False-negative result in molecular diagnosis of SARS-CoV-2 in samples with amplification inhibitors
| Autor: | Marcelo Fruehwirth, Açucena V. Rivas, Andressa F. R. Fitz, Aline Cristiane C. A. Batista, Cleypson Vinicius Silveira, Robson M. Delai |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Jornal Brasileiro de Patologia e Medicina Laboratorial, Vol 56 (2020) |
| Druh dokumentu: | article |
| ISSN: | 1678-4774 1676-2444 |
| DOI: | 10.5935/1676-2444.20200060 |
| Popis: | ABSTRACT Introduction: Although reverse transcription-polymerase chain reaction (rRT-PCR) is the gold standard method for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), some factors, such as the presence of amplification inhibitors, lead to false-negative results. Objective: Here we describe the differences between rRT-PCR results for SARS-CoV-2 infection in normal and diluted samples, simulating the need for dilution due to the presence of amplification inhibitors. Material and method: Viral ribonucleic acid (RNA) from samples of nasopharyngeal swabs from 20 patients previously detected as “Negative” and 21 patients detected as “Positive” for SARS-CoV-2 was performed with the EasyExtract DNA-RNA kit (Interprise®). The rRT-PCR was performed with the OneStep/COVID-19 kit (IBMP), with normal and diluted (80 µl of H2O RNAse free) samples, totaling 82 tests. Results: The results indicate that there is an average variation (a < 0.05) delaying the Cq between the results of amplification of the internal control (IC), N gene (NG), and ORF1ab (OF), 1.811 Cq, 3.840 Cq, and 3.842 Cq, respectively. Discussion: The extraction kit does not completely purify the inhibitor compounds; therefore, no amplified product result may occur. In this study, we obtained a 19.04% false-negative diagnosis after sample dilution; this process reduces the efficiency of rRT-PCR to 29.8% in detecting SARS-CoV-2. Conclusion: Knowing the rRT-PCR standards of diluted samples can assist in the identification of false-negative cases and, consequently, avoid incorrect diagnosis. |
| Databáze: | Directory of Open Access Journals |
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