20-Minute POC Test to Diagnose STIs from Rectal and Throat Swabs

By HospiMedica International staff writers
Posted on 09 Jun 2023

Image: Linear dichroism technology provides accurate results and measures multiple targets simultaneously (Photo courtesy of Linear Diagnostics)

Every day, over a million new cases of sexually transmitted infections (STIs) are identified across the globe, making diseases such as gonorrhea and Chlamydia significant health concerns. Although Chlamydia is the most frequently diagnosed STI, gonorrhea cases have also been on the rise. The World Health Organization (WHO) has reported a swift increase in multi-drug resistant gonorrhea, with almost all confirmed treatment failures linked to pharyngeal infections, impacting the throat. Traditional tests involve identifying DNA from swabs or urine samples, which require lab processing and could result in delays from several days to weeks between testing and result delivery. The extraction of DNA from rectal or pharyngeal swabs, however, presents more difficulties Now, a new testing platform technology is being optimized and validated to diagnose STIs from rectal and pharyngeal (throat) swabs.

Linear Diagnostics (Birmingham, UK), a University of Birmingham (Birmingham, UK) spinout, has received funding from the National Institute for Health and Care Research (NIHR, London, UK) to optimize and validate its LDx-CTNG platform technology. This innovative approach utilizes linear dichroism, where a beam of polarized light detects multiple targets from a single sample. The process works by detecting a shift in the plane of polarized light when a target is bound to a detector. Various molecular recognition methods can be used on the detector molecules to measure the target analytes of interest, such as using antibodies to detect antigens or oligonucleotides to capture corresponding target DNA sequences.

Linear Diagnostics' linear dichroism detection technology can identify short, rapidly synthesized DNA strands, enabling the utilization of EXPAR, an ultrafast DNA amplification method. This has drastically reduced the result delivery time compared to traditional PCR and simplified the necessary hardware due to the isothermal nature of EXPAR, which does not require complex heating and cooling cycles. The incorporation of dyes for multiplexing that absorb in the visible light spectrum has facilitated the use of affordable optical components, enabling the device to be miniaturized to a fully portable size. Moreover, the system can be operated using an internal rechargeable battery, eliminating dependence on main power sources or computer access. By pairing linear dichroism with a disposable cartridge and instrument, it is possible to perform simple point-of-care testing. A proof-of-concept study has already indicated that this technology can provide rapid and accurate diagnostic testing.

“For STIs, the rapidity of the testing procedure is key, as patients prefer to get test results quickly and start treatment immediately,” said Brendan Farrell, Chairman of Linear Diagnostics. “We are aiming to produce a testing platform that will meet the WHO stipulations of being easy to use with minimal training, so people can present for testing and collect their treatment in a single visit.”

Related Links:
Linear Diagnostics
University of Birmingham
NIHR