Antonietta D'Antuono

Evaluation of LIAISON Treponema Screen, a Novel Recombinant Antigen-Based Chemiluminescence Immunoassay for Laboratory Diagnosis of Syphilis

ABSTRACT The purpose of this study was to evaluate the diagnostic performance of LIAISON Treponema Screen (DiaSorin, Saluggia, Italy), a new automated chemiluminescence immunoassay (CLIA), in comparison with that of rapid plasma reagin (RPR) and the following currently used treponemal tests: hemagglutination test (TPHA), immunoenzymatic assay (EIA), and Western blot (WB). First, a retrospective study was performed with a panel of 2,494 blood donor sera, a panel of 131 clinical and serologically characterized syphilitic sera, and 96 samples obtained from subjects with potentially interfering diseases or conditions. A prospective study was also performed by testing 1,800 unselected samples submitted to the Microbiology Laboratory of the St. Orsola Hospital in Bologna, Italy, for routine screening for syphilis. As expected, RPR was the least specific method, especially when potentially cross-reacting sera were tested. On the contrary, all of the treponemal tests proved to be very specific (99.9%) and they performed with the following sensitivities: 100% (WB), 99.2% (CLIA), 95.4% (EIA), and 94.7% (TPHA).

Western immunoblotting with five Treponema pallidum recombinant antigens for serologic diagnosis of syphilis.

ABSTRACT Five immunodominant Treponema pallidum recombinant polypeptides (rTpN47, rTmpA, rTpN37, rTpN17, and rTpN15) were blotted onto strips, and 450 sera (200 from blood donors, 200 from syphilis patients, and 50 potentially cross-reactive) were tested to evaluate the diagnostic performance of recombinant Western blotting (recWB) in comparison with in-house whole-cell lysate antigen-based immunoblotting (wclWB) and T. pallidum hemagglutination (MHA-TP) for the laboratory diagnosis of syphilis. None of the serum specimens from blood donors or from potential cross-reactors gave a positive result when evaluated by recWB, wclWB, or MHA-TP. The evaluation of the immunoglobulin G immune response by recWB in sera from patients with different stages of syphilis showed that rTmpA was the most frequently identified antigen (95%), whereas only 41% of the specimens were reactive to rTpN37. The remaining recombinant polypeptides were recognized as follows: rTpN47, 92.5%; rTpN17, 89.5%; and rTpN15, 67.5%. The agreement between recWB and MHA-TP was 95.0% (100% with sera from patients with latent and late disease), and the concordance between wclWB and MHA-TP was 92.0%. The overall concordance between recWB and wclWB was 97.5% (100% with sera from patients with secondary and late syphilis and 94.6 and 98.6% with sera from patients with primary and latent syphilis, respectively). The overall sensitivity of recWB was 98.8% and the specificity was 97.1% with MHA-TP as the reference method. These values for sensitivity and specificity were slightly superior to those calculated for wclWB (sensitivity, 97.1%, and specificity, 96.1%). With wclWB as the standard test, the sensitivity and specificity of recWB were 98.9 and 99.3%, respectively. These findings suggest that the five recombinant polypeptides used in this study could be used as substitutes for the whole-cell lysate T. pallidum antigens and that this newly developed recWB test is a good, easy-to-use confirmatory method for the detection of syphilis antibodies in serum.

Prenatal Syphilis Infection Is A Possible Cause Of Preterm Delivery Among Immigrant Women From Eastern Europe

Objective:to evaluate the prevalence of maternal syphilis at delivery and neonatal syphilis infection in an Italian urban area, in connection with the increased flow of immigration. Study design: A prospective surveillance study was carried out in Bologna, Italy, from November 2000 to March 2006. All pregnant women were screened for syphilis at delivery. Infants born to seropositive mothers were enrolled in a prospective follow-up. Results: During the study period 19 205 women gave birth to 19 548 infants. A total of 85 women were seropositive for syphilis at delivery. The overall syphilis seroprevalence in pregnant women was 0.44%, but it was 4.3% in women from eastern Europe and 5.8% in women from Central–South America. Ten women were first found positive at delivery, as they did not receive any prenatal care. Nine of these were from eastern Europe. All their infants were asymptomatic, but six had both reactive immunoglobulin (Ig)M western blot and rapid plasma reagin tests and were considered prenatally infected. Three of six were preterm (gestational age <37 weeks). Conclusions: In Italy, congenital syphilis infection is strictly related to immigration from eastern Europe. Although it is asymptomatic, it could cause premature delivery. Therefore, it is necessary to perform serological tests during the third trimester in mothers coming from endemic areas to adequately treat syphilis in pregnancy and prevent congenital infection. If the mother’s test results are not available at delivery, it is necessary to investigate the newborn, especially if it is born prematurely.

