Infectious Disease · Medical Literature
[Articles] Antimicrobial susceptibility patterns of Neisseria gonorrhoeae across anatomical sites within and between individuals in the Netherlands: a retrospective observational study
Abstract
These findings suggest that higher resistance levels observed at the population level may reflect between-person variation rather than consistent within-person anatomical-site differences. Approximately 10% of individuals showed within-person MIC discordance, potentially leading to missed AMR cases if only one site is sampled. This finding suggests that culturing specimens from multiple anatomical sites could improve AMR detection, surveillance accuracy, and treatment decision-making. Further studies are needed to clarify the role of different anatomical sites in the transmission and development of gonococcal AMR.
Clinical relevance
Do Neisseria gonorrhoeae isolates from different anatomical sites (pharyngeal, anorectal, urogenital) within the same individual exhibit clinically meaningful differences in antimicrobial susceptibility (MIC patterns), and does between-person variation account for population-level resistance differences observed across anatomical sites? __SNAPSHOT__ {"studyDesign":"Retrospective observational study","setting":"Sexual health centres (SHCs) participating in the Dutch Gonococcal Resistance to Antimicrobials Surveillance (GRAS) programme, the Netherlands","sampleSize":"Not reported in abstract; GRAS programme historically includes thousands of isolates (prior GRAS analyses included >13,000 isolates); exact n for this study not reported in available abstract","population":"Men who have sex with men (MSM) and women with culture-confirmed Neisseria gonorrhoeae infection at one or more anatomical sites, January 1, 2016 to December 31, 2023","intervention":"Antimicrobial susceptibility testing (MIC determination) of N. gonorrhoeae isolates collected from multiple anatomical sites (pharyngeal, anorectal, and/or urogenital) within the same individual","comparator":"Between-individual (population-level) comparison of anatomical site MIC patterns versus within-individual comparison of MIC patterns across anatomical sites","primaryOutcome":"Antimicrobial susceptibility patterns (MIC values) across anatomical sites, assessed both at the population level and within individuals; within-person MIC discordance rate across anatomical sites","followUp":"Not reported (cross-sectional isolate-level analysis within consultation episodes)","fundingSource":"Not reported in available abstract"}
Key findings
At the population (between-individual) level, pharyngeal isolates demonstrated higher levels of elevated MICs for ceftriaxone and azithromycin resistance among both MSM and women compared to isolates from anogenital sites. However, within-individual analyses — which directly compared isolates from multiple anatomical sites in the same person — revealed fewer differences in MIC patterns between anatomical sites. Approximately 10% of individuals with multi-site cultures showed within-person MIC discordance across anatomical sites, meaning that resistance detected at one site was not consistently detected at another site within the same person. Specific MIC values, confidence intervals, p-values, and NNT/NNH are not reported in the available abstract. The authors conclude that higher resistance rates observed at the pharynx at the population level likely reflect between-person variation (i.e., differences in patient mix) rather than a consistent biological predisposition of the pharyngeal anatomical niche to harbor more resistant strains within a given individual. No adverse events are applicable given the observational design.
Practice implications
This study established that a meaningful proportion (~10%) of individuals with gonorrhea at multiple anatomical sites exhibit within-person MIC discordance, which has direct implications for AMR surveillance and clinical management: culturing from only a single anatomical site may miss AMR in approximately 1 in 10 multi-site gonorrhea cases. The finding that population-level pharyngeal resistance signals are largely driven by between-person rather than within-person variation is an important methodological insight that challenges prior interpretations of anatomical site-specific resistance patterns drawn from single-isolate studies. The study did not establish causality for pharyngeal AMR development, nor did it clarify whether the pharynx is a selective driver of resistance acquisition (e.g., via horizontal gene transfer with commensal Neisseria) within individuals. Findings apply primarily to MSM and women attending Dutch SHCs; heterosexual men were not described as included, and generalizability to other healthcare settings or geographic regions with different resistance prevalences is uncertain. Clinical importance of the 10% discordance figure is potentially significant for treatment decision-making and surveillance design but requires quantification of absolute MIC distributions and formal statistical analysis (not available in abstract alone). Practice should not change based on an abstract alone; full data review, including specific MIC distributions, multivariable analyses, and specimen collection protocols, is needed. NOTE: This summary is based on the published abstract only; the full dataset, statistical models, and granular results are not available for review, which limits certainty of interpretation. __LIMITATIONS__ Only the abstract was available for review; complete methodology, statistical analyses, effect sizes, confidence intervals, and sensitivity analyses cannot be assessed.,Retrospective observational design introduces selection bias; patients with multi-site cultures may not be representative of all gonorrhea cases.,The GRAS programme enrolls patients from SHCs, limiting generalizability to primary care, emergency, or lower-resource settings.,Population restricted to MSM and women; findings may not apply to heterosexual men or transgender individuals.,MIC discordance is a phenotypic measure; the study does not resolve whether discordance reflects true within-host microevolution, re-infection with a different strain, sampling variability, or laboratory measurement error.,Temporal trends across 2016–2023 may introduce confounding due to changes in treatment guidelines, sexual networks, and resistance epidemiology over the study period.,The causal role of specific anatomical sites in gonococcal AMR development (e.g., gene transfer in the pharynx) was explicitly acknowledged as unresolved by the authors.,Funding source is not reported, limiting assessment of potential conflicts of interest.,Statistical significance of the 10% within-person MIC discordance estimate and population-level anatomical site differences is not reported in the abstract. __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ This Dutch GRAS programme study demonstrates that population-level pharyngeal resistance signals for N. gonorrhoeae primarily reflect between-person patient-mix differences rather than consistent within-individual anatomical site variation. Approximately 10% of individuals with multi-site cultures showed within-person MIC discordance, suggesting that single-site culture strategies may miss AMR in a clinically relevant subset of patients. Multi-site culture collection should be considered to improve AMR detection and inform treatment decisions, pending full publication and external validation.