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Related Experiment Video

Updated: Dec 15, 2025

Author Spotlight: Leptospira DNA Detection in Water for Environmental Analysis and Disease Surveillance

Author Spotlight: Leptospira DNA Detection in Water for Environmental Analysis and Disease Surveillance

Published on: June 14, 2024

Survival Tests for Leptospira spp.

Clémence Mouville¹, Nadia Benaroudj²

¹Unité de Biologie des Spirochètes, Institut Pasteur, Paris, France.

Methods in Molecular Biology (Clifton, N.J.)

|July 8, 2020

Summary

Assessing microorganism viability is crucial. This study compares the colony-forming unit method with Alamar Blue® Assay and LIVE/DEAD BacLight® assay for Leptospira spp., highlighting their respective strengths and limitations.

Keywords:

Absorbance Colony-forming unit Fluorescence Leptospira Plating Propidium iodide Resazurin Resorufin Spirochetes Survival Syto9

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Area of Science:

Microbiology
Bacteriology
Cell Viability Assays

Background:

Assessing microbial viability is essential for understanding bacterial physiology and pathogenesis.
Leptospira spp. require specific viability assessment methods due to their unique characteristics.

Purpose of the Study:

To compare the traditional colony-forming unit (CFU) method with two alternative viability assays for Leptospira spp.: Alamar Blue® Assay and LIVE/DEAD BacLight® assay.
To evaluate the advantages and limitations of each method for quantifying viable Leptospira.

Main Methods:

Colony-forming unit (CFU) method: traditional, labor-intensive, but sensitive and linear.
Alamar Blue® Assay: measures metabolic activity via resazurin reduction to resorufin, quantifiable by absorbance or fluorescence.
LIVE/DEAD BacLight® assay: differentiates live and dead cells using nucleic acid dyes (Syto9 and propidium iodide) based on membrane integrity.

Main Results:

The CFU method is the most sensitive and linear but is labor-intensive.
Alamar Blue® Assay and LIVE/DEAD BacLight® assay are less laborious and suitable for high-throughput screening.
The alternative methods have limitations in their detection range and linearity compared to the CFU method.

Conclusions:

The choice of viability assay for Leptospira spp. depends on the study's requirements, balancing throughput, sensitivity, and linearity.
Alamar Blue® Assay and LIVE/DEAD BacLight® assay offer convenient alternatives to the CFU method for specific applications.
Further optimization may be needed to enhance the range and linearity of the alternative viability assays for Leptospira.