Chronic Antibiotic Use, Gut Microbiota Dysbiosis, and Increased Risk of Colorectal Cancer: An Emerging Threat

The gut microbiota plays a vital role in host health by regulating metabolic processes, immune function, and epithelial barrier functions. Chronic use of antibiotics can alter this environment and introduce gut dysbiosis, which is defined as an alteration of microbial communities characterized by a loss of beneficial microbes and overgrowth of pathogenic microbes. Gut dysbiosis is increasingly associated with the development and progression of colorectal cancer (CRC). We explored the relationship between long-term antibiotic exposure, gut microbiota dysbiosis, and CRC risk, as well as strategies for preventing and restoring gut microbiomes.

Relevant information was extracted from published articles available in PubMed, Scopus, and Google Scholar. The keywords "Gut," "Dysbiosis," "Antibiotic," "Colorectal," and "Microbiota" were used to search for relevant information.

Studies have demonstrated that chronic antibiotic exposure significantly reduces microbial diversity, particularly by decreasing beneficial species (e.g., Lactobacillus, Bifidobacterium, and Faecalibacterium), while favoring pathogenic species (e.g., Klebsiella pneumoniae and Enterococcus faecium). Antibiotic-induced dysbiosis reduces the production of microbial metabolites, including short-chain fatty acids, which are essential for supporting epithelial integrity and immune homeostasis. Prior antibiotic use is associated with a 13% increased risk of CRC, with antibiotic-induced microbiota alterations lasting for months to years. Several factors, including diet, pollution, and over-the-counter access to antibiotics in low-and middle-income countries, may contribute to an increased risk of dysbiosis and CRC. Additionally, interventions such as dietary fiber, probiotic supplementation, fecal microbiota transplantation, next-generation probiotics, and phage therapy may be potential strategies to restore the microbiome and achieve gut health.

Substantial use of antibiotics may alter the gut microbiota and increase the risk of CRC. To mitigate this risk, it is essential to practice prudent antibiotic use and adopt dietary, probiotic, and microbiome-restoring practices to support the health of the gut microbiome.