Related Experiment Video
Updated: Dec 23, 2025
Swabbing the Urban Environment - A Pipeline for Sampling and Detection of SARS-CoV-2 From Environmental Reservoirs
Published on: April 9, 2021
Detection and analysis of nucleic acid in various biological samples of COVID-19 patients
Jianguo Wu1, Jiasheng Liu1, Shijun Li1
1Department of Infection Disease Ward Five, Renmin Hospital of Wuhan University, Wuhan, 430060, Hubei province, China; Department of Gastrointestinal Surgery, Renmin Hospital of Wuhan University, Wuhan, 430060, Hubei province, China.
Insights
Detecting SARS-CoV-2 (COVID-19) nucleic acid in multiple sample types, like sputum, improves detection rates compared to only using nasopharyngeal swabs. This comprehensive approach enhances diagnostic accuracy for COVID-19 patients.
Area of Science:
- Virology
- Infectious Diseases
- Diagnostic Medicine
Background:
- COVID-19, caused by SARS-CoV-2, is an acute respiratory illness that rapidly spread globally.
- Nasopharyngeal swabs are the standard for RT-PCR diagnosis, but their positive rate can be low.
- Limited data exists on the clinical utility of SARS-CoV-2 nucleic acid detection in various biological samples.
Purpose of the Study:
- To evaluate the diagnostic yield of SARS-CoV-2 nucleic acid detection across multiple biological samples in COVID-19 patients.
- To compare the positive rates of different sample types for SARS-CoV-2 detection.
- To assess the impact of multi-sample testing on diagnostic accuracy and clinical management.
Main Methods:
- An observational study involving 132 COVID-19 patients admitted to a designated hospital in Wuhan.
- Collected nasopharyngeal swabs, sputum, blood, feces, and anal swabs for SARS-CoV-2 RT-PCR testing.
- Utilized standardized RT-PCR kits and protocols, with rigorous quality control measures.
Main Results:
- Sputum samples showed a higher positive rate (48.68%) for SARS-CoV-2 nucleic acid than nasopharyngeal swabs (38.13%).
- SARS-CoV-2 nucleic acid was also detected in blood (3.03%), feces (9.83%), and anal swabs (10.00%).
- Multi-sample testing demonstrated a higher overall detection rate and reduced false negatives.
Conclusions:
- SARS-CoV-2 nucleic acid detection in sputum yields a higher positive rate than nasopharyngeal swabs.
- Viral RNA can be detected in blood and the digestive tract, indicating systemic involvement.
- Multi-sample testing for SARS-CoV-2 is crucial for improving diagnostic accuracy, reducing false negatives, and guiding clinical treatment.
Abstract:
COVID-19 (corona virus disease 2019) is a kind of acute severe pneumonia caused by 2019-nCoV (2019-nCoV) infection. Since December 2019, it has been found in Wuhan, Hubei Province, and then spread to the whole country. Some parts of the world also showed an outbreak trend [1-3]. Real-time fluorescence quantitative reverse transcriptase polymerase chain reaction (reverse transcriptase-polymerase chain reaction,RT-PCR) and viral gene sequencing are the gold standard for the diagnosis of COVID-19. At present, upper respiratory tract nasopharyngeal swabs are mostly used as nucleic acid detection samples in China, but the positive rate is low. However, there are few reports on clinical application of 2019-nCoV nucleic acid detection in other biological samples.
Methods:
| The East Section of Renmin Hospital of Wuhan University is a designated COVID-19 hospital in Wuhan City, Hubei Province, China. This observation study included 132 patients diagnosed with COVID-19 in the infectious disease areas of the East Section of Renmin Hospital of Wuhan University from 2020.1.31 to 2020.2.29. COVID-19 diagnostic criteria: according to China's ⟪pneumonia diagnosis and treatment Program of novel coronavirus infection (trial version 7) ⟫, in accordance with the relevant epidemiological and clinical manifestations, nasopharyngeal swabs real-time fluorescence RT-PCR detection of 2019-nCoV nucleic acid positive, COVID-19 cases were divided into mild, ordinary, severe and severe [1]. The nasopharyngeal swabs of 132 cases of COVID-19 were positive for 2019-nCoV nucleic acid on admission, including 72 males and 60 females, with an average age of 66.7 ± 9.1 years, including 80 cases of common type, 44 cases of severe type and 8 cases of critical type. During the period of admission, under the condition of tertiary protection, nasopharyngeal swabs, sputum, blood, feces and anal swabs of COVID-19 cases were collected many times in the isolation ward for 2019-nCoV nucleic acid detection. All biological samples are sealed and transferred to the laboratory in strict accordance with the standard process. The RT-PCR test kits (BioGerm) were recommended by the Chinese Center for Disease Control and Prevention. The same technician and brand of test kit was used for all RT-PCR testing reported; both internal controls and negative controls were routinely performed with each batch of tests.
Results:
| 132 the results of 2019-nCoV nucleic acid test of various biological samples during the treatment of confirmed COVID-19 cases are as follows: the positive rate of 2019-nCoV nucleic acid test of nasopharyngeal swab is 38.13% (180/472 times), the positive rate of 2019-nCoV nucleic acid test of sputum is 48.68% (148/304 times), the positive rate of blood 2019-nCoV nucleic acid test is 3.03% (4/132 times), and the positive rate of 2019-nCoV nucleic acid test of feces is 9.83% (24/244 times). The positive rate of 2019-nCoV nucleic acid detection in anal swabs is 10.00% (12/120 times).
Discussion|:
In this study, it was found that the positive rate of 2019-nCoV nucleic acid in sputum of 132 patients with COVID-19 was higher than that of nasopharyngeal swabs, and viral nucleic acids were also detected in blood and digestive tract (fecal/anal swabs). Simple detection of nasopharyngeal swab 2019-nCoV nucleic acid detection positive rate is not high, multi-sample 2019-nCoV nucleic acid detection can improve the accuracy, reduce the false negative rate, better guide clinical treatment and evaluate the therapeutic effect.
