Virulence and resistance determinants of Klebsiella pneumoniae isolated from a Portuguese tertiary university hospital centre over a 31-year period

Abstract

Introduction: The rapid and complex evolution of bacterial resistance mechanisms in Klebsiella pneumoniae producing extended-spectrum β-lactamases and carbapenemases in Klebsiella pneumoniae is one of the most significant threats to public health. However, questions and controversies regarding the interactions between resistance and virulence in multidrug-resistant K. pneumoniae isolates remain unclear.

Methods: A retrospective cohort study was performed with 100 K. pneumoniae isolates recovered from a tertiary care university hospital centre in Lisbon over a 31-year period. Resistance and virulence determinants were screened using molecular methods (PCR, M13-PCR and MLST).

Results: The predominant virulence profile (fimH, mrkD_v1, khe) was shared by all isolates, indicative of an important role of type 1 and 3 fimbrial adhesins and haemolysin, regardless of the type of β-lactamase produced. However, accumulation of virulence factors was identified in KPC-3-producers, with a higher frequency (p<0.05) of capsular serotype K2 and iucC aerobactin when compared with non-KPC-3 β-lactamases or carbapenemases. Additionally, 9 different virulence profiles were found, indicating that the KPC-3 carbapenemase producers seem to adapt successfully to the host environment and maintain virulence via several pathways.

Conclusion: This study describes an overlapping of multidrug-resistance and virulence determinants in ST-14^K2 KPC-3 K. pneumoniae clinical isolates that may impose an additional challenge in the treatment of infections caused by this pathogen.

Keywords: Bacterial infections; Beta-lactamasas; Beta-lactamases; Cross-infection; Infecciones bacterianas; Infección cruzada; Klebsiella pneumoniae; Virulence; Virulencia.