Methane, Bacteria, Fungi, and Fermentation: Pathophysiology, Diagnosis and Treatment Strategies for Small Intestinal Bacterial Overgrowth, Intestinal Methanogen Overgrowth and Small Intestinal Fungal Overgrowth.

The human gastrointestinal tract hosts a complex ecosystem known as the gut microbiota, which plays a crucial part in digestion and immune system function. Among the clinically recognized manifestations of dysbiosis in this system are Small Intestinal Bacterial Overgrowth (SIBO), Intestinal Methanogen Overgrowth (IMO), Small Intestinal Fungal Overgrowth (SIFO), and Large Intestinal Bacterial Overgrowth (LIBO). This study aims to investigate the complex pathophysiological mechanisms underlying these syndromes and their diagnostics and therapeutic options, focusing primarily on the roles of methane-producing archaea and fungal overgrowth. The methods employed in this study involve a comprehensive analysis and synthesis of peer-reviewed articles, systematic reviews, clinical trials, and meta-analyses. This review summarizes that methane production by Methanobrevibacter smithii was linked to altered fermentation, reduced microbial diversity, and slowed intestinal transit. Fungal species were associated with increased intestinal permeability, inflammation, and biofilm formation. Targeted interventions addressing microbial imbalances demonstrated potential therapeutic value. This review highlights the complex and multifactorial nature of gut dysbiosis, revealing its impact beyond the gastrointestinal tract. While emerging therapies targeting methanogens, fungi, and biofilms show promise, further research is essential to optimize their clinical application. The findings emphasize the need for interdisciplinary collaboration to refine diagnostic and therapeutic strategies.