Comment on: Rifaximin in the treatment of irritable bowel syndrome. is there a high risk for development of antimicrobial resistance?

Impact of Antibiotic Resistance Genes in Gut Microbiome of Patients With Cirrhosis

BACKGROUND AND AIMS

Cirrhosis is associated with changes in intestinal microbiota that can lead to hepatic encephalopathy (HE) and infections, especially with antibiotic-resistant organisms. However, the impact of gut microbial antibiotic resistance gene (ARG) burden on clinical outcomes is unclear. The aims of the study were to determine the impact of ARGs in cirrhosis-related gut metagenome on outcomes and disease progression, study the effect of rifaximin on ARG burden, and compare ARGs in cirrhosis with chronic kidney disease (CKD) and diabetes.

METHODS

In outpatients with cirrhosis who underwent metagenomics, we evaluated change in ARG abundances with progression and their multivariable impact on 90-day hospitalizations and deaths over 1 year. We also studied ARGs pre- and 8 weeks post-rifaximin in patients with compensated cirrhosis in an open-label trial. Finally, ARGs from CKD and diabetes studies were compared with cirrhosis on machine learning.

RESULTS

A total of 163 patients with cirrhosis (43 compensated, 20 ascites-only, 30 HE-only, 70 both) and 40 controls were included. ARG abundances were higher in cirrhosis versus controls and worsened with advancing cirrhosis severity; 44 patients were hospitalized and 14 died. ARG abundances were associated with hospitalizations and mortality while controlling for cirrhosis complications, medications, and demographics. Rifaximin trial: ARG abundance patterns were minimally affected in 19 patients post-rifaximin. CKD/diabetes comparison: ARG abundance patterns in cirrhosis are distinguishable on machine learning and include more gram-positive ARGs.

CONCLUSIONS

Cirrhosis is associated with high gut microbial ARG gene burden compared with controls, which worsens with disease progression and may be different from CKD and diabetes. ARGs are not affected by rifaximin and are associated with hospitalizations and death.

Changes in Fecal Calprotectin After Rifaximin Treatment in Patients With Nonconstipated Irritable Bowel Syndrome

BACKGROUND

Fecal calprotectin, an indicator of colonic inflammation, is associated with nonconstipated irritable bowel syndrome. Rifaximin is an antibiotic used to treat nonconstipated irritable bowel syndrome. We performed a retrospective review of patient charts to investigate the changes in fecal calprotectin levels and intestinal symptoms following treatment with rifaximin in patients with nonconstipated irritable bowel syndrome with elevated fecal calprotectin.

METHODS

This study included 198 patients presenting with gastrointestinal complaints consistent with Rome III criteria for irritable bowel syndrome. We treated them with rifaximin for 4-12 weeks, until fecal calprotectin levels were normalized, and divided these into 4-, 8-, and 12-week groups according to the treatment period. Fecal calprotectin levels and gastrointestinal symptoms were assessed following rifaximin therapy.

RESULTS

A total of 162 subjects achieved normalized fecal calprotectin values. Of these, most patients who used rifaximin for 8 or 12 weeks showed a significant improvement in gastrointestinal symptoms by the fourth week of treatment, and gradually improved symptoms after 4 weeks. Fecal calprotectin levels were reduced with concomitant improvement of clinical symptoms. In addition, 36 patients who had elevated fecal calprotectin even after 12 weeks of rifaximin treatment showed a gradual reduction in gastrointestinal symptoms and fecal calprotectin during the course of treatment for 12 weeks.

CONCLUSIONS

These findings suggest that fecal calprotectin might be a useful biomarker for measuring the effect of rifaximin therapy in nonconstipated irritable bowel syndrome patients with elevated fecal calprotectin values.

Determination of rifaximin treatment period according to lactulose breath test values in nonconstipated irritable bowel syndrome subjects

Small intestinal bacterial overgrowth (SIBO) can partly explain irritable bowel syndrome (IBS), and rifaximin has been observed to improve abdominal symptoms in nonconstipated IBS patients. However, there are few reports on the association of the rifaximin treatment periods with the results of a lactulose breath test (LBT). Therefore, we performed a retrospective review of patient charts to investigate the relation between the rifaximin treatment periods with LBT results in nonconstipated IBS patients. We also evaluated the time to achieve a symptomatic improvement in the IBS patients as compared to the changes in the LBT. We reviewed the charts for patients who showed IBS symptoms with documented positive results for LBT during their initial visit and who had a follow-up LBT after treatment with rifaximin. The LBT values were compared to the subjects' symptom scores. A total of 102 subjects had a follow-up LBT to assess LBT normalization. The subjects were divided into groups according to treatment periods of 4 weeks (n = 36), 8 weeks (n = 43), and 12 weeks (n = 23). The groups with a longer treatment exhibited an increase in the hydrogen gas value at 90 min and its sum during 90 min at the initial LBT. There were significant differences in hydrogen gas value at 90 min and in its sum during 90 min at the initial LBT between the groups treated for 4 and 12 weeks. The most significant treatment response was observed during the first 4 weeks for all treatment groups. Symptomatic improvement occurred earlier than LBT normalization in the treatment period over 4 weeks. The results indicate that different rifaximin treatment periods are needed in accordance with LBT levels to effectively eradicate SIBO.