ICEGpa1804, a novel integrative and conjugative element carrying eight resistance genes, identified in Glaesserella parasuis.

• This study characterized a novel integrative and conjugative element, carrying eight resistance genes and seven IS elements, from a serovar 2 Glaesserella parasuis ST279 isolate. • Tn6743, a novel transposon carrying six resistance genes, was identified. • This study characterized a novel insertion element ISGpa1, which is the first characterized example in G. parasuis. ICE Gpa1804 was identified in the genome of a serovar 2, ST279 isolate EHP1804 carrying eight different resistance genes from 200 Glaesserella parasuis strains isolated from swine with lower respiratory tract infection in seven provinces of China. Susceptibility testing for EHP1804 was determined by broth microdilution, and its genetic profile was determined by whole-genome sequencing. The complete ICE Gpa1804 was analysed by polymerase chain reaction, conjugation assay and bioinformatics tools. The conjugation assay was performed using EHP1804 as the donor and G. parasuis V43 (rifampicin-resistant) as the recipient. ICE Gpa1804 has a size of 71,880 bp and contains 83 genes, including eight resistance genes [ tet (B), bla Rob-1 , aphA1, strA, strB, aac(3)-IId, catA3 and sul2 ]. The conjugation assay showed that ICE Gpa1804 could be transferred to G. parasuis V43 with frequencies of 4.3 × 10−7. To the best of the authors' knowledge, this is the first study to identify a novel integrative and conjugative element (ICE) carrying eight resistance genes and seven insertion sequence (IS) elements from a G. parasuis isolate. Tn 6743 , a novel transposon carrying six resistance genes, was identified. Moreover, IS Gpa1 , a novel IS 256 family insertion element, is the first characterized example of a G. parasuis insertion element. Multiple mobile genetic elements involved in resistance genes were located in chromosomal ICE Gpa1804 , which showed that ICEs may serve as a vital platform for the accumulation of resistance genes. [ABSTRACT FROM AUTHOR]