An Investigation on the Performance of Different Microbiological Methods Used in the Diagnosis of COVID-19

Introduction: Coronavirus disease 2019 (COVID-19) pandemic continues to be a global public health problem. The present study aimed to investigate SARS-CoV-2 antibodies and evaluate the results using an immunochromatographic method and an ELISA method, in patients with suspected COVID-19, who were tested by reverse transcription polymerase chain reaction (RT-PCR) technique to detect SARS-CoV-2 RNA.Materials and Methods: The study was conducted at the SARS-CoV-2 authorized diagnostic laboratory of our hospital at the beginning of the COVID-19 pandemic, between 27 March and 14 May 2020. The nasopharynx and oropharynx swab samples of the patients included in the study were tested by the SARS-CoV-2 RT-PCR (Bioeksen, Istanbul, Turkey), where the serum samples were tested by an immunochromatographic test (Beijing Hotgen Biotech Co., Ltd, China) and Anti-SARS-CoV-2 ELISA IgG (Euroimmun, Luebeck, Germany) test. The dates the patients' symptoms started and the samples were collected for RT-PCR and serological testing were recorded. The patients were divided into two groups based on the data retrieved from the files containing the clinical information and microbiolog-ical results of the patients: individuals, who were diagnosed with COVID-19, and individuals, for whom the COVID-19 diagnosis was excluded.Results: Of the 115 patients included in the study, 92 (80%) individuals presented to the clinic with COVID-19 similar symptoms, while 23 (20%) individuals had contact with patients diagnosed with COVID-19. Sixty-one (66.3%) of 92 patients with symptoms were diagnosed with COVID-19, where 6 (26%) individuals out of 23 without symptoms were diagnosed with COVID-19. Fifty-one (76.1%) individuals out of 67 patients diagnosed with COVID-19 had positive RT-PCR results. Sixteen individuals with COVID-19, who were tested negative for RT-PCR, had positive Euroimmun Anti-SARS-CoV-2 ELISA IgG results. Of the 67 patients diagnosed with COVID-19, 61 (91%) were symptomatic and the extended time periods between the onset of the symptoms and the date of sampling for the RT-PCR test was associated with lower rates of being tested positive for the RT-PCR test (p= 0.01).Conclusion: The present study investigated the performance of the COVID-19 tests and showed that antibody tests intended for patients with suspected COVID-19, even in cases where the RT-PCR test is negative, would contribute to the diagnosis. The study con-tributes in the relevant literature as to which tests would be more useful in certain conditions, considering the fact that there is no test available that can provide 100% accurate results for the diagnosis of COVID-19.