ABSTRACT:Klebsiella pneumoniae
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
K. pneumoniae
isolates and evaluate their virulence using the
Galleria mellonella
model. Biomass production, metabolic activity, capsule formation, and siderophore production were assessed in 27
K
.
pneumoniae
isolates from hospital-associated infections. Lethality curves were generated using the
G. mellonella
model, with survival monitored hourly from 16 to 48 hours. The most common sequence types (ST) identified were the high-risk clones ST307 (
N
= 10), ST512 (
N
= 8), ST101 (
N
= 7), and ST661 (
N
= 2). These STs were associated with distinct K-locus, including KL102, KL107, KL17, and KL39. Most isolates belonged to the O2afg locus (
N
= 18), with the
K. pneumoniae
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
G. mellonella
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
G. mellonella
model may serve as an effective
in vivo
system for evaluating the virulence of emerging
K. pneumoniae
lineages.
IMPORTANCE:
We demonstrate that the
Galleria mellonella
model is a useful tool to analyze the virulence of carbapenem-resistant
Klebsiella pneumoniae
strains. Our findings highlight the pathogenicity of carbapenem-resistant
K pneumoniae
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.