Two Cases of Rare Manifestations Due to Neisseria meningitidis During the Post-COVID-19 Era in Greece

<b>Background/Objectives</b>: <i>Neisseria meningitidis</i> is a human-specific pathogen capable of causing life-threatening illnesses. Occasionally, it is recovered from unusual sites, other than the bloodstream or the central nervous system. Herein, we describe two rare manifestations due to <i>N. meningitidis</i> within a year (2024) in Greece. <b>Methods</b>: Atypical infection due to <i>N. meningitidis</i> was diagnosed in two different patients: <i>Case-1</i> presented with an inflammatory swelling in the mid-line of the neck, and <i>Case-2</i> presented with swelling of the left knee. Both patients had high fever and no neurological signs at admission; <i>Case-2</i> progressed to meningoencephalitis. Phenotypic and genotypic identifications were carried out in both cases. <b>Results</b>: <i>Case-1</i> and <i>Case-2</i> isolates were identified as follows: MenX: 18, 25-44, F5-5, ST-823; 198cc and MenB: 7-1, 1, F3-3, ST-7460; 32cc for <i>Por</i>A, <i>Fet</i>A and MLST, respectively. MenX was identified for the first time in Greece and finetyping revealed rare genotypic characteristics. Both isolates were susceptible to cefotaxime, ceftriaxone and rifampicin, while <i>Case-2</i> isolate expressed reduced susceptibility to penicillin and resistance to ciprofloxacin. Both patients recovered fully. <b>Conclusions</b>: Although uncommon, <i>N. meningitidis</i> may be isolated from atypical sites and specimens. Clinicians and microbiologists should remain aware that meningococcus is a potential cause of infections beyond meningitis and septicaemia.