Application and Quality Control of Ureaplasma urealyticum/Chlamydia trachomatis/Neisseria gonorrhoeae/Mycoplasma genitalium Nucleic Acid Detection Kit (Fluorescence PCR Method) in Reproductive Tract Infection Screening

Clinical Value of the Quadruplex Assay in Screening for Reproductive Tract Infections

Ureaplasma urealyticum, Chlamydia trachomatis, Neisseria gonorrhoeae, and Mycoplasma genitalium are common pathogens causing reproductive tract infections in both men and women (such as urethritis, cervicitis, and pelvic inflammatory disease), and multiple mixed infections are frequently present. The detection rate of Neisseria gonorrhoeae by traditional culture methods is greatly affected by sample transport conditions and strain drug resistance, while immunological assays lack sufficient sensitivity in early infections or at low pathogen loads. The Ureaplasma urealyticum/Chlamydia trachomatis/Neisseria gonorrhoeae/Mycoplasma genitalium nucleic acid detection kit (fluorescence PCR method) enables simultaneous screening for four pathogens with a single sampling, making it particularly suitable for screening asymptomatic carriers and for emergency scenarios requiring rapid identification of pathogenic microorganisms. Clinical data show that, compared with single-target PCR, the quadruplex assay achieves a positive agreement rate of 90%–98% and can effectively avoid missed detection of mixed infection cases (such as Chlamydia trachomatis co-infected with Mycoplasma genitalium).

Key Points for Implementing Internal Laboratory Quality Control

To ensure the reliability of test results, laboratories should establish a comprehensive quality control system. Each batch of testing should include a negative control (such as sterile TE buffer or eluate from healthy human swabs), a weak positive control (containing plasmid DNA or inactivated bacteria for each target, at a concentration approximately 5–10 times the upper limit of detection), and a strong positive control. The Ct values of quality control materials should fall within the preset range; when the deviation exceeds 3 Ct values, inter-batch reagent differences or instrument status should be evaluated. In addition, regular internal comparisons should be conducted, such as weekly blind testing using reference specimens with known results. When interpreting results, attention should be paid to whether the amplification curve exhibits a typical S shape; if nonspecific fluorescence signals appear (such as abnormal slope or Ct value greater than the threshold but with a flat curve), retesting and confirmation are required. Cross-contamination in the sample processing area is a common cause of false positives; therefore, strict zoning should be implemented (reagent preparation, sample processing, amplification and analysis), and separate pipettes and work attire should be used.

Result Interpretation and Clinical Correlation Analysis

A negative result can usually rule out infection with the four pathogens, but it should be noted that if the amount of Ureaplasma urealyticum in the sample is extremely low (below the lower limit of detection), or if PCR inhibitors are present, a false negative may occur. Clinically, it is recommended to make a comprehensive judgment based on the patient's symptoms (such as purulent discharge and burning pain during urination), leukocyte esterase testing, and whether the patient belongs to a high transmission risk population. Among positive results, particular attention should be paid to the fact that Ureaplasma urealyticum can also be carried by some healthy individuals (especially with an asymptomatic carriage rate of up to 40%); therefore, clinicians should decide whether to treat based on pathogen load (high or low Ct value) combined with the patient's symptoms. At present, industry consensus generally regards Ct values