Performance evaluation of the Access anti-HBc Total assay on the DxI 9000 Access Immunoassay Analyzer.

This study evaluated the diagnostic and analytical performances of the Access anti-HBc Total assay on the DxI 9000 Access Immunoassay System (Beckman Coulter Inc.). The multicenter study involved both prospective and retrospective sample collection from non-selected blood donors, hospitalized patients, or presumed anti-HBc Total positive individuals. Fresh/previously-frozen samples were tested with the Access and comparator assays to determine concordance; discrepant samples were tested with a second CE-marked assay. Among the 5983 non-selected fresh blood donor samples deemed anti-HBc Total negative, clinical specificity of the Access assay was 99.58% (95%CI: 99.38-99.72%). Clinical specificity was 99.27% (97.37-99.80%) among 273 anti-HBc Total negative hospitalized patient samples. Clinical sensitivity on 450 anti-HBc Total positive samples was 99.78% (98.75-99.96%). Evaluation in seroconversion panels revealed an average 1.4-day earlier detection versus a comparator assay. The Access assay demonstrated excellent clinical and analytical performances comparable to existing CE-marked anti-HBc Total assays. NCT04904835.

Performance evaluation of the Access HBsAg and Access HBsAg confirmatory assays on the DxI 9000 Access Immunoassay Analyzer.

Introduction: This study evaluated the clinical and analytical performances of the Access HBsAg and the Access HBsAg Confirmatory assays on the DxI 9000 Access Immunoassay Analyzer (Beckman Coulter, Inc.). Materials and methods: Diagnostic specificity and sensitivity of the Access HBsAg and Access HBsAg Confirmatory assays were evaluated by comparing the Access assays to the final HBsAg sample status determined using the Architect, PRISM, or Elecsys HBsAg assays, along with Architect or PRISM HBsAg Confirmatory assays. Imprecision, sensitivity on seroconversion panels, analytical sensitivity on WHO, and recognition of HBV variants were also evaluated. Results: A total of 7534 samples were included in the analysis (6047 blood donors, 1032 hospitalized patients, 455 positive patients' samples). Access HBsAg assay sensitivity and specificity were at 100.00% (99.19-100.0) and 99.92% (99.82-99.97), respectively. Sensitivity of Access HBsAg Confirmatory assay was 100.00% (99.21-100.0) on the 464 HBsAg positive samples. The use of a high positive algorithm for the Access HBsAg assay, wherein samples with S/CO ≥ 100.00 were considered positive without requiring repeat or confirmatory testing, was successfully evaluated with all 450 specimens with S/CO greater than 100.00 (sensitivity 100.00%; 99.19-100.0). Access HBsAg assay demonstrated good analytical performance, equivalent recognition of seroconversion panels compared to Architect assay, and an analytical sensitivity between 0.022 and 0.025 IU/mL. All HBV genotypes, subtypes and mutants were well detected without analytical sensitivity loss. Conclusion: Access HBsAg and Access HBsAg Confirmatory assays demonstrated robust performances. They provide low samples volume requirements and a simplified process, no systematic retesting for high positive samples.

Is there Lyme borreliosis in French Guiana? Descriptive study among patients referred for a suspected Lyme borreliosis in an Amazonian hospital between 2010 and 2022.

Lyme borreliosis (LB) existence in South America is debated, especially in the Amazon region. The infection with Lyme borreliae has never been reported in French Guiana where Borrelia burgdorferi sensu lato is not found in ticks. We describe the final diagnosis and presumed place of acquisition in patients consulting for suspicion of LB. We retrospectively collected data from all consecutive patients consulting for a suspicion of LB between 2010 and 2021 at Cayenne Hospital, French Guiana. Patients were classified by an adjudication committee as confirmed LB if they met the criteria of the French consensus, as possible LB if they had compatible symptoms and a good outcome after appropriate treatment, or excluded when a differential diagnosis was found. The place of acquisition was discussed in case of possible or confirmed case. Twenty-six patients were included. Rheumatologic symptoms were the most reported (88 %) followed by neurological symptoms (61 %). Twenty-four (92 %) of these patients were born out of French Guiana. Diagnosis of LB was considered as confirmed in 2 patients (8 %), for whom the place of acquisition was likely mainland France, and as possible in 3 patients (11 %) with early localized LB presumably acquired in French Guiana. Functional somatic disorders were diagnosed in 13 (50 %) patients whereas 9 (35 %) were found with another disease. This study did not confirm the acquisition of LB in French Guiana. However, three possible autochthonous cases encourage clinicians working in the Amazon area to stay aware of LB.

