Because slow-release drug formulations are increasingly available for the treatment, there is a concrete risk that delayed OCTT may impair the efficacy of these formulations.

AIMS

We investigated OCTT before and after therapy using lactulose H2-breath test and we studied whether OCTT can influence the clinical response to therapy with slow-release mesalazine formulations in adult CD patients.(2)

PATIENTS AND METHODS

We studied 45 adult patients with non-obstructive CD and Crohn's Disease Activity Index (CDAI) <200 (29 men, 16 women; mean age 42 years, range 22-73 years). Twenty patients had ileocolonic, 16 colonic and 9 ileal localization of CD. The control group consisted of 20 healthy subjects (13 men, seven women; mean age 53 years, range 22-71 years). After OCTT assessment, 29 patients were treated with time-dependent mesalazine 3.6 g/day, while 16 patients were treated with pH-dependent mesalazine 3.6 g/day. If bacterial overgrowth was detected, the patients were also treated with rifaximin 800 mg/day for 7 days.

RESULTS

OCTT was delayed (120 min, range 115-210 min) in 30 of the 45 CD patients (67%). Four patients (9%) showed bacterial overgrowth, while OCTT was regular (82.5 min, range 75-90 min) in 11 patients (24%). In the control group, the mean OCTT was 88.2 min (range 75-135 min); (P<0.01). OCTT was more prolonged in ileal localization (182.2 min, range 150-210 min), rather than in patients with ileocolonic (122 min, range 75-180 min) or colonic (106 min, range 75-150 min) localization of CD; (P<0.01). Thirty-nine patients showed normal OCTT after starting therapy (83 min, range 75-105 min), while OCTT remained slightly delayed in the remaining patients (110 min, range 105-115 min); (P<0.01). CDAI was <100 (mean value 83) in all patients with reduction of OCTT to normal value 4 months after starting therapy, while it was >140 (mean value 143) in patients with a slight reduction but not normalization of OCTT respectively (five patients with ileal and one with ileocolonic localization of CD) with a statistically significant correlation between OCTT and CDAI (P<0.01).

CONCLUSIONS

This study shows clearly for the first time that OCTT is not only delayed in patients with active CD, but also that it is prolonged in ileal and ileocolonic rather than colonic localization of CD. Moreover we obtained these results using a simple, sensitive, non-invasive and repeatable method, namely, a lactulose hydrogen breath test.