RESUMO
We characterized two bacteriophages, ΦFG02 and ΦCO01, against clinical isolates of Acinetobacter baumannii and established that the bacterial capsule is the receptor for these phages. Phage-resistant mutants harboured loss-of-function mutations in genes responsible for capsule biosynthesis, resulting in capsule loss and disruption of phage adsorption. The phage-resistant strains were resensitized to human complement, beta-lactam antibiotics and alternative phages and exhibited diminished fitness in vivo. Using a mouse model of A. baumannii infection, we showed that phage therapy was effective.
Assuntos
Infecções por Acinetobacter/microbiologia , Infecções por Acinetobacter/terapia , Acinetobacter baumannii/virologia , Antibacterianos/farmacologia , Bacteriófagos/fisiologia , Terapia por Fagos , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Animais , Cápsulas Bacterianas/virologia , Proteínas do Sistema Complemento/farmacologia , Modelos Animais de Doenças , Farmacorresistência Bacteriana , Feminino , Humanos , Mutação com Perda de Função , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Inibidores de beta-Lactamases/farmacologiaRESUMO
The function of the bighorn sheep horn prompted quantification of the various parametric effects important to the microstructure and mechanical property relationships of this horn. These parameters included analysis of the stress-state dependence with the horn keratin tested under tension and compression, the anisotropy of the material structure and mechanical behavior, the spatial location along the horn, and the wet-dry horn behavior. The mechanical properties of interest were the elastic moduli, yield strength, ultimate strength, failure strain and hardness. The results showed that water has a more significant effect on the mechanical behavior of ram horn more than the anisotropy, location along the horn and the type of loading state. All of these parametric effects showed that the horn microstructure and mechanical properties were similar to those of long-fiber composites. In the ambient dry condition (10 wt.% water), the longitudinal elastic modulus, yield strength and failure strain were measured to be 4.0 G Pa, 62 MPa and 4%, respectively, and the transverse elastic modulus, yield strength and failure strain were 2.9 GPa, 37 MPa and 2%, respectively. In the wet condition (35 wt.% water), horn behaves more like an isotropic material; the elastic modulus, yield strength and failure strain were determined to be 0.6G Pa, 10 MPa and 60%, respectively.