Evaluation of the Application of Urea Dissociation Treatment to Reduce the False-Positive Rate of ELISA for Syphilis Detection.

OBJECTIVE

Exploring the application of urea dissociation treatment to reduce the false-positive rate of ELISA for syphilis detection.

METHODS

From January 2023 to January 2024, eleven false-positive syphilis samples were collected from Xi'an Regional Medical Laboratory Centre as the experimental group, five positive specimens as the control group, and five negative specimens as the control group. All specimens were divided into three groups: A, B, and C. They were treated with 6 mol/L urea for 10 min, 6 mol/L urea for 20 min, and 10 mol/L urea for 10 min, respectively, and then processed according to the experimental procedures. Combined with the analysis of the TPPA and TP immunoblotting results, the Wilcoxon test was used to compare the S/CO values of each group.

RESULTS

Specimens 2 and 3 still had no < 1.0 S/CO in group A, while B and C had < 1.0 S/CO after completion of the separation. Meanwhile, specimens 7 and 8 of the experimental group had S/CO close to 1.0 after dissociation in all three groups. The positive control group had an S/CO ratio of greater than 1.0 in all three groups. The negative control specimens, both before and after separation, had no effect. The differences in S/CO values between experimental groups A, B, and C before and after dissociation were statistically significant (p < 0.05). The values of TP are below the manufacturer's allowable imprecision requirements.

CONCLUSION

Urea dissociation by ELISA is effective in reducing the false-positive rate of syphilis.