Eradication of intestinal bacterial overgrowth as a treatment method for functional dyspepsia
Authors: Tkach S. M. , Kharchenko N. V. , Dorofeev A. E. 
Published: December 2021

Functional dyspepsia (FD) is one of the most common gastrointestinal functional diseases, occurring in an average of 10 % of the adult population. Recently, much attention is being paid to the infectious factor in FD pathophysiology. In addition to H. pylori infection and acute gastrointestinal infections, consideration is given to the syndrome of intestinal bacterial overgrowth (SIBO), in which the number of bacteria in the small intestine increases significantly.
Objective — to establish the SIBO prevalence in patients with different FD subtypes and to establish the clinical and microbiological efficacy of rifaximin‑a (Alpha Normix®) at this pathology.
Materials and methods. To refine the SIBO prevalence, 118 patients with FD were examined in three gastroenterological centers, including 45 men, 73 women aged 22 to 45 years (mean age — 35 ± 10 years). The control group consisted of 30 clinically healthy people with the mean age 33 ± 12 years. The diagnosis of FD and establishment of its subtype was performed according to Rome IV criteria. All patients underwent upper endoscopy with biopsy and H. pylori testing, which did not show any structural abnormalities. To diagnose SIBO, all patients underwent H2‑breath test with lactulose (H2‑LBT). All patients, depending on the FD subtype, received basic therapy with either a proton pump inhibitor (Omeprazole 20 mg once a day) at FD with epigastric pain syndrome (EPS) (group 1, n = 37), or prokinetic (Itopride in a dose of 50 mg three times a day) at FD with postprandial distress syndrome (PDS) (group 2, n = 36) for two weeks. Patients with positive H2‑LBT result, which predicted SIBO presence, were administered monotherapy with rifaximin‑a  (Alpha Normix®) in a dose of 1200 mg/day for 10 days. The effectiveness of the treatment was assessed after 2 and 4 weeks based on the dynamics of the scores of SAGIS (Structured Assessment of Gastrointestinal Symptom) scale.
Results. According to the positive H2‑LBT results, SIBO presence was recorded in 45 of 118 patients with FD (38.1 %) and 2 (6.6 %) subjects from the control group. Positive H2‑LBT result was significantly more often recorded in patients with FD‑PDS (45.4 %) compared with patients with FD‑EPS (28.8 %, p < 0.01) and all patients with FD (38.1 %). Moreover, SIBO was significantly more common in patients with postinfectious FD (50 % of patients, p < 0.01). The use of rifaximin in a dose of 1200 mg/day for 10 days was accompanied by the clinical improvement in 28 of 45 patients (62.2 %) after 4 weeks of treatment. The clinical efficacy of rifaximin in FD patients on the SAGIS scale did not differ significantly from the efficacy of PPIs and prokinetics used in FD‑EPS and FD‑PDS, respectively. After 4 weeks, in 36 of 45 patients, repeated H2‑LBT was negative, which indirectly indicated the SIBO eradication and high antibacterial efficacy of rifaximin. Rifaximin treatment was safe, and minor side effects were observed in only 3 patients (6.6 %).
Conclusions. SIBO is quite often associated with FD and is observed in more than every third patient. In patients with FD‑PDS, SIBO was found significantly more often than in patients with FD‑EPS, which emphasizes the important role of slowing gastric emptying in the development of SIBO. Also, SIBO is significantly more common in patients with postinfectious FD, which emphasizes the important role of the intestinal microbiome in maintaining the stability of the structural and functional state of the gastrointestinal tract. The obtained data allow to consider SIBO as a possible pathogenetic factor of FD, at least in some patients. This requires timely diagnosis and correction of SIBO in patients with FD, in particular with the use of rifaximin‑a.