Small Intestinal Bacterial Overgrowth (cont.)
How is small intestinal bacterial overgrowth treated?
"Classic" SIBO
SIBO has been recognized for many
years as a problem with severe disorders of intestinal muscles and intestinal
obstruction. The treatment has been antibiotics, and they are very effective.
The difficulty is that the disease causing the SIBO often cannot be corrected.
As a result, symptoms frequently return when antibiotics are stopped, and it may
be necessary to treat the patient with antibiotics repeatedly or even
continuously.
SIBO associated with IBS
There are very few rigorous, scientific
studies on the treatment of irritable bowel syndrome with therapies that are directed specifically to
the possibility of underlying SIBO. That has not stopped physicians from trying
unproven treatments. The discussion of treatment that follows is based on the
minimal scientific evidence that is available as well as the anecdotal (observed
but not scientifically demonstrated) experience of physicians who see patients
with irritable bowel syndrome.
The two most common treatments for SIBO among patients
with irritable bowel syndrome are oral antibiotics and probiotics. Probiotics are live bacteria that,
when ingested by an individual, result in a health benefit. The most common probiotic
bacteria are lactobacilli (also used in the production of yogurt) and
bifidobacteria. Both of these bacteria are found in the intestine of normal
individuals. There are numerous explanations for how probiotic bacteria might
benefit individuals. However, the beneficial action has not been identified
clearly. It may be that the probiotic bacteria inhibit other bacteria in the
intestine that may be causing symptoms, or it may be that the probiotic bacteria
act on the host's intestinal immune system to suppress inflammation.
Several antibiotics either alone or in combination have
been reported to be successful. Treatment success, when measured by either
symptom improvements or by normalization of the hydrogen breath test, ranges from 40-70%. When
one antibiotic fails, the doctor may add another antibiotic or change to a different antibiotic. However,
the doses of antibiotics, the duration of treatment, and the need for
maintenance therapy to
prevent recurrence of SIBO have not been adequately
studied. Most physicians use standard doses of antibiotics for one to two weeks.
Probiotics may be used alone, in combination with antibiotics, or for prolonged
maintenance. When probiotics are used, it probably is best to use one of the
several probiotics that have been studied in medical trials and shown to have
effects on the small intestine, though not necessarily in SIBO. The commonly sold
probiotics in health-food stores may not be effective. Moreover, they often do
not contain the bacteria stated on the label or the bacteria are dead. The
following are some treatment options:
- Neomycin orally for 10 days. One observation that has
been made is that neomycin eradicates methane-producing bacteria and
alleviates constipation.
- Levofloxacin (Levaquin) combined with metronidazole
(Flagyl) for 7 days.
- Rifaximin (Xifaxan)
for 7 days. Rifaximin is a unique antibiotic that is not absorbed from the
intestine, and, therefore, acts only within the intestine. Because very little
rifaximin is absorbed into the body, it has few important side effects. Higher than normal doses of rifaximin (1200 mg/day for 7 days)
were superior to standard lower doses (800 or 400 mg/day) in normalizing the
hydrogen breath test in patients with SIBO and IBS. However, it is not yet known whether the
larger dose is any better at suppressing symptoms.
- Commercially available probiotics such as VSL#3 or
Flora-Q, which are mixtures of several different bacterial species, have been
used for treating SIBO and IBS, but their effectiveness is not known.
Bifidobacterium infantis 35624 is the only probiotic that has been demonstrated
to be effective for treating patients with IBS.
Treatment with antibiotics
versus probiotics
It is the author's personal belief that for short-term
(1-2 weeks) treatment, antibiotics are more effective than probiotics. However,
antibiotics do have certain disadvantages. Specifically, symptoms tend to recur
after treatment is discontinued, and prolonged or repeated courses of treatment
may be necessary in some patients. Physicians are reluctant to prescribe
prolonged or repeated courses of antibiotics because of concern over long-term
side effects of the antibiotics and the emergence of bacteria that are resistant
to the antibiotics. Physicians have less concern over long-term side effects or
the emergence of resistant bacteria with probiotics and, therefore, are more
willing to prescribe probiotics repeatedly and for prolonged periods. One option
is to initially treat the patient with a short course of antibiotics and then
long-term with probiotics. Long-term studies comparing antibiotics, probiotics,
and combinations of antibiotics and probiotics are badly needed.
Next: What's new in small intestinal bacterial overgrowth? »
- metronidazole, Flagyl - Explains the medication metronidazole (Flagyl) an antibiotic drug used against anaerobic bacterteria and certain parasites like giardia and ameba that can infect parts of the human body. Article includes descriptions, uses, drug interactions, and side effects.
- Hydrogen Breath Test - Read about the hydrogen breath test used to assist in diagnosing lactose intolerance, bacterial overgrowth of the small bowel, celiac disease, and pancreatic insufficiency.
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