Pathogens (Oct 2024)

A Loop-Mediated Isothermal Amplification Assay Utilizing Hydroxy Naphthol Blue (LAMP-HNB) for the Detection of <i>Treponema pallidum</i> Subspp. <i>pallidum</i>

  • Saranthum Phurijaruyangkun,
  • Pongbun Tangjitrungrot,
  • Pornpun Jaratsing,
  • Suphitcha Augkarawaritsawong,
  • Khurawan Kumkrong,
  • Sawanya Pongparit,
  • Pawita Suwanvattana,
  • Supatra Areekit,
  • Kosum Chansiri,
  • Somchai Santiwatanakul

DOI
https://doi.org/10.3390/pathogens13110949
Journal volume & issue
Vol. 13, no. 11
p. 949

Abstract

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Treponema pallidum subspp. pallidum is a spirochaete bacterium that causes syphilis, one of the most common sexually transmitted diseases. Syphilis progresses through four distinct stages, each characterized by specific symptoms, namely primary, secondary, latent, and late (tertiary) syphilis. Serology has been considered the primary diagnostic approach. However, it is plagued by problems such as the limited specificity of nontreponemal tests and the inadequate correlation of treponemal tests with disease activity. In this study, we focused on the development of a loop-mediated isothermal amplification assay utilizing hydroxy naphthol blue (LAMP-HNB) for the diagnosis of T. pallidum subspp. pallidum. Specifically, this study seeks to determine the analytical sensitivity (limit of detection; LOD) and analytical specificity. Four hundred clinical serum samples were analyzed for diagnostic sensitivity, specificity, and predictive value, and each technique’s 95% confidence intervals (95% CI, p Leptospira interrogans, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, human immunodeficiency virus (HIV), and healthy human serum in PCR-AGE, LAMP-AGE, and LAMP-HNB. The diagnostic sensitivity, diagnostic specificity, positive predictive value (PPV), and negative predictive value (NPV) for PCR-AGE were 100.00 (100.00)%, 94.50 (94.40–94.60)%, 94.79 (94.69–94.88)%, and 100.00 (100.00)%, respectively. While, for LAMP-AGE and LAMP-HNB, they were 100.00 (100.00)%, 91.00 (90.87–91.13)%, 91.74 (91.63–91.86)%, and 100.00 (100.00)%, respectively. The LAMP-HNB test is simple, rapid, highly sensitive, and highly specific, without requiring expensive equipment. In the future, the LAMP-HNB assay may develop into a single-step diagnostic process, enabling the use as point-of-care testing for the diagnosis, prevention, and management of syphilis infection.

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