Abstract
Background: 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.
Methods: 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.
Results: 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.
Conclusions: SARS-CoV-2 culture may be used as a surrogate marker for infectivity and inform de-isolation protocols.
Keywords: COVID-19; SARS-CoV-2; de-isolation; infection control; viral culture.
【저자키워드】 COVID-19, SARS-CoV-2, infection control, viral culture, De-isolation, 【초록키워드】 coronavirus disease, infection control, Coronavirus disease 2019, coronavirus, intensive care, Infection, intensive care unit, severe acute respiratory syndrome Coronavirus, RNA, polymerase chain reaction, PCR, Culture, cycle threshold, Patient, Isolation, shedding, virus replication, ICU Patients, outpatients, correlation, viral culture, upper respiratory tract, patients, marker, CPE, Cytopathic effect, protocols, Vero, SARS-CoV-2 PCR, Chain Reaction, Inpatients, Inpatient, symptom onset, acute respiratory syndrome, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, PCR-positive, culture supernatant, positive, virions, infective, Cell, ICU patient, polymerase chain, defined, tested, collected, significantly more, was performed, indicate, absence, 【제목키워드】 Infectivity, assessment,