Abstract
Access to community-based point-of-care, low-cost, and sensitive tuberculosis (TB) diagnostics remains an unmet need. Objective: The objective of this study was to combine principles in nanotechnology, TB biology, glycochemistry, and engineering, for the development of a nanoparticle-based colorimetric biosensing assay (NCBA) to quickly and inexpensively detect acid-fast bacilli (AFB) in sputum samples. Methods: In NCBA, the isolation of AFB from sputum samples was accomplished through glycan-coated magnetic nanoparticles (GMNP) interacting with AFB and then using a simple magnet to separate the GMNP-AFB complex. Acid-fastness and cording properties of mycobacteria were utilized to provide visually observable red-stained clumps of bacteria that were surrounded by brown nanoparticles under a light microscope on prepared smears. The NCBA technique was compared against sputum smear microscopy (SSM) and Xpert MTB/RIF in 500 samples from patients that were suspected to have TB. Results: Statistical analysis showed that NCBA had sensitivity and specificity performances in perfect agreement with Xpert MTB/RIF as gold standard for all 500 samples. SSM had a sensitivity of 40% for the same samples. Conclusion: NCBA technique yielded full agreement in terms of sensitivity and specificity with the Xpert MTB/RIF in 500 samples. The method is completed in 10–20 min through a simple process at an estimated cost of $0.10 per test. Implementation of NCBA in rural communities would help to increase case finding and case notification, and would support programs against drug-resistance. Its use at the first point-of-contact by patients in the healthcare system would facilitate quick treatment in a single clinical encounter, thus supporting the global “End TB Strategy” by 2035.
Highlights
Despite decades of effective treatment being available, tuberculosis (TB) is still in the top 10 causes of death worldwide [1]
glycan-coated magnetic nanoparticles (GMNP) occur occur in in clusters clusters with with several several iron iron oxide oxide nanoparticles nanoparticles being being enclosed enclosed in the glycan polymer, as shown in
The average bacterial load of this cohort of samples could be in the range of 102 to 106 CFU/ mL, which implies that nanoparticle-based colorimetric biosensing assay (NCBA) can detect as low as 102 CFU/mL of acid-fast bacilli (AFB) in the sputum sample
Summary
Despite decades of effective treatment being available, tuberculosis (TB) is still in the top 10 causes of death worldwide [1]. It is caused by the bacteria Mycobacterium tuberculosis (Mtb), which most often affect the lungs. In 2016, 10.4 million people got sick of TB and 1.7 million died from the disease, of which 95% occurred in low- and medium-income countries [1]. About one-fourth of the human population is infected with latent TB and 5–15% of this population has a lifetime risk of falling ill with TB [1]. In Nepal, TB is the sixth leading cause of death in the country [2].
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