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Small Intestinal Bacterial Overgrowth
Accepted Manuscript Small Intestinal Bacterial Overgrowth Robert M. Craig, M. D., Professor Emeritus
PII: DOI: Reference:
S1542-3565(16)00219-6 10.1016/j.cgh.2016.02.021 YJCGH 54650
To appear in: Clinical Gastroenterology and Hepatology Accepted Date: 22 February 2016 Please cite this article as: Craig RM, Small Intestinal Bacterial Overgrowth, Clinical Gastroenterology and Hepatology (2016), doi: 10.1016/j.cgh.2016.02.021. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
RI PT
Small Intestinal Bacterial Overgrowth
AC C
EP
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No conflicts of interest No assistance in the writing
M AN U
Correspondence: 1025 Terrace Court, Lake Geneva WI 53147 [email protected] T: 312-664-3324 F: 312-873-4426
SC
Robert M. Craig, M. D. Professor Emeritus, Northwestern University Feinberg School of Medicine.
1
ACCEPTED MANUSCRIPT
RI PT
I was delighted to read the articles on the glucose-hydrogen breath test as they relate to the complexities of the physiology of digestion and absorption, and the pathophysiology of diarrhea and malabsorption (1, 2). Patients with irritable bowel or diarrhea might have small intestinal bacterial overgrowth (SIBO), which is a cause of fat malabsorption, mostly due to duodeno-jejunal deconjugation of bile salts, resulting in diminished micelle formation; carbohydrate malabsorption due to its consumption by the bacteria; and vitamin B12 malabsorption due to the bacterial consumption or binding.
SC
Although the authors indicate that jejunal cultures and H2 carbohydrate breath tests are the preferred methods for evaluating SIBO, they fail to mention the Schillings test for vitamin B12 absorption, the 72-hour fecal fat determination for fat absorption, and the D-xylose test for non-carrier mediated monosaccharide absorption. An improvement in any of these tests following antibiotic therapy clinches the diagnosis of SIBO.
M AN U
Malabsorption of a substrate is best described kinetically as diminished bioavailability, due to a decreased rate of absorption, for example, from celiac disease; or an increased rate of non-absorptive loss, for example, from SIBO or “intestinal hurry” (3). The fecal fat and D-xylose tests are abnormal for both diminished rate of absorption (celiac disease) and increased rate of non-absorptive loss (SIBO). A combination of defects is also possible. Someone with irritable bowel and diarrhea might have celiac disease, “intestinal hurry,” and SIBO in combination, complicating the evaluation.
EP
TE D
When testing a new diagnostic tool, it is incumbent upon the investigators to use an appropriate gold standard, against which the new test is compared. King’s and Toskes’ seminal studies on subjects with SIBO met that bill as their subjects with SIBO had positive jejunal cultures and their controls did not (4). They showed that the 1 gm 14C D-xylose breath discriminated between SIBO and controls, but the 80 gm H2 glucose and the 10 gm H2 lactulose breath tests did not. Lin and Massey fail to compare their results from the 80 gm glucose H2 breath tests to a gold standard.
AC C
Another serious difficulty with carbohydrate breath tests is the osmolality of the solution provided. 80 gms glucose is a large osmotic load, which will induce diarrhea in many normals, with consequent increased rate of non-absorptive loss. If scintigraphy is used, it should be done both with the test solution and without to control for the osmotic load-induced “intestinal hurry.”
1. Lin EC, Massey BT. Scintigraphy demonstrates high rate of false-positive results from glucose breath tests for small bowel bacterial overgrowth. Clin Gastroenterol Hepatol 2016;14:203-208. 2. Sellin JH. A breath of fresh air. J Clin Gastroenterol Hepatol 2016;14:209-211. 2
ACCEPTED MANUSCRIPT
3. Craig RM, Atkinson AJ, Jr. D-xylose testing. A review. Gastroenterology 1988;95:223-231.
AC C
EP
TE D
M AN U
SC
RI PT
4. King CE, Toskes PP. Comparison of the 1-gm (14C) xylose, 10 gm lactulose H2, and 80 gm lactulose H2 breath tests in patients with small intestinal bacterial overgrowth. Gastroenterology 1986;91:1447-1451.
3
PII: DOI: Reference:
S1542-3565(16)00219-6 10.1016/j.cgh.2016.02.021 YJCGH 54650
To appear in: Clinical Gastroenterology and Hepatology Accepted Date: 22 February 2016 Please cite this article as: Craig RM, Small Intestinal Bacterial Overgrowth, Clinical Gastroenterology and Hepatology (2016), doi: 10.1016/j.cgh.2016.02.021. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
RI PT
Small Intestinal Bacterial Overgrowth
AC C
EP
TE D
No conflicts of interest No assistance in the writing
M AN U
Correspondence: 1025 Terrace Court, Lake Geneva WI 53147 [email protected] T: 312-664-3324 F: 312-873-4426
SC
Robert M. Craig, M. D. Professor Emeritus, Northwestern University Feinberg School of Medicine.
1
ACCEPTED MANUSCRIPT
RI PT
I was delighted to read the articles on the glucose-hydrogen breath test as they relate to the complexities of the physiology of digestion and absorption, and the pathophysiology of diarrhea and malabsorption (1, 2). Patients with irritable bowel or diarrhea might have small intestinal bacterial overgrowth (SIBO), which is a cause of fat malabsorption, mostly due to duodeno-jejunal deconjugation of bile salts, resulting in diminished micelle formation; carbohydrate malabsorption due to its consumption by the bacteria; and vitamin B12 malabsorption due to the bacterial consumption or binding.
SC
Although the authors indicate that jejunal cultures and H2 carbohydrate breath tests are the preferred methods for evaluating SIBO, they fail to mention the Schillings test for vitamin B12 absorption, the 72-hour fecal fat determination for fat absorption, and the D-xylose test for non-carrier mediated monosaccharide absorption. An improvement in any of these tests following antibiotic therapy clinches the diagnosis of SIBO.
M AN U
Malabsorption of a substrate is best described kinetically as diminished bioavailability, due to a decreased rate of absorption, for example, from celiac disease; or an increased rate of non-absorptive loss, for example, from SIBO or “intestinal hurry” (3). The fecal fat and D-xylose tests are abnormal for both diminished rate of absorption (celiac disease) and increased rate of non-absorptive loss (SIBO). A combination of defects is also possible. Someone with irritable bowel and diarrhea might have celiac disease, “intestinal hurry,” and SIBO in combination, complicating the evaluation.
EP
TE D
When testing a new diagnostic tool, it is incumbent upon the investigators to use an appropriate gold standard, against which the new test is compared. King’s and Toskes’ seminal studies on subjects with SIBO met that bill as their subjects with SIBO had positive jejunal cultures and their controls did not (4). They showed that the 1 gm 14C D-xylose breath discriminated between SIBO and controls, but the 80 gm H2 glucose and the 10 gm H2 lactulose breath tests did not. Lin and Massey fail to compare their results from the 80 gm glucose H2 breath tests to a gold standard.
AC C
Another serious difficulty with carbohydrate breath tests is the osmolality of the solution provided. 80 gms glucose is a large osmotic load, which will induce diarrhea in many normals, with consequent increased rate of non-absorptive loss. If scintigraphy is used, it should be done both with the test solution and without to control for the osmotic load-induced “intestinal hurry.”
1. Lin EC, Massey BT. Scintigraphy demonstrates high rate of false-positive results from glucose breath tests for small bowel bacterial overgrowth. Clin Gastroenterol Hepatol 2016;14:203-208. 2. Sellin JH. A breath of fresh air. J Clin Gastroenterol Hepatol 2016;14:209-211. 2
ACCEPTED MANUSCRIPT
3. Craig RM, Atkinson AJ, Jr. D-xylose testing. A review. Gastroenterology 1988;95:223-231.
AC C
EP
TE D
M AN U
SC
RI PT
4. King CE, Toskes PP. Comparison of the 1-gm (14C) xylose, 10 gm lactulose H2, and 80 gm lactulose H2 breath tests in patients with small intestinal bacterial overgrowth. Gastroenterology 1986;91:1447-1451.
3