ABSTRACT
【Objective】 To evaluate the feasibility of confirming syphilis reactive blood donors. 【Methods】 The serum of donors with anti-TP reaction by ELISA were confirmed by treponema pallidum particle agglutination (TPPA) and Western blotting (WB). The results of two confirmation methods that were negative, suspicious or inconsistent were followed up and compared. At the same time, the analytical index values of the screening reagent A, B and C and their combinations were evaluated and compared using the the receiver operating characteristic curve (ROC curve) based on the results of the two confirmation methods. 【Results】 The positive rate of 223 ELISA anti-TP reactive samples (including 124 double-reagent ELISA reactive samples and 99 single-reagent ELISA reactive samples) was 57.40% confirmed by TPPA and 38.57% confirmed by WB (89.52% vs 17.17% by TPPA and 52.42% vs 21.21% by WB for double-reagent and single-reagent ELISA reactive samples). The confirmed negative rate of TPPA was 35.43% and that of WB was 42.60% (6.45% vs 71.72% of TPPA and 29.84% vs 58.59% of WB for double-reagent and single-reagent ELISA reactive samples). According to Kappa test, the confirmed results between the two methods were not consistent, especially for those single-regent ELISA reactive samples. Thirty six cases were followed up successfully, of which 17 (47.22%) confirmed changes in the test results but the changes were irregular. Based on the confirmed results of TPPA and WB, the ROC curve analysis was performed on the anti-TP screening S/CO values of double-reagent ELISA reactive samples. When combining ELISA screening reagents as A/B and A/C, the optimal S/CO values of reagent A were 1.815, 5.73 and 10.205, 16.165, respectively. 【Conclusion】 TPPA and WB have poor consistency in the confirmation of ELISA anti-TP reactive blood samples, and the outcome of follow-up confirmation is unclear. The S/CO threshold of ROC curve is affected by the combination of confirmatory screening reagents, and it is difficult to confirm the results of ELISA anti-TP reactive blood donors.
ABSTRACT
【Objective】 To evaluate the infection status and potential infectivity of Treponema pallidum specific antibody (anti-TP) reactive blood donors, and to provide reference for the key prevention and screening of TP under the current screening strategy. 【Methods】 From February to October 2021, 133 blood donors were tested reactive by two different anti-TP ELISA kits (77 cases were dual-reagent reactive and 56 cases were single-reagent reactive). Syphilis specific IgM antibody (TP-IgM) and IgG antibody (TP-IgG) were detected by Western blot (WB), and TRUST was conducted. The results were analyzed. 【Results】 Of the 133 samples, 24 (18.05%) were positive for TP-IgM, 40 (30.07%) were positive for TP-IgG, and 3 (2.26%) were positive for TRUST. Among them, 12 cases (15.58%) were TP-IgM positive and 40 cases (51.95%) were TP-IgG positive in 77 cases of double reagent reactivity, and 12 cases (21.43%) were TP-IgM positive and 0 was TP-IgG positive in 56 cases of single reagent reactivity. There was no significant difference in the positive rate of TP-IgM between the two groups (P>0.05), while the positive rate of TP-IgG in donors with double reagent reaction was higher than that in donors with single reagent reaction (P<0.05). In addition, among the 133 anti-TP-reactive blood donors, 15 cases were positive for single TP-IgM (11.28%, accounting for 62.50% of the total positive number of TP-IgM, a total of 12 cases of TP-IgM positive among the single reagent reactive patients, and all of them were TP-IgM positive and TP-IgG negative); 30 cases were positive for single TP-IgG (22.56%, accounting for 75.00% of the total positive number of TP-IgG). There were 55 cases (41.35%) who were negative for TP-IgM and TP-IgG, and 8 cases (6.02%) were both positive. 【Conclusion】 The TP-IgM positive donors in anti-TP reactive blood donors are infectious, but the positive rate is not high. Those with single reagent reactivity and single TP-IgM positive are prone to miss detection, which should be controlled. Those who were both TP-IgM and TP-IgG negative and those who were only TP-IgG positive may be false reactivity and the phenomenon of lifelong antibody expression. It is suggested to consider adding TP-IgM detection as a measurement index for permanent deferral of both reagents.