The role of mobile genetic elements in the dissemination of resistance genes in Klebsiella spp. clinical strains

João Francisco Marmelo Ramalho

Key information

Authors:

João Francisco Marmelo Ramalho (João Francisco Marmelo Ramalho)

Supervisors:

Cátia Sofia Gabriel Caneiras; Leonilde de Fátima Morais Moreira (Leonilde de Fátima Morais Moreira)

Published in

11/29/2023

Abstract

Healthcare-associated infections (HAIs) represent a significant health threat. Klebsiella species are among the leading causes, with carbapenem resistance becoming increasingly prevalent. This study includes 1140 strains from three hospital centers in Portugal. Klebsiella pneumoniae was identified as the predominant species (93.3%). This study also reveals the presence of other members of the K. pneumoniae species complex (KpSC) (n=8), Klebsiella aerogenes (n=17), and Klebsiella oxytoca species complex (KoSC) (n=10). A strong correlation was found between lineages and the main carbapenemases produced. The blaOXA-181 gene was associated with K. pneumoniae ST17-KL25-O5 and ST147-KL64-O2 strains, and in K. aerogenes ST93-O2 strains. And the blaKPC-3 gene in ST147-KL64-O2 and ST13-KL3-O1 K. pneumoniae. All ST2-KL74 K. oxytoca strains encoded blaOXA-48 and co-production of two distinct carbapenemases was confirmed in all three species groups. Despite this, IncF and Col-like were the most represented plasmid families in all Klebsiella species, and different strains shared similar blaKPC- and blaOXA-181-harbouring plasmids. Moreover, these genes were found within the Tn4401d and IS26-like transposon, respectively. The study also reports a novel carbapenemase, KPC-98, which confers resistance to ceftazidime-avibactam, and is related with a high fitness cost, leading to the loss of the resistance gene over time, highlighting the dynamic nature of resistance mechanisms. This research offers insights into the complex landscape of carbapenem resistance in Klebsiella species in Portuguese healthcare facilities, emphasizing the urgent need for continuous surveillance of antimicrobial resistance, as well as the importance of understanding the role of mobile genetic elements (MGE) in resistance dissemination.