Whole genome sequencing of increased number of azithromycin-resistant Shigella flexneri 1b isolates in Ontario

Abstract Azithromycin (AZM) resistance among Shigella is a major public health concern. Here, we investigated the epidemiology of Shigella flexneri serotype 1b recovered during 2016–2018 in Ontario, to describe the prevalence and spread of AZM resistance. We found that 72.3% (47/65) of cases were AZM–resistant (AZMR), of which 95.7% (45/47) were among males (P 95% nucleotide similarity to pKSR100. Plasmid-borne resistance limiting treatment options to AZM, ceftriaxone (CRO) and CIP was noted in a single isolate. We characterized AZMR isolates circulating locally among males and found that genomic analysis can support targeted prevention and mitigation strategies against antimicrobial-resistance