Identification of pandemic ST147, ESBL-type β-lactamases, carbapenemases, and virulence factors in Klebsiella pneumoniae isolated from southern Peru.

Multidrug-resistant Klebsiella pneumoniae (MDR K. pneumoniae) is a significant pathogen associated with nosocomial infections, often leading to high morbidity and mortality. This resistance is largely due to the efficient horizontal transfer of mobile genetic elements such as plasmids, which carry resistance genes and virulence factors. These elements contribute to the production of extended-spectrum β-lactamases (ESBL) and carbapenemases, which further complicates treatment. Despite the high prevalence of MDR K. pneumoniae in Peruvian hospitals, the genomic characterization of these strains remains limited. This study investigated the phenotypic and molecular identification of extended-spectrum β-lactamases (ESBLs), carbapenemases, and virulence factors in 91 MDR K. pneumoniae strains collected from three hospitals between 2022 and 2023. Phenotypic detection of ESBLs was performed using the Jarlier method, while carbapenemases were identified via double-disk synergy testing with boronic acid, EDTA, and Carba NP test. The positive isolates were further analyzed for resistance genes (blaCTX-M, blaTEM, blaSHV, blaKPC, blaNDM, blaIMP, and blaVIM). Four isolates were subjected to whole-genome sequencing (WGS) for further characterization. All multidrug-resistant K. pneumoniae strains (100%) were ESBL-positive, with 14.3% producing carbapenemases, primarily KPC-type and metallo-β-lactamases (MBLs). The virulence factor analyses revealed that only 7.7% exhibited hypermucoviscosity. Protease activity was detected in 19.8% of the strains, and lipase activity in 1.1%. Regarding biofilm formation, 85.7% of the strains showed moderate adherence. Molecular analysis identified ESBL (blaCTX-M, 78%; blaTEM, 71.4%; blaSHV, 82.4%) and carbapenemase genes (blaKPC 7.7%, blaNDM 4.4%). Genomic analysis revealed various antimicrobial resistance mechanisms, including porin-coding gene mutations, aminoglycoside resistance linked to fluoroquinolone resistance, and multidrug efflux pump regulators. Sequence typing has identified high-risk clones (ST147, ST629, and ST37) associated with hospital outbreaks globally. These findings underscore the considerable concern of MDR and hypervirulent K. pneumoniae in Peruvian hospitals. These findings emphasize the pressing need for sustained genomic surveillance, enhanced infection control measures, and strategies to address the expanding problem of MDR K. pneumoniae.