mNGS-identified cellulitis due to quinolone-resistant Edwardsiella tarda: a case report

<i>Edwardsiella tarda</i> is frequently isolated from aquatic animals and environments. While human infections caused by <i>E. tarda</i> are rare, some extraintestinal infections can be severe. This case report describes a patient with cellulitis of the right upper extremity of unknown origin. Metagenomic next-generation sequencing (mNGS) indicated that the patient was infected with <i>E. tarda</i>. Antimicrobial susceptibility testing revealed that the isolate was resistant to quinolones and trimethoprim/sulfamethoxazole. The isolate, positive for four virulence genes (<i>fimA, gadB, mukF</i>, and <i>sodB</i>), was confirmed to be virulent using the <i>Galleria mellonella</i> larvae model. Following early pus drainage and a 9-day course of imipenem, the patient ultimately recovered. This case report aimed to illustrate the presentation, diagnosis, and management of uncommon cellulitis caused by drug-resistant, virulent <i>E. tarda</i>.