Neisseria sicca Bloodstream Infection in a Patient with Aortic Valve Replacement: Case Report and Genomic Analysis

Neisseria sicca is usually a commensal of the oropharynx but can occasionally cause invasive disease. Herein, we report a rare case of N. sicca bacteremia in a female with a 7-year history of aortic valve replacement (AVR), who presented with persistent fever but no respiratory symptoms or valvular vegetations. Blood cultures yielded N. sicca, identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and confirmed via 16S rRNA sequencing. Appropriate antibiotic therapy with ticarcillin-clavulanate led to a significant clinical improvement. To gain insight into the pathogenicity and resistome of this strain, whole-genome sequencing of N. sicca junzhu_1 was performed using the Illumina NovaSeq platform. The resistome of the N. sicca strain consists of three antimicrobial resistance genes: macB, macA, and mtrD. Virulence gene analysis revealed that the pathogenicity of N. sicca was associated with mntB, mntC, farA, farB, mtrD, mtrE, msrA/B (pilB), rfaF, rfaC, hpuB, pilT, and recN. This case underscores the potential of N. sicca to act as an opportunistic pathogen in bloodstream infections (BSIs).