Nutritional deficiencies and nonspecific gastrointestinal symptoms such as nausea, vomiting, and poor oral tolerance are commonly observed following bariatric surgery. When these symptoms persist, especially when accompanied by malnutrition and hypoalbuminemia, may indicate an underlying inflammatory process contributing to these conditions such as small intestine bacterial overgrowth (SIBO). This case study describes a 34-y-old pregnant woman with a history of bariatric surgery, who presented with generalized swelling, persistent nausea, bloating, steatorrhea, and was found to have severe malnutrition, 18 mo after biliopancreatic diversion with duodenal switch (BPS/DS). She was empirically treated for SIBO using systemic antibiotics and was started on parenteral nutrition to prevent further calorie deficit during pregnancy. This case underlines the complexity and challenges in diagnosing SIBO after bariatric surgery that includes the creation of Roux-en-Y anatomy, including BPS/DS, and the relationship between albumin, malnutrition, and the effect of systemic inflammation on the latter two.

Rifaximin, a broad-spectrum antibiotic, boasts a unique chemical composition and pharmacokinetic profile, rendering it highly effective in treating irritable bowel syndrome (IBS). Its minimal systemic absorption confines its impact to the gastrointestinal (GI) tract, where it yields significant therapeutic benefits. This review examines rifaximin\'s physico-chemical attributes and its role in managing IBS symptoms. Its molecular structure facilitates intestinal lumen retention postoral administration, minimizing systemic exposure and adverse effects. This targeted action is crucial in addressing the gut microbiota\'s role in IBS pathophysiology. By modifying microbial populations and their metabolite production, rifaximin mitigates symptoms like bloating, irregular bowel habits, and abdominal pain associated with IBS. It achieves this by reducing pathogenic bacteria and altering bacterial metabolism, enhancing mucosal and immune function. Clinical trials affirm rifaximin\'s superiority over placebo and conventional therapies in alleviating overall IBS symptoms and addressing small intestine bacterial overgrowth (SIBO). Despite its promising efficacy and sustained symptom relief, further research is essential to optimize long-term effectiveness and dosing regimens. Rifaximin stands as a vital treatment option for IBS due to its distinctive properties and clinical utility; yet, ongoing investigation is imperative for maximizing its therapeutic benefits.

Small intestinal bacterial overgrowth (SIBO) is a pathology of the small intestine and may predispose individuals to various nutritional deficiencies. Little is known about whether specific subtypes of SIBO, such as the hydrogen-dominant (H+), methane-dominant (M+), or hydrogen/methane-dominant (H+/M+), impact nutritional status and dietary intake in SIBO patients. The aim of this study was to investigate possible correlations between biochemical parameters, dietary nutrient intake, and distinct SIBO subtypes. This observational study included 67 patients who were newly diagnosed with SIBO. Biochemical parameters and diet were studied utilizing laboratory tests and food records, respectively. The H+/M+ group was associated with low serum vitamin D (p < 0.001), low serum ferritin (p = 0.001) and low fiber intake (p = 0.001). The M+ group was correlated with high serum folic acid (p = 0.002) and low intakes of fiber (p = 0.001) and lactose (p = 0.002). The H+ group was associated with low lactose intake (p = 0.027). These results suggest that the subtype of SIBO may have varying effects on dietary intake, leading to a range of biochemical deficiencies. Conversely, specific dietary patterns may predispose one to the development of a SIBO subtype. The assessment of nutritional status and diet, along with the diagnosis of SIBO subtypes, are believed to be key components of SIBO therapy.

OBJECTIVE: Patients with intestinal failure (IF) have abnormal intestinal anatomy, secretion, and dysmotility, which impairs intestinal homeostatic mechanisms and may lead to small intestinal bacterial overgrowth (SIBO). We conducted a systematic review and meta-analysis to determine the prevalence of SIBO in patients with IF and to identify risk factors for SIBO.
METHODS: MEDLINE (PubMed) and Embase electronic databases were searched from inception to December 2023 for studies that reported the prevalence of SIBO in IF. The prevalence rates, odds ratio (OR), and 95% confidence intervals of SIBO in IF and the risk factors for SIBO in IF were calculated using random effects model.
RESULTS: Final dataset included nine studies reporting on 407 patients with IF. The prevalence of SIBO in IF was 57.5% (95% CI 44.6-69.4), with substantial heterogeneity in this analysis (I2 = 80.9, P = 0.0001). SIBO prevalence was sixfold higher in patients with IF who received parenteral nutrition (PN) compared with IF patients not on PN (OR = 6.0, 95% CI 3.0-11.9, P = 0.0001). Overall, the prevalence of SIBO in patients with IF using PPI/acid-suppressing agents (72.0%, 95% CI 57.5-83.8) was numerically higher compared with IF patients not using these agents (47.6%, 95% CI 25.7-70.2).
CONCLUSIONS: This systematic review and meta-analysis suggests that there is an increased risk of SIBO in patients with IF and that PN, and potentially, the use of PPI/acid-suppressing agents is risk factors for SIBO development in patients with IF. However, the quality of evidence is low and can be attributed to lack of case-control studies and clinical heterogeneity seen in the studies.

