Infecciones respiratorias virales en episodios de fiebre en niños con trasplante de precursores hematopoyéticos

Abstract Background: Children undergoing hematopoietic stem cell transplant (HSCT) can develop respiratory viral infections (RVI) during fever episodes. There are few data about clinical outcomes in RVI and compared to bacterial infections (BI) in this population. Aim: To determine clinical outcome of RVI, compared to BI in children with HSCT. Methods: Prospective study, patients ≤ 18 years with cancer and HSCT admitted with fever at a National Bone Marrow Transplant Center (Hospital Calvo Mackenna), Chile, (April-2016 to May-2019). Clinical assessment, laboratory tests, blood cultures, nasopharyngeal sample for multiplex-PCR (Filmarray®), viral loads by PCR and cytokine panel (Luminex®, 38 cytokines) were performed. The following outcomes were evaluated: upper/lower respiratory tract disease (RTD), admission to ICU, mechanical ventilation, mortality and antimicrobial withdrawal. Results: Of 56 febrile episodes, 35 (63%) were RVI, 12 (21%) BI and 9 (16%) with unknown etiology (UE). Median of age was 8.5 years, 62% male gender. Rhinovirus (54%) and coronavirus (15%) were the more frequent detected viruses. No significant differences in cytokine levels were observed between RVI and BI. 94% of RVI patients had symptomatic RTD, versus 33% in BI and 33% in UE group (p < 0.001), with lower-RTD in 69% of RVI group (p < 0,001). Admission to ICU was 11% in RVI, 17% in BI and 11% in UE group (p = 0.88);only 2 patients required mechanical ventilation (p = 0.37) and no mortality was reported. After an RVI was detected by PCR, antimicrobials were withdrawal in 26% of patients with RVI (p: 0.04). Conclusion: RVI are frequent etiologic agents in febrile episodes of patients with HSCT. Viral detection might help to rationalize the use of antimicrobials in this population.

Performance of SARS-CoV-2 rapid antigen test compared with real-time RT-PCR in asymptomatic individuals.

Screening, testing and contact tracing plays a pivotal role in control of the COVID-19 pandemic. To enable this it is necessary to increase the testing capacity. This study compared a SARS-CoV-2 rapid antigen test (RAT) and RT-PCR in 842 asymptomatic individuals from Tarapacá, Chile. A sensitivity of 69.86%, specificity of 99.61%, PPV of 94.44% and NPP of 97.22% with Ct values (Ct > 27) that were significantly higher among individuals with false-negative RAT were reported. These results support the fact that RAT might have a significant impact on the identification of asymptomatic carriers in areas that lack suitable laboratories to perform SARS-CoV-2 real-time RT-PCR diagnostics, or the results take more than 24-48 h, as well as zones with high traffic of individuals such as border/customs, airports, interregional bus, train stations or in any mass testing campaign requiring rapid results.

Optimizing RT-PCR detection of SARS-CoV-2 for developing countries using pool testing

The global shortage of reagents and kits for nucleic acid extraction and molecular detection of SARS-CoV-2 requires new cost-effective strategies for the diagnosis of suspected COVID-19 cases, especially in countries that need to increase detection capacity. Pooled nucleic acid testing has been extensively used as a cost-effective strategy for HIV, HepB, HepC and influenza. Also, protocols dispensing of RNA extraction appears as an attractive option for detection of SARS-CoV-2. In this study, we found that pooling of 5 samples showed that CT variations were in the range of 1.0-4,5 units, with less likelihood of a false negative result. Results of the sample without nucleic acid ex-traction, was unsatisfactory, with a significant increase in CT values, and thus for risk of a false negative result. In conclusion, pooling nasopharyngeal samples with both