Soft tissue infection with multidrug-resistant Kluyvera ascorbata of extended-spectrum bêta-lactamase type (CTX-M): Case report and literature review

Kluyvera ascorbata, which belongs to the Enterobacteriaceae family, is a commensal bacterium that is very rarely described in human infections. In this report, we describe a case of soft tissue infection due to Kluyvera ascorbata in a 72-year-old man with comorbidities. He was admitted to the vascular surgery department for the treatment of a gas gangrene of the left foot. The patient received probabilistic antibiotic therapy with metronidazole, ceftriaxone and gentamicin by parenteral route with an amputation of the left leg following critical ischemia of the left lower limb (LLL). Due to the superinfection of the left leg amputation stump, the patient underwent an amputation of the left thigh, followed by multiple debridements of the left thigh amputation stump and drainage of an abscess on the anterior surface of the left thigh in the operating room. A sample of superficial pus was collected intraoperatively for microbiological examination to identify the pathogen and guide therapeutic adjustments. This examination revealed the exclusive presence of Kluyvera ascorbata. The isolate was resistant to the majority of β-lactams, aminoglycosides and sulfonamides. However, it was susceptible at standard dosage to carbapenems, fluoroquinolones, chloramphenicol, fosfomycin-trometamol and nitrofurantoin. The antibiogram highlighted the potential for multi-resistance type ESBL (extended spectrum B-lactamases) which characterizes this bacterium. In addition, Kluyvera spp. have an innate antibiotic resistance mechanism, and it is now accepted that CTX-M are derived from chromosomal beta lactamases of species of the genus Kluyvera. They are part of the extended spectrum β-lactamases (ESBL). Given the above, the treatment regimen has been adapted according to the results of the antibiogram. The patient received parenteral antibiotic therapy with levofloxacin, and the clinical evolution was favorable. This leads us to discuss the pathogenicity of this germ and its multi-resistant potential.