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The human gut microbiota creates a complex microbial ecosystem, characterized by its high population density, wide diversity, and complex interactions. Any imbalance of the intestinal microbiome, whether qualitative or quantitative, may have serious consequences for human health, including small intestinal bacterial overgrowth (SIBO). SIBO is defined as an increase in the number of bacteria (103-105 CFU/mL), an alteration in the bacterial composition, or both in the small intestine. The PubMed, Science Direct, Web of Science, EMBASE, and Medline databases were searched for studies on SIBO and related diseases. These diseases were divided into 12 groups: (1) gastrointestinal disorders; (2) autoimmune disease; (3) cardiovascular system disease; (4) metabolic disease; (5) endocrine disorders; (6) nephrological disorders; (7) dermatological diseases; (8) neurological diseases (9); developmental disorders; (10) mental disorders; (11) genetic diseases; and (12) gastrointestinal cancer. The purpose of this comprehensive review is to present the current state of knowledge on the relationships between SIBO and these 12 disease groups, taking into account risk factors and the causal context. This review fills the evidence gap on SIBO and presents a biological-medical approach to the problem, clearly showing the groups and diseases having a proven relationship with SIBO, as well as indicating groups within which research should continue to be expanded.

BACKGROUND: Glucose breath test (GBT) is used for the diagnosis of small intestine bacterial overgrowth. A restrictive diet without fibers and/or fermentable food is recommended on the day before the test. The aim of our retrospective study was to evaluate the impact of two different restrictive diets on the results of GBT.
METHODS: A change of the pretest restrictive diet was applied in our lab on September 1, 2020. The recommended diet was a fiber-free diet before this date, and a fiber-free diet plus restriction of all fermentable food afterward. We thus compared the results of GBT performed before (group A) and after (group B) this pretest diet modification. Demographics, reasons to perform GBT, digestive symptoms, and hydrogen and methane baseline values and variations after glucose ingestion were compared between the two groups.
RESULTS: 269 patients underwent GBT in group A, and 316 patients in group B. The two groups were comparable in terms of demographics. Methane and hydrogen baseline values were significantly higher in group A (respectively 14 [18] vs. 8 [14] ppm, p < 0.01 and 11 [14] vs. 6 [8] ppm, p < 0.01). The percentage of positive tests was higher in group A for methane (43% vs. 28%, p < 0.05), and for hydrogen (18% vs. 12%, p = 0.03).
CONCLUSIONS: This retrospective study suggests the importance of the restrictive diet prior to GBT. A strict limitation of fibers and fermentable food decreased hydrogen and methane baseline values, and the prevalence of positive GBT. Thus a strict restrictive diet should be recommended on the day before the test, in order to limit the impact of food on hydrogen and methane breath levels, and possibly improve the diagnosis quality of GBT.