An improved HIV antigen/antibody prototype assay for earlier detection of acute HIV infection.

BACKGROUND: Early detection of acute HIV infection by HIV antigen/antibody assays depends on antigen sensitivity. Maintaining consistently high sensitivity across diverse HIV strains is critical to ensure equal detection. OBJECTIVES: The performance of an improved HIV antigen/antibody prototype, HIV Combo Next, was evaluated for detection of genetically-diverse HIV strains and seroconversion samples. STUDY DESIGN: Antigen sensitivity of the prototype was evaluated and compared to five FDA-approved HIV antigen/antibody assays using World Health Organization (WHO) HIV p24 antigen standard and reference panels, 17 virus isolates and 9 seroconversion panels. Antibody sensitivity and assay specificity of the prototype were also assessed with 1062 disease-staged and genotyped samples, and samples from 3000 blood donors and 955 individuals with low-risk for HIV infection. RESULTS: Compared with other assays evaluated, the prototype demonstrated the best analytical sensitivity for WHO antigen standard, reference panels including 12 HIV-1 variants (0.04 - 0.25 IU/ml) and one HIV-2 variant, and 17 HIV virus isolates including HIV-1 group M, N, P and O and HIV-2 (0.3 -16 pg/ml). The enhanced sensitivity was also observed for seroconversion samples, detecting more PCR-positive samples with detection up to 7 days earlier than the other assays. Improvement in antigen sensitivity did not compromise antibody sensitivity or assay specificity, detecting all HIV disease-staged and genotyped samples, with assay specificity of 99.97% for blood donors and 99.68% for the low-risk population. CONCLUSIONS: These data indicate that the new prototype HIV Combo Next assay will be of diagnostic value, providing improved early detection for acute HIV infection from divergent HIV strains.

Evaluation of the performance of a new automated HIV combination assay.

BACKGROUND: More and more countries test for HIV infection using combination assays that simultaneously detect p24 antigen and HIV antibodies. OBJECTIVE: To assess the performance of a new HIV combo assay: LIAISON® XL murex HIV Ab/Ag HT. STUDY DESIGN: The assays were examined with a total of 3090 samples that included 769 selected HIV antibody-negative samples, 1849 unselected HIV samples, 15 HIV-1 p24 Ag reference samples, 90 primary HIV-1 infection (PHI) samples, 167 HIV-1 antibody-positive samples (well characterized of groups M and O), 95 HIV-1 antibody-positive samples and 105 HIV-2 antibody-positive samples. RESULTS: The specificity of the LIAISON® XL murex HIV Ab/Ag HT was 99.7%. The analytical sensitivity of Ag p24 of the LIAISON® XL murex HIV Ab/Ag HT was 0.58IU/mL and 9.93pg/mL when using WHO and French national standards, respectively. All screened HIV subtypes was identified by this assay. Also, 90 PHI specimens were detected by this screening assay. CONCLUSION: The sensitivity and specificity of the LIAISON® XL murex HIV Ab/Ag HT assay are high. Hence the assay offers automated high-throughput screening with ability to detect primary infection.

Resolution of discrepant results for Candida species identification by using DNA probes.

Candida species bloodstream isolates were collected from institutions participating in an active, population-based surveillance for candidemia. Species identifications were performed locally and then confirmed at the Centers for Disease Control and Prevention (CDC) by phenotype-based methods. Discrepancies in species identification between the referring institution and the CDC were noted for 43 of 935 isolates (4.6%). A DNA probe-based species identification system (PCR-enzyme immunoassay [EIA]) was then used to resolve these discrepancies. The PCR-EIA result was identical to the CDC phenotypic identification method for 98% of the isolates tested. The most frequently misidentified species was Candida glabrata (37% of all discrepant identifications). Such misidentifications could lead to the administration of inappropriate therapy given the propensity of C. glabrata to develop resistance to azole antifungal drugs.