# In vivo selection of CMY-219 conferring resistance to ceftazidime-avibactam in an OXA-484-producing E. coli ST410

## TL;DR

This study shows how a variant of the CMY-42 enzyme can cause resistance to a key antibiotic in a specific strain of E. coli.

## Contribution

The study identifies CMY-219 as a novel variant linked to ceftazidime-avibactam resistance in an OXA-484-producing E. coli ST410.

## Key findings

- Ceftazidime-avibactam resistance was conferred by the CMY-219 variant in an OXA-484-producing E. coli ST410.
- ST410 and related clones are at risk of selecting CMY variants under ceftazidime-avibactam exposure.
- These clones commonly carry CMY-42 and modified PBP3, increasing their potential for carbapenemase acquisition.

## Abstract

Resistance to ceftazidime-avibactam (CAZ-AVI) is a growing problem. This study describes the selection of CMY-219, a CMY-42 variant (G156D), conferring resistance to CAZ-AVI in an OXA-484-producing Escherichia coli ST410 after treatment. It raises concern about the risk of selection of CMY variants under CAZ-AVI exposure in ST410 and related clones, which commonly carry CMY-42, are prone to carbapenemase acquisition, and harbor modified PBP3.