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).” 
- “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.” 
- “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.” 
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.” 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.“
- “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.” 
- “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.” 
- Hydrogen sulphide in exhaled breath: a potential biomarker for small intestinal bacterial overgrowth in IBS.
- “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 some12,16,17 but not all studies.18,19,20” 
- “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.”
- Breath Testing for Small Intestinal Bacterial Overgrowth: Should We Bother? 
- Are we underestimating the prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome?
- Small intestinal bacterial overgrowth: duodenal aspiration vs glucose breath test.
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.” — 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%”
- “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.”
- “SIBO was found to be associated with deep vein thrombosis (DVT).”  — which implies coagulation may be associated with SIBO (i.e. thick blood).
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. (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.” 
- ” 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.” 
- “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.” 
- “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.”