SXT was first discovered in MO10, which is a Vibrio cholerae O139 clinical strain isolated from India in the early 1990s. The SXT/R391 ICE family is one of the largest ICE families, with the most abundant diversity and members among Gram-negative bacteria 6. Many varieties of ICEs have been found in diverse Gram-positive and Gram-negative bacteria 2, 3, 4, 5. Once excised, ICEs form a circular intermediate that can be transferred to another cell via conjugation 1. Integrative and conjugative elements (ICEs) are self-transmissible mobile genetic elements that can be excised from the chromosome of the host cell. It is therefore necessary to continuously monitor the antimicrobial resistance and related mobile elements among Proteus isolates. Our results demonstrate abundant genetic diversity and multidrug resistance of the SXT/R391 ICEs carried by Proteus isolates, which may have significance for public health. Six isolates were resistant to chloramphenicol, kanamycin, streptomycin, trimethoprim-sulfamethoxazole, sulfisoxazole and tetracycline, which are drug resistances commonly encoded by ICEs. Collectively, the ICE-carrying isolates carried resistance genes for 20 tested drugs. Notably, a class A β-lactamase gene was identified in nine SXT/R391 ICEs. The SXT/R391 ICEs shared a common structure with a set of conserved genes, five hotspots and two variable regions, which contained more foreign genes, including drug-resistance genes. Using core gene phylogenetic analysis, the fifteen SXT/R391 ICEs were grouped into six distinct clusters, including a dominant cluster and three clusters that have not been previously reported in Proteus isolates. BLASTn searches against GenBank showed that the fifteen SXT/R391 ICEs were closely related to that from different Enterobacteriaceae species, including Proteus mirabilis. Here, we determined fifteen SXT/R391 ICEs carried by Proteus isolates from food (4.2%) and diarrhoea patients (17.3%). SXT/R391 integrative and conjugative elements (ICEs) are self-transmissible mobile genetic elements that are found in most members of Enterobacteriaceae.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |