New and emerging SXT/R391 integrative conjugative elements as vehicles for stable mobile element transfer and spread of antibiotic resistance in both human and animals.

Abstract

peer-reviewedThe integrative conjugative elements, ICE s SXT and R391 are the prototypes of a group of gram negative integrative elements known as the SXT/R391 group. R391 was identified in a clinical isolate of Providencia in the late 1960 s in South Africa, while SXT was initially isolated in 1992 in a clinical isolate of Vibrio cholerae O139 and variants have since been isolated in pandemic strains throughout the world. Subsequent sequencing of both elements demonstrated a high degree of structural similarity leading to the group being classified as the SXT/R391 group. The SXT/R391 ICE elements are characterised as integrating into a specific chromosomal site within gram ve hosts, being extremely stable and promiscuous and possessing a number of element hotspots for integration of heterologous DNA including increasingly, antibiotic resistance determinants. This makes such ICE s highly adapted for antibiotic spread. New evidence emerging indicates that SXT/R391-like ICE s are increasingly being identified worldwide particularly in Asia not only from Vibrio species, where they have been found widely in human clinical isolates, but from other gram -ve associated infections of domestic animals and fish. Evidence of more such elements may emerge in the future as a new trapping vector pIceCap has been developed to capture them in a circular form, aiding characterisation. The types of the novel ICE s now emerging, their comparison with prototype elements and the antibiotic resistances associated with them are important given their promiscuous nature and stability. PUBLISHEDPeer reviewe

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