Genomic DNA was extracted and sequenced via Illumina MiSeq or NextSeq benchtop sequencer (Illumina, Inc., San Diego, CA) as previously described 34 . Long read sequencing was performed using PacBio RS II (Pacific Biosciences of California, Inc., Menlo Park, CA). Kraken 2 was used to identify isolate species and check for contamination 35 . Short-read sequencing data were trimmed for adapter sequence content and quality using bbduk 36 . De novo assembly was performed using Newbler v2.9 37 . Minimum thresholds for contig size and coverage were set at 200 bp and 49.5×, respectively. Long-read sequencing data were assembled using HGAP 3.0 in the SMRT Analysis portal. In silico multilocus sequence typing (MLST) was performed using the scheme developed by Curran and Dawson 38 . Antimicrobial resistance genes were annotated using a combination of AMRFinderPlus and ARIBA 39, 40 . The genomes of all 253 ST-621 isolates have been deposited in the National Center for Biotechnology Information under BioProject PRJNA852179.