Abstract
ICEHpa1 was identified in the genome of a serovar 8 Haemophilus parasuis ST288 isolate YHP170504 from a case of swine lower respiratory tract infection. The aim of the present study was to characterize the integrative conjugative element ICEHpa1 and its multiresistance region. Susceptibility testing was determined by broth microdilution and the complete ICEHpa1 was identified by WGS analysis. The full sequence of ICEHpa1 was analyzed with bioinformatic tools. The presence of ICEHpa1, its circular intermediate and integration site were confirmed by PCR and sequence analysis. Transfer of ICEHpa1 was confirmed by conjugation. ICEHpa1 has a size of 68,922 bp with 37.42% GC content and harbors 81 genes responsible for replication and stabilization, transfer, integration, and accessory functions, as well as seven different resistance genes [blaRob–3, tet(B), aphA1, strA, strB, aac(6)′-Ie-aph(2′)-Ia, and sul2]. Conjugation experiments showed that ICEHpa1 could be transferred to H. parasuis V43 with frequencies of 6.1 × 10–6. This is the first time a multidrug-resistance ICE has been reported in H. parasuis. Seven different resistance genes were located on a novel integrative conjugative element ICEHpa1, which suggests that the ICEHpa1 is capable of acquiring foreign genes and serving as a carrier for various resistance genes.
Highlights
The gram-negative bacterium Haemophilus parasuis is the causative agent of Glasser’s disease characterized by polyarthritis, fibrinous polyserositis, and meningitis in swine (Oliveira and Pijoan, 2004)
We identified ICEHpa1, a novel integrative and conjugative elements (ICEs) carrying multiple resistance genes, in the chromosome of a serovar 8 H. parasuis ST288 isolate YHP170504, in a feedlot from Henan, China, in 2017
WGS analysis showed that all seven resistance genes were located on a novel integrative conjugative element, designated as ICEHpa1 (Figure 1A) according to the nomenclature of ICEs2
Summary
The gram-negative bacterium Haemophilus parasuis is the causative agent of Glasser’s disease characterized by polyarthritis, fibrinous polyserositis, and meningitis in swine (Oliveira and Pijoan, 2004). The H. parasuis infection may cause great economic losses to the global pig industry (Oliveira et al, 2001). In H. parasuis, the resistant genes are usually located on small plasmids, in which mob genes (mobA, mobB, mobC, mobA-like, mobC-like, and mobA-L) and ISApl are usually identified flanking the resistant genes (Lancashire et al, 2005; Chen et al, 2010; Yang et al, 2013; Li et al, 2015; Moleres et al, 2015). No other mobile genetic elements [transposons, integrons, and integrative and conjugative elements (ICEs)] have been found to be associated with the resistant genes in H. parasuis. ICEs are self-transmissible mobile elements that are widespread
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