Genomic and Functional Characterization of CTX-M-15-Producing Klebsiella pneumoniae ST307 Isolated from Imported Leopard Tortoises in Germany

The Klebsiella pneumoniae ST307 clone, identified in the mid-1990s, has emerged as a global antimicrobial-resistant (AMR) high-risk clone, significantly contributing to the global health challenge also posed by other AMR K. pneumoniae lineages. The acquisition of a blaCTX-M-15-carrying plasmid has facilitated its widespread dissemination. At Europe’s major transport hub for the movement of live animals, Frankfurt Airport, a shipment of 20 live leopard tortoises was sampled during German border control in 2014. Phylogenetic analysis (MLST) identified a K. pneumoniae ST307 strain, prompting further investigation. Our analysis revealed the presence of a ~193 kb plasmid carrying a broad range of AMR genes, including blaCTX-M-15, blaTEM-1B, blaOXA-1, aac(3)-IIa, aac(6′)-Ib-cr, aph(3″)-Ib, aph(6)-Id, and qnrB1. Additionally, mutations in the quinolone resistance-determining region in gyrA (S83I) and parC (S80I) were detected. Phenotypic testing demonstrated resistance of the isolate to the most common antimicrobials used in both human and veterinary medicine; exceptions included carbapenems and newer β-lactamase inhibitor combinations. Because the role of imported exotic animals in the dissemination of AMR genes is largely deficient, the present study fills yet missing mosaic pieces in the complete picture of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales.