Interpretation of CMIA test results of syphilis antibody in children
SONG Qin-wei, WANG Ya-lin, LIU Zhi-yuan, ZHANG Yi, GAO Shuang, MA Li-juan
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Objective To explore how to correctly interpret the results of CMIA screening for anti-treponema pallidum specific antibody(S/CO ＞ 1) in children. Methods From July 2018 to June 2019, 23 038 patients had been screened for anti-TP antibody by CMIA, the positive results(S/CO ＞ 1) were re-examined by Treponema pallidum particle agglutination assay(TPPA), TP nonspecific antibody was checked by tolulized red unheated serum test(TRUST) and TP specific IgG and IgM antibody were confirmed by Western blot. Results Totally 23 038 patients were screened for anti-TP antibody by CMIA, among them 141 were positive(S/CO＞1) with and the positive rate as 0.61%(141/23 038). The re-test results of 141 children(S/CO＞1) were as follows: the number of positive cases of TRUST, TPPA, IgG and IgM were 2(1.42%, 2/141), 7(4.96%, 7/141), 13(9.22%, 13/141) and 6(4.25%, 6/141), respectively. In addition, 11 cases with S/CO＞10, including the number of positive cases of TRUST, TPPA, IgG and IgM were 2(18.18%, 2/11),7(63.64%,7/11), 10(90.91%, 10/11) and 3(27.27%, 3/11) , respectively, 10(90.91%, 10/11) cases of parents had syphilis history and 9(81.82%, 9/11) cases were younger than 6 months. Conclusions Screening the children with Treponema pallidum by CMIA, when the S/CO＜10, the false-positive rate was high when the S/CO＜10, which must be excluded by confirmatory methods. The correct interpretation of syphilis test results should combine with the age of the child and the history of syphilis of his or her parents.