Safety and Efficacy of Lyophilized Faecal Microbiota Transplantation Via Capsules in Treatment of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder affecting approximately 7-21% of the population in Western countries. In Croatia, the estimated prevalence is up to 28%. IBS is a symptom-based condition with a chronic course that significantly affects quality of life, social functioning, and work productivity. It is characterized by disturbances in gastrointestinal motility, altered intestinal secretion, and visceral hypersensitivity in the absence of identifiable structural or biochemical abnormalities.

The exact etiology and pathophysiology of IBS remain incompletely understood. Current evidence suggests that IBS develops through a complex interaction of multiple mechanisms rather than a single underlying cause. These mechanisms include abnormal gastrointestinal motility, visceral hypersensitivity, low-grade intestinal inflammation, psychosocial factors, alterations in the brain-gut axis, and environmental influences. Increasing attention has been directed toward the role of intestinal microbiota, as changes in the composition and diversity of gut microorganisms have been observed in patients with IBS.

IBS symptoms vary widely between individuals and can significantly impair daily functioning and overall well-being. According to the Rome IV diagnostic criteria, IBS can be classified into four subtypes based on predominant bowel habits: diarrhea-predominant (IBS-D), constipation-predominant (IBS-C), mixed type (IBS-M), and unclassified IBS (IBS-U). Studies have demonstrated differences in intestinal microbiota composition between these subtypes, suggesting that microbial imbalance may contribute to the development and persistence of symptoms.

Management of IBS remains challenging. Current treatment strategies include dietary modifications, antidepressants, pro- and anti-motility drugs, serotonin receptor agonists and antagonists, antibiotics, and probiotics. However, these approaches often provide limited or temporary relief, and many patients continue to experience persistent symptoms despite treatment.

Considering the growing evidence that alterations in gut microbiota play an important role in IBS pathogenesis, fecal microbiota transplantation (FMT) has emerged as a potential therapeutic option for gastrointestinal disorders associated with dysbiosis. FMT involves the transfer of processed stool from a healthy donor to a recipient with the goal of restoring a balanced intestinal microbiota. The effectiveness of FMT has been well established in the treatment of recurrent Clostridioides difficile infection. However, the efficacy of FMT in IBS remains under investigation, with clinical trials producing mixed results. Some studies have reported improvements in IBS symptoms after FMT, while others have not demonstrated significant benefits.