High frequency of acquired virulence factors in carbapenemase-producing isolates from a large German university hospital, 2013-2021.

Carbapenemase-producing (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 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 was present in 18/109 of the CP-Kp isolates. Other acquired virulence factors, such as , , , , , and hypervirulence-associated capsule types were detected in various combinations among these isolates. The -positive isolates produced OXA-232 ( = 7), OXA-48 ( = 6), OXA-48+NDM ( = 3), NDM, and KPC (each = 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 or . In 15/18 patients, -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 isolates in Germany, warranting continuous monitoring of infections caused by these strains.