Carvalho, I.

Carvalho, S.

Cavaleiro, A.

Henriques, Mariana

Universidade do Minho: RepositoriUM

   Search for novel antifungal molecules active against Candida species biofilms H. Tournu1, H. Huang2, S. Kucharikova1, M.-A. Jabra-Rizk3, W.M. De Borggraeve4, G. Luo5, W. Luyten6,P. Van Dijck11Department of Molecular Microbiology, VIB, and Laboratory of Molecular Cell Biology, KU Leuven, Kasteelpark Arenberg 31 bus 2438, 3001 Heverlee, Belgium 2 School of Pharmacy, Gannan Medical University, Ganzhou 341000, China; Department of Biology, KU Leuven, 3000 Leuven, Belgium 3 Dental School, University of Maryland, Baltimore, Maryland, USA 4 Department of Chemistry, KU Leuven, 3001 Heverlee, Belgium 5 Department of Chemistry, Tsinghua University, Beijing 100084, China 6 Medical School, KU Leuven, 3001 Leuven, Belgium Candida species, and in particular C. albicans, are a common cause of nosocomial infections worldwide.  C.albicans favours certain types of surfaces commonly used in medical practice, such as silicon and polyurethane, to adhere to and grow as a biofilm population. These biofilms serve as a local and disseminative reservoir of infection.  C. albicans is also able to adhere to biotic surfaces, and can colonize a wide range of tissues, including mucosal surfaces and the oral cavity. A critical characteristic of biofilms is their intrinsic resistance to antimicrobial agents, as doses up to 100 fold higher than the minimal inhibitory concentrations are necessary to eradicate biofilms in vitro.  In an effort to identify novel antifungal molecules, we employed two approaches. First, we screened a collection of 10 000 compounds, and tested their potency against several Candida species, including C. albicans, C. glabrata, C. parapsilosis and C. krusei.  After several rounds of selection, including chemical class analysis, efficacy against biofilms and broad-spectrum activity, we selected less than ten compounds. Amongst those, several showed high potency against dual-species biofilms, such as C. albicans-Staphylococcus aureus biofilms. By mean of an ex-vivo model of tongue infection, we could show their potency in inhibiting adhesion to the host tissue. In a second approach, we screened several extracts from 35 chinese medical plants. Interestingly, some three extracts were potents against C. albicans and C. glabrata biofilms in vitro. By further fractionation of the extracts, we could identify some of the active compounds, as potential new antifungals. While their activity in in vitro assays was clearly demonstrated, in vivo data are in their infancy. Using a sub-cutaneous biofilm model of Candida infection, we could however demonstrate some anti-biofilm activity in vivo. The mode of action of these molecules remains to be elucidated. Nevertheless, these data hold great promises in the search for novel antifungal agents. Keywords Candida; biofilm; chemical genetics; plant extractsII International Conference on Antimicrobial Research - ICAR2012               Lisbon (Portugal) 21-23 November 2012323Silver impact on Staphyloccocus epidermidis adhesion to Ag-TiCN coatings I. Carvalho1, M. Henriques2, A. Cavaleiro3, S. Carvalho11GRF-CFUM, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal 2 IBB-Institute for Biotechnology and Bioengineering Centre for Biological Engineering University of Minho, Campus de Gualtar, 4700-057, Portugal 3SEG-CEMUC Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra The failure of medical devices occurs among other factors by microbial infection that can happen at the time of placing in the surgery or during a subsequent infection caused by diseases. Staphylococcus epidermidis haveemerged as one of the major nosocomial pathogens associated with these infections. The initial adhesion of these organisms to biomaterials' surface is thought to be an important stage in their colonization. The aim of this work is to develop surfaces that are able to prevent microbial colonization. Thus, the present work explores the potentialities of silver-containing carbonitride-based (Ag-TiCN) thin films. The Ag-TiCN coatings were deposited onto stainless steel 316L, by DC reactive magnetron sputtering using two targets, Ti and Ti+Ag, in an Ar + C2H2 + N2 atmosphere. Silver pellets were placed in the area of erosion of Ti target in order to obtain a silver content up to 20 at. %. Compositional analysis was achieved by Electron Probe Microanalysis (EPMA).Morphology and topography analysis were achieved by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) respectively. With the increase on the Ag content, the coatings show a more dense morphology. It is also observed a decrease on the roughness of the films from 47 nm for the sample without Ag to 7 nm with 20 at. % Ag content. Superficial tension of coatings was measured and the results show that with the increase on the silver content onto coatings promote an increase in hydrophobicity. Bacterial adhesion and biofilm formation on coatings were assessed by enumeration of colony forming units (CFUs) in order to assess the number of viable cells. The results showed that the surface with the lowest roughness and highest hydrophobicity leads to greater bacterial adhesion and biofilm formation, highlighting that surface morphology and hydrophobicity rule materials colonization. Additionally, SEM was also used to observe the bacteria adhesion and biofilm formation confirming the above results. Keywords: Sputtering; microorganisms’ adhesion; biofilm; hydrophobicity; biomaterial II International Conference on Antimicrobial Research - ICAR2012               Lisbon (Portugal) 21-23 November 2012324

Silver impact on Staphyloccocus epidermidis adhesion to Ag-TiCN coatings

http://repositorium.sdum.uminho.pt/bitstream/1822/26145/1/Pages%20from%20ICAR2012-8.pdf

Silver impact on Staphyloccocus epidermidis adhesion to Ag-TiCN coatings

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