West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, 610041, China.
Sichuan Center for Disease Control and Prevention, Chengdu, 610041, China.
BMC Microbiol. 2021 Feb 19;21(1):56. doi: 10.1186/s12866-021-02118-0.
Gastrointestinal symptoms are common in COVID-19 patients and SARS-CoV-2 RNA has been detected in the patients' feces, which could lead to fecal-oral transmission. Therefore, fecal sample testing with real-time RT-PCR is highly recommended as a routine test for SARS-CoV-2 infection. However, varying rates of detection in fecal sample have been reported. The aim of this study was to provide insights into the detection rates of SARS-CoV-2 in COVID-19 patients' fecal sample by using four real-time RT-PCR kits and two pretreatment methods (inactive and non-inactive).
The detection rate of Trizol pretreatment group was slightly higher than that of Phosphate Buffered Saline (PBS) groups, showing that pretreatment and inactivation by Trizol had no influence to SARS-CoV-2 nucleic acid test (NAT) results. 39.29% detection rate in fecal sample by DAAN was obtained, while Bio-germ was 40.48%, Sansure 34.52%, and GeneoDx 33.33%. The former three kits had no significant difference. The DAAN kit detection rates of ORF1ab and N gene were nearly equal and Ct value distribution was more scattered, while the Bio-germ kit distribution was more clustered. The positive rate of SARS-COV-2 in fecal samples correlated with the severity of the disease, specifically, severe cases were less likely to be identified than asymptomatic infection in the DAAN group (adjusted OR 0.05, 95%CI = 0.00 ~ 0.91).
Trizol should be of choice as a valid and safe method for pretreatment of fecal samples of SARS-CoV-2. All real-time RT-PCR kits assessed in this study can be used for routine detection of SARS-CoV-2 in fecal samples. While DAAN, with high NAT positive rate, could be the best out of the 4 kits used in this study. SARS-CoV-2 positive rate in fecal sample was related to the severity of illness.
胃肠道症状在 COVID-19 患者中很常见，SARS-CoV-2 RNA 已在患者粪便中检测到，这可能导致粪-口传播。因此，实时 RT-PCR 粪便样本检测被高度推荐作为 SARS-CoV-2 感染的常规检测。然而，粪便样本的检测率报告不一。本研究旨在通过使用四种实时 RT-PCR 试剂盒和两种预处理方法（非活性和非活性），提供 COVID-19 患者粪便样本中 SARS-CoV-2 检测率的见解。
Trizol 预处理组的检测率略高于磷酸盐缓冲盐水（PBS）组，表明 Trizol 预处理和灭活对 SARS-CoV-2 核酸检测（NAT）结果没有影响。DAAN 检测到的粪便样本的检测率为 39.29%，而 Bio-germ 为 40.48%，Sansure 为 34.52%，GeneoDx 为 33.33%。前三种试剂盒之间没有显著差异。DAAN 试剂盒对 ORF1ab 和 N 基因的检测率几乎相等，Ct 值分布较为分散，而 Bio-germ 试剂盒的分布较为集中。粪便样本中 SARS-COV-2 的阳性率与疾病的严重程度相关，具体而言，DAAN 组中严重病例的检出率低于无症状感染（调整后的 OR 0.05，95%CI=0.00~0.91）。
Trizol 应该是预处理 SARS-CoV-2 粪便样本的有效且安全的方法。本研究评估的所有实时 RT-PCR 试剂盒都可用于常规检测粪便样本中的 SARS-CoV-2。虽然 DAAN 的 NAT 阳性率较高，但在本研究中使用的 4 种试剂盒中是最好的。粪便样本中 SARS-CoV-2 的阳性率与疾病的严重程度有关。
