Virulence profile of carbapenem-resistant strains by an model of .

is a significant healthcare-associated pathogen, notable for its diverse virulence and antibiotic resistance profiles. This study aimed to characterize the genotypic and phenotypic diversity of isolates and evaluate their virulence using the model. Biomass production, metabolic activity, capsule formation, and siderophore production were assessed in 27 . isolates from hospital-associated infections. Lethality curves were generated using the model, with survival monitored hourly from 16 to 48 hours. The most common sequence types (ST) identified were the high-risk clones ST307 ( = 10), ST512 ( = 8), ST101 ( = 7), and ST661 ( = 2). These STs were associated with distinct K-locus, including KL102, KL107, KL17, and KL39. Most isolates belonged to the O2afg locus ( = 18), with the carbapenemase genotype detected in 96.3% of strains. None of the isolates were classified as hypervirulent. Phenotypically, ST661 exhibited the highest biomass production despite showing similar metabolic activity to other STs. A positive correlation was observed between biomass and siderophore production, while capsule production was inversely correlated with biomass. In the model, ST661 demonstrated the highest virulence, resulting in 100% mortality by 48 hours, compared to survival rates of 21.4% for ST101, 38.0% for ST307, and 31.2% for ST512. These findings underscore the pathogenic potential of ST661 isolates with enhanced biofilm production. The model may serve as an effective system for evaluating the virulence of emerging lineages.IMPORTANCEWe demonstrate that the model is a useful tool to analyze the virulence of carbapenem-resistant strains. Our findings highlight the pathogenicity of carbapenem-resistant isolates, particularly the role of the ST661 that, despite being a rare lineage, harbors the blaVIM gene and is associated with high biofilm production and the highest mortality rates.