Abstract:
OBJECTIVES: Escherichia coli ST410 (Ec-ST410) is an emerging, multidrug-resistant clone. Recent investigations of its global epidemiology and evolution have been based almost exclusively on isolates from Europe and North America. It is unclear whether Ec-ST410 in Southeast Asia belong to these same clones or represent regionally-disseminated variants. We characterized antibiotic resistance mechanisms among Southeast Asian-origin E. coli ST410 (SEA-Ec-ST410) and investigated whether they belonged to regional variants by contextualizing them within a global collection. METHODS: We identified 7 Ec-ST410 among a recent collection of expanded-spectrum cephalosporin-resistant E. coli recovered from 91 healthy women (stool) and 26 infected patients (blood and urine) living in Phnom Penh, Cambodia. We identified 9 additional Ec-ST410 genomes from Thailand (n=7) and Vietnam (n=2) through EnteroBase and PubMed searches. We characterized assembled genomes and created a SNP-based phylogenetic tree comparing these 16 SEA-Ec-ST410 to a previously published Ec-ST410 collection, primarily sourced from Europe (97/128) and North America (24/128). RESULTS: SEA-Ec-ST410 belonged to several distinct branches within previously described clonal clades. SEA-Ec-ST410 within the B3/H24Rx sub-lineage encoded blaCTX-M-55 genes (8/12) and F18:A-:B1 plasmid replicons (6/12), neither of which were detected among other Ec-ST410 belonging to this clade. Three of four SEA-Ec-ST410 within the B4/H24RxC sub-lineage lacked both the blaOXA-181 gene and an IncX3 plasmid replicon, which were harbored by 97% and 100% of all other Ec-ST410 in this sub-lineage (n=64), respectively. CONCLUSION: Ec-ST410 are present in Southeast Asia following multiple introductions. The unique pattern of antibiotic resistance elements harbored by SEA-Ec-ST410 suggests independent circulation in the region.
