Pathogenic Escherichia coli O-serogroups: A Link Between Virulence Gene, Immune Evasion, and Antimicrobial Resistance

Background: Escherichia coli is a common intestinal commensal that includes pathogenic strains responsible for sepsis, gastrointestinal infections, and urinary tract infections (UTIs). Its diverse pathotypes, virulence factors, and O-serogroups contribute to its clinical significance. The emergence of multidrug-resistant (MDR) strains has complicated treatment strategies, representing a critical global health concern. Methods: A literature search was conducted on PubMed, Scopus, and Google Scholar using the keywords E. coli, pathogenicity, O-serogroups, immune evasion, and antibiotic resistance to identify peer-reviewed English-language studies. Included were studies focusing on E. coli virulence, immune evasion, and MDR, while non-English studies, case reports, and editorials were excluded. Results: Our analysis indicates that O-serogroups O25, O78, O145, and O157 are predominantly associated with MDR profiles, especially against β-lactams and aminoglycosides. This high prevalence of MDR in these serogroups significantly complicates clinical management, often leading to prolonged hospital stays, increased treatment failures, and higher rates of severe complications such as hemolytic uremic syndrome (HUS) in EHEC infections or recurrent UTIs in UPEC cases. For instance, resistance of O25 to β-lactams, observed in 92% of isolates for piperacillin, limits the efficacy of first-line therapies and necessitates the use of last-line antibiotics such as carbapenems, which may increase healthcare costs and the risk of further resistance development. The high resistance rates in these serogroups are attributed to O-antigen variability and the horizontal transfer of resistance determinants. Conclusion: This study underscores the clinical significance of O-serogroup diversity in E. coli infections and its impact on therapeutic challenges. Understanding the distribution of virulence factors and resistance genes among key serogroups provides critical insights for developing effective management strategies for MDR E. coli infections. Future research should prioritize innovative therapeutic approaches targeting serogroup-specific resistance mechanisms.