A prophage and two ICESa2603-family integrative and conjugative elements (ICEs) carrying optrA in Streptococcus suis

Abstract

Objectives To investigate the presence and transfer of the oxazolidinone/phenicol resistance gene optrA and identify the genetic elements involved in the horizontal transfer of the optrA gene in Streptococcus suis. Methods A total of 237 S. suis isolates were screened for the presence of the optrA gene by PCR. Whole-genome DNA of three optrA-positive strains was completely sequenced using the Illumina MiSeq and Pacbio RSII platforms. MICs were determined by broth microdilution. Transferability of the optrA gene in S. suis was investigated by conjugation. The presence of circular intermediates was examined by inverse PCR. Results The optrA gene was present in 11.8% (28/237) of the S. suis strains. In three strains, the optrA gene was flanked by two copies of IS1216 elements in the same orientation, located either on a prophage or on ICESa2603-family integrative and conjugative elements (ICEs), including one tandem ICE. In one isolate, the optrA-carrying ICE transferred with a frequency of 2.1 × 10−8. After the transfer, the transconjugant displayed elevated MICs of the respective antimicrobial agents. Inverse PCRs revealed that circular intermediates of different sizes were formed in the three optrA-carrying strains, containing one copy of the IS1216E element and the optrA gene alone or in combination with other resistance genes. Conclusions A prophage and two ICESa2603-family ICEs (including one tandem ICE) associated with the optrA gene were identified in S. suis. The association of the optrA gene with the IS1216E elements and its location on either a prophage or ICEs will aid its horizontal transfer.

Antimicrobial resistance phenotypes and genotypes of Streptococcus suis isolated from clinically healthy pigs from 2017 to 2019 in Jiangxi Province, China

“…2019; Shang et al . 2019). Besides ICEs, integrative mobilizable elements likely play a major role in the horizontal transfer of AMR genes in S. suis (Libante et al .…”

Update on the Mechanisms of Antibiotic Resistance and the Mobile Resistome in the Emerging Zoonotic Pathogen Streptococcus suis

“…Amphenicol resistance is mediated by several mechanisms in S. suis . The first is the Cfr rRNA methyl-transferase encoded by the cfr gene as described above [ 37 ], and the second is a chloramphenicol acetyl-transferase mediated by the cat gene [ 57 ]. S. suis antimicrobial resistance genes also encode efflux proteins of the major facilitator superfamily that transport amphenicol-chloramphenicol outside the bacteria, in particular the FexA protein composed of 14 transmembrane helices [ 24 , 37 , 44 , 58 ].…”

“…S. suis antimicrobial resistance genes also encode efflux proteins of the major facilitator superfamily that transport amphenicol-chloramphenicol outside the bacteria, in particular the FexA protein composed of 14 transmembrane helices [ 24 , 37 , 44 , 58 ]. S. suis can also harbor the optr A gene that encodes an ATP-binding cassette (ABC) transporter [ 44 , 57 , 59 ] ( Figure 1 ).…”

Comparative genomics of global optrA-carrying Enterococcus faecalis uncovers a common chromosomal hotspot for optrA acquisition within a diversity of core and accessory genomes

“…In Streptococcus suis pig isolates, optrA has been recently described within a novel composite IS1216E-araC-optrA-hp-catpC 194 -IS1216E transposon integrated on a phage similar to Φm46.1 [73]. optrA was identified in prophages and ICEs only in Streptococcus suis [32,73,74], but the mobilization of optrA through phage-mediated transduction cannot be discarded also in enterococci. Wang et al [75] also recently demonstrated by a metagenomic approach in swine feedlot wastewater samples that phages were more likely to harbor ABC transporter family and ribosomal protection genes including optrA.…”