Inhibition on Candida albicans biofilm formation using divalent cation chelators (EDTA)
ABSTRACT Candida albicans can readily form biofilms on both inanimate and biological surfaces. In this study we investigated a means of inhibiting biofilm formation using EDTA (Ethylenediaminetetra-acetic acid), a divalent cation chelating agent, which has been shown to affect C. albicans filamentation. Candida albicans biofilms were formed in 96-well microtitre plates. Cells were allowed to adhere for 1, 2, and 4 h at 37 degrees C, washed in PBS, and then treated with different concentrations of EDTA (0, 2.5, 25, and 250 mM). EDTA was also added to the standardized suspension prior to adding to the microtiter plate and to a preformed 24 h biofilm. All plates were then incubated at 37 degrees C for an additional 24 h to allow for biofilm formation. The extent and characteristics of biofilm formation were then microscopically assessed and with a semi-quantitative colorimetric technique based on the use of an XTT-reduction assay. Northern blot analysis of the hyphal wall protein (HWP1) expression was also monitored in planktonic and biofilm cells treated with EDTA. Microscopic analysis and colorimetric readings revealed that filamentation and biofilm formation were inhibited by EDTA in a concentration dependent manner. However, preformed biofilms were minimally affected by EDTA (maximum of 31% reduction at 250 mM). The HWP1 gene expression was reduced in EDTA-treated planktonic and biofilm samples. These results indicate that EDTA inhibits C. albicans biofilm formation are most likely through its inhibitory effect on filamentation and indicates the potential therapeutic effects of EDTA. This compound may serve a non-toxic means of preventing biofilm formation on infections with a C. albicans biofilm etiology.
- SourceAvailable from: William F Walkenhorst
[Show abstract] [Hide abstract]
- "In our previous work  we investigated the effect of a wide range of pH and ionic strength values on CAMP activity. Metals and toxic ions have been used in medicine and agriculture since antiquity    and new applications such as in combating biofilms and improved wound care continue to be explored   . Heavy metals in particular have a long history of use in medicine and have recently garnered renewed interest in the form of nanoparticle and modified surface technologies  . "
ABSTRACT: Recently we described the pH dependence of activity for a family of cationic antimicrobial peptides (CAMPs) selected from a combinatorial library. In the current work we report on the effects of toxic ions (Cu(2+), Zn(2+), and F(-)) and the chelator EDTA on the activity profiles of one member of this family, the 12-residue cationic antimicrobial peptide *ARVA, against a panel of microorganisms. All four ions exhibited either synergy or additivity with *ARVA for all organisms tested with the exception of *ARVA combined with NaF against Candida albicans which exhibited indifference. CuCl2 and ZnCl2 exhibited synergy with *ARVA against both the Gram negative Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus as well as strong additivity against E. coli at submillimolar concentrations. The chelator EDTA was synergistic with *ARVA against the two Gram negative organisms but showed only simple additivity with S. aureus and C. albicans despite their much lower MICs with EDTA. This effect may be related to the known differences in the divalent ion binding properties of the Gram negative LPS layer as compared to the peptidoglycan layer of the Gram positive organism. Unlike the other ions, NaF showed only additivity or indifference when combined with *ARVA and required much higher concentrations for activity. The yeast C. albicans did not show synergy or strong additivity with any of the inhibitory compounds tested. The effects of toxic ions and chelators observed here have important implications for applications using CAMPs and for the design of novel formulations involving CAMPs. This article is part of a Special Issue entitled: Interfacially active peptides and proteins.Biochimica et Biophysica Acta (BBA) - Biomembranes 05/2014; 1838. DOI:10.1016/j.bbamem.2014.05.005 · 3.43 Impact Factor
[Show abstract] [Hide abstract]
- "This increases the need for the discovery of agents with antibiofilm but not bactericidal activity, in order to reduce selection pressure and in turn the development of resistance . Although various agents with anti-biofilm activity have been reported for both Gram-positive and Gram-negative bacteria, the need for such agents is vast (Ramage et al. 2007; Nithya et al. 2011; Simoes 2011; Chusri et al. 2012; Venkata Nancharaiah et al. 2012). A few synthetic compounds have been found to show promise as anti-biofilm agents but production costs and success rates, in general, make drugs from natural compounds preferable (Kong et al. 2009). "
ABSTRACT: Staphylococcus aureus is now amongst the most important pathogenic bacteria responsible for bloodstream nosocomial infections and for biofilm formation on indwelling medical devices. Its increasing resistance to common antibiotics, partly attributed to its ability to form biofilms, is a challenge for the development of new antimicrobial agents. Accordingly, the goal of this study was to evaluate the effect of a coral associated actinomycete (CAA)-3 on S. aureus biofilms both in vitro and in vivo. Methanolic extracts of CAA-3 showed a reduction in in vitro biofilm formation by S. aureus ATCC 11632, methicillin resistant S. aureus ATCC 33591 and clinical isolates of S. aureus at the biofilm inhibitory concentration (BIC) of 0.1 mg ml(-1). Furthermore, confocal laser scanning microscope (CLSM) studies provide evidence of CAA-3 inhibiting intestinal colonisation of S. aureus in the nematode Caenorhabditis elegans. To conclude, this study for the first time, reports CAA as a promising source of anti-biofilm compounds, for developing novel drugs against highly resistant staphylococcal biofilms.Biofouling 08/2010; 26(6):711-7. DOI:10.1080/08927014.2010.511200 · 3.70 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Evaluation of fungal biofilm formation can be performed using several techniques. In this protocol, we describe methods used to form Candida biofilms on three different medical device substrates (denture strips, catheter disks and contact lenses) to quantify them and to evaluate their architecture and drug susceptibility. Biofilm formation involves adhesion of fungal cells to pretreated substrates, followed by growth in medium. Formed biofilms are quantified by determining their metabolic activity and dry weight, whereas their gross morphology and architecture are evaluated using fluorescence microscopy, scanning electron microscopy and confocal scanning laser microscopy techniques. Susceptibility of biofilms is determined by comparing their metabolic activity in the presence of antifungal agents with that in their absence. The methods described here can be completed in a typical laboratory with minimum involvement of software. Evaluation of the growth of fungal biofilms and their analyses can be completed using the described methods in approximately 15 d.Nature Protocol 02/2008; 3(12):1909-24. DOI:10.1038/nprot.2008.192 · 8.36 Impact Factor