Background Research on the duration of infectivity of ICU patients with COVID-19 has been sparse. Tests based on Reverse Transcriptase polymerase chain reaction (RT-PCR) detect both live virus and non-infectious viral RNA. We aimed to determine the duration of infectiousness based on viral culture of nasopharyngeal samples of patients with COVID-19. Methods Prospective observational study in adult intensive care units with a diagnosis of COVID-19 Pneumonia. Patients had repeated nasopharyngeal sampling performed after day 10 of ICU admission. Culture positive rate (based on viral culture on Vero cells in a level 4 lab) and Cycle threshold from RT-PCR were measured. Results Nine patients of the 108 samples (8.3%, 95% CI 3.9–15.2%) grew live virus at a median of 13 days (interquartile range 11–19) after their initial positive test. 74.1% of patients were RT-PCR positive but culture negative, and the remaining (17.6%) were RT-PCR and culture negative. Cycle threshold showed excellent ability to predict the presence of live virus, with a Ct < 25 with an AUC of 0.90 (95% CI 0.83–0.97, p < 0.001). The specificity of a Ct > 25 to predict negative viral culture was 100% (95% CI 70–100%). Conclusion 8.3% of our ICU patients with COVID-19 grew live virus at a median of 13 days post-initial positive RT-PCR test. Severity of illness, use of mechanical ventilation, and time between tests did not predict the presence of live virus. Cycle threshold of > 25 had the best ability to determine the lack of live virus in these patents.
【저자키워드】 COVID-19, infection control, RT-PCR, viral culture, 【초록키워드】 COVID-19 pneumonia, mechanical ventilation, prospective observational study, Test, intensive care unit, RT-PCR, observational study, polymerase chain reaction, specificity, Viral, Reverse transcriptase polymerase chain reaction, Culture, cycle threshold, infectiousness, nasopharyngeal, Prospective, Patient, ICU admission, ICU Patients, Viral RNA, PCR test, viral culture, threshold, positive rate, predict, Live virus, positive RT-PCR, AUC, best, reverse transcriptase, Chain Reaction, severity of illness, interquartile range, Level 4, 95% CI, cycle, Nasopharyngeal samples, Positive test, Vero cells, positive, non-infectious, Vero Cell, nasopharyngeal sampling, nasopharyngeal sample, repeated, lab, ICU patient, polymerase chain, initial, Result, performed, detect, lack, median, determine, were measured, diagnosis of COVID-19, patients with COVID-19, with COVID-19, 【제목키워드】 Critically ill patient,