Publicação
Evaluation of the antimicrobial activity of a bacteriophage-honey formulation in an ex vivo skin model
| Resumo: | Nowadays, the main treatments used on infected chronic wounds are antibiotics. However, the incorrect and overuse of these led to the appearance of antimicrobial resistances (AMR). In fact, along time multiple bacteria acquired the ability to express properties that help them to engage in a sessile community environment in order to protect themselves from external factors. These communities are called biofilms and are known to be tolerant to biocides and to the host immune response. As so, it is important to find different strategies. This study proposes a bacteriophage-honey combination due to their potential already verified when used separately. The effect of the bacteriophage-honey formulations was tested using both in vitro in polystyrene plates and ex vivo using pig skin explants against the pathogenic bacterial strains Escherichia coli and Pseudomonas aeruginosa. The pig skin model was used since it is anatomically similar to human skin. The Portuguese honey C1 with floral origin from Castanea sativa revealed to be sufficient to eradicate completely the E. coli biofilm cells in vitro when used at 50% (w/v) concentration. In ex vivo experiments, honey alone did not demonstrate such high efficacy. In fact, 25% (w/v) concentrated honey resulted in similar biofilm cells reduction effects as 50% (w/v), and a maximum biofilm reduction (2 log) was achieved for both concentrations when combined with phage. The commercial Manuka honey was also tested against E. coli biofilms as a term of comparison, and generally, statistically similar results to C1 for both in vitro and ex vivo experiments were obtained. For P. aeruginosa biofilm cells formed ex vivo, the maximum reduction observed, 2.4 log at 12 h, was obtained with 50% (w/v) C1 together with bacteriophage. This experiment suggests that the surface influences the biofilm structure, leading to different bacteria-surface interactions, and consequently to different responses to the used treatment. Both strains seemed to have benefited from the presence of the other in dual-species biofilms, resulting in a synergistic effect when honey was combined with bacteriophage in the case of P. aeruginosa. In fact, it was obtained a maximum reduction of 3.1 log for P. aeruginosa after 12 h and 1.8 log for E. coli at 24 h when 50% (w/v) C1 was combined with bacteriophage. The synergy is believed to be due to honeys capacity to damage the bacterial cell membrane, promoting the subsequent bacteriophage infection. |
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| Autores principais: | Sousa, Jéssica Carolina da Silva |
| Assunto: | chronic wounds biofilms bacteriophage-honey pig skin synergy feridas crónicas biofilmes bacteriófagos-mel pele de porco sinergia |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Nowadays, the main treatments used on infected chronic wounds are antibiotics. However, the incorrect and overuse of these led to the appearance of antimicrobial resistances (AMR). In fact, along time multiple bacteria acquired the ability to express properties that help them to engage in a sessile community environment in order to protect themselves from external factors. These communities are called biofilms and are known to be tolerant to biocides and to the host immune response. As so, it is important to find different strategies. This study proposes a bacteriophage-honey combination due to their potential already verified when used separately. The effect of the bacteriophage-honey formulations was tested using both in vitro in polystyrene plates and ex vivo using pig skin explants against the pathogenic bacterial strains Escherichia coli and Pseudomonas aeruginosa. The pig skin model was used since it is anatomically similar to human skin. The Portuguese honey C1 with floral origin from Castanea sativa revealed to be sufficient to eradicate completely the E. coli biofilm cells in vitro when used at 50% (w/v) concentration. In ex vivo experiments, honey alone did not demonstrate such high efficacy. In fact, 25% (w/v) concentrated honey resulted in similar biofilm cells reduction effects as 50% (w/v), and a maximum biofilm reduction (2 log) was achieved for both concentrations when combined with phage. The commercial Manuka honey was also tested against E. coli biofilms as a term of comparison, and generally, statistically similar results to C1 for both in vitro and ex vivo experiments were obtained. For P. aeruginosa biofilm cells formed ex vivo, the maximum reduction observed, 2.4 log at 12 h, was obtained with 50% (w/v) C1 together with bacteriophage. This experiment suggests that the surface influences the biofilm structure, leading to different bacteria-surface interactions, and consequently to different responses to the used treatment. Both strains seemed to have benefited from the presence of the other in dual-species biofilms, resulting in a synergistic effect when honey was combined with bacteriophage in the case of P. aeruginosa. In fact, it was obtained a maximum reduction of 3.1 log for P. aeruginosa after 12 h and 1.8 log for E. coli at 24 h when 50% (w/v) C1 was combined with bacteriophage. The synergy is believed to be due to honeys capacity to damage the bacterial cell membrane, promoting the subsequent bacteriophage infection. |
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