New Method for Lawsonia intracelullaris Quantification Based on Optical Density by Spectrophotometry

Area of Science:

• Microbiology
• Veterinary Science

Background:

• Lawsonia intracellularis requires specific growth conditions, making traditional quantification difficult.
• Current quantification relies on real-time quantitative PCR (RT-qPCR), which is time-consuming.
• Immediate bacterial quantification is often subjective due to RT-qPCR's limitations.

Purpose of the Study:

• To establish a correlation between optical density (OD) spectrophotometry and RT-qPCR for Lawsonia intracellularis quantification.
• To enable rapid, accurate bacterial concentration measurements in experimental settings.

Main Methods:

• Bacterial suspensions of L. intracellularis were quantified using OD spectrophotometry at 405 nm and 450 nm (cuvette and microplate formats).
• RT-qPCR was used to determine bacterial concentrations and establish a standard curve.
• Four variations comparing OD measurements to RT-qPCR results were evaluated.

Main Results:

• All four OD spectrophotometry variations showed a correlation greater than 80% with RT-qPCR results (p < 0.05).
• Specific OD conversion equations were derived to estimate bacterial concentration (microorganisms/mL) from RT-qPCR Ct values.
• The study demonstrated the feasibility of using OD spectrophotometry for immediate bacterial quantification.

Conclusions:

• Optical density spectrophotometry provides a rapid and accurate alternative for quantifying Lawsonia intracellularis suspensions.
• This method enhances experimental accuracy and efficiency by allowing immediate bacterial concentration determination.
• Researchers can now utilize straightforward spectrophotometry for timely L. intracellularis quantification.