Nathalie,
This is a great question, and we will be addressing this in the lecture for Module #6 next week.
If you look up the definition, or definitions (there are many), for SIBO it defines the condition as being related to various symptoms such as bloating/abdominal pain, flatulence, nausea, heartburn, diarrhea, etc. being triggered by an overgrowth of colonic bacteria (greater than 100,000 organisms per ml) in the small intestine – primarily the jejunum and ileum.
In addition, the diagnosis often hinges on the excess production of fermentation gases of hydrogen, sulfide, and methane. Therefore, many sources indicate that SIBO is defined by the presence of these gases.
Clostridia could certainly be part of the SIBO picture. However, for classic SIBO excess gas production is the main criteria. Is it possible for people to still have these symptoms even without the gas production? In our experience most definitely. That is why evaluating for other pathogens and problems in the digestive system are key. It likely there is a spectrum of problems that lead up to SIBO for many people.
If you have never done a hydrogen or methane breath test, then by current definitions you cannot really diagnosis SIBO. However, SIBO is a collection of symptoms that has now been given a attached name, which in the past was called IBS in some cases. The breath tests are helpful though in establishing the severity of small bowel fermentation.
The bottom line is we still have to evaluate people for chronic infections, maldigestion, poor motility, bacterial overgrowth, etc.
Dr. Woeller