Salmonella Genomic Island 1 is Broadly Disseminated within Gammaproteobacteriaceae

Abstract

<i>Salmonella</i> genomic island 1 (SGI1) is an integrative mobilisable element that plays an important role in the capture and spread of multiple drug resistance. To date, SGI1 has been found in clinical isolates of <i>Salmonella</i><i>enterica</i> serovars, <i>Proteus mirabilis</i>, <i>Morganella</i><i>morganii</i>, <i>Acinetobacter</i><i>baumannii</i>, <i>Providencia</i><i>stuartii</i>, <i>Enterobacter</i><i>spp</i><i>,</i> and recently in <i>Escherichia coli</i>. SGI1 preferentially targets the 3´-end of <i>trmE</i>, a conserved gene found in the Enterobacteriaceae and among members of the Gammaproteobacteria. It is, therefore, hypothesised that SGI1 and SGI1-related elements (SGI1-REs) may have been acquired by diverse bacterial genera. Here, Bitsliced Genomic Signature Indexes (BIGSI) was used to screen the NCBI Sequence Read Archive (SRA) for putative SGI1-REs in Gammaproteobacteria. Novel SGI-REs were identified in diverse genera including <i>Cronobacter</i> spp, <i>Klebsiella</i> spp, and <i>Vibrio</i> spp and in two additional isolates of <i>Escherichia coli</i>. An extensively drug-resistant human clonal lineage of <i>Klebsiella pneumoniae</i> carrying an SGI1-RE in the United Kingdom and an SGI1-RE that lacks a class 1 integron were also identified. These findings provide insight into the origins of this diverse family of clinically important genomic islands and expand the knowledge of the potential host range of SGI1-REs within the Gammaproteobacteria.