Silent spreaders: multidrug-resistant and hypermucoviscous Klebsiella from animals threaten one health.

This study investigated the identification, antimicrobial resistance patterns, and phenotypic and genotypic traits of 30 Klebsiella isolates recovered from diverse animal species and infection sites. MALDI-TOF MS demonstrated higher accuracy in species-level identification than conventional phenotypic approaches, revealing a predominance of Klebsiella pneumoniae (80%), followed by K. variicola, K. aerogenes, and K. oxytoca. Multidrug resistance was detected in 46.6% of isolates, while 43.3% were extended-spectrum β-lactamase (ESBL) producers carrying genes such as blaTEM, blaCTX, and blaSHV. One carbapenemase-producing isolate was confirmed, and carbapenemase-encoding genes (blaOXA-48, blaNDM, blaKPC) were identified in additional strains. Notably, hypermucoviscosity was observed in four isolates, including the first report of a hypermucoviscous K. variicola from a dog. These findings highlight the presence of antimicrobial-resistant Klebsiella isolates in animal sources and support the need for integrated One Health surveillance.