Centre for Infectious Diseases and Microbiology Laboratory Services, New South Wales Health Pathology-Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, New South Wales, Australia.
Centre for Infectious Diseases and Microbiology-Public Health, Westmead Hospital, Westmead, New South Wales, Australia.
Clin Infect Dis. 2021 Nov 2;73(9):e2952-e2959. doi: 10.1093/cid/ciaa1579.
The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA by reverse-transcription polymerase chain reaction (PCR) does not necessarily indicate shedding of infective virions. There are limited data on the correlation between the isolation of SARS-CoV-2, which likely indicates infectivity, and PCR.
A total of 195 patients with Coronavirus disease 2019 were tested (outpatients, n = 178; inpatients, n = 12; and critically unwell patients admitted to the intensive care unit [ICU] patients, n = 5). SARS-CoV-2 PCR-positive samples were cultured in Vero C1008 cells and inspected daily for cytopathic effect (CPE). SARS-CoV-2-induced CPE was confirmed by PCR of culture supernatant. Where no CPE was observed, PCR was performed on day 4 to confirm absence of virus replication. The cycle thresholds (Cts) of the day 4 PCR (Ctculture) and the PCR of the original clinical sample (Ctsample) were compared, and positive cultures were defined where Ctsample - Ctculture was ≥3.
Of 234 samples collected, 228 (97%) were from the upper respiratory tract. SARS-CoV-2 was isolated from 56 (24%), including in 28 of 181 (15%), 19 of 42 (45%), and 9 of 11 samples (82%) collected from outpatients, inpatients, and ICU patients, respectively. All 56 samples had Ctsample ≤32; CPE was observed in 46 (20%). The mean duration from symptom onset to culture positivity was 4.5 days (range, 0-18). SARS-CoV-2 was significantly more likely to be isolated from samples collected from inpatients (P < .001) and ICU patients (P < .0001) compared with outpatients, and in samples with lower Ctsample.
SARS-CoV-2 culture may be used as a surrogate marker for infectivity and inform de-isolation protocols.
逆转录聚合酶链反应（PCR）检测严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）RNA 不一定表示有感染性病毒颗粒的脱落。关于SARS-CoV-2 的分离与 PCR 之间的相关性，目前仅有有限的数据。SARS-CoV-2 的分离可能表明具有感染性，而 PCR 则不然。
共对 195 例 2019 年冠状病毒病患者进行了检测（门诊患者，n=178；住院患者，n=12；入住重症监护病房[ICU]的危重患者，n=5）。对 SARS-CoV-2 PCR 阳性样本进行 Vero C1008 细胞培养，并每天检查细胞病变效应（CPE）。通过培养上清液的 PCR 来确认 SARS-CoV-2 诱导的 CPE。如果未观察到 CPE，则在第 4 天进行 PCR 以确认无病毒复制。比较第 4 天 PCR（Ctculture）和原始临床样本 PCR（Ctsample）的循环阈值（Ct），如果 Ctsample-Ctculture≥3，则定义为阳性培养。
在采集的 234 个样本中，228 个（97%）来自上呼吸道。从 56 个样本中分离出 SARS-CoV-2，包括 181 个门诊患者样本中的 28 个（15%）、42 个住院患者样本中的 19 个（45%）和 11 个 ICU 患者样本中的 9 个（82%）。所有 56 个样本的 Ctsample≤32；46 个样本观察到 CPE（20%）。从症状发作到培养阳性的平均时间为 4.5 天（范围 0-18）。与门诊患者相比，住院患者和 ICU 患者样本中 SARS-CoV-2 分离的可能性明显更高（P<0.001），且这些样本的 Ctsample 较低。
SARS-CoV-2 培养可用作感染性的替代标志物，并为解除隔离方案提供信息。
