Browsing by Author "Ferreira, Magda"
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- Antimicrobial effect of polymeric biomaterials for bone infection treatmentPublication . Ferreira, Magda; Bettencourt, Ana; Jordão, LuísaBone infection, mainly caused by Staphylococcus aureus, is a public health concern. Treatment is challenging due to multi-resistant strains, and S. aureus ability to adhere and form biofilm on bone and implant surfaces, as well as to invade and persist in osteoblast cells. The present work consisted in the preparation and evaluation of novel acrylic polymeric systems that provide local and controlled antibiotic delivery for the treatment of bone infection, namely levofloxacin-loaded acrylic bone cement (BC), and vancomycin or daptomycin-loaded acrylic microparticles (MP). Properties of both delivery systems with high impact on clinical performance were tested. Namely, contact angle and surface energy were determined in BC matrices and encapsulation efficiency in MP formulations. Release studies of levofloxacin-loaded BC matrices were also conducted. Also, the anti-biofilm activity of these systems was evaluated against S. aureus strains. Furthermore, BC and MP formulations were tested concerning the antibacterial intracellular activity using a human osteoblast infection model. Overall, both BC formulations’ surface characteristics and MP encapsulation efficiency were in agreement with previously published data. The release studies of levofloxacin from BC matrices showed that the drug release is size- and incubation medium-dependent. All BC matrices loaded with levofloxacin concentrations of 1.5 % or higher exhibited anti-biofilm activity against all S. aureus tested strains. For BC matrices and Vancomycin-loaded MP, a decrease of viable intracellular bacteria was observed. For Daptomycin-loaded MP, no viable intracellular bacteria were detected. In conclusion, this work has shown that the BC formulations with drug concentration of 1.5 % or 2.5 % and daptomycin-loaded MP show potential to be used in the context of bone infection treatment.
- Biofilmes, micobactérias não tuberculosas e infeçãoPublication . Bandeira, Maria; Wenner, Sigurd; Ferreira, Magda; Carvalho, Patricia Almeida; Jordão, LuísaAs micobactérias não tuberculosas (MNTs) são agentes infeciosos emergentes responsáveis por infeções diversas, nomeadamente infeções associadas aos cuidados de saúde. Neste trabalho foi avaliada a capacidade de formação de biofilmes por duas MNTs (M. smegmatis e M. chelonae). Os biofilmes foram caracterizados utilizando microscopia eletrónica e a eficácia de diversos desinfetantes foi avaliada contra MNTs recuperadas de biofilmes. Os resultados obtidos demonstram que as MNTs são capazes de formar biofilmes em materiais presentes em ambiente hospitalar e de resistir à ação de diversos desinfetantes.
- Levofloxacin-loaded bone cement delivery system: highly effective against intracellular bacteria and Staphylococcus aureus biofilmsPublication . Ferreira, Magda; Rzhepishevska, Olena; Grenho, Liliana; Malheiros, Danila; Gonçalves, Lídia; Almeida, António J.; Jordao, Luisa; Ribeiro, Isabel A.; Ramstedt, Madeleine; Gomes, Pedro; Bettencourt, AnaStaphylococcus aureus is a major pathogen in bone associated infections due to its ability to adhere and form biofilms on bone and/or implants. Moreover, recrudescent and chronic infections have been associated with S. aureus capacity to invade and persist within osteoblast cells. With the growing need of novel therapeutic tools, this research aimed to evaluate some important key biological properties of a novel carrier system composed of acrylic bone cement (polymethylmethacrylate - PMMA), loaded with a release modulator (lactose) and an antibiotic (levofloxacin). Levofloxacin-loaded bone cement (BC) exhibited antimicrobial effects against planktonic and biofilm forms of S. aureus (evaluated by a flow chamber system). Moreover, novel BC formulation showed high anti-bacterial intraosteoblast activity. This fact led to the conclusion that levofloxacin released from BC matrices could penetrate the cell membrane of osteoblasts and be active against S. aureus strains in the intracellular environment. Furthermore, levofloxacin-BC formulations showed no significant in vitro cytotoxicity and no allergic potential (measured by the in vivo chorioallantoic membrane assay). Our results indicate that levofloxacin-loaded BC has potential as a local antibiotic delivery system for treating S. aureus associated bone infections.