Novel transmission element of antibiotic resistance genes ISCR and its ecological risk

Abstract

Antibiotic resistance genes (ARGs) as emerging environmental pollutants have become the focus of attention of many disciplines. The transmission and dissemination of ARGs in various environmental media has great hazards to environment and poses serious threat to human health. ISCR (insertion sequence common regions) elements are newly discovered resistance genes transmission elements. Because of the special genetic structure, ISCR elements can move any adjacent DNA sequences by rolling-circle replication and homologous recombination, and have become the efficient transmission elements of ARGs among different DNA molecules or bacterial species. Around the world, 27 members of the ISCR family have been discovered up to now. A lot of circumstantial evidence has indicated that ISCR elements may be associated with the mobility and transmission of kinds of ARGs, especially multiple drug resistance genes (MDR). In this review, we described some aspects of ISCR elements, including the horizontal transfer of ARGs, structural characteristics of ISCRs, classification of ISCRs and their related ARGs, research methods of these elements, possible ecological risk of ISCRs and proposal of research directions, hoping to provide help for further related research in the future.