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- [00:00]
Podcast Host
Welcome back to Run the List, a medical education podcast in internal medicine. As a quick disclaimer, this podcast is made for educational and informational purposes only and should not be understood as medical advice under any circumstances. Before we get to the show, a quick word on the sponsors for today's episode.
- [00:16]
Sponsor Representative
Open Evidence is the premier AI powered medical information platform for physicians and medical students. It's like ChatGPT for anyone who practices clinical medicine. Whether you have a clinical question, a question that comes up during your literature review. If you have a question that comes up when you're trying to synthesize a topic you're going to teach, you can just go to openevidence.com, enter your question and it'll synthesize the answer for you while also linking to those actual articles. It's an outstanding resource.
- [00:56]
Allie Shebe
Welcome back to Run the List. I am Ali Shebe, a current third year medical student at Harvard and a recent member of the RTL team. I am back with Dr. Kumar, a gastroenterologist at Brigham and Women's Hospital and one of the co founders of rtl. For our third and final episode of our series on sibo. Today we will discuss how to treat sibo.
- [01:16]
Dr. Kumar
Thank you so much Allie. Let's wrap up our SIBO series today and run the list.
- [01:22]
Allie Shebe
So now that we are all on the same page, let me quickly summarize the past two episodes. SIBO is due to a pathological increase in bacteria in the small bowel with associated diarrhea and abdominal abdominal bloating worse after meals. Diagnosis is most commonly established via lactulose breath testing which measures methane and hydrogen produced by bacteria over time. If hydrogen rises by greater than or equal to 20 ppm or methane levels reach 10 ppm or higher at any point during the test, the diagnosis of SIBO is made. So let's return to our case for one final time. Ms. R is a 45 year old female with a history of obesity status post Roux en y gastric bypass who presents to primary care clinic with two months of worsening bloating, flatulence and diarrhea. She is found to have SIBO on breath testing and now that we have established her diagnosis, how do we treat her?
- [02:20]
Dr. Kumar
Thank you Allie. So the first step is to identify the subtype of Sibo that Ms. R has and there's basically two different types. She can either have hydrogen predominant SIBO or methane predominant sibo. You'll recall in our last episode on diagnosis we talked about the importance of the breath test measuring for both of those gas levels, hydrogen and methane, because the treatment is dictated by the type of pattern we see between those two gas levels. So let's assume that she has hydrogen predominant sibo. In that case, the best antibiotic approach is to use an antibiotic called rifaximin or xifaxan, which is dosed at 550mg three times a day for 14 days. You may recall this antibiotic as a use for hepatic encephalopathy in patients with cirrhosis. It is the same antibiotic, but it's a different dosage and again, it's just for a two week course. Whereas patients with cirrhosis and hepatic encephalopathy will take it indefinitely for their hepatic encephalopathy. So what is rifaximin? Well, it's a non absorbable antibiotic that has gram positive, gram negative and anaerobic coverage, and it effectively decreases the bacterial population of the small bowel. As a non absorbable antibiotic, rifaximin's primary effect is within the intestinal tract. And what's nice about that is that you have less side effects from systemic absorption. So in my experience, the most common side effects that patients may have on rifaximin are GI upset and diarrhea, because again, the main area of action is within the intestinal tract. But some patients also can develop some lightheadedness, so it's nice to caution them about these potential side effects before they start. To be honest, the main issue with rifaximin is the cost of the antibiotic, as it's very expensive if it's not covered by insurance. So I always tell my patients, let me see if I can get this antibiotic covered for you, but do not fill it if it's not covered by insurance because the cost is very, very high. So when that happens, when rifaximin is not covered, there are many other alternative antibiotics that can also be used and have been studied for sibo, and they all work generally about the same efficacy. Rifaximan, again, is our preferred antibiotic, but if it's not available or not covered, you can use these alternative antibiotics, such as augmentin, which is often my primary choice due to the safety profile of this antibiotic, as well as metronidazole, ciprofloxacin or Bactrim.
- [04:50]
Allie Shebe
Awesome. That was a great explanation. Sounds like there's a lot of options for antibiotic treatment and ideally we would be able to prescribe misr rifaximin. Now what Would you recommend her if the SIBO breath testing was positive for methadgins?
- [05:06]
Dr. Kumar
So if she had methanogens, and especially if it's methane predominant sibo, the optimal antibiotic approach is actually to use two antibiotics. So again, we use rifaximin, which is used at that same dosage, which is 550mg three times a day for 14 days. But then the recommendation is to add a second antibiotic known as neomycin, that's dosed at 500 milligrams twice a day for 14 days, and those two antibiotics are taken together. So it's a lot of antibiotics within a short time period of two weeks. Now, neomycin has a more concerning side effect profile as an aminoglycoside, and so it can cause ototoxicity, kidney injury, and nerve damage. And the one I've actually seen occur is the ototoxicity, which manifests with a permanent tinnitus or ear ringing of the ear. So it's really important to counsel your patients about the potential side effects of neomycin because they are serious and as I mentioned, they can be permanent. So one thing I always check with my patients before prescribing neomycin is to see if they have any baseline issues with hearing or kidney injury or nerve issues, because if they do, I'm really hesitant to use that medication, the neomycin in those patients, just to know. Neomycin also has a higher rate of GI distress. And so I often tell patients if it seems like they'll be okay taking it, they should take it with food because that will help minimize some of the GI side effects, including nausea. Now, given all the potential side effects that I mentioned with the neomycin, many patients and providers too, for good reason, prefer to avoid the risk of neomycin. And, and so in some cases, even if it's methane predominant sibo, they will treat with just rifaximin alone to see if that will be enough to take care of the methanogens in those patients. Small intestinal tract. And sometimes it does work, sometimes it doesn't, but it's always a risk benefit. Discussion with the addition of neomycin because of those potentially permanent and damaging side effects.
