Detection and characterisation of Salmonella enterica serovar Infantis (eBG31) harbouring blaCTX-M-1 causing clinical disease in humans in England
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Salmonella enterica serovar Infantis, comprising eBurst groups (eBGs), eBG31 and eBG297, is the fourth most common serovar in humans across Europe. eBGs31 causes the highest burden of human disease and is the predominant group in animal reservoirs, especially in poultry.
There is an increasing number of reports of S. Infantis harbouring plasmids carrying multiple resistance determinants, termed 'plasmid of emerging S. enterica Infantis’ (pESI). pESI plasmids often carry genes conferring resistance to tetracycline, trimethoprim, sulfamethoxazole, antiseptics, heavy metals and genes associated with virulence.
UKHSA undertake routine genomic surveillance of critically important serovars for purposes of One Health, especially in those serovars/eBGs with know animal reservoir. Such routine surveillance has recently identified an isolate of S. Infantis eBG31 harbouring blaCTX-M-1 .
Of the 2509 clinical isolates of S. Infantis in the UKHSA archives between 2012 and 2022, 21 (0.8%) had blaCTX-M-1 . 12 of these isolates were chosen for re-sequencing using Oxford Nanopore Technologies and were the focus of this study (Table 1).
The aim of this study was to interrogate the UKHSA archive of Salmonella isolates for the present of S. Infantis eBG31 harbouring blaCTX-M-1 to characterise the AMR determinants using a combination of short and long-read sequencing technologies.