Silvia Accardo

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).

Laboratory diagnosis of syphilis with automated immunoassays.

The serological detection of specific antibodies to Treponema pallidum is of particular importance in the diagnosis of syphilis. The purpose of this study was to evaluate diagnostic performances of automated immunoassays in comparison with T. pallidum hemagglutination test (TPHA) and Western Blot (WB). The retrospective study was performed with different panels of sera: 244 clinical and serological characterized syphilitic sera and 203 potentially interfering samples. All the sera were tested by Enzygnost Syphilis, ARCHITECT Syphilis TP, TPHA, and homemade WB. The diagnostic performances of the two assays were very similar: both Enzygnost Syphilis and ARCHITECT Syphilis TP performed with a sensitivity of 99.2%, whereas the specificity was 98.5 and 98.4%, respectively. Considering the suitability for automation, both immunoassays may represent a good choice as a screening test. However, the use of a confirmatory test, such as TPHA or WB, remains a must in order to avoid false‐positive results. J. Clin. Lab. Anal. 23:1–6, 2009.

Activity of Cathelicidin Peptides against Chlamydia spp

ABSTRACT The in vitro activity of six cathelicidin peptides against 25 strains of Chlamydia was investigated. SMAP-29 proved to be the most active peptide, reducing the inclusion numbers of all 10 strains of Chlamydia trachomatis tested by ≥50% at 10 μg/ml. This peptide was also active against C. pneumoniae and C. felis.

Borrelia burgdorferi VlsE antigen for the serological diagnosis of Lyme borreliosis

In this study, raising and development of antibody response to Borrelia burgdorferi infection in 66 Italian patients suffering from culture-confirmed Lyme borreliosis erythema migrans (EM) was investigated. Sixty-two of 66 cultures obtained from biopsies were identified as B. afzelii by PCR. A total of 175 serially collected serum samples were tested by using two different sets of commercial assays: Enzygnost Lyme link VlsE/IgG and Enzygnost Borreliosis IgM (DADE Behring, Marburg, Germany) and LIAISON Borrelia IgG and IgM (Diasorin, Saluggia, Italy). Considering only samples obtained at first presentation when EM was clinically evident, 49/66 patients (72.4%) were IgG or IgM positive by Enzygnost, whereas 33/66 (50.0%) patients were IgG or IgM positive by LIAISON. Taking into account the follow-up period, eight patients sero-converted for IgG or IgM by Enzygnost and four by LIAISON. Similar and very good specificity values were obtained by all methods. Testing sera obtained from blood donors (n = 300) and from patients suffering from some of the most common biological conditions possibly resulting in false-positive reactivity in Lyme disease serology (n = 100) showed that Enzygnost Lyme link VlsE/IgG was the more specific (98.3%), followed by LIAISON Borrelia IgG (96.5%), and considering IgM tests, Enzygnost Borreliosis IgM showed to be 95.3%% specific, whereas the LIAISON Borrelia IgM was 92.8% specific. Recombinant VlsE antigens obtained from all three B.burgdorferi genospecies pathogenic to humans (included in Enzygnost Lyme link VlsE/IgG) greatly improved serodiagnosis of Lyme disease.

A Decrease in the Immunoglobulin G Antibody Response against the VlsE Protein of Borrelia burgdorferi Sensu Lato Correlates with the Resolution of Clinical Signs in Antibiotic-Treated Patients with Early Lyme Disease

ABSTRACT The purpose of this study was to evaluate the diagnostic performance of the LIAISON Borrelia Screen (Diasorin, Saluggia, Italy), a new automated immunoassay based on the chemiluminescent technology (chemiluminescence immunoassay). To assess whether a decrease in a negative value in the anti-VlsE immunoglobulin G (IgG) antibody titer was correlated with a positive response to treatment, a group of serially collected serum samples from 67 patients with culture-confirmed erythema migrans was retrospectively studied. All the patients had been treated with antibiotics and were free of disease within 3 to 6 months of follow-up. All the 15 patients who were found to be IgG positive at the time of enrollment and who were bled at least four times during the follow-up became IgG seronegative at 2 to 6 months posttreatment. These results indicate that a decline in the anti-VlsE antibody titer coincides with effective antimicrobial therapy in patients with early localized Lyme disease.

Use of Enzygnost Anti-human IgA conjugate in combination with the kit Enzygnost toxoplasmosis IgG (Siemens Healthcare Diagnostics) for the detection of IgA anti-Toxoplasma gondii

Laboratory diagnosis of toxoplasmosis is mainly based on serological methods, particularly important in the most challenging situations, as the diagnosis of primary infection during pregnancy and diagnosis of congenital infection. Tests for the detection of IgA antibodies are especially important in the newborns, because they are more sensitive than IgM conventional methods. The purpose of this study was to evaluate diagnostic performances of Enzygnost system for IgA detection, achieved by using Enzygnost Anti-human IgA/POD conjugate in combination with Enzygnost toxoplasmosis IgG (Siemens Healthcare Diagnostics Products GmbH, Marburg, Germany). A retrospective study was performed with 591 serum samples submitted to the Microbiology Laboratory of S. Orsola Hospital in Bologna for toxoplasmosis screening.All the sera were tested by Enzygnost toxoplasmosis IgG, Enzygnost toxoplasmosis IgM and Enzygnost system for IgA (Siemens Healthcare Diagnostics). Border-Line or positive IgM results were confirmed by Vidas Toxo IgM (bioMerieux, Marcy l’Etoile, France). Finally, IgG Avidity was performed by Vidas Toxo IgG Avidity (bioMerieux) and LDBio Toxoplasma WB IgG/IgM (LDBio Diagnostics, Lyon, France). During the study period, 453 sera were IgA negative, 53 were Border-Line and 85 were positive when tested by Enzygnost system for IgA. No significative correlation was found between IgA positive results and low Avidity results.Three babies were correctly diagnosed as congenital toxoplasmosis infected infants because of the presence of IgA antibodies at birth. Enzygnost system for IgA anti-Toxoplasma showed good diagnostic performances.We conclude that the high sensitivity and specificity of and its suitability for automation make it an ideal screening test.