1259. Novel lensfree microscope technology based on shadow imaging for detection of Giardia lamblia oocysts in stool
Session: Poster Abstract Session: Travel/Tropical Medicine and Parasitology
Saturday, October 22, 2011
Room: Poster Hall B1
Background:  Giardia lamblia is a waterborne parasite which causes chronic diarrhea with malnutrition in children from developing countries. In this setting, routine diagnostics by conventional microscopy are unavailable. Investigators at UCLA demonstrated a lensfree on-chip microscope based on digital in-line holography that achieves sub-cellular resolution (~1.5µm) over a large field of view (FOV) of ~24mm2.  It is miniaturized by utilizing a light emitting diode (LED) and a digital sensor array to record the holograms of the objects which then permits reconstruction of their microscopic images. It offers a compact, cost-effective and high-throughput diagnostics tool for rapid medical assessment even in resource-limited settings

Methods: Stool specimens were collected from patients submitting samples for suspected giardiasis at UCLA. Specimens found to be negative were pooled. A 0.5mL aliquot of stool was seeded with 500,000 Giardia lamblia oocysts (formalin-fixed). Serial dilutions were performed on stool for clear visualization of oocysts via brightfield as well as field-portable lensfree on-chip microscopy. Samples were prepared on a drop of water sandwiched between 2 coverslips.

Results: Stool specimens were diluted to a 13:1 ratio, (point of maximum visualization following dispersion) Giardia oocysts were clearly identified, and differentiated from sediment using lensfree on-chip microscopy. Imaging resolution demonstrated that morphology and size of Giarida were identical across lensfree and conventional microscopy.

Conclusion: Lensfree on-chip microscopy can identify Giardia oocysts in stool, and distinguish the organism from stool sediment over an imaging FOV that is more than an order-of-magnitude larger than a 10X objective FOV. Lensfree microscope images demonstrated in this work can be further improved using a super-resolution technique, recently developed at UCLA, which can provide <1µm resolution over the same imaging area (e.g., ~24mm2). Future experiments in field settings will assess the sensitivity and specificity of lensfree on-chip microscopy in comparison to conventional lens-based microscopy. This will enable its use for rapid diagnosis of giardiasis and other parasites in resource-poor environments.


Subject Category: D. Diagnostic microbiology

Santhosh Nadipuram, MD, Pediatric Infectious Diseases, University of California Los Angeles, Los Angeles, CA, Onur Mudanyali, MSc, Electrical Engineering, University of California at Los Angeles, Los Angeles, CA, Karin Nielsen, MD, Pediatric Infectious Diseases, University of California, Los Angeles, Los Angeles, CA, Thomas Brewer, BS, MBA, Pathology and Laboratory Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA and Aydogan Ozcan, PhD, Electrical Engineering, University of California, Los Angeles, Los Angeles, CA

Disclosures:

S. Nadipuram, None

O. Mudanyali, None

K. Nielsen, None

T. Brewer, None

A. Ozcan, None

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