Extracellular Traps at the Crossroads of Immune Evasion and Antimicrobial Resistance: The Case of Escherichia coli in the Reproductive Tract

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) is among the bacterial pathogens associated with infections of the female and male reproductive tracts, where it may contribute to inflammatory processes and impaired reproductive function. In this context, neutrophils constitute a critical component of host defense through the release of neutrophil extracellular traps (NETs), web-like structures composed of decondensed chromatin, histones, and antimicrobial proteins that capture and eliminate invading microorganisms. However, the interaction between E. coli and NETs is highly dynamic, as the bacterium has evolved immune-evasion mechanisms that facilitate persistence within the host. This raises a critical paradox: NETs may shift from an antimicrobial defense mechanism to a microenvironmental factor that inadvertently favors bacterial persistence and chronic inflammation. This review synthesizes current evidence on the colonization, virulence, and immune-evasion mechanisms of E. coli in the reproductive tract, with particular emphasis on the modulation of NETosis, biofilm formation, and their contribution to antimicrobial resistance. We further discuss the dual role of NETs as an innate immune defense mechanism and, conversely, as a potential contributor to tissue injury, oxidative stress, and chronic inflammation when dysregulated. Understanding the interplay among E. coli, extracellular traps, and antimicrobial resistance provides a valuable conceptual framework for the development of novel therapeutic approaches aimed at limiting bacterial persistence, preserving reproductive function, and addressing the growing global threat of antimicrobial resistance.