- [07:12]
Allie Shebe
Excellent. I'm sure you get a lot of patients who may not be keen to start antibiotics. And given all that you've discussed in terms of some of the side effects that can be pretty severe, are there any alternative modes of treatment for sibo?
- [07:27]
Dr. Kumar
Yes, you are certainly right that many patients do not want to expose themselves to These antibiotics, especially the neomycin piece, as we discussed, because of the potential side effects. And so there are other options that can be pursued to address the symptoms that arise from sibo. The main non antibiotic approach is truly to modify the diet so dietary changes can be another option for SIBO management. And what the idea is here is for patients to focus on eating foods that have low amounts of fermentation products, which those small intestinal bacteria like to break down. So the way to do this, it's most reliably achieved by following a low fodmap diet that is an acronym that stands for fermentable oligo di and monosaccharides and polyols. So it'll be hard to actually memorize what foods fall into each category. There's some great resources online to look at. The one that I love to use is www.katescarlotta.com. she's a nutritionist who has a lot of experience in this area. And so it's very helpful to go to that website, share it with your patients so that they can start looking at what a low fodmap diet may be. And what I love about it shows options of foods that they can have and then foods that they should try to avoid. The challenge is that many of these food items that they're trying to avoid, like broccoli, cauliflower, are otherwise part of a very healthy diet. And so patients have to strike this balance between controlling their SIBO symptoms and optimizing their nutritional intake. And for this reason, it makes a lot of sense if it's available to your patients to refer them to nutrition. The dietitians can be very helpful in helping to guide patients in terms of balancing the avoidance of high FODMAP foods, but still getting appropriate and well balanced meals into their GI systems. So another treatment mechanism that might be brought up by patients is probiotics. So probiotics, despite their growing popularity in recent years, are generally not considered an effective treatment for sibo. There is some limited evidence that probiotics can improve gut motility. And as we talked in episode one about how sibo is often attributed to impaired motility, this theoretical benefit has not actually translated into meaningful clinical results. In fact, our current national guidelines suggest to not use probiotics because the evidence is so limited for benefit to patients. So as a result, we are not recommending probiotics as a mainstay of diet therapy for sibo. Now, lastly, there are some other symptomatic treatments that we can offer to our patients, like Peppermint oil and simethicone that can help with the symptoms of sibo, particularly gas and bloating. So I often tell patients about these two other supplements that they can try just to help them manage their gas symptoms from the underlying condition.
- [10:21]
Allie Shebe
That is very helpful for most patients. Antibiotics, ideally rifaximin, remain the cornerstone of treatment, but dietary modifications can be a reasonable alternative for those who prefer to avoid antibiotics due to the side effects or other reasons, and should be pursued for patients who take an antibiotic course as well to try to minimize recurrence of symptoms. Thank you for an overview of SIBO management. Dr. Kumar, any final pearls you'd like to leave us with?
- [10:51]
Dr. Kumar
Absolutely, Allie. Let's, as always, do our three key takeaways from our RTL episodes. So number one, remember to look at the specific type of SIBO that your patients have as the gas pattern, whether it's hydrogen versus methane predominant is going to influence the antibiotic choice that you make for them. Number two is rifaximin is the best studied and safest antibiotic for treating sibo. It has less efficacy in methane predominant sibo. And in those cases, when you're dealing with patients who have methane predominant sibo, consider the risk benefit profile of adding neomycin to the antibiotic regimen as it does have a higher rate of efficacy, but you again have to consider the potential side effects. And then number three, given the benefit of adhering to a low fodmap diet for all patients, and particularly those who prefer to avoid antibiotics, think about referring your patients to nutrition to help modify their diets in a safe and healthy manner. The low fodmap diet can be extremely helpful in patients with SIBO and with IBS symptoms. And so it's something to always encourage your patients to try to pursue. It can be difficult to adhere to it long term and so that's why it's very helpful to have your patients work with a nutritionist as well as they go forward along this journey.
- [12:06]
Allie Shebe
Thank you, Dr. Kumar, for joining me to discuss the treatment of SIBO. We made it through our last episode on SIBO. I learned a lot over these past three episodes and hopefully we'll be back to run the list soon.
- [12:18]
Dr. Kumar
Thank you so much. Allie. You are such a wonderful guest host. You did an amazing job putting these three episodes together. We covered a topic that I know is very interesting for both patients and providers and comes up a lot. So I'm glad we're able to dive in and talk about the three key parts of sibo. All the way from presentation to diagnosis and now treatment.