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January 14, 2026Open Access

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

Key Points

To identify and describe a novel genotype of extensively drug-resistant Shigella sonnei carrying the blaDHA-1 gene.
Conducted whole-genome sequencing on Shigella isolates
Analyzed genetic relatedness among unrelated cases
Investigated transmission routes of the novel genotype.
Identified a novel XDR Shigella sonnei genotype harboring blaDHA-1
Demonstrated close genetic relatedness between two unrelated cases
Highlighted potential for community spread beyond sexually transmitted cases.

Abstract

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.

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

Key Points

Abstract

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