Saliva is a valid alternative to nasopharyngeal swab in chemiluminescence-based assay for detection of sars-cov-2 antigen

Brunella Posteraro, Maurizio Sanguinetti, Giulia Menchinelli, Alessandra Amendola, Giuseppe Sberna, Eleonora Lalle, Francesca Colavita, Concetta Castilletti, Giuseppe Ippolito, Licia Bordi, Maria Rosaria Capobianchi

Risultato della ricerca: Contributo in rivistaArticolo in rivista

Abstract

Diagnostic methods based on SARS-CoV-2 antigens detection are a promising alternative to SARS-CoV-2 RNA amplification. We evaluated the automated chemiluminescence-based Lumipulse® G SARS-CoV-2 Ag assay on saliva samples, using Simplexa™ COVID-19 Direct assay as a reference test. Analytical performance was established on a pool of healthy donors’ saliva samples spiked with the 2019-nCoV/Italy-INMI1 isolate, whereas clinical performance was assessed on fresh saliva specimens collected from hospitalized patients with suspect or confirmed COVID-19 diagnosis. The limit of detection (LOD) was 0.65 Log TCID50/mL, corresponding to 18,197 copies/mL of SARS-CoV-2 RNA. Antigen concentrations and SARS-CoV-2 RNA were highly correlated (r = 0.99; p < 0.0001). Substantial agreement (80.3%) and significant correlation (r = −0.675; p = 0.0006) were observed between Lumipulse® G assay results and Ct values on clinical samples, with 52.4% sensitivity and specificity 94.1%. Sensitivity exceeded 90.0% when calculated on samples with Ct < 25, and specificity was 100% when excluding samples from recovered patients with previous COVID-19 diagnosis. Overall, chemiluminescence-based antigen assay may be reliably applied to saliva samples to identify individuals with high viral loads, more likely to transmit the virus. However, the low positive predictive value in a context of low SARS-CoV-2 prevalence underscores the need for confirmatory testing in SARS-CoV-2 antigen-positive cases.
Lingua originaleEnglish
pagine (da-a)1471-N/A
RivistaJournal of Clinical Medicine
Volume10
DOI
Stato di pubblicazionePubblicato - 2021

Keywords

  • Antigen detection
  • Diagnosis
  • SARS-CoV-2
  • Saliva samples
  • RT-PCR

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