By December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus started a new pandemic respiratory disease named 2019 novel Coronavirus infectious disease (COVID-19).1,2Lombardy region (Northern Italy) has been involved in a dramatic COVID-19 epidemic episode since February 20th with a rapid increase in the rate of infected patients. At the time of writing, the number of infected people in Italy was higher than 97,000 with more than40% of cases reported in the Lombardy Region.2
To date, the diagnosis of COVID-19 is based on detection of SARS-CoV-2 RNA in respiratory samples such as nasal swab (NS).3However the evidence that NS in patients with COVID-19 pneumonia were sometimes negative raise the attention to collect other clinical specimens that may be useful for etiologic diagnosis since bronchoalveolar lavage (BAL) collection is not always possible.4 In the present study, we examined the presence of SARS-CoV-2 RNA in multiple biologic specimens collected simultaneously to respiratory samples from COVID-19 patients in order to determine the detection rate of viral RNA and the possibility of transmission by alternative routes.5
Overall, 143 patients with a confirmed diagnosis of COVID-19 by RT-PCR in respiratory samples and admitted to Infectious Diseases Department or at the Intensive Care Unit at Fondazione IRCCS Policlinico San Matteo, were included in the study. In detail,104/143 (72.7%) were males, and the mean age was 66.2 years (range, 2-94 years). Of them, 143 NS, 107 rectal swabs (RS), 85 urine, 26 plasma, and 5 feces were examined. We examined 18 urine and 39 RS samples from 59 NS patients admitted to the emergency room department with respiratory distress.
Total nucleic acids (DNA/RNA) were extracted from 200 µl of samples using the QIAsymphony® instrument with QIAsymphony® DSP Virus/Pathogen Midi Kit (Complex 400 protocol) according to the manufacturer’s instructions (QIAGEN, Qiagen, Hilden, Germany). Specific real-time RT-PCR targeting RNA-dependent RNA polymerase and E genes were used to detect the presence of SARS-CoV-2 according to the WHO guidelines1 and Corman et al. protocols.3
Median and range were given for quantitative variables, while qualitative variables were shown as percentages or frequencies.
A total of 366 specimens corresponding to 143 consecutive patients were examined. In detail 11/107 (10.3%) patients had a COVID-19 positive RS, 2/26 (7.7%) COVID-19 positive plasma, while only 1/98 (1%) had a COVID-19 positive urine sample. None of the 5 stool specimens tested positive.
The median viral load detected in respiratory samples was 4 x 106 copies/ml (range 17.3-36.9),while was 4.1 x 106copies/ml(range 1.7-6.5)in RS and 2.9 x 106copies/ml (range 2.9 - 3) in two positive plasma (Table 1). The most common clinical features of hospitalized patients with COVID-19 were fever, dry cough, dyspnea, diarrhea, asthenia, and respiratory disorders as pneumonia and sore throat.
None of the 116 specimens (59 NS, 18 urine, and 39 RS), from 59 COVID-19 negative control patients, tested positive.
Table 1. RNA load test results of the 145 hospitalized patients SARS-CoV-2 positive by real-time RT-PCR.