Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium are the major causes of leukorrhea. C. trachomatis is the most common sexually transmitted bacterial agent. In women, C. trachomatis causes cervicitis, urethritis, endometritis, and salpingitis. Prolonged C. trachomatis infection may result in tubal scarring, infertility, and ectopic pregnancy. Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease gonorrhea. In women, the most common symptom of N. gonorrhoeae infection is endocervical infection which, if left untreated, may develop into vulvovaginitis and pelvic inflammatory disease. As a protozoan parasite, Trichomonas vaginalis is the causative agent of the sexually transmitted disease trichomoniasis. T. vaginalis infection is the primary cause of vaginitis, cervicitis and urethritis in women. Routine clinical diagnosis usually depends on microscopic identification of the parasite in wet mount preparations, which are only 60% sensitive as compared to culture-positive women. The sensitivity and specificity of PCR testing for C. trachomatis and N. gonorrhoeae are superior to the HCII (probe-based) assay which has a sensitivity/specificity of 75% / 97%, and 90.8% / 99.3%, respectively.
Due to overlapping symptoms of gonorrhea, chlamydia, and trichomoniasis, It is important to test for M. genitalium especially given the difference in treatment options. Recent studies have shown that macrolide resistance to the M. genitalium primary antibiotic regimen (azithromycin), which highly correlates with treatment failure, ranges from 44% to 90% in the United States, Canada, Western Europe, and Australia. In the Sexually Transmitted Infections Treatment Guidelines, 2021, published by the Centers for Disease Control and Prevention (CDC), they state that ideally, Mycoplasma genitalium antibiotic resistance testing should be performed and used to guide therapy. In this assay, DNA is extracted from the specimen and subjected to PCR amplification.