Development and Characterization of an In Vivo Central Venous Catheter Candida albicans Biofilm Model

Biofilms represent a niche for microorganisms where they are protected from both the host immune system and antimicrobial therapies. Biofilm growth serves as an increasing source of clinical infections. Candida infections are difficult to manage due to their persistent nature and associated drug resistance. Observations made in biofilm research have generally been limited to in vitro models. Using a rat central venous catheter model, we characterized in vivo Candida albicans biofilm development. Time-course quantitative culture demonstrated a progressive increase in the burden of viable cells for the first 24 h of development. Fluorescence and scanning electron microscopy revealed a bilayered architecture. Adjacent to the catheter surface, yeast cells were densely embedded in an extracellular matrix. The layer adjacent to the catheter lumen was less dense. The outermost surface of the biofilm contained both yeast and hyphal forms, and the extracellular material in which they were embedded appeared fibrous. These architectural features were similar in many respects to those described for in vitro models. However, scanning electron microscopy also revealed host cells embedded within the biofilm matrix. Drug susceptibility was determined by using two assays and demonstrated a biofilm-associated drug resistance phenotype. The first assay demonstrated continued growth of cells in the presence of supra-MIC antifungal drug concentrations. The second assay demonstrated reduced susceptibility of biofilm-grown cells following removal from the biofilm structure. Lastly, the model provided sufficient nucleic material for study of differential gene expression associated with in vivo biofilm growth. Two fluconazole efflux pumps, CDR1 and CDR2, were upregulated in the in vivo biofilm-associated cells. Most importantly, the studies described provide a model for further investigation into the molecular mechanisms of C. albicans biofilm biology and drug resistance. In addition, the model provides a means to study novel drug therapies and device technologies targeted to the control of biofilm-associated infections

What Motivates ICT4D Champions?

Part 2: Digital Platforms for DevelopmentInternational audienceThe paper seeks to identify the factors that motivate a person who champions ICT4D initiatives. Given the important contributions of ICT4D champions to initiative success, better understanding of their motivations holds the potential to identify, develop and deploy such individuals more effectively, harnessing their potential positive contributions to ICT4D initiative success. A multiple case study strategy is used to explore the motivational factors of three successful ICT4D champions in the South African context. The Work Preference Inventory (WPI) of personal motivations was used to design in-depth interviews with the champions and semi-structured interviews with 29 other stakeholders. It found ICT4D champions are motivated by the need for personal actualization, business success and to address social concerns – origins of these motives could be traced to various internal and environmental stimuli. Practical implications drawn from the research are that profiling of stakeholder motivations in an ICT4D initiative is feasible and that organizations can use such information to create a conducive environment for grooming and empower new and existing champions to function more effectively. This first investigation of ICT4D champion motivations shows its importance and the potential thereof towards improving initiative success and emphasizes the need for further research of this nature