Epidemiologic and Genomic Investigation of Sexually Transmitted Shigella sonnei, England

Abstract

Shigellosis is a bacterial infection that causes enteric illness and can be sexually transmitted, particularly among gay, bisexual, and other men who have sex with men. Multiple extensively drug-resistant Shigella strains have been detected through genomic surveillance and are associated with plasmids carrying the gene variant bla in the United Kingdom. We report an increase in possible sexually transmitted cases of Shigella bacte- ria carrying the bla gene variant, which was pre- viously associated with travel. In 2023, there were 117 cases belonging to the 10 single-nucleotide polymor- phism linkage cluster t10.1814. Although this cluster has been documented in England since August 2019, genetic analyses revealed that the blaCTX-M-15 gene variant entered the lineage on a novel resistance plasmid coincid- ing with the first outbreak case. Our analysis highlights the shifting antimicrobial resistance landscape of sexually transmitted Shigella bacteria. Parallel emergence of resistance determinants against third-generation cephalosporins in sexual transmission networks suggests high levels of antimicrobial selection pressure.