This issue often comes up in discussions with CFS/FM/IBS

• “Recent research shows that patients with CFS have marked alterations in microbial flora, including lowered levels of bifidobacteria and small intestinal bacterial overgrowth (SIBO).” [2003]
• “a considerable proportion of patients with fibromyalgia experience gastrointestinal symptoms that are commonly overlooked in the studies that are not specifically dedicated to evaluate these manifestations.” [2015]
• “Recent investigations have shown that bacterial overgrowth of the small intestine is associated with a number of functional somatic disorders, including irritable bowel syndrome (IBS), fibromyalgia, and chronic fatigue syndrome.” [2002]

The model that I use is based on a shift of the microbiome — some overgrowth and some undergrowth. SIBO is a subset of this definition.

• “Some studies reported up to 80% of patients with irritable bowel syndrome (IBS) have SIBO (using the hydrogen breath test). Subsequent studies demonstrated statistically significant reduction in IBS symptoms following therapy for SIBO.^{[20][21][22]” Wikipedia}

According to wikipedia, there are multiple methods of diagnosis — the basis of these methods is abnormal results with “some physicians suggest that if the suspicion of bacterial overgrowth is high enough, the best diagnostic test is a trial of treatment. If the symptoms improve, an empiric diagnosis of bacterial overgrowth can be made.^[39]“

• “Diagnosis of SIBO is challenging due to the low specificity of symptoms, the frequent association with other diseases of the gastrointestinal tract and the absence of optimal objective diagnostic tests.” [2016]
• “The diagnosis of SIBO is controversial. There is substantial disagreement in the literature regarding which test is the most appropriate in either the clinical or research setting.” [2007]
• Hydrogen sulphide in exhaled breath: a potential biomarker for small intestinal bacterial overgrowth in IBS.[2016]
  • “The hydrogen breath test depends on the presence of hydrogen producing bacteria. However, a considerable proportion of non‐hydrogen producing bacteria, which can yield false negative results, has been observed in some^12,16,17 but not all studies.^{18,19,20” [2006]}
  • “False positive results may also be due to the oral bacterial flora and if the subject has failed to adhere to a low fibre diet the day before the test.”[2006]
• Breath Testing for Small Intestinal Bacterial Overgrowth: Should We Bother? [2016]
• Are we underestimating the prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome?[2015]
• Small intestinal bacterial overgrowth: duodenal aspiration vs glucose breath test[2015].

Under treatment: ” However, if the condition recurs, antibiotics can be given in a cyclical fashion in order to prevent tolerance. For example, antibiotics may be given for a week, followed by three weeks off antibiotics, followed by another week of treatment. Alternatively, the choice of antibiotic used can be cycled.^{[39]” — the cycling of antibiotic choices is a regular part of Jadin’s protocol for CFS.}

Latest from PubMed

• For rifaximin, “The overall eradication rate according to intention-to-treat analysis was 70.8%…The overall rate of adverse events was 4.6%… improvement or resolution of symptoms in patients with eradicated SIBO was found to be 67.7%”[2017]
  • “Although the rifaximin group showed a greater percentage of global symptom improvement, this was limited to bloating, as scores for abdominal pain, diarrhea, and constipation did not improve significantly.”[2007]
• “SIBO was found to be associated with deep vein thrombosis (DVT).” [2016] — which implies coagulation may be associated with SIBO (i.e. thick blood).

Bottom Line

SIBO is a common condition with vague diagnosis criteria. Often the treatment and diagnosis is for one particular group of bacteria — for example Hydrogen Sulfide. A MD may tell the patient, your SIBO is resolved and the reality is that only the Hydrogen Sulfide producing bacteria has been reduced, the rest remain active — creating symptoms of FM, CFS, etc.

In short, SIBO — both tests and treatment are a part of the solution to CFS/FM/IBS but is not the full answer and likely, IMHO, not a major part of the answer. False positives and negatives are common with common tests.

On the PLUS SIDE — as with chronic lyme, SIBO can be a justification(defense) for a MD to prescribe antibiotics. Prescribing antibiotics for CFS or FM is not politically acceptable in most countries.

• A proof-of-concept study showing antibiotics to be more effective in irritable bowel syndrome with than without small-intestinal bacterial overgrowth: a randomized, double-blind, placebo-controlled trial[2016]. (800 mg/day norfloxacin for 10 days – likely applies for any fluoroquinolone)
• “Antibiotic trials with both neomycin(aminoglycoside) and rifaximin show improvement in global IBS symptoms that correlates with breath test normalization in diarrhea-predominant patients.” [2016]
• ” Treatment of SIBO remains empirical; generally, broad spectrum antibiotics are recommended for 2 weeks (amoxicillin, rifaximin, ciprofloxacin, etc.) but evidence for their use is fair.” [2016]
• “Antibiotics for presumed small intestinal bacterial overgrowth have been shown to improve irritable bowel syndrome symptoms in at least 40% of subjects …. A lactulose breath test appears to be useful in predicting response to antibiotics in patients with the irritable bowel syndrome. A hydrogen + methane rise <20 ppm throughout the duration of the test is most predictive.” [2016]
• “SIBO is common in patients with malabsorption syndrome due to various causes and quinolones may be the preferred treatment. This needs to be proved further by a randomized controlled trial.” [2003]