Development and clinical evaluation of a novel SHERLOCK test for Mycoplasma genitalium

Mycoplasma genitalium (MG) is a sexually transmitted pathogen associated with urethritis. Nucleic acid amplification tests are the gold standard for its diagnosis but often require specialized equipment, which limits their use in point-of-care testing. This study aimed to develop a rapid, sensitive detection method for MG using a specific high-sensitivity enzymatic reporter unlocking (SHERLOCK) test, which combines isothermal recombinase polymerase amplification and a clustered regularly interspaced short palindromic repeats (CRISPR)-Cas13a reaction. We developed a novel SHERLOCK test targeting the Mg219 gene in MG. The SHERLOCK method was evaluated using 128 first-void urine samples collected from male patients who were suspected of MG urethritis in Japan. The results of SHERLOCK were compared to those of the cobas TV/MG test and in-house quantitative PCR. SHERLOCK was optimized for use with crude DNA extracted from clinical urine samples. The results were detected via a lateral flow assay, allowing for visual interpretation within 60 min. The method demonstrated a limit of detection of 10 copies/reaction and showed no cross-reactivity with other pathogens. In clinical evaluations of 128 urine samples, SHERLOCK showed an overall agreement rate of 91.4% with the cobas TV/MG PCR test; the positive and negative agreement rates were 79.6 and 100%, respectively. SHERLOCK showed superior performance to quantitative PCR. This study demonstrates that the novel SHERLOCK assay for MG has potential as a point-of-care test in the clinical setting. Further evaluation in prospective studies is needed to confirm its clinical value.IMPORTANCEMycoplasma genitalium (MG) is a causative agent of sexually transmitted infections and is associated with urethritis and prostatitis in men. To prevent the transmission of MG, it is essential to identify infected individuals through diagnostic testing and provide appropriate treatment. Nucleic acid amplification tests are commonly used for MG diagnosis in the clinical setting, but the point-of-care testing (POCT) for MG remains limited. In this study, we developed a novel nucleic acid amplification test-specific high-sensitivity enzymatic reporter unlocking (SHERLOCK)-for MG, combining crude DNA extraction with a lateral flow assay. Our SHERLOCK assay successfully detected MG in approximately 1 h, with a detection limit of 10 copies/reaction. Clinical evaluations using urine samples showed a high agreement rate with the cobas TV/MG test. SHERLOCK is expected to be a useful tool for POCT for MG.