Evaluation of a fully automated treponemal test and comparison with conventional VDRL and FTA-ABS tests.

We evaluated analytic performances of an automated treponemal test and compared this test with the Venereal Disease Research Laboratory test (VDRL) and fluorescent treponemal antibody absorption test (FTA-ABS). Precision performance of the Architect Syphilis TP assay (TP; Abbott Japan, Tokyo, Japan) was assessed, and 150 serum samples were assayed with the TP before and after heat inactivation to estimate the effect of heat inactivation. A total of 616 specimens were tested with the FTA-ABS and TP, and 400 were examined with the VDRL. The TP showed good precision performance with total imprecision of less than a 10% coefficient of variation. An excellent linear relationship between results before and after heat inactivation was observed (R(2) = 0.9961). The FTA-ABS and TP agreed well with a κ coefficient of 0.981. The concordance rate between the FTA-ABS and TP was the highest (99.0%), followed by the rates between FTA-ABS and VDRL (85.0%) and between TP and VDRL (83.8%). The automated TP assay may be adequate for screening for syphilis in a large volume of samples and can be an alternative to FTA-ABS.

[Pilot study for sentinel surveillance of syphilis in Galati county]. / Sistemul pilot de supraveghere tip santinela a sifilisului în judetul Galati.

Sexually transmitted diseases are still a major public health problem in the world. The incidence rate of syphilis reported in Romania increased from 1990 (23.2 cases per 100,000 population) to 2002 (58.3 cases per 100,000 population). Although the rate is slowly decreasing after 2003, syphilis remains a priority for public health (syphilis and gonorrhea are included in the list of priorities diseases for the surveillance in Romania). The purpose of this study was to report the results of the sentinel surveillance pilot system implemented with the support of a PHARE project in 2004, in Galati district. Galati, one of the 41 districts in Romania is located in the southeast part of the country and presents higher incidence rates of syphilis (ex. 99.2 cases per 100,000 populations in 2002). High and low risk groups were included in the study and were tested for syphilis. For diagnosis the Venereal Disease Research Laboratory (VDRL) and Treponema pallidum haemagglutination (TPHA) and RPR carbon tests were used.

Sífilis congénita en el Servicio de Salud Metropolitano Sur: pesquisa de casos / Congenital syphilis in the south metropolitan health area: case surveillance

Sífilis congénita es una enfermedad absolutamente prevenible mediante la pesquisa de la infección en la mujer embarazada. Más de la mitad de los recién nacidos infectados son asintomáticos al nacer 'y, al no disponer de in test diagnóstico que permita asegurar o descartar la infección en el recién nacido, el diagnóstico es complejo, debiendo éste basarse en elementos clínicos, serológicos y epidemiológicos, no siempre disponibles, lo que probablemente lleva a subnotificación de esta infección. Sugerimos por esto adoptar la recomendación actual del CDC de E.U.A. que permite definir, tratar y notificar un caso de sífilis congénita al nacer, evitando el riesgo de no tratar a recién nacidos infectados por no cumplimiento del seguimiento posterior

The influence of different sera on the in vitro immobilisation of Percoll purified Treponema pallidum, Nichols strain.

OBJECTIVES: Investigation of sera, especially rabbit serum, in preventing in vitro immobilisation of Percoll purified T. pallidum. MATERIALS AND METHODS: The immobilisation of Percoll purified T. pallidum (Nichols) was studied after pre-incubations with basal reduced medium (BRM), heat-inactivated serum of seven different species of animals, heat-inactivated normal human serum (NHS) and rabbit sera containing a different level of antitreponemal antibodies. Also increasing percentages of heat-inactivated normal rabbit serum (NRS) were studied. RESULTS: The rapid immobilisation of purified treponemes by NHS is delayed by pre-incubation with NRS in a dose-dependent manner. The treponemes from 5-day infections were immobilised significantly more slowly than treponemes from 7- and 8-day infections. Compared with NRS, pre-incubations with a high-titred, low-titred and "autologous" serum resulted in significantly more rapid immobilisation of the treponemes. With most other animal sera resistance to immobilisation was slight compared with that produced by NRS. Immunofluorescent studies revealed that the treponemes were covered with a layer of the human third complement factor (C3b), within an hour of incubation. With two sequential pre-incubations, a delay of the immobilisation was only noted in those test mixtures in which NRS had been present in both preincubations. CONCLUSION: Rabbit serum delays the rapid in vitro immobilisation of Percoll purified treponemes by normal human serum. There was no evidence that this was caused by preventing access of antibodies (in vivo as well as in vitro) to, or preventing the activation of complement on, the treponemal surface. The evidence points to a mechanism in the fluid phase, suggesting participation of a third factor in the immobilisation process, for instance an enzyme, which can be partially inhibited by rabbit serum component(s).

Rapid in vitro immobilisation of purified Treponema pallidum (Nichols strain), and protection by extraction fluids from rabbit testes.

The use of Percoll-purified treponemes in an assay similar to the Treponema pallidum Immobilisation test demonstrated that immobilisation of purified treponemes by seronegative normal human serum proceeded at a much higher rate than that of unpurified treponemes. This suggests that the removal of the testicular extract makes the treponemes more vulnerable to this action. A preincubation of the purified treponemes with the testicular extract from infected or uninfected testes delayed their rate of immobilisation to that demonstrated by the unpurified treponemes. This showed that substances produced during the infection are probably not responsible for the delay in immobilisation. Discrimination between the classical and the alternative pathway of complement activation, studied by the ethylene glycol-bis (beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) method, showed that the classical pathway was responsible for the rapid immobilisation of the purified treponemes. However, the slow immobilisation in the EGTA-serum samples suggested a minor role of the alternative pathway in the immobilisation of the purified treponemes. Since the testicular extracts exerted an anti-complement activity, it needs to be investigated whether the protection offered to the purified treponemes by the testicular extracts is based on their deteriorating effect on the classical complement pathway or is due to a re-establishment of the protective cover around the treponemes.

Statistical aspects of the treponemal counts in the TPI test.

A method of counting treponemes in randomly selected visual fields is described. It was found that Treponema pallidum is distributed as a Poisson distribution among the visual fields and also among samples drawn from the same suspension. Immobilized treponemes are binomally distributed among the total number of treponemes. Application of the parameters of the Poisson and the binomial distributions should be made in order to determine the dosage of T. pallidum in animal experimentation and to evaluate the outcome of the TPI test. Some statistical aspects of the investigation of treponemal survival are presented.