Expanding the diversity of origin of transfer-containing sequences in mobilizable plasmids.

Conjugative plasmids are important drivers of bacterial evolution. Most plasmids lack genes for conjugation and characterized origins of transfer (oriT), which has hampered our understanding of plasmid mobility. Here we used bioinformatic analyses to characterize occurrences of known oriT families across 38,057 plasmids, confirming that most conjugative and mobilizable plasmids lack identifiable oriTs.

Capsules and their traits shape phage susceptibility and plasmid conjugation efficiency.

Bacterial evolution is affected by mobile genetic elements like phages and conjugative plasmids, offering new adaptive traits while incurring fitness costs. Their infection is affected by the bacterial capsule. Yet, its importance has been difficult to quantify because of the high diversity of confounding mechanisms in bacterial genomes such as anti-viral systems and surface receptor modifications.

Emergence of novel non-aggregative variants under negative frequency-dependent selection in .

is an emergent human pathogen causing diverse infections, some of which in the urinary tract. However, little is known about the evolution and maintenance of genetic diversity in this species, the molecular mechanisms and their population dynamics. Here, we characterized the emergence of a novel rdar-like (ough and ry) morphotype which is contingent both on the genetic background and the environment.

Latent evolution of biofilm formation depends on life-history and genetic background.

Adaptation to one environment can often generate phenotypic and genotypic changes which impact the future ability of an organism to thrive in other environmental conditions. In the context of host-microbe interactions, biofilm formation can increase survival rates in vivo upon exposure to stresses, like the host's immune system or antibiotic therapy. However, how the generic process of adaptation impacts the ability to form biofilm and how it may change through time has seldomly been studied.

Adaptation to novel spatially-structured environments is driven by the capsule and alters virulence-associated traits.

The extracellular capsule is a major virulence factor, but its ubiquity in free-living bacteria with large environmental breadths suggests that it shapes adaptation to novel niches. Yet, how it does so, remains unexplored. Here, we evolve three Klebsiella strains and their capsule mutants in parallel.

Cefoxitin as an alternative to carbapenems in a murine model of urinary tract infection due to Escherichia coli harboring CTX-M-15-type extended-spectrum β-lactamase.

We investigated the efficiency of the cephamycin cefoxitin as an alternative to carbapenems for the treatment of urinary tract infections (UTIs) due to Escherichia coli producing CTX-M-type extended-spectrum β-lactamases. The susceptible, UTI-inducing E. coli CFT073-RR strain and its transconjugant CFT073-RR Tc (pbla(CTX-M-15)), harboring a bla(CTX-M-15) carrying-plasmid, were used for all experiments.