Escherichia coli O25B O-antigen (O25B)

The Escherichia coli O25B O-antigen is a specific polysaccharide side chain of the lipopolysaccharide (LPS) located on the outer membrane of certain pathogenic E. coli strains [8, 15]. It is most notably associated with the sequence type 131 (ST131) clone, a globally disseminated multidrug-resistant (MDR) lineage responsible for a significant portion of extraintestinal pathogenic E. coli (ExPEC) infections [1, 8]. Biologically, the O-antigen serves as a protective barrier against host innate immune mechanisms, including the complement system and phagocytic cells, thereby facilitating bacterial survival and dissemination within the host [8, 16]. In the context of disease, the O25B serotype is frequently implicated in severe conditions such as urinary tract infections, bacteremia, and neonatal meningitis, often complicated by resistance to multiple antibiotic classes [1, 20]. As a therapeutic target, the O25B O-antigen is being utilized in the development of monoclonal antibodies and glycoconjugate vaccines [3, 10]. These therapies aim to neutralize the endotoxic effects of LPS and promote bacterial clearance through complement-mediated killing and opsonophagocytosis, providing a non-antibiotic alternative for managing MDR infections [5, 7].

Other names

O25b antigenO25b polysaccharideO25b LPS side chainST131-O25b antigenEscherichia coli O25b somatic antigen

Induction of complement-mediated bactericidal activity, opsonophagocytic killing, and endotoxin neutralization [1, 5, 7].