High frequency of acquired virulence factors in carbapenemase-producing <i>Klebsiella pneumoniae</i> isolates from a large German university hospital, 2013–2021

Abstract

Carbapenemase-producing <i>Klebsiella pneumoniae</i> (CP-Kp) isolates are a public health concern as they can cause severe hospital-acquired infections that are difficult to treat. It has recently been shown that CP-Kp can take up virulence factors from hypervirulent <i>K. pneumoniae</i> lineages. In this study, 109 clinical CP-Kp isolates from the University Hospital Cologne were examined for the presence of acquired virulence factors using whole-genome sequencing and phenotypic tests, and results were linked to clinical data. The virulence factor <i>iuc</i> was present in 18/109 of the CP-Kp isolates. Other acquired virulence factors, such as <i>ybt</i>, <i>cbt</i>, <i>iro</i>, <i>rmpA/rmpA2</i>, <i>peg-344</i>, and hypervirulence-associated capsule types were detected in various combinations among these isolates. The <i>iuc</i>-positive isolates produced OXA-232 (<i>n</i> = 7), OXA-48 (<i>n</i> = 6), OXA-48+NDM (<i>n</i> = 3), NDM, and KPC (each <i>n</i> = 1), and 7/18 isolates were resistant to ceftazidime-avibactam, colistin, and/or cefiderocol. Four isolates carried hybrid plasmids that harbored acquired virulence factors alongside the carbapenemase genes <i>bla</i>_NDM-1/5 or <i>bla</i>_OXA-48. In 15/18 patients, <i>iuc</i>-positive CP-Kp were isolated from a clinically manifest infection site. Among these, four patients had osteomyelitis, and four patients died from pneumonia with OXA-232-producing ST231 isolates, three of them as part of an outbreak. In conclusion, acquired virulence factors are frequently detected in various combinations in carbapenemase-producing <i>K. pneumoniae</i> isolates in Germany, warranting continuous monitoring of infections caused by these strains.