BACKGROUND: The objective was to investigate the efficacy of different doses of levothyroxine therapy among pregnant women exhibiting high-normal thyroid stimulating hormone levels and positive thyroid peroxidase antibodies throughout the first half of pregnancy.
METHODS: Pregnant women exhibiting high-normal thyroid stimulating hormone levels and thyroid peroxidase antibodies positivity throughout the initial half of pregnancy were selected from January 2021 to September 2023. Based on the different doses of levothyroxine, the pregnant women were categorized into the nonintervention group (G0, 122 women), 25 µg levothyroxine intervention group (G25, 69 women), and 50 µg levothyroxine intervention group (G50, 58 women). Serum parameters, gastrointestinal symptoms, small intestinal bacterial overgrowth (SIBO), maternal and neonatal outcomes were compared after the intervention among the three groups.
RESULTS: After the intervention, in the G25 and G50 groups, the thyroid stimulating hormone, triglyceride and low-density lipoprotein levels were notably less in contrast to those in the G0 group (P < 0.05). The rates of abdominal distension and SIBO in the G25 and G50 groups were notably lower in contrast to the G0 group (P = 0.043 and 0.040, respectively). The G50 group had a lower rate of spontaneous abortion and premature membrane rupture than the G0 group (P = 0.01 and 0.015, respectively). Before 11+ 2 weeks of gestation and at thyroid peroxidase antibodies levels ≥ 117 IU/mL, in contrast to the G0 group, the G50 group experienced a decreased rate of spontaneous abortion (P = 0.008). The G50 group had significantly higher newborn weight than the G0 group (P = 0.014), as well as a notably longer newborn length than the G0 and G25 groups (P = 0.005).
CONCLUSIONS: For pregnant women with high-normal thyroid stimulating hormone levels and thyroid peroxidase antibodies positive during the first half of pregnancy, supplementation with 50 µg levothyroxine was more effective in improving their blood lipid status and gastrointestinal symptoms, reducing the incidence of SIBO and premature rupture of membranes, and before 11+2 weeks, TPOAb ≥ 117 IU/mL proved more beneficial in mitigating the risk of spontaneous abortion.

Gut dysbiosis and subclinical intestinal damage are common in cirrhosis. The aim of this study was to examine the association of intestinal damage biomarkers (diamine oxidase [DAO], claudin 3, and intestinal fatty acid binding protein [I-FABP; FABP2]) with the state of the gut microbiota in cirrhosis. The blood levels of DAO were inversely correlated with blood levels of claudin 3, lipopolysaccharide (LPS), presepsin, TNF-α, and the severity of cirrhosis according to Child-Pugh scores. The blood level of I-FABP was directly correlated with the blood level of claudin 3 but not with that of DAO. Patients with small intestinal bacterial overgrowth (SIBO) had lower DAO levels than patients without SIBO. There was no significant difference in claudin 3 levels and I-FABP detection rates between patients with and without SIBO. The DAO level was directly correlated with the abundance of Akkermansiaceae, Akkermansia, Allisonella, Clostridiaceae, Dialister, Lactobacillus, Muribaculaceae, Negativibacillus, Ruminococcus, Thiomicrospiraceae, Verrucomicrobiae, and Verrucomicrobiota; and it was inversely correlated with the abundance of Anaerostipes, Erysipelatoclostridium, and Vibrio. The I-FABP level was directly correlated with Anaerostipes, Bacteroidia, Bacteroidota, Bilophila, Megamonas, and Selenomonadaceae; and it was inversely correlated with the abundance of Brucella, Pseudomonadaceae, Pseudomonas, and Vibrionaceae. The claudin 3 level was directly correlated with Anaerostipes abundance and was inversely correlated with the abundance of Brucella, Coriobacteriia, Eggerthellaceae, and Lactobacillus.

OBJECTIVE: Malabsorption of levothyroxine (LT4) is often seen in patients with hypothyroidism and gastrointestinal (GI) conditions. Our study was designed to establish the prevalence of small intestinal bacterial overgrowth (SIBO) in patients with hypothyroidism and irritable bowel syndrome (IBS), and to demonstrate that liquid LT4 is more consistently absorbed vs tablet, leading to improvement in thyroid and GI symptoms.
METHODS: This was a single-center, open label, prospective cohort study of liquid LT4 in 75 adult patients with hypothyroidism and IBS. Patients were transitioned from LT4 tablets to solution at equivalent dosing. Patients returned at 6 and 12 weeks for repeat thyroid levels and completion of validated questionnaires. A standard 2-hour SIBO breath test was administered at Week 6. Patients recorded daily stool appearance and frequency.
RESULTS: Prevalence of SIBO was 65.3%. Liquid LT4 normalized thyroid stimulating hormone (TSH) in a higher percentage of patients vs tablet (77.55% vs 57.14%); significantly decreased TSH in subjects with SIBO; improved hypothyroid symptoms, IBS symptoms, stool appearance in all groups, and significantly altered bowel frequency among those with SIBO.
CONCLUSIONS: Small intestinal bacterial overgrowth (SIBO) is common in patients with hypothyroidism and IBS. Among SIBO patients, LT4 tablets were inefficiently absorbed, leading to suboptimal thyroid control; however, transitioning from LT4 tablets to solution normalized TSH and improved hypothyroid symptoms. Liquid LT4 also significantly improved GI symptoms in all patients with hypothyroidism and IBS, regardless of SIBO status. Additionally, 1 in 5 patients had complete resolution of IBS symptoms after switching from LT4 tablets to solution, independent of changes in TSH.