Treponema pallidum surface immunofluorescence assay for serologic diagnosis of syphilis.

ABSTRACT A surface immunofluorescence assay (SIFA) using live spirochetes was analyzed and compared with Western blot (WB), fluorescent treponemal antibody absorption (FTA-ABS), microhemagglutination (MHA-TP), and Treponema pallidum immobilization (TPI) assays for detecting serum antibodies to T. pallidum in patients with syphilis, in disease controls, and in healthy subjects. SIFA and WB were 99% sensitive (99 of 100 positive specimens) and specific (140 of 140 negative specimens); FTA-ABS showed a sensitivity and a specificity of 90 and 89% (90 of 100 positive and 125 of 140 negative specimens), respectively. MHA-TP showed a sensitivity of 84% (84 of 100 positive specimens) and a specificity of 98.5% (138 of 140 negative specimens). Finally, TPI had a sensitivity of 52% (52 of 100 positive specimens) and a specificity of 100% (140 of 140 negative specimens). The T. pallidum SIFA was therefore highly specific, showing no equivocal reactivities with control sera, and sensitive. The results suggest the possible use of SIFA as a confirmatory test in the serologic diagnosis of syphilis.

Prevalence of STDs and HIV infection among immigrant sex workers attending an STD centre in Bologna, Italy

Recent research (ISTAT: Italian Statistics Institute, data regarding 1998) has shown that in Italy there are about 50 000 street sex workers—20 000 of them are occasional; the remaining full time workers included 5000 Italians, generally not street walking, and 25 000 migrant street walking prostitutes. Migrant prostitution in Italy represents a real emergency because of their number, which is increasing in proportion to clandestine immigration coming from east Europe and from Africa. Sex workers are often the focus of control measures for sexually transmitted diseases (STDs) because they are seen as the source.1 Recent data show that in Bologna city there are about …

Phenotypic and genotypic characterization of Neisseria gonorrhoeae in parts of Italy: detection of a multiresistant cluster circulating in a heterosexual network

Data concerning Neisseria gonorrhoeae infections in Italy are scarce, and there is little information on the phenotypic and genotypic characteristics of the circulating strains. In this study, 326 isolates collected from 397 patients, with or without concurrent human immunodeficiency virus (HIV) infection, were cultured and characterized by serovar and antimicrobial susceptibility to five antimicrobials. N. gonorrhoeae multi-antigen sequence typing (NG-MAST) was also performed for strain characterization and to identify a transmission network. Gonococcal infection was diagnosed in 364 males and 33 females, 296 of whom were Italian and 96 of whom were foreigners (nationality was unknown in five cases). Among the 364 males, 197 were heterosexual, and the median age was 31 years. Approximately 8.3% of all the investigated patients were HIV-1-positive. The isolates were assigned to three different serovars (IA, IB, IA/IB), IB being the most frequently encountered. A significant rate of resistant gonococci was also observed; 34%, 25.5% and 19.1% of ciprofloxacin-resistant, penicillin-resistant and tetracycline-resistant phenotypes, respectively, were detected, and 10.2% of strains were multidrug-resistant. Together with the presence of different sequence types (STs), identified by NG-MAST, a multidrug-resistant cluster, ST661, was detected in a heterosexual network in a precise geographical area of the country. In particular, all strains belonging to ST661 showed identical profiles according to pulsed-field gel electrophoresis (PFGE), all were serotype IB, and all were resistant to penicillin, ciprofloxacin and tetracycline.