Digest Dis Sci：肠道细菌在肠易激综合征中发挥重要作用

近日，研究人员发现肠道细菌的增生与肠易激综合症（IBS）有关，该发现是第一次证实细菌与这种疾病有关。

以往的研究已近提示细菌在疾病中发挥了重要作用发挥了作用，而这项研究是首次使用细菌培养方法证实了两者之间的联系。

研究人员检查了疾病患者中小肠样本以确认是否存在小肠细菌过度生长的现象，结果发现在IBS患者中有超过三分之一的人被确诊为小肠细菌过度生长。

医学博士Mark Pimentel说：有关细菌在疾病中发挥作用的明确证据提示了我们将来的临床试验结果，也表明抗生素是可以成功治疗IBS的。

IBS是美国最常见的胃肠道紊乱症，影响估计有30万人。患者带有的症状包括疼痛腹胀、便秘、腹泻或两者交替症状。

doi:10.1007/s10620-012-2197-1
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PMID:

Methanobrevibacter smithii Is the Predominant Methanogen in Patients with Constipation-Predominant IBS and Methane on Breath

Gene Kim, Fnu Deepinder, Walter Morales, Laura Hwang, Stacy Weitsman, Christopher Chang, Robert Gunsalus and Mark Pimentel

Purpose

Among irritable bowel syndrome (IBS) patients, breath methane producers overwhelmingly have constipation predominance (C-IBS). Although the most common methanogen in humans is Methanobrevibacter smithii, incidence and type of methanogenic bacteria in C-IBS patients are unknown.

Methods

By use of a questionnaire and lactulose breath testing, subjects with Rome II C-IBS and methane (>3 ppm) were selected (n = 9). The control group included subjects with IBS who had no breath methane (n = 10). Presence of bacterial DNA was assessed in a stool sample of each subject by quantitative-PCR using universal 16S rDNA primer. M. smithii was quantified by use of a specific rpoB gene primer.

Results

M. smithii was detected in both methane and non-methane subjects. However, counts and relative proportion of M. smithii were significantly higher for methane-positive than for methane-negative subjects (1.8 × 10⁷ ± 3.0 × 10⁷ vs 3.2 × 10⁵ ± 7.6 × 10⁵ copies/g wet stool, P < 0.001; and 7.1 ± 6.3 % vs 0.24 ± 0.47 %, P = 0.02 respectively). The minimum threshold of M. smithii resulting in positive lactulose breath testing for methane was 4.2 × 10⁵ copies/g wet stool or 1.2 % of total stool bacteria. Finally, area-under-curve for breath methane correlated significantly with both absolute quantity and percentage of M. smithii in stool (R = 0.76; P < 0.001 and R = 0.77; P < 0.001 respectively).

Conclusions

M. smithii is the predominant methanogen in C-IBS patients with methane on breath testing. The number and proportion of M. smithii in stool correlate well with amount of breath methane.