Staphylococcus aureusandEscherichia colidual‐species biofilms on nanohydroxyapatite loaded with CHX or ZnO nanoparticles

Abstract

Implant-associated infections are caused by surface-adhering microorganisms persisting as biofilms, resistant to host defense and antimicrobial agents. Given the limited efficacy of traditional antibiotics, novel strategies may rely on the prevention of such infections through the design of new biomaterials. In this work, two antimicrobial agents applied to nanohydroxyapatite materials-namely, chlorhexidine digluconate (CHX) and zinc oxide (ZnO) nanoparticles-were compared concerning their ability to avoid single- or dual-species biofilms of Staphylococcus aureus and Escherichia coli. The resulting biofilms were quantified by the enumeration of colony-forming units and examined by confocal microscopy using both Live/Dead staining and bacterial-specific fluorescent in situ hybridization. The sessile population arrangement was also observed by scanning electron microscopy. Both biomaterials showed to be effective in impairing bacterial adhesion and proliferation for either single- or dual-species biofilms. Furthermore, a competitive interaction was observed for dual-species biofilms wherein E. coli exhibited higher proliferative capacity than S. aureus, an inverse behavior from the one observed in single-species biofilms. Therefore, either nanoHA-CHX or nanoHA-ZnO surfaces appear as promising alternatives to antibiotics for the prevention of devices-related infections avoiding the critical risk of antibiotic-resistant strains emergence. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 491-497, 2017.

Anin vitromodel ofFusobacterium nucleatumandPorphyromonas gingivalisin single- and dual-species biofilms

“…However, there is limited knowledge regarding the time period necessary for establishing a mature biofilm. Although oral biofilms are typically polymicrobial, mixed biofilms constructed with selected microbial species allow controlled in vitro assays, which enable a better understanding of the impact of materials and/or new treatments on pathogenic species [ 24 25 26 ]. Our purpose in this study was to develop a pathogenic dual-species biofilm model with P. gingivalis and F. nucleatum to use in further in vitro research.…”

Research on the effect of TiO2 nanotubes coated by gallium nitrate on Staphylococcus aureus‐Escherichia coli biofilm formation

“…Barros et al take nano‐hydroxyapatite as the carrier and mix with E coli / S aureus mixed bacterial solution (1.25 × 108 cells/mL) for 24 hours to form a mixed bacterial biofilm. Compared with a single biofilm, the amount of mixed biofilm is increased, and the number of E coli in the mixed biofilm is more than that of S aureus 11 . The research of Makovcova et al 12 shows that the double bacterial biofilm can be formed when S aureus and non‐pathogenic E coli are mixed in culture.…”

Current Approaches for Exploration of Nanoparticles as Antibacterial Agents

“…Both standardized and modified microdilution and macrodilution methods have been applied to the determination of MIC and MBC values to evaluate the antimicrobial susceptibility of several microorganisms to nanoparticles [76,109,[110][111][112][113][114][115][116]. Additionally, resazurin staining assay has been employed to determine the MIC.…”

“…Agar disk diffusion tests performed both according to the standardized protocols and with modifications are frequently used for susceptibility assessment and evaluation of antimicrobial activity of nanoparticles [109,[121][122][123][124]. Paper disc method has been employed as an alternative to standardized single disk method [112]. Further, agar well diffusion assays have been successfully utilized for the evaluation of antimicrobial effects of nanoparticles [120,125,126].…”

“…Even though measurement of optical density is a straightforward method, it is not the most suitable for measuring the activity of nanoparticles because nanoparticles as such can also interfere with the optical density [46,127]. Viable plate counts have been frequently performed according to the various protocols to assess the antimicrobial efficacy of nanoparticles against both planktonic and biofilm-growing bacteria [109,128,[110][111][112]116]. Samples can either be spread or pipetted on agar plates followed by overnight incubation and determination of the number of CFUs [116,111,[113][114][115].…”