Semi-automated, occupationally safe immunofluorescence microtip sensor for rapid detection of Mycobacterium cells in sputum

PLoS One. 2014 Jan 22;9(1):e86018. doi: 10.1371/journal.pone.0086018. eCollection 2014.

Abstract

An occupationally safe (biosafe) sputum liquefaction protocol was developed for use with a semi-automated antibody-based microtip immunofluorescence sensor. The protocol effectively liquefied sputum and inactivated microorganisms including Mycobacterium tuberculosis, while preserving the antibody-binding activity of Mycobacterium cell surface antigens. Sputum was treated with a synergistic chemical-thermal protocol that included moderate concentrations of NaOH and detergent at 60°C for 5 to 10 min. Samples spiked with M. tuberculosis complex cells showed approximately 10(6)-fold inactivation of the pathogen after treatment. Antibody binding was retained post-treatment, as determined by analysis with a microtip immunosensor. The sensor correctly distinguished between Mycobacterium species and other cell types naturally present in biosafe-treated sputum, with a detection limit of 100 CFU/mL for M. tuberculosis, in a 30-minute sample-to-result process. The microtip device was also semi-automated and shown to be compatible with low-cost, LED-powered fluorescence microscopy. The device and biosafe sputum liquefaction method opens the door to rapid detection of tuberculosis in settings with limited laboratory infrastructure.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biosensing Techniques / instrumentation
  • Biosensing Techniques / methods*
  • Fluorescent Antibody Technique / instrumentation
  • Fluorescent Antibody Technique / methods*
  • Host-Pathogen Interactions
  • Humans
  • Lab-On-A-Chip Devices
  • Microchip Analytical Procedures / methods*
  • Microscopy, Fluorescence / methods
  • Mycobacterium tuberculosis / cytology*
  • Mycobacterium tuberculosis / physiology
  • Occupational Health
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Sputum / microbiology*
  • Time Factors
  • Tuberculosis / diagnosis*
  • Tuberculosis / microbiology