Circular intermediate-mediated horizontal transfer of the chromosome-encoded cfr(C) gene in multi-drug resistant Campylobacter coli from swine sources

• Published in: Frontiers in microbiology 2023, Vol.14, p.1274245-1274245
• Main Authors: An, Jae-Uk, Lee, Soomin, Guk, Jae-Ho, Woo, Jungha, Song, Hyokeun, Cho, Seongbeom
• Format: Article
• Language: English
• Subjects: Campylobacter coli; chromosome-encoded; circular intermediate; horizontal transfer; whole genome sequencing
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2023.1274245

is a major zoonotic pathogen that causes gastrointestinal and, rarely, immune diseases in humans. The antimicrobial-resistance gene carried by and is a -like gene that targets bacterial 23S rRNA through A2503 methylation. confers cross-resistance to five antimicrobial classes (PhLOPS ), including lincosamide, streptogramin A, and pleuromutilin, which are classified as critically important antimicrobials to human by the World Health Organization. To elucidate the genetic variation and horizontal transfer mechanism of , we analyzed the genetic background and horizontal transfer unit of -derived through comparative genomic analysis. We identified nine -positive strains of 157 strains isolated from swine sources. Three novel gene single nucleotide polymorphism (SNP) sites (19delA, 674C > A, and 890 T > C) were identified from nine -positive strains. Among six identified SNP variant types (SNP-I to -VI), five types of randomly inserted -cassettes on chromosome and one type of plasmid-like element were identified, their gene cassette composition differing depending on the variants. Three of six cassette types contained aminoglycoside-streptothricin resistance cluster " - - ." The gene cassette with gene (GC-1, GC-4, and GC-5) formed a -mediated circular intermediate " -hp- - ," which has not been previously reported. Other two cassette-types with ISChh1 formed circular intermediate "ISChh1- - - - - -hp-ATPase" and "ISChh1- - -hp." In conjugation assay, the -mediated circular intermediate was naturally transferred to the plasmid of recipient wild-type strain from swine source, and comparative genomic analysis revealed that encoded in -mediated circular intermediate was inserted into the plasmid of recipient by homologous recombination with and . This study revealed that novel multidrug resistance gene carried by from swine sources can be highly genetically diverse and transferable. Moreover, we suggest that the transferability of chromosomal may contribute to the global spread of multidrug resistance against clinically important antimicrobials.