Emergence of Multidrug-Resistant NDM-5-Producing ST307 Klebsiella pneumoniae in Uruguay, 2023.

Carbapenem and colistin-resistant Klebsiella pneumoniae pose a significant threat to public health, particularly in intensive care units, due to high morbidity and mortality rates. This study aimed to analyze five NDM carbapenemase-producing multidrug-resistant K. pneumoniae isolates from different hospitals. Antimicrobial susceptibility testing, hypermucoviscosity analysis, biofilm production assessment, MLST, PCR, and whole-genome sequencing were conducted. All isolates harbored NDM-5 metallo-β-lactamase, belonging to MLST 307, were biofilm producers and exhibited a stop codon (Q30) along MgrB. Genomic analysis revealed multiple-replicon plasmids carrying resistance genes, notably bla_NDM-5, bla_CTX-M-15, rmtB, and qnrB1, with complex genetic structures encoding several mobile genetic elements, including the Tn3 family and IS26. All isolates harbored wzi173 (capsule-locus KL102), iutA (a siderophore-associated gene), and the type 3 fimbriae mrkABCDFHIJ operon. The core genome single nucleotide polymorphisms (SNPs) analysis suggests the circulation of two strains of ST307 clone (SNPs range differences 4-77). These findings highlight the potential plasticity of the high-risk ST307 clone and the urgent need for surveillance and intervention strategies to combat antimicrobial resistance. To our knowledge, this is the first report of K. pneumoniae ST307 carrying bla_NDM-5 and the first description of ST307 in Uruguay. The presence of bla_NDM-5 and pan-aminoglycoside resistance rmtB genes are identified for the first time in Uruguay.