LAS VEGAS – Patients with systemic sclerosis, mixed connective tissue disease, and Ehlers-Danlos syndrome who have a gastrointestinal symptom cluster that includes bloating, early satiety, and postprandial “brain fog” may be suffering from small intestine bacterial overgrowth, or SIBO.
This treatable condition occurs when enteric flora from the colon creep north into the small intestine, which is usually a relatively sterile environment. In addition to the bloating, dyspepsia, and nausea that SIBO can cause, patients may have an erratic bowel movement pattern, and can occasionally suffer from vitamin deficiencies and weight loss, Ali Rezaie, MD, said at the annual Perspectives in Rheumatic Diseases held by the Global Academy for Medical Education.
“SIBO is not a primary disease,” said, professor of gastroenterology at Cedars-Sinai Medical Center, Los Angeles, and lead author of a 2016 review on the diagnosis and treatment of SIBO ( ).
For patients with scleroderma or mixed connective tissue diseases as well as hypermobility disorders such as Ehlers-Danlos syndrome, the small bowel dysmotility associated with their conditions is often the primary disease. However, diabetes-associated gastroparesis and the presence of anti-vinculin and anti-CdtB antibodies in irritable bowel syndrome patients can also cause dysmotility, provoking SIBO.
Surgical procedures that can set patients up for SIBO include gastric bypass and ileocecal resection; medications such as opioids and anticholinergic or antidiarrheal medications also can be SIBO risk factors. Finally, chronic proton pump inhibitor use, autoimmune gastritis, and gastrectomy can all reduce gastric acid secretion, permitting bacterial overgrowth in the small intestine.
Normally, jejunal contents have around 100 colony-forming units (CFU) per mL, with Lactobacillus and Streptococcus predominating. However, in SIBO, there are more bacteria in the small intestine – greater than 1,000 CFU/mL – and enteric flora predominate.
Depending on the species predominating, an excess of hydrogen or methane may be produced during bacterial fermentation of food in the small intestine, Dr. Rezaie said. Though the preferred method for diagnosis is small-bowel aspiration, “this is an invasive, costly, and time-consuming procedure,” he said.
By contrast, breath testing is noninvasive and inexpensive, and detects excess levels of hydrogen or methane on the breath when performed at a fixed time after the patient is fed a bolus of lactulose or glucose. The test is diagnostic for SIBO because “the sole source of methane and hydrogen [as H2] in our body is from the bacterial metabolism,” Dr. Rezaie said.
SIBO breath testing is considered positive if there are 10 or greater parts per million of methane at any time point, or if hydrogen levels rise by at least 20 parts per million within 90 minutes of the bolus feed.
The treatment for SIBO can be thought of in three phases, Dr. Rezaie said in an interview, referencing the consensus statement. The three treatment stages include induction of remission, maintenance of remission, and treatment of recurrence, should it recur.
Therapy for induction of remission is guided by the breath test results. If excessive methane production is not detected, then a broad-spectrum antibiotic such as amoxicillin, ciprofloxacin, trimethoprim-sulfamethoxazole, or rifaximin can be given for 14 days. If excess methane is detected, then the broad spectrum antibiotic should be combined with neomycin 500 mg by mouth for 14 days as well.
If a clinical response occurs, then a maintenance strategy can include restricting highly fermentable foods, using promotility drugs such as low-dose macrolides, tegaserod, or other 5HT4 agonists, and ongoing vigilance for recurrent symptoms. If there’s a primary cause that can be remedied – for example, stopping a proton pump inhibitor or lysing identifiable intestinal lesions – then those factors can be addressed during remission as well.
For patients who can’t be brought into remission with one antibiotic course, another course of alternative antibiotics can be considered. Some patients may benefit from an elemental diet.
Managing recurrences involves further rounds of antibiotics together with optimizing motility and addressing other risk factors.
In terms of how SIBO affects management of the primary rheumatologic disease, patients should try to avoid frequent use of nonsteroidal anti-inflammatory drugs because of the potential for further untoward effects on a disrupted gut. However, there’s no reason to alter medical therapy otherwise, and biologic therapy “is generally well-tolerated in patients with small intestine bacterial overgrowth,” Dr. Rezaie said.
He pointed out that rheumatology patients can have so many medical issues that gastrointestinal symptoms may not rise to the surface, so a thorough review of systems should include careful questioning about digestive health. “Rheumatologists need to incorporate this knowledge into the management of their patients,” he said. “It’s a quality of life issue.”
Dr. Rezaie reported having received honoraria and consulted for Valeant Pharmaceuticals. Global Academy for Medical Education and this news organization are owned by the same parent company.