SARS-CoV-2 infection diagnosed only by cell culture isolation before the local outbreak in an Italian seven-week-old suckling baby

Abstract

SARS-CoV-2 emerged in China in December 2019 and has now been declared a pandemic by the World Health Organization. This paper described the case of a 7-week-old suckling baby from Italy who was SARS-CoV-2-positive only by the cell culture method, with no clinical suspicion of and/or risk factors for SARS-CoV-2 infection. The baby was referred to hospital, with signs and symptoms of upper respiratory tract infection, before the virus had spread to the province. Nasal and pharyngeal swabs and a nasopharyngeal aspirate were used for conventional and molecular diagnostic assays not including the SARS-CoV-2 virus. Bacteria referred to the resident population were revealed in nasal and pharyngeal swabs. No viruses were detected using both immunofluorescence assay and nucleic acid amplification assays in the nasopharyngeal aspirate. The baby was discharged in good condition after 3 days of hospitalisation. Later, a cytopathic effect on the cell monolayers currently used for respiratory viruses was observed and the viral particles were identified as Coronaviridae by transmission electron microscopy. SARS-CoV-2 was identified by RT-PCR performed both on cell culture and on the stored aliquot of the original sample. The virus isolate was named SARS-Cov-2/human/Parma/1/2020. Cell culture still remains the only reference diagnostic method also for emerging viruses, allowing it to reveal cytopathogenic viruses and demonstrate their infectivity.

Human respiratory viruses, including SARS-CoV-2, circulating in the winter season 2019–2020 in Parma, Northern Italy

“…The qualitative detection of SARS-CoV-2 nucleic acid was carried out accordingly to the “Real-time RT-PCR panel” for detection of 2019-Novel Coronavirus, which was published on February 4, 2020 by the Centers for Disease Control and Prevention ( Centers for Disease Control and Prevention, 2020 ) with some modifications, as previously described ( Calderaro et al, 2020 ).…”

“…After incubation, the slide was washed three times with PBS. Stained cells were observed under a fluorescence microscope (Leica DMLB) ( De Conto et al, 2019 , Calderaro et al, 2020 ).…”

“…The inoculated cell monolayers were observed daily under an inverted optical microscope in order to check cellular morphology modifications possibly related to virus replication (cytopathic effect) ( De Conto et al, 2019 , Calderaro et al, 2020 ).…”

COVID-19 Is a Multifaceted Challenging Pandemic Which Needs Urgent Public Health Interventions

“…However, the neonatal diagnosis of SARS-CoV-2 should not be limited to molecular testing, when there is also the possibility of cultivating the virus in vitro. In fact, a recent Italian author highlighted the importance of viral culture to be used in parallel with molecular techniques to detect the presence of cytopathogenic viral agents, as demonstrated in an Italian 7-week-old lactating infant who tested positive for SARS-CoV-2 only with the cell culture method, without any clinical suspicion and/or risk factor for SARS-CoV-2 infection [ 56 ]. More detailed studies will be required to confirm these preliminary results.…”

Diagnostic technologies for COVID-19: a review

“…Adriana et al, reported that a 7 week-old baby was diagnosed with SARS-CoV-2 infection before the COVID-19 outbreak in Italy, through cell-culture isolation, transmission electron microscopy, and real-time reverse-transcription polymerase chain reaction (RT-PCR) identication. 7 In addition, live virus propagation allows for large amounts of virus to be developed and used for further research, such as antiviral drug testing, vaccine development, and comparative genomic analyses of viruses isolated from different regions. Finally, rapid and coordinated sharing of research ndings across scientic communities and public health agencies is critical for the effective study of viruses.…”