Emergence of ciprofloxacin-resistant Neisseria meningitidis ST-175 in Tunisia: Clinical case description and genomic characterization

Abstract

We describe a case of meningococcal bloodstream infection complicated by purpura fulminans in a 49-year-old woman in Tunisia in May 2025, caused by a ciprofloxacin-resistant Neisseria meningitidis. The patient presented with rapidly progressive purpura and septic shock requiring intensive care and empirical cefotaxime therapy. Blood cultures, molecular testing, and whole-genome sequencing (WGS) were investigated to characterize the N. meningitidis isolate. The strain was non-groupable and belonged to ST-175 (cc175), with BAST profile 3645 and a MenDeVAR Index indicating insufficient evidence for vaccine coverage. WGS identified penA mutations (F504L, A510V, I515V, H541N, I566V) associated with reduced amoxicillin susceptibility and a gyrA T91I mutation conferring ciprofloxacin resistance. Comparative genomic analysis showed close relatedness to European isolates, representing the first genomic documentation of cc175 in Tunisia. This case underscores the value of genomic analysis for detecting emerging antimicrobial resistance and monitoring unusual meningococcal lineages in adult patients.