The World Health Organization recommends ciprofloxacin (a fluoroquinolone) as a first-line treatment for shigellosis, and azithromycin (a macrolide), ceftriaxone (a third-generation cephalosporin), or pivmecillinam (an extended-spectrum penicillin) as second-line therapies (7). Isolates are classified as multidrug-resistant (MDR) (technical note C) or extensively drug-resistant (XDR) (technical note D) based on the presence of genetic markers of resistance.

Among presumptive MSM (technical note B), antimicrobial resistance is consistently high in both S. sonnei and S. flexneri isolates, with 96% and 92% of isolates classified as MDR or XDR in 2022 (to Q2), respectively (Figure 5).

There has been a sustained increase in the proportion of XDR S. sonnei from 58% in 2020 to 70% in 2021, and subsequently 80% of diagnoses in 2022 (to Q2), this is driven by the resurgence of a S. sonnei Clade 5 outbreak strain that had acquired ceftriaxone resistance and was characterised as XDR in Q3 2021 (6) (Figure 5). Reporting of XDR S. flexneri isolates was also relatively more frequent in 2022 (9%) compared to 2021 (3%). In addition, 14% (25 out of 183) of S. flexneri isolates reported in 2022 harboured markers of resistance to third generation cephalosporins relative to 2% (6 out of 261) in 2021.

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