Mucosal Immune Markers and Their Impact on Antimicrobial Resistance: A Systematic Review

<b>Objectives: </b>This systematic review aimed to evaluate the role of secretory immunoglobulin A (sIgA) and related mucosal immune markers in modulating susceptibility to colonization or infection by antimicrobial-resistant (AMR) bacteria in human and animal models.<br /> <b>Methods: </b>Studies were included if they assessed mucosal sIgA levels about AMR outcomes, reported original data, and were published in English between 2015 and June 2025. Exclusion criteria included a lack of mucosal immune data or AMR-related endpoints. Databases searched included PubMed, ScienceDirect, and EBSCO (Knowledge and Library Hub), with the last search performed on June 10, 2025. The quality of the included studies was assessed using the checklist for quantitative studies, and data were extracted and synthesized narratively, stratified by immune markers, study design, and mucosal compartment.<br /> <b>Results: </b>After the systematic search of the databases considered for this review and review of available literature indexed in them, eleven studies that met the inclusion criteria of this study were included in this review.  The mucosal sites investigated in most of these studies were gastrointestinal, respiratory, oral, and genitourinary mucosa. Of the eleven (11) studies, four carried out investigations in humans while the remaining seven utilized animal models. All the included studies reported secretory immunoglobulin A (sIgA) level, whereas five of the studies reported other indicators, such as cytokines and IgG, alongside sIgA levels. There was consistency in their results as increased sIgA levels were linked to decreased infection or colonization by AMR pathogens. Moreover, vaccination-based interventional studies showed an increase in sIgA post-vaccination or probiotic treatment.<br /> <b>Conclusion: </b>Although in this review we included studies with varying methodological approaches as well as studies featuring humans and animal models, the evidence from this review indicates that mucosal sIgA offers protection against antimicrobial-resistant (AMR) bacteria colonization. Therefore, findings from this study suggest that in the quest for addressing AMR that approaches targeting mucosal immunity preventative measures should be explored through standardized trials.