Lumipulse G SARS-CoV-2 Ag assay evaluation using clinical samples from different testing groups

Giulia Menchinelli, Licia Bordi, Flora Marzia Liotti, Ivana Palucci, Maria Rosaria Capobianchi, Giuseppe Sberna, Eleonora Lalle, Lucio Romano, Giulia De Angelis, Simona Marchetti, Maurizio Sanguinetti, Paola Cattani Franchi, Brunella Posteraro

Risultato della ricerca: Contributo in rivistaArticolo in rivista

Abstract

Objectives: Compared to RT-PCR, lower performance of antigen detection assays, including the Lumipulse G SARS-CoV-2 Ag assay, may depend on specific testing scenarios. Methods: We tested 594 nasopharyngeal swab samples from individuals with COVID-19 (RT-PCR cycle threshold [Ct] values ≤ 40) or non-COVID-19 (Ct values > 40) diagnoses. RT-PCR positive samples were assigned to diagnostic, screening, or monitoring groups of testing. Results: With a limit of detection of 1.2 × 104 SARS-CoV-2 RNA copies/ml, Lumipulse showed positive percent agreement (PPA) of 79.9% (155/194) and negative percent agreement of 99.3% (397/400), whereas PPAs were 100% for samples with Ct values of <18 or 18–<25 and 92.5% for samples with Ct values of 25–<30. By three groups, Lumipulse showed PPA of 87.0% (60/69), 81.1% (43/53), or 72.2% (52/72), respectively, whereas PPA was 100% for samples with Ct values of <18 or 18–<25, and was 94.4, 80.0, or 100% for samples with Ct values of 25–<30, respectively. Additional testing of RT-PCR positive samples for SARS-CoV-2 subgenomic RNA showed that, by three groups, PPA was 63.8% (44/69), 62.3% (33/53), or 33.3% (24/72), respectively. PPAs dropped to 55.6, 20.0, or 41.7% for samples with Ct values of 25–<30, respectively. All 101 samples with a subgenomic RNA positive result had a Lumipulse assay’s antigen positive result, whereas only 54 (58.1%) of remaining 93 samples had a Lumipulse assay’s antigen positive result. Conclusions: Lumipulse assay was highly sensitive in samples with low RT-PCR Ct values, implying repeated testing to reduce consequences of false-negative results.
Lingua originaleEnglish
pagine (da-a)1468-1476
Numero di pagine9
RivistaClinical Chemistry and Laboratory Medicine
Volume59
DOI
Stato di pubblicazionePubblicato - 2021

Keywords

  • Antigen detection
  • Lumipulse assay
  • Nasopharyngeal swab
  • SARS-CoV-2
  • Testing group

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