Biology subjects

Doublet, B.

Publications and source records attributed to Doublet, B..

3 recordsLinked to original sources

bioRxiv2026

Phage-Inducible Chromosomal Jumbo Islands (PICJIs) spreading antimicrobial resistance, host-adaptation factors and defense systems, a novel satellite family of nucleus-forming Chimalliviridae

Phage satellites are mobile genetic elements that depend on helper bacteriophages to promote their own dissemination. Here, we identified a novel family of large satellites, named Phage-Inducible Chromosomal Jumbo Islands (PICJIs), that are widespread in Escherichia coli and Salmonella enterica among diverse hosts, worldwide. These largest satellites to date (71.6 {+/-} 15.8 kbp) are specifically transduced by the persistent jumbo bacteriophage Goslarvirus of the nucleus-forming Chimalliviridae family. Furthermore, PICJIs carried numerous accessory genes associated with clinically relevant antimicrobial resistances, host-adaptation, and several anti-phage defense systems.

microbiology↗

bioRxiv2022

Conjugative IncC plasmid entry triggers the SOS response and promotes effective transfer of the integrative antibiotic resistance element SGI1

The broad host range IncC plasmid family and the integrative mobilizable Salmonella Genomic Island 1 (SGI1) and its derivatives enable the spread of medically-important antibiotic resistance genes among Gram-negative pathogens. Although several aspects of the complex functional interactions between IncC plasmids and SGI1 have been recently deciphered regarding their conjugative transfer and incompatibility, the biological signal resulting in the hijacking of the conjugative plasmid by the integrative mobilizable element remains unknown. Here, we demonstrate that the conjugative entry of IncC/IncA plasmids is detected at an early stage by SGI1 through the transient activation of the SOS response, which induces the expression of the SGI1 master activators SgaDC, shown to play a crucial role in the complex biology between SGI1 and IncC plasmids. Besides, we developed an original tripartite conjugation approach to directly monitor SGI1 mobilization in a time-dependent manner following conjugative entry of IncC plasmids. Finally, we propose an updated biological model of the conjugative mobilization of the chromosomal resistance element SGI1 by IncC plasmids. IMPORTANCEAntimicrobial resistance has become a major public health issue, particularly with the increase in multidrug resistance (MDR) in both animal and human pathogenic bacteria, and with the emergence of resistance to medically important antibiotics. The spread between bacteria of successful mobile genetic elements such as conjugative plasmids and integrative elements conferring multidrug resistance is the main driving force in the dissemination of acquired antibiotic resistances among Gram-negative bacteria. Broad-host range IncC plasmids and their integrative mobilizable SGI1 counterparts contribute to the spread of critically-important resistance genes (e.g., ESBLs, and carbapenemases). A better knowledge of the complex biology of these broad-host range mobile elements will help to understand the dissemination of antimicrobial resistance genes that occurred across{gamma} -proteobacteria borders.

microbiology↗

bioRxiv2019

Global phylogenomics of multidrug resistant Salmonella enterica serotype Kentucky ST198

Salmonella enterica serotype Kentucky (S. Kentucky) can be a common causative agent of salmonellosis, usually associated with consumption of contaminated poultry. Antimicrobial resistance (AMR) to multiple drugs, including ciprofloxacin, is an emerging problem within this serotype. We used whole-genome sequencing (WGS) to investigate the phylogenetic structure and AMR content of 121 S. Kentucky ST198 isolates from five continents. Population structure was inferred using phylogenomic analysis and whole genomes were compared to investigate changes in gene content, with a focus on acquired AMR genes. Our analysis showed that multidrug resistant (MDR) S. Kentucky isolates belonged to a single lineage, which we estimate emerged circa 1989 following the acquisition of the AMR-associated Salmonella genomic island 1 (variant SGI1-K) conferring resistance ampicillin, streptomycin, gentamicin, sulfamethoxazole, and tetracycline. Phylogeographic analysis indicates this clone emerged in Egypt before disseminating into Northern, Southern and Western Africa, then to the Middle East, Asia and the European Union. The MDR clone has since accumulated various substitution mutations in the quinolone resistance determining regions (QRDR) of DNA gyrase (gyrA) and DNA topoisomerase (parC), such that most strains carry three QRDR mutations which together confer resistance to ciprofloxacin. The majority of AMR genes in the S. Kentucky genomes were carried either on plasmids or SGI structures. Remarkably, each genome carried a different SGI1-K derivative structure; this variation could be attributed to IS26-mediated insertions and deletions, which appear to have hampered previous attempts to trace the clone's evolution using sub-WGS resolution approaches. Several different AMR plasmids were also identified, encoding resistance to chloramphenicol, third-generation cephalosporins, carbapenems, and/or azithromycin. These results indicate that most MDR S. Kentucky circulating globally result from the clonal expansion of a single lineage that acquired chromosomal AMR genes 30 years ago, and has continued to diversify and accumulate additional resistances to last-line oral antimicrobials.

microbiology↗