With the alarming increase in antibiotic resistance and the global spread of resistance mechanisms,
the emergence of antibiotic-resistant Klebsiella spp. has become a significant challenge in clinical
settings. It is therefore important to monitor the characteristics of Klebsiella isolates in circulation
to develop mitigation solutions.
The aim of this study was to characterize the genetic and phenotypic characteristics of 21 Multidrug-
Resistant (MDR) Klebsiella isolates, including 19 K. pneumoniae, and 2 K. variicola isolated from
patients admitted to two central hospitals in northern Portugal using whole-genome sequencing
(WGS) and subsequent bioinformatic analysis of several virulence factors, including capsule types
(K-types), LPS O antigen serotype and sequence types (ST). Furthermore, we assessed the in vitro
biofilm-forming capacity and the hypermucoviscosity of Klebsiella isolates, as well as the ability of
Klebsiella spp. to infect Galleria mellonella, a larval in vivo model.
Genetic results showed a high prevalence of O1/O2 serotypes (14/21; 67%) among the isolates
tested, which is consistent with previous reports from Portugal. In contrast, a wide variety of K locus
types was found, in our study, where ST15-KL19 (4/21; 19%) associated to serotype O1/O2v2 was
the dominant. Within the O1/O2v2 serotype, a ST15-KL23 K. variicola, was the one harbouring a
high number of virulence genes. We also found statistical differences in the ability to produce biofilm
biomass within the strains, with a ST280-KL23 K. pneumoniae outcompeting with nine other strains.
According to our results, the most prominent serotype able to cause the death of G. mellonella was
the KL105-O1/O2v2.
In conclusion, our results emphasize the importance of conducting continuous molecular
surveillance in order to identify the key molecular features to be considered in the development of
novel strategies for the treatment of Klebsiella spp.-associated infections.This work was financially supported by: LA/P/0045/2020 (ALiCE), UIDB/00511/2020 and UIDP/00511/2020 (LEPABE), funded by national funds through FCT/MCTES (PIDDAC). In addition, this study was also funded by FCT (Portuguese Foundation for Science and Technology), under the scope of the strategic funding of UIDB/04469/2020 unit, LABELS—Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems—LA/P/0029/2020 (CEB), Inov4Agro-Associate Laboratory for Inovation, Building and Sustainability in Agri-Food Production—LA/P/0126/2020, and projects UIDB/04033/2020 and UIDP/04033/2020 (CITAB). J.C. also thanks FCT for the CEEC Individual (2022.06886.CEECIND).info:eu-repo/semantics/publishedVersio
