Clinical value of anal swab positive in COVID-19 patients / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the value of anal swabs positive for 2019-nCoV in patients with COVID-19 and the clinical features of the patients.Methods:Throat swabs, sputum and blood samples, and anal swabs were collected from 104 patients with COVID-19 at admission to test for 2019-nCoV nucleic acid. Clinical characteristics and hematological indexes were compared between viral nucleic acid-positive and -negative groups of different sample types. Fifteen patients whose anal swabs were positive for viral nucleic acid were selected to analyze the length of time before the nucleic acid turned negative in different specimens.Results:Compared with the patients having negative anal swab test results, those having positive test results showed decreased lymphocytes, increased lactate dehydrogenase (LDH) and high-sensitivity C-reactive protein (HsCRP), and higher incidence of severe COVID-19. The levels of HsCRP and IL-6 and the incidence of severe COVID-19 were significantly higher in patients with positive throat swab test results than in those with negative results. No significant difference in hematological indexes or the proportion of severe cases was detected between the patients with positive and negative sputum test results. Only 1.92% of the patients had positive blood test results, but all of them were severe patients. The positive rate of sputum test was the highest, which was 46.15%. Patients with positive results of both throat and anal swab test had significantly decreased lymphocytes, increased HsCRP and IL-6 levels, and higher incidence of critical COVID-19. It took longer time for patients to have negative anal swab and sputum test results. Moreover, it should be noticed that the viral nucleic acid in sputum might become positive again after it turned negative.Conclusions:Patients with positive anal swab test results had reduced lymphocytes, enhanced inflammatory response and higher incidence of severe COVID-19, suggesting that a positive anal swab test might be an indicator of severe COVID-19. Moreover, the time of 2019-nCoV nucleic acid turning negative in anal swabs was longer than that in throat swabs. The combined detection of throat swabs and anal swabs would help to predict the occurrence of severe COVID-19.