202 1 Tianjin medical laboratory science: syphilis detection methods

Syphilis is a chronic systemic sexually transmitted disease caused by Treponema pallidum. It is mainly transmitted through sexual channels, and can be clinically manifested as primary syphilis, secondary syphilis, tertiary syphilis, latent syphilis and congenital syphilis (fetal syphilis). The common difficulty in syphilis examination is the detection method of syphilis. At present, the commonly used syphilis detection methods in medicine are mainly divided into two categories: one is pathogen detection; The other is serological testing.

1. Pathogen detection method: At present, the detection aimed at directly observing pathogens is rarely used in clinic, and few hospitals can carry it out. Pathogen detection includes: ① dark field microscopy. ② Silver plating dyeing inspection.

Second, serological testing includes two categories:

(1) Serum test using non-treponema pallidum antigen:

①VDRL (STD research laboratory test).

②USR (unheated serum reagin test).

③RPR (accelerated plasma reagin ring card test).

④TRUST (toluidine red unheated serum test).

At present, RPR and TRUST are two main methods for detecting non-treponema pallidum antigen in serum in China.

(2) Treponema pallidum antigen serum test:

①FTA-ABS (Treponema pallidum fluorescent antibody absorption)

②TPPA/TPHA (Treponema pallidum agglutination test)

③ Enzyme linked immunosorbent assay

④CIA (Luminescence Method)

⑤GICA (colloidal gold immunochromatography)

⑥ western blot test

⑦PCR polymerase chain reaction

⑧ Detection of IgM antibody against Treponema pallidum

It is a widely used method to determine whether you are infected with syphilis by checking antibodies in blood.

(3) At present, the commonly used clinical syphilis detection methods have their own advantages and disadvantages:

1. Chemiluminescence ELISA: It has high sensitivity and specificity, and can detect multiple antibodies at the same time. This method is simple and often used for large-scale screening.

Disadvantages: Positive results can't distinguish past infection from present infection.

2.TRUSTRPR: This method is simple and rapid, and is suitable for detecting a large number of specimens. It is used for clinical screening test and observation of the course and curative effect of syphilis.

Disadvantages: TRUST can only detect chancre after 4 weeks, and the detection rate of primary syphilis is low, which is suitable for diagnosis of secondary syphilis. It is also prone to biological false positive reactions; Observe the results with the naked eye and make subjective judgments.

3.TPPA: It has high sensitivity and specificity, and can be used as a confirmation test for positive samples of serological test of non-treponema pallidum antigen.

Disadvantages: manual operation, complicated steps and high requirements for operators. Results It is not suitable for preservation and large-scale screening experiment because it depends on naked eye observation.

By dividing syphilis detection methods into two directions, the common methods in clinical detection are summarized, and candidates can analyze them according to specific problems.