ABSTRACT
Italy was one of the most affected nations by coronavirus disease 2019 outside China. The infections, initially limited to Northern Italy, spread to all other Italian regions. This study aims to provide a snapshot of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) epidemiology based on a single-center laboratory experience in Rome. The study retrospectively included 6565 subjects tested for SARS-CoV-2 at the Laboratory of Virology of Sapienza University Hospital in Rome from 6 March to 4 May. A total of 9995 clinical specimens were analyzed, including nasopharyngeal swabs, bronchoalveolar lavage fluids, gargle lavages, stools, pleural fluids, and cerebrospinal fluids. Positivity to SARS-CoV-2 was detected in 8% (527/6565) of individuals, increased with age, and was higher in male patients (P < .001). The number of new confirmed cases reached a peak on 18 March and then decreased. The virus was detected in respiratory samples, in stool and in pleural fluids, while none of gargle lavage or cerebrospinal fluid samples gave a positive result. This analysis allowed to gather comprehensive information on SARS-CoV-2 epidemiology in our area, highlighting positivity variations over time and in different sex and age group and the need for a continuous surveillance of the infection, mostly because the pandemic evolution remains unknown.
Subject(s)
COVID-19 , Pandemics , SARS-CoV-2/pathogenicity , Adolescent , Adult , Aged , Aged, 80 and over , Bronchoalveolar Lavage Fluid/virology , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19 Testing , Child , Child, Preschool , Feces/virology , Female , Hospitals, University , Humans , Infant , Infant, Newborn , Laboratories , Male , Middle Aged , Nasopharynx/virology , Pleural Effusion/virology , Retrospective Studies , Reverse Transcriptase Polymerase Chain Reaction , Rome/epidemiology , SARS-CoV-2/genetics , Severity of Illness IndexABSTRACT
The aim of the study was to evaluate the clinical performance of FTD SARS-CoV-2 compared to the RealStar RT-PCR kit 1.0. The analysis of 100 nasopharyngeal swabs showed an overall agreement of 88 %. The positive percentage agreement was 85.6 % and the negative percentage agreement was 91 %. In conclusion we observed a substantial agreement among the two methods, with discrepancies mainly observed in specimens with relatively low amount of viral RNA.
Subject(s)
COVID-19 , Frontotemporal Dementia , Humans , Nasopharynx , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2 , Sensitivity and SpecificityABSTRACT
BACKGROUND: The detection of a low amount of viral RNA is crucial to identify a SARS-CoV-2 positive individual harboring a low level of virus, especially during the convalescent period. However, the detection of one gene at high Cycle threshold (Ct) has to be interpreted with caution. In this study we address this specific issue and report our real-life experience. STUDY DESIGN: A total of 1639 nasopharyngeal swabs (NPS) were analyzed with Xpert® Xpress SARS-CoV-2. Positive samples showing high Ct values (Ct>35) were concentrated by centrifugation and re-tested with Cepheid or other methods (RealStar SARS-CoV2 RT-PCR, Altona Diagnostics; GeneFinder COVID-19 Plus RealAmp Kit, Elitech). RESULTS: 1599 (97.5%) negative samples, 36 (2.3%) positive samples and 4 (0.2%) presumptive positive samples were detected. In 17 out of 36 positive patients, very low viral RNA copies were suspected since positivity was detected at high Ct. We confirmed positivity for patients who showed both E and N genes detected and for patients with only N detected but with Ct <39. On the contrary, samples with only gene N detected with Ct values >39 were found negative. NPS taken 24 hours after the first collection confirmed the negativity of the 12 samples. Clinical data sustained these results since only 2 of these 12 patients showed COVID-19-like symptoms. CONCLUSIONS: These data support our consideration that detection of the N2 gene at high Ct needs to be interpreted with caution, suggesting that collaboration between virologists and clinicians is important for better understanding of results.