Abstract
Systemic Candida infections remain a leading cause of nosocomial infections in the United States and worldwide. Many challenges remain in achieving rapid, direct diagnosis of fungal bloodstream infections due to limitations of conventional diagnostic methods that continue to demonstrate poor sensitivity, prolonged culture times that lead to delayed treatment, and detection variability between tests that compromises result reproducibility. Despite advancements in technology, mortality, and cost of care presented by blood stream infection with Candida spp. (candidemia) continues to rise and there is an urgent need for the development of novel methods to accurately detect Candida species present within the blood. This is especially true when patients are infected with drug resistant strains of Candida where accurate and immediate therapeutic treatment is of the importance. This study presents a method of separating fungal cells from lysed blood using inertial forces applied through microfluidics in order to abbreviate the time required to achieve a diagnosis by mitigating the need to grow blood cultures. We found that C. albicans can segregate into a focused stream distinct from white blood cells isolated within the Inertial Fungal Focuser (IFF) after red blood cell lysis. As a result of the focusing process, the collected cells are also concentrated 2.86 times. The same IFF device is applicable to non-albicans species: Candida parapsilosis, Candida glabrata, and Candida tropicalis, providing both isolation from lysed blood and a reduction in solution volume. Thus, the devised platform provides a means to isolate medically significant fungal cells from blood and concentrate the cells for further interrogation.
Highlights
Life-threatening fungemias can result from the introduction of Candida spp. or other fungal organisms to the bloodstream, with the potential to become a debilitating disease to both community and hospital-based populations
Cell manipulation using microfluidic inertial forces allows for different cell types to be focused into unique fluidic equilibrium positions that are determined by biophysical characteristics of the different cell types
Fungal cells in the planktonic form differ in size between species but are, on average, smaller than white blood cells (WBCs) that range from 7 to 25 μm between the various types of leukocytes
Summary
Life-threatening fungemias can result from the introduction of Candida spp. or other fungal organisms to the bloodstream, with the potential to become a debilitating disease to both community and hospital-based populations. Systemic fungal infections often present higher patient mortality, lengthened hospital stays, and burdening healthcare costs (Zaoutis et al, 2010). Before positive fungal blood culture results, antifungals are only added to the regimen at the physician’s discretion and usually only recommended for high-risk patients (Morrell et al, 2005). The most prominent fungal infection is elicited by Candida albicans. The non-albicans species are often seen in patients with cancer or hematological malignancies, and exhibit a level of virulence that results in significant mortality (Krcmery and Barnes, 2002)
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