# Emergence of a novel genotype of extensively drug-resistant Shigella sonnei carrying blaDHA-1 in diverse patient populations, Los Angeles, 2024–2025

## TL;DR

A new drug-resistant strain of Shigella sonnei with the blaDHA-1 gene was found in unrelated patients, suggesting community spread.

## Contribution

Identification of a novel XDR Shigella sonnei genotype with blaDHA-1 in diverse patients and evidence of community transmission.

## Key findings

- A novel XDR S. sonnei strain carrying blaDHA-1 was identified in two unrelated cases.
- Whole-genome sequencing showed close genetic relatedness, indicating potential community spread.
- The transmission route of this XDR strain remains unknown.

## Abstract

Extensively drug-resistant (XDR) Shigella is a public health threat, historically linked to blaCTX-M-15 gene in sexually transmitted cases. We describe a novel XDR S. sonnei carrying an AmpC-type blaDHA-1 gene from two unrelated cases with unknown transmission route; whole-genome sequencing revealed close genetic relatedness, signaling broader community spread.