Comparison of SARS-CoV-2 Detection by Rapid Antigen and by Three Commercial RT-qPCR Tests: A Study from Martin University Hospital in Slovakia.

The global pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is having a tremendous impact on the global economy, health care systems and the lives of almost all people in the world. The Central European country of Slovakia reached one of the highest daily mortality rates per 100,000 inhabitants in the first 3 months of 2021, despite implementing strong prophylactic measures, lockdowns and repeated nationwide antigen testing. The present study reports a comparison of the performance of the Standard Q COVID-19 antigen test (SD Biosensor) with three commercial RT-qPCR kits (vDetect COVID-19-MultiplexDX, gb SARS-CoV-2 Multiplex-GENERI BIOTECH Ltd. and Genvinset COVID-19 [E]-BDR Diagnostics) in the detection of infected individuals among employees of the Martin University Hospital in Slovakia. Health care providers, such as doctors and nurses, are classified as "critical infrastructure", and there is no doubt about the huge impact that incorrect results could have on patients. Out of 1231 samples, 14 were evaluated as positive for SARS-CoV-2 antigen presence, and all of them were confirmed by RT-qPCR kit 1 and kit 2. As another 26 samples had a signal in the E gene, these 40 samples were re-isolated and subsequently re-analysed using the three kits, which detected the virus in 22, 23 and 12 cases, respectively. The results point to a divergence not only between antigen and RT-qPCR tests, but also within the "gold standard" RT-qPCR testing. Performance analysis of the diagnostic antigen test showed the positive predictive value (PPV) to be 100% and negative predictive value (NPV) to be 98.10%, indicating that 1.90% of individuals with a negative result were, in fact, positive. If these data are extrapolated to the national level, where the mean daily number of antigen tests was 250,000 in April 2021, it points to over 4700 people per day being misinterpreted and posing a risk of virus shedding. While mean Ct values of the samples that were both antigen and RT-qPCR positive were about 20 (kit 1: 20.47 and 20.16 for Sarbeco E and RdRP, kit 2: 19.37 and 19.99 for Sarbeco E and RdRP and kit 3: 17.47 for ORF1b/RdRP), mean Ct values of the samples that were antigen-negative but RT-qPCR-positive were about 30 (kit 1: 30.67 and 30.00 for Sarbeco E and RdRP, kit 2: 29.86 and 31.01 for Sarbeco E and RdRP and kit 3: 27.47 for ORF1b/RdRP). It confirms the advantage of antigen test in detecting the most infectious individuals with a higher viral load. However, the reporting of Ct values is still a matter of ongoing debates and should not be conducted without normalisation to standardised controls of known concentration.

Early postnatal changes in superior mesenteric artery blood flow velocity in healthy term infants.

OBJECTIVES: After birth, the newborn intestinal circulation undergoes physiological changes. The purpose of this work was to characterize the changes in mesenteric blood flow velocity occuring during the first three days of life in healthy term infants. METHODS: 30 healthy term newborns were studied repeatedly at the age of 2, 24 and 70 hours. Blood flow velocity in superior mesenteric artery (SMA) was measured by Doppler ultrasound, peak systolic velocity (PSV), end-diastolic velocity (EDV) and time-averaged mean velocity (TAV) were recorded at each time point. Resistance index (RI) and pulsatility index (PI) were calculated. RESULTS: SMA EDV increased from 2 h [-5.2+/-6.8 cm/s (mean +/- SD)] to 24 h (12.9+/-3.8 cm/s, p<0.001) with further insignificant increase to 70 h (14.9+/-4.7 cm/s). At 2 h of age the mean EDV was negative in 23 of 30 cases (76.7%). PSV did not change between 2 h (58.0+/-21.8 cm/s) and 24 h (58.5+/-15.0 cm/s) but it increased to 70 h (79.6+/-17.7 cm/s). TAV showed a significant increase with time. RI decreased from 2 h (1.09+/-0.11) to 24 h (0.78+/-0.06, p<0.001) with further insignificant increase to 70 h (0.81+/-0.06). CONCLUSIONS: The blood flow velocity in SMA increases during the early neonatal period in term infants. The most remarkable changes occur within the first 24 hours of life. At 2 h of age a reversed blood flow is present in majority of infants.

Two novel RFX6 variants in siblings with Mitchell-Riley syndrome with later diabetes onset and heterotopic gastric mucosa.

Mitchell-Riley syndrome, an autosomal recessive disorder caused by mutations in the RFX6 gene, is defined as a combination of neonatal diabetes mellitus and serious congenital gastrointestinal defects. We describe Mitchell-Riley syndrome in two sisters with two novel compound heterozygous variants in the RFX6 gene: c.1154G > A, p.(Arg385Gln), and c.1316_1319delTCTA, p.(Ile439Thrfs*13). Both sisters present milder forms of the syndrome, likely due to possible residual activity of the p.Arg385Gln variant, which is localized in a dimerization domain of the RFX6 transcription factor. We propose that the prognosis is dependent on patient RFX6 genotype and possible residual activity of RFX6 transcription factor. Both sisters had atypical later onset of diabetes, at 2 years and 10 months and 2 years and 7 months, respectively. This supports the need of extending the definition of diabetes in Mitchell-Riley syndrome from neonatal to childhood onset and regular glyceamia check in patients with gastrointestinal tract malformations typical for Mitchell-Riley syndrome. The clinical course in both sisters improved significantly after surgical removal of parts of the small intestine with heterotopic gastric mucosa. We suggest that gastric mucosa heterotopy is an important actionable part of Mitchell-Riley syndrome and could have been responsible for the malabsorption, failure to thrive and severe anemia present in previously reported patients with Mitchell-Riley syndrome.

Comparison of Doppler parameters of central versus intraparenchymal renal arteries in physiologically normal newborns.

BACKGROUND: Changes in renal arterial Doppler flow may identify parenchymal disease, but in newborns knowledge of normal physiological parameters is a prerequisite for correct interpretation. OBJECTIVE: To evaluate renal blood flow in healthy newborns by means of Doppler US. MATERIALS AND METHODS: On the fourth day of life we examined 100 normal term newborn infants (200 kidneys). Blood flow in the central renal arteries was compared with that in the intraparenchymal arteries. Maximum systolic velocity ( V(max)), end-diastolic velocity ( V(ed)), mean flow velocity ( V(mean)), resistive index (RI) and pulsatility index (PI) were assessed. RESULTS: All parameters were significantly higher in the central renal arteries than in the intraparenchymal arteries (RI 0.78+/-0.07 vs 0.62+/-0.05, P<0.0001; PI 1.84+/-0.52 vs 1.09+/-0.18, P<0.0001). CONCLUSIONS: Physiological data are presented that are necessary for the correct interpretation of neonatal Doppler US.