Extensively Drug-Resistant Shigellosis in Australia among Men Who Have Sex with Men

Extensively Drug-Resistant Shigellosis in Australia among Men Who Have Sex with MenTo the Editor: In high-income countries, most shigellosis is associated with international travel to areas in which the condition is endemic or with sexual transmission among men who have sex with men (MSM).In cases of shigellosis in which oral antimicrobial treatment is indicated, the recommended first-line oral antimicrobial treatment for shigellosis is ciprofloxacin, with azithromycin as an alternative.Some studies have used whole-genome sequencing to describe the dissemination of antimicrobial-resistant Shigella sonnei and S. flexneri lineages among MSM. 1,2 Although resistant to multiple antimicrobials, MSM-related shigella lineages have generally remained susceptible to at least one orally available antimicrobial.To date, sporadic shigellosis clusters that are resistant to all orally available antimicrobials (i.e., extensively drug-resistant shigella) have been reported among MSM. 3,4 In the absence of oral antimicrobials, and in severe disease, intravenous treatment with ceftriaxone may be the only alternative treatment option.In Australia, shigellosis is a notifiable disease under public health legislation.The Microbiological Diagnostic Unit Public Health Laboratory receives all shigella isolates in the state of Victoria, Australia (population, approximately 6.4 million).Isolates undergo antimicrobial susceptibility testing and routine whole-genome sequencing.Details of the methods are provided in the Supplementary Appendix, available with the full text of this letter at NEJM.org.Between February 1, 2018, and May 31, 2019, a total of 184 isolates of extensively drug-resistant S. sonnei were identified from 12 female patients and 172 male patients in Victoria (Fig. 1).Phylogenomic analysis indicated that 171 of the isolates formed a distinct clonal lineage within