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Mobile digital fluorescence microscopy for diagnosis of tuberculosis.

  • Author(s): Tapley, Asa
  • Switz, Neil
  • Reber, Clay
  • Davis, J Lucian
  • Miller, Cecily
  • Matovu, John Baptist
  • Worodria, William
  • Huang, Laurence
  • Fletcher, Daniel A
  • Cattamanchi, Adithya
  • et al.

Published Web Location

http://jcm.asm.org/content/51/6/1774.full.pdf+html
No data is associated with this publication.
Abstract

Access to sputum smear microscopy in high-tuberculosis (TB)-burden regions is limited by a scarcity of microscopes and experienced technicians. We evaluated the accuracy of CellScope, a novel digital fluorescence microscope that may expand access to microscopy. The study utilized smear microscopy slides prepared from sputum specimens submitted by consecutive adults with ≥ 2 weeks of cough who were admitted to Mulago Hospital (Kampala, Uganda). Conventional light-emitting diode (LED) fluorescence microscopy (FM) and mycobacterial culture were performed by experienced technicians. Two U.S.-based postgraduate researchers without prior microscopy experience restained, imaged, and interpreted the slides using CellScope. We assessed whether sensitivity and specificity of CellScope-based LED FM was noninferior to conventional LED FM by using a preselected margin of inferiority of 15%. Of 525 patients included, 72% were HIV seropositive and 39% had culture-confirmed TB. The proportions of positive results were similar with CellScope and conventional LED FM (34% versus 32%, respectively; P = 0.32), and agreement was substantial. CellScope accuracy was within the noninferiority margin for both sensitivity (63% versus 70%; difference, -7%; 95% confidence interval [CI], -13% to -1%) and specificity (85% versus 92%; difference, -7%; 95% CI, -12% to -3%). A subanalysis of 43 slides evaluated by each CellScope reader found substantial interreader reliability (custom-weighted kappa, 0.65) and variable intrareader reliability (custom-weighted kappa, 0.11 versus 0.48). CellScope offers promise for expanding microscopy services. Future studies should evaluate the device when operated by health workers in low-resource settings, the feasibility of image transmission and analysis by experienced microscopists, and the accuracy of automated image analysis algorithms.

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