Los Angles Shigellosis Outbreak Caused by Mutation

In 2024, the unfortunate leader in extensively drug-resistant (XDR) Shigellosis outbreaks was the state of California, with 4,365 of the 20,621 cases reported nationwide.

A Brief Report published by AJIC on December 9, 2024, describes a mutation of Shigella sonnei, a strain of Shigella bacteria resistant to five of the antibiotic classes most commonly prescribed for such infections.

This report describes a distinct genetic mutation that made the bacteria resistant to another class of antibiotics, the cephalosporins.

These researchers say this XDR Shigella strain appears unique to LA country.

"These cases highlight the rapid expansion of extensively drug-resistant Shigella in the United States and the urgent need for appropriate detection and management,' wrote these UCLA and Quest researchers.

Since first detected in California in 2017, XDR Shigella has been increasing in prevalence. By 2022, 3.2% of Shigella isolates were XDR. From January through May 2024, 12% (118/978) of California Shigella isolates were reported as XDR. Shigella sonnei isolates accounted for the most significant percentage (78%) of cases.

The U.S. CDC estimates that Shigellosis cases occur annually, making it the third most common bacterial enteric disease. As of week #52, ending December 28, 2024, the CDC confirmed 20,621 Shigella cases, led by California and New York (2,990).

In 2023, the CDC reported 17,176 cases in the U.S.

From a prevention perspective, Valneva SE and LimmaTech Biologics AG are co-developing the Shigella4V (S4V), a tetravalent bioconjugate vaccine candidate against Shigellosis. On November 13, 2024, the companies launched a Phase 2b clinical trial for Shigella4V.

Previously, the U.S. FDA granted Shigella4V Fast Track designation.