Cross-border emergence of clonal lineages of ST38 Escherichia coli producing the OXA-48-like carbapenemase OXA-244 in Germany and Switzerland

Abstract

Background: Carbapenemase-producing Gram-negative bacteria cause infections that are difficult to treat and represent a rising threat to healthcare systems worldwide. This study analysed isolates of Escherichia coli (E. coli), a species associated with nosocomial-acquired and community-acquired infections, from hospitals in Germany and Switzerland exhibiting a slight decrease in susceptibility to carbapenems.

Methods: E. coli strains from Germany and Switzerland, obtained mainly in 2019, were first screened for carbapenemase genes by PCR and subsequently whole-genome-sequenced and analysed for their clonal relationship using multilocus sequence typing, single nucleotide polymorphisms, virulence and antibiotic-resistance gene content.

Results: The analysis revealed the presence of extended β-lactamase (ESBL)-producing E. coli clones producing OXA-244, a point-mutation derivative of OXA-48, with a predominance of isolates exhibiting the sequence type (ST) ST38 in both Germany and Switzerland. These clustered exclusively into two distinct lineages: one encoding CTX-M-27, a recently emerged extended-spectrum β-lactamase, and the other CTX-M-14b. All OXA244/CTX-M-27 ST38 isolates harboured the Dr adhesin operon and a representative isolate exhibited a diffuse adherence (DAEC) phenotype and was invasive for Hela cells.

Conclusion: Clonal lineages of ST38 are members of E. coli phylogenetic group D commonly associated with extra-intestinal infections. Their increased isolation in two different European countries indicates ongoing spread of ST38 ESBL-producing and OXA-244-producing E. coli clonal lineages. It is possible that members of the multidrug-resistant DEAC ExPEC group have expanded globally, but that this is currently underreported because of the inherent difficulty in detecting isolates expressing the OXA-244 allele.

Keywords: CTX-M-27/14b; Carbapenemase-producers; Diffusely adhering E. coli (DAEC); Escherichia coli; OXA-244.