A. James Clark School of Engineering

Permanent URI for this communityhttp://hdl.handle.net/1903/1654

The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

Browse

Subject: search.filters.subject.Candida albicans

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Elimination of Bloodstream Infections Associated with Candida albicans Biofilm in Intravascular Catheters
    (MDPI, 2015-06-29) Akbari, Freshta; Kjellerup, Birthe Veno
    Intravascular catheters are among the most commonly inserted medical devices and they are known to cause a large number of catheter related bloodstream infections (BSIs). Biofilms are associated with many chronic infections due to the aggregation of microorganisms. One of these organisms is the fungus Candida albicans. It has shown to be one of the leading causes of catheter-related BSIs. The presence of biofilm on intravascular catheters provide increased tolerance against antimicrobial treatments, thus alternative treatment strategies are sought. Traditionally, many strategies, such as application of combined antimicrobials, addition of antifungals, and removal of catheters, have been practiced, but they were not successful in eradicating BSIs. Since these fungal infections can result in significant morbidity, mortality, and increased healthcare cost, other promising preventive strategies, including antimicrobial lock therapy, chelating agents, alcohol, and biofilm disruptors, have been applied. In this review, current success and failure of these new approaches, and a comparison with the previous strategies are discussed in order to understand which preventative treatment is the most effective in controlling the catheter-related BSIs.
  • Thumbnail Image
    Item
    Protein Engineering Approaches to Improve the Therapeutic Potential of Histatin-5 for Candida albicans Infections
    (2019) Leissa, Jesse Alton; Karlsson, Amy J; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The salivary peptide histatin 5 has been studied as a novel therapeutic to address rising drug resistance and limited therapeutics for treating infections caused by the fungal pathogen Candida albicans. While histatin 5 possesses antifungal activity, degradation from secreted aspartic proteases produced by C. albicans hinders its potential. To develop a strategy that will identify variants of histatin 5 with improved proteolytic stability, the peptide was integrated into a yeast surface display system, and the proteolytic degradation conditions were optimized to improve the resolution between proteolytically stable (K11RK17R) and proteolytically susceptible (K13L) variants. Additionally, histatin 5 and K11RK17R were embedded in polyelectrolyte multilayer films (PEMs) to investigate their ability to prevent biofilm formation on surfaces. Significant biofilm formation was prevented at high concentrations of K11RK17R, while histatin 5 encouraged biofilm formation. My results support the therapeutic potential of histatin 5 and will enable the design of improved peptide-based therapeutic approaches.
  • Thumbnail Image
    Item
    PROTEIN ENGINEERING APPROACHES TO IMPROVING DIAGNOSIS AND TREATMENT OF CANDIDA ALBICANS INFECTIONS
    (2017) Ikonomova, Svetlana Pavlova; Karlsson, Amy J; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Candida albicans is an opportunistic pathogen that can cause infections that range from mild rashes to life-threatening bloodstream infections. The antifungal drug resistance of some Candida strains and the deficiencies in the current methods used to identify infection-causing species call for improvements in treatment and diagnosis of Candida infections. Towards improving therapeutics, the antimicrobial peptide histatin 5 (Hst-5) was studied. Hst-5 is a salivary peptide with strong antifungal activity against C. albicans. However, the pathogen produces a family of secreted aspartic proteases (Saps), some of which can degrade and inactivate Hst-5. Of the family, Sap2 and Sap9 have been previously shown to degrade Hst-5. Variants of Hst-5 with one or two amino acid substitutions were designed and tested to evaluate the effect on the proteolysis of the peptide by the Saps. The results showed that even a single amino acid substitution results in a significant reduction or enhancement of proteolysis by Saps. The K17R and K17L modifications led to significantly enhanced resistance to proteolysis to both Saps. The substitutions also had site-, residue-, and Sap-dependent effects and the proteases have preferences for certain amino acids at the substitution sites, such as leucine at the 13th residue by Sap9. The substitutions affect not only the cleavage at the substitution sites but also the degradation of the peptide as a whole. Some of the modifications (K11R, E16R, E16L) also led to enhanced antifungal activity. Furthermore, combination of two modifications (K11R-K17R) resulted in a peptide with both enhanced proteolytic resistance to Saps and enhanced antifungal activity, demonstrating its potential as an alternative therapeutic. Towards improving diagnostics, a purification-free method to immobilize single-chain variable fragment (scFv) antibodies was developed. Two biotinylation tags—the biotin carboxyl carrier protein or the AviTag minimal sequence—were genetically fused to scFvs to allow for in vivo, site-specific biotinylation by endogenous Escherichia coli biotin ligases during protein expression. scFvs with different frameworks and antigens were all successfully immobilized directly from cell lysates onto streptavidin-coated plates, and the immobilized scFvs maintained their functionality for over 100 days at 4 °C. The simplicity and robustness of this method make it a suitable approach to create diagnostic arrays and could be used to capture and identify Candida infections.