A patient in Sweden presented with a false-positive Neisseria gonorrhoeae (NG) result from an Abbott Alinity m STI assay. Subsequent genomic analysis identified the causative agent as Neisseria meningitidis (NM). This finding highlights a critical diagnostic challenge where the assay's target region, specifically the porA pseudogene, showed high homology between NG and NM, leading to cross-reactivity. The patient's clinical picture was not consistent with NG infection, prompting further investigation. This case underscores the importance of confirmatory testing and genomic characterization, especially when initial molecular diagnostics yield unexpected or discordant results, to prevent misdiagnosis and ensure appropriate patient management.
Key note: Molecular assays targeting highly conserved regions can lead to false-positive results due to cross-reactivity with closely related non-pathogenic or less pathogenic organisms.