Detection of pathogenic Leptospira with rapid extraction followed by recombinase polymerase amplification (RPA) and quantitative polymerase chain reaction (qPCR) assay-A comprehensive study from Sri Lanka

PLoS One. 2024 Mar 15;19(3):e0295287. doi: 10.1371/journal.pone.0295287. eCollection 2024.

Abstract

Leptospirosis is the most widespread zoonosis in the world. The disease is more prevalent in tropical regions where the majority of developing countries are located. Leptospirosis is considered a protean manifestation zoonosis with severity of the disease ranging from a mild febrile illness to a severe and life-threatening illness. Clinical symptoms of leptospirosis overlap with other tropical febrile illnesses. Early, rapid, and definitive diagnosis is important for effective patient management. Since Polymerase Chain Reaction (PCR)-based assays are not readily available in most clinical settings, there is a need for an affordable, simple, and rapid diagnostic test. Quantitative PCR (qPCR) and Recombinase Polymerase Amplification (RPA) were implemented at the Faculty of Medicine, University of Kelaniya, and a prospective study to evaluate RPA for diagnosis of acute phase of leptospirosis was conducted. Results indicate that RPA and qPCR were positive in 81% (98/121) of the total positive and acute clinical samples. Of the 81 positive MAT confirmed patients 60 (74%) and 53 (65%) were positive with qPCR and RPA respectively. Retrospective evaluation revealed a high diagnostic accuracy (sensitivity-70% and specificity-87%) of RPA compared to MAT as the reference gold standard. Results further suggest that there is no significant difference between the two assays, qPCR and RPA-SwiftX (P = 0.40). Laboratory procedures for the extraction and detection by qPCR in the laboratory have been optimized to obtain results within 6 hours. However, the RPA-SwiftX method under field conditions took 35 minutes. The RPA-SwiftX method could replace the qPCR which shows similar sensitivity and specificity. Therefore, RPA established under the current study presents a powerful tool for the early and rapid diagnosis of leptospirosis at point-of-care.

MeSH terms

  • Animals
  • Humans
  • Leptospira* / genetics
  • Leptospirosis* / diagnosis
  • Nucleic Acid Amplification Techniques / methods
  • Nucleotidyltransferases
  • Polymerase Chain Reaction
  • Prospective Studies
  • Real-Time Polymerase Chain Reaction / methods
  • Recombinases
  • Retrospective Studies
  • Sensitivity and Specificity
  • Sri Lanka
  • Zoonoses

Substances

  • Recombinases
  • Nucleotidyltransferases

Grants and funding

This work was funded by grant RP/03/SR/04/16/01/2016 awarded by University of Kelaniya, Sri Lanka to Prof. Menaka Hapugoda. Funds received from Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig An den Tierkliniken 43 D-04103 Leipzig, Germany to Dr. Ahmed Abd El Wahed for publication of the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.