Cross-Border Emergence of Escherichia coli Producing the Carbapenemase NDM-5 in Switzerland and Germany

A series of clinical NDM-5-producing Escherichia coli isolates obtained from two surveillance networks for carbapenem-producing Enterobacterales from 2018 to 2019, namely, Switzerland (NARA) and Germany (SurvCARE), were analyzed. The 33 NDM-5-producing E. coli isolates were highly resistant to beta-lactams, including novel beta-lactam/beta-lactamase inhibitor combinations (ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam), and remained susceptible to fosfomycin, colistin, and tigecycline. These isolates were assigned to different sequence types (STs) and indicated a predominance of isolates exhibiting ST167 in Switzerland and Germany (n= 10) (phylogenetic group C), followed by ST405 (n = 4) (phylogenetic group E), ST1284 (n= 4) (phylogenetic group C), and ST361 (n = 4) (phylogenetic group C). The bla(NDM-5) gene was predominantly present on an IncF-type plasmid (n = 29) and, to a lesser extent, on the narrow-host-range IncX3 plasmid (n = 4). Sequence analyses of eight NDM-5 plasmids indicated that NDM-5-encoding F-type plasmids varied in size between 86 and 132 kb. The two IncX3 plasmids pCH8NDM5 and pD12NDM5 were 46 and 45 kb in size, respectively. The highly conserved blaNDM- 5 genetic surrounding structures (Delta ISAba125-bla(NDM-5)-ble(MBL)-trpT-dsbD-IS26) of both the F-type and IncX3 plasmids suggested a common genetic origin. The emergence of the NDM-5 carbapenemase was evidenced in particular for the E. coli ST167 clone, which is a successful epidemic clone known to be associated with both multiresistance and virulence traits and is therefore of high public health concern. The occurrence of clonally related NDM-5-producing E. coli isolates in Switzerland and Germany further indicates the international spread of this multidrug-resistant superbug at least throughout Europe.

Automated summary

Clinical NDM-5-producing Escherichia coli isolates from Switzerland and Germany were highly resistant to beta-lactams but remained susceptible to certain antibiotics, mainly associated with the ST167 clone. The bla(NDM-5) gene was predominantly present on IncF plasmids with conserved genetic structures. This suggests a common genetic origin and international spread of this multidrug-resistant superbug, particularly associated with the ST167 clone.