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

Researchers in Los Angeles identified a previously unreported genotype of extensively drug-resistant (XDR) Shigella sonnei harboring an AmpC-type β-lactamase gene blaDHA-1 in isolates from two unrelated patients with no clear epidemiologic link, suggesting broader community spread beyond traditional high-risk groups; whole-genome sequencing showed the isolates were closely related, and their resistance profiles compromised most commonly used oral antibiotics, underscoring an urgent public health concern and the need for enhanced genomic surveillance and tailored treatment strategies.