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Doctoral Thesis
Full name
Roseli Salomoni
Knowledge Area
Date of Defense
São Paulo, 2017
Rodrigues, Maria Filomena de Andrade (President)
Gomez, José Gregorio Cabrera
Léo, Patricia
Ottoni, Cristiane Angelica
Silva, Sonia Regina da
Title in Portuguese
Ação de nanopartículas de prata em linhagens hospitalares e sua aplicação em cateteres intraluminais.
Keywords in Portuguese
Linhagens hospitalares
Nanopartículas de prata
Resistência bacteriana
Abstract in Portuguese
A prata metálica é um conhecido agente antimicrobiano, e a sua aplicação na forma de nanopartículas de prata vem sendo apontada como uma alternativa para aplicação em dispositivos médico hospitalares. Vários métodos foram sugeridos para a prevenção da infecção relacionada ao acesso vascular, entre eles, os cateteres revestidos com nanopartículas de prata têm recebido atenção mais recentemente, por oferecerem desempenho superior em aspectos onde outros métodos falharam. Este trabalho propôs avaliar a ação de nanopartículas de prata (AgNPs) em linhagens hospitalares e sua aplicabilidade em cateteres intraluminais. Na primeira fase, 12 linhagens (3 linhagens de referência e 8 linhagens hospitalares) foram testadas frente a diferentes concentrações de nanopartículas de prata de 10 nm; e na segunda fase, duas linhagens de referência foram escolhidas para os testes com os cateteres impregnados com uma solução polimérica contendo nanopartículas de prata. Os resultados obtidos atestam que as nanopartículas de prata funcionam como uma opção para controle bactericida.
Title in English
Silver nanoparticles action in hospital strains and their application in intraluminal catheter.
Keywords in English
Bacterial resistance
Hospital strains
Silver nanoparticles
Abstract in English
In recent years, there has been increased concern regarding the use of antimicrobials (antibiotics) in general practices and in hospital-medicine devices, a factor that may contribute for the development and selection of antibiotic-resistant strains. The metallic silver is a known antimicrobial agent. Currently, its application in the form of nanoparticles (nanosilver) has been suggested as an alternative for use in hospital medical devices. Central venous catheters (CVCs) are commonly used in critically ill patients to administer fluids, blood products and parenteral nutrition. The contamination of catheters introduced into the bloodstream and subsequent infection, severe sepsis and septic shock are associated with high morbidity and mortality. This is one of the greater challenges of treating critically ill patients. Various methods have been suggested for prevention of infection related to the vascular access, including, catheters coated with silver nanoparticles which have received attention more recently, since they offer higher performance in aspects in that other methods have failed. This alternative consists in associating nanoparticles of metallic silver to a polymeric material that coats the catheter inner and externally. The main characteristics of the coating that can potentially be ajusted are the intensity and spectrum of bactericidal activity, the rate of bactericidal releasing and resistance to biofilm formation. This work proposes to evaluate the effects of silver nanoparticles (AgNPs) in hospital strains and their applicability in intraluminal catheter. In the first stage, 12 strains (3 reference strains and 9 hospital strains) were tested against different concentrations of silver nanoparticles of 10 nm (SIGMA-Aldrich); and in the second phase, two reference strain (a Gram-positive and Gram-negative) were selected for the tests with catheters impregnated with a polymer solution containing silver nanoparticles of 10 nm (SIGMA-Aldrich). The results obtained in the first stage showed a high efficiency of nanoparticles on three reference strains - S. aureus IPT 246, P. aeruginosa IPT 322 and K. pneumoniae IPT 412-, and moderate efficiency on hospital strains - S. aureus S.a. 1 and S.a. 2; P. aeruginosa P.a. 1 and P.a.2 ; and A. baumannii Acb. 2, Acb. 4 and Acb. 8, indicating that silver nanoparticles work as an option for bacterial control. A preliminary search of silver resistance genes in the strains indicates the possibility that 5 of these strains have genes related to silver resistance similar to those described in the literature. The results obtained in the second phase show that the process of impregnation of the intraluminal catheter has reached the desired goal in both the coating device, and in reducing bioburden according the tests carried with the reference strains S. aureus 246 IPT and P. aeruginosa IPT 322.
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