Rapid, Automated Test Detects Gonorrhea and Determines Antibiotic Susceptibility

An inexpensive, portable diagnostic test that gives results in only 15 minutes is expected to revolutionize detection of sexually transmitted diseases such as gonorrhea.

Effective treatment of sexually transmitted diseases (STIs) - such as gonorrhea with more than 87 million cases worldwide each year - is limited by diagnostic methods that cannot deliver results rapidly while the patient is still in the clinic. Currently gonorrhea is diagnosed by classical culture methods or with more advanced, but expensive and time consuming, nucleic acid-based techniques such as PCR.

To address the need for fast and affordable diagnostic tests for STIs, investigators at Johns Hopkins University (Baltimore, MD, USA) developed a portable, rapid, on-cartridge magnetofluidic purification and testing (PROMPT) polymerase chain reaction (PCR) test.

The PROMPT device uses an automated procedure to analyze swab samples of urethral or penile fluid. First, the swab sample is mixed with a solution of magnetic particles in a tube, and a drop of the mixture is loaded into a cartridge, which snaps into the device. The device transfers the magnetized particles to reagents in the cartridge, which carries out 40 PCR cycles before displaying the results on the screen of a cellphone. Probes in the cartridge enable the device to both identify the presence of Neisseria gonorrhoeae, the pathogen causing gonorrhea, as well as genotyping the pathogen for the DNA signature linked to resistance to the antimicrobial drug ciprofloxacin. Results are received in less than 15 minutes.

The PROMPT device was used to analyze penile swab samples from sexual health clinics in Baltimore, MD, USA (n = 66) and Kampala, Uganda (n = 151) with an overall sensitivity and specificity of 97.7% and 97.6%, respectively, for N. gonorrhoeae detection and 100% concordance with culture results for ciprofloxacin resistance.

"Our portable, inexpensive testing platform has the potential to change the game when it comes to diagnosing and enabling rapid treatment of sexually transmitted infections," said senior author Dr. Tza-Huei Wang, professor of mechanical engineering at Johns Hopkins University. "It ensures that patients are diagnosed on the spot, and treatment can begin immediately, improving clinical outcomes. This will be especially valuable in low-resource settings, where well-equipped laboratories are not always available to every patient."

The PROMPT device for rapid diagnosis of gonorrhea was described in the May 12, 2021, online edition of the journal Science Translational Medicine.

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