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In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa

Authors Nour El Din S, El-Tayeb T, Abou-Aisha K, El-Azizi M

Received 13 December 2015

Accepted for publication 28 February 2016

Published 27 April 2016 Volume 2016:11 Pages 1749—1758


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Thomas Webster

Suzanne Nour El Din,1 Tarek A El-Tayeb,2 Khaled Abou-Aisha,1 Mohamed El-Azizi1

1Department of Microbiology, Immunology and Biotechnology, Faculty of Pharmacy and Biotechnology, German University in Cairo, 2National Institute for Laser Enhanced Sciences, Cairo University, Cairo, Egypt

Abstract: Silver nanoparticles (AgNPs) have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×105 colony forming unit/mL) was investigated at its minimal inhibitory concentration (MIC) and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial activity of AgNPs and visible blue light was significantly enhanced (P<0.001) when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001) inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed infection, where signs of improvement were observed after 1 week, and the wound completely healed after 4 weeks. To our knowledge, this combinatorial therapy has not been investigated before. It was proved efficient and promising in managing infections caused by multidrug resistant bacteria and could be used as an alternative to conventional antibiotic therapy.

Keywords: biofilm, invasive sepsis, wound colonization, murine model, bioplastic disc, nonconventional therapy

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