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In vitro hydrogen production by enteric bacteria cultured from children with small bowel bacterial overgrowth
Khin-Maung-U1, Tin-Aye, Ku-Tin-Myint
1Clinical Research Division, Ministry of Health (Rangoon) Yangon, Burma,Myanmar.
Insights
The lactulose breath hydrogen test may misdiagnose small bowel bacterial overgrowth. Some gut bacteria, like E. coli, don't produce hydrogen, leading to false negatives in this common diagnostic test.
Area of Science:
- Microbiology
- Gastroenterology
- Pediatrics
Background:
- Small bowel bacterial overgrowth (SBBO) is a condition diagnosed using the lactulose breath hydrogen test.
- The test relies on detecting hydrogen produced by bacterial fermentation of lactulose in the small intestine.
Purpose of the Study:
- To investigate the in vitro hydrogen production of jejunal bacteria isolated from children undergoing SBBO diagnosis.
- To assess the implications of bacterial hydrogen production variability on the accuracy of the lactulose breath hydrogen test.
Main Methods:
- Simultaneous administration of lactulose breath hydrogen test and Enterotest string test in 19 children (3-5 years old).
- Isolation and in vitro incubation of jejunal bacteria with lactulose at neutral pH.
- Quantification of hydrogen production by bacterial isolates.
Main Results:
- Anaerobic bacteria were prevalent in most children's jejunal fluid.
- Escherichia coli was the most frequent hydrogen producer (67%), followed by Streptococcus (9%) and Clostridia (8%).
- A significant proportion of isolated bacteria, including Bifidobacterium and Veillonella, did not produce hydrogen in vitro.
Conclusions:
- The lactulose breath hydrogen test's diagnostic accuracy for SBBO may be limited by the presence of non-hydrogen-producing enteric bacteria.
- A 'flat' breath hydrogen response in the initial 60 minutes could indicate SBBO caused by bacteria that do not ferment lactulose to produce detectable hydrogen.
- Further research is needed to refine diagnostic strategies for SBBO, considering the metabolic diversity of small intestinal microbiota.
Abstract:
Lactulose breath hydrogen test and Enterotest string test were carried out simultaneously on 19 children 3-5 years old. Bacteria isolated from the jejunal fluid in upper small intestines of these children were incubated with lactulose at neutral pH. Anaerobes were present in all but one child, and in 15 children they were present in numbers greater than 5 log10 organisms per ml. Most of these bacteria did not produce hydrogen in vitro. Hydrogen production (greater than 100 ppm) was observed with the following bacteria: Bacteroides (5%), clostridia (8%), anaerobic corynebacteria (5%), Escherichia coli (67%), Lactobacillus (8%), Staphylococcus (8%), and Streptococcus (9%). The following bacteria did not produce hydrogen in vitro: Actinobacter, Actinomyces, anaerobic cocci, Bifidobacterium, Fusobacterium, micrococci, Neisseria, Sarcina, and Veillonella. This study suggests that in the diagnosis of small bowel bacterial overgrowth using lactulose breath hydrogen test, it is important to consider that patients with a flat breath hydrogen response to a carbohydrate challenge during the first 60 min may be infected with enteric bacteria which are not capable of producing H2.