Oncomicrobes on the rise in colorectal cancer among Egyptian patients: Enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, and Streptococcus gallolyticus

Background: Colorectal cancer (CRC) is a complex disease that develops through several stages and involves various factors. Recent studies suggest that microbes may contribute to the development of CRC. Disruptions in the balance of gut microbiota can lead to intestinal conditions like CRC. This study aimed to investigate the association between enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, Streptococcus gallolyticus, and CRC. Methods: The study recruited 100 patients (42 males and 58 females) from Alexandria University's Surgical Endoscopy Unit, divided into two groups: 50 neoplastic (benign, malignant) and 50 non-neoplastic (inflammatory & non-inflammatory). DNA was extracted from fresh tissue biopsies, and SYBR Green real-time PCR was done to examine the prevalence of S. gallolyticus, F. nucleatum, and ETBF in both groups. Results: Female patients with neoplastic illnesses had a higher percentage (56.0%) than male patients (44.0%), but no significant difference was observed. Nevertheless, a high statistical difference was observed between the same groups regarding age. Neoplastic patients were older than non-neoplastic patients. The prevalence of F. nucleatum, S. gallolyticus, and B. fragilis was higher in neoplastic patients than in non-neoplastic patients, which reflects a higher concentration of these bacteria in the neoplastic group. However, no significant difference was found between inflammatory and non-inflammatory groups regarding the prevalence of these oncomicrobes of interest. Patients with neoplastic disease had a significantly higher frequency of B. fragilis toxin (BFT) compared to non-neoplastic (inflammatory and non-inflammatory) patients. Conclusion: This study provides robust evidence supporting the role of these bacterial candidates as tumor-promoting factors in colorectal cancer, with indications of complex synergistic interactions between them that requires further investigations.