Thermophilic helicase-dependent DNA amplification using the IsoAmp™ SE experimental kit for rapid detection of Streptococcus equi subspecies equi in clinical samples.

The researchers proposed an easy and portable testing method for Streptococcus equi subspecies equi, a bacteria that infects horses. The test is based on DNA amplification and was found to be a reliable alternative to traditionally used culture or PCR assays, in terms of specificity, sensitivity, cost, and convenience.

Objective of the Study

• The research aims to develop an efficient, cost-effective, and convenient method for detecting Streptococcus equi subspecies equi, which is a key infectious agent in horses. The proposed method uses thermophilic helicase-dependent DNA amplification in conjunction with visual detection.

Methodology Approach

• The study used the IsoAmp™ SE experimental kit to evaluate the proposed detection assay.
• A thermophilic helicase-dependent reaction was employed for the amplification of S. equi-specific DNA sequence.
• The amplified DNA product, called an amplicon, was then visually detected in a disposable lateral flow cassette.

Results and Findings

• The new assay showed a sensitivity of 50 copies of S. equi genomic DNA per reaction, suggesting it can detect a relatively low amount of the bacterial DNA.
• When applied to nasal swabs and washes, the IsoAmp SE assay had a specificity of 100%, indicating that it didn’t falsely detect other species as S. equi.
• The assay was more sensitive than culture methods but less sensitive than nested polymerase chain reaction (PCR), a common procedure in molecular biology used for amplifying a specific DNA sequence.

Conclusion

• The novel test offers a practical alternative to culture or PCR assays due to its cost-effectiveness and convenience. It does not need expensive equipment or extensive training of personnel to perform.
• In addition to detecting S. equi in clinical samples, it also fast-tracks the identification of atypical colonies of S. equi and Streptococcus zooepidemicus in the lab.