The cell envelope of the Gram-negative Burkholderia cepacia complex (Bcc) presents unique restrictions to antibiotic penetration. As a consequence, Bcc species are notorious for causing recalcitrant multidrug-resistant infections in immunocompromised individuals, such as those living with cystic fibrosis. To systematically identify cell envelope-associated resistance and susceptibility determinants at the genome level, we constructed a high-density, randomly-barcoded transposon mutant library in the clinical isolate B. cenocepacia K56-2 and exposed it to a panel of more than twenty cell envelope-targeting antibiotics. By quantifying relative mutant fitness with BarSeq, followed by validation with CRISPR-interference, we profiled over a hundred new functional associations and identified novel mediators of antibiotic susceptibility in the Bcc cell envelope. We revealed new connections between β-lactam susceptibility, peptidoglycan synthesis, and blockages in undecaprenyl phosphate metabolism, which highlight a vulnerability in sharing this lipid intermediate. We then show that the clinically relevant synergy of the β-lactam/β-lactamase inhibitor combination ceftazidime/avibactam is primarily mediated by inhibition of the PenB carbapenemase. Importantly, we found that avibactam more strongly potentiates the activity of aztreonam and meropenem than ceftazidime in a panel of Bcc clinical isolates. Finally, we characterize for first time in the Bcc the iron and receptor-dependent activity of the novel siderophore-cephalosporin antibiotic, cefiderocol. Overall, our work has implications for antibiotic target prioritization, and for using additional combinations of β-lactam/β-lactamase inhibitors that can extend the utility of our current clinical arsenal of antibacterial therapies.

Highly porous zirconia (ZrO2) scaffolds fabricated by the replication method were coated with fluorapatite (FA). The FA coating was obtained by dipping the ZrO2 scaffolds into stabilized aqueous FA slips having different viscosity values (≤5.0 mPa.s). The influence of the FA slip viscosity and the immersion time on the reduction in the scaffold porosity and microstructure of the coated scaffolds were investigated. Cell spreading and survival of bone marrow‐derived stromal cells (BMSC) and pre‐osteoblastic MC3T3‐E1 cells on the uncoated and coated scaffolds were examined using fluorescence and SEM microscopy, and MTT assay.The FA slip with the lowest viscosity value did not lead to a continuous film along the strut network and the macropores remained uncoated. The slips with the highest viscosity value produced a partial blocking of macropores. The porous structure obtained after coating with slips of 2.2 mPa.s viscosity for 2 seconds exhibited a low reduction in porosity and pore size (400‐420 μm), due to the formation of the FA layer, and a continuous film distributed along the strut surfaces. Morphology, spreading, and survival of BMSC and MC3T3‐E1 cells over a 7‐day culture period evidenced good biocompatibility of FA‐coated ZrO2 scaffolds processed by dip coating.

mol% yttria-partially stabilized zirconia (Y-TZP) powder and a sol-gel derived

The composition and morphology of bones implanted with stainless steel (316L-SS) and a metal alloy made of zinc, aluminum, and copper (Zinalco) are compared. Small-angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) results show that with time Zinalco is corroded and zinc, aluminum, and copper diffuse into the osseous tissue, promoting nonhomogeneous bone. Instead, 316L-SS does not incorporate into bone, and the bone recovers homogeneously at a lower speed.

The cell envelope of the Gram-negativeBurkholderia cepaciacomplex (Bcc) presents unique restrictions to antibiotic penetration. As a consequence, Bcc species are notorious for causing recalcitrant multidrug-resistant infections in immunocompromised individuals, such as those living with cystic fibrosis. To systematically identify cell envelope-associated resistance and susceptibility determinants at the genome level, we constructed a high-density, randomly-barcoded transposon mutant library in the clinical isolateB. cenocepaciaK56-2 and exposed it to a panel of more than twenty cell envelope-targeting antibiotics. By quantifying relative mutant fitness with BarSeq, followed by validation with CRISPR-interference, we profiled over a hundred new chemical-genetic interactions and identified novel mediators of antibiotic susceptibility in the Bcc cell envelope. We first reveal new connections between broad-spectrum β-lactam susceptibility, peptidoglycan synthesis, and blockages in undecaprenyl phosphate metabolism, highlighting a β-lactam critical vulnerability associated with sharing this common lipid intermediate. We then show that the clinically relevant synergy of the β-lactam/ β-lactamase inhibitor combination ceftazidime/avibactam is primarily mediated by inhibition of the PenB carbapenemase, over more than twenty other putative β-lactamases. Importantly, avibactam more strongly potentiates the activity of aztreonam and meropenem than ceftazidime in a panel of Bcc clinical isolates. Finally, we characterize for first time in the Bcc the iron and receptor-dependent activity of the novel siderophore cephalosporin antibiotic, cefiderocol. Overall, our work has implications for antibiotic target prioritization, and for using additional combinations of β-lactam/ β-lactamase inhibitors that can extend the utility of our current clinical arsenal of antibacterial therapies.