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Dig Dis Sci. 2012 Dec;57(12):3213-8. doi: 10.1007/s10620-012-2197-1. Epub 2012 May 10.

Methanobrevibacter smithii is the predominant methanogen in patients with constipation-predominant IBS and methane on breath.

Author information

1
GI Motility Program, Division of Gastroenterology, Cedars Sinai Medical Center, 8730, Alden Dr, Suite 225 E, Los Angeles, CA 90048, USA.

Abstract

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 × 10(7) ± 3.0 × 10(7) vs 3.2 × 10(5) ± 7.6 × 10(5) 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 × 10(5) 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.

PMID:
22573345
DOI:
10.1007/s10620-012-2197-1
[Indexed for MEDLINE]

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