RT Journal Article SR Electronic(1) A1 Locke, Rebecca K. A1 Greig, David R. A1 Jenkins, Claire A1 Dallman, Tim J. A1 Cowley, Lauren A.YR 2021 T1 Acquisition and loss of CTX-M plasmids in Shigella species associated with MSM transmission in the UK JF Microbial Genomics, VO 7 IS 8 OP SP 000644 DO https://doi.org/10.1099/mgen.0.000644 PB Microbiology Society, SN 2057-5858, AB Shigellosis in men who have sex with men (MSM) is caused by multidrug resistant Shigellae, exhibiting resistance to antimicrobials including azithromycin, ciprofloxacin and more recently the third-generation cephalosporins. We sequenced four bla CTX-M-27-positive MSM Shigella isolates (2018–20) using Oxford Nanopore Technologies; three S. sonnei (identified as two MSM clade 2, one MSM clade 5) and one S. flexneri 3a, to explore AMR context. All S. sonnei isolates harboured Tn7/Int2 chromosomal integrons, whereas S. flexneri 3a contained the Shigella Resistance Locus. All strains harboured IncFII pKSR100-like plasmids (67-83kbp); where present bla CTX-M-27 was located on these plasmids flanked by IS26 and IS903B, however bla CTX-M-27 was lost in S. flexneri 3a during storage between Illumina and Nanopore sequencing. IncFII AMR regions were mosaic and likely reorganised by IS26; three of the four plasmids contained azithromycin-resistance genes erm(B) and mph(A) and one harboured the pKSR100 integron. Additionally, all S. sonnei isolates possessed a large IncB/O/K/Z plasmid, two of which carried aph(3’)-Ib/aph(6)-Id/sul2 and tet(A). Monitoring the transmission of mobile genetic elements with co-located AMR determinants is necessary to inform empirical treatment guidance and clinical management of MSM-associated shigellosis., UL https://www.microbiologyresearch.org/content/journal/mgen/10.1099/mgen.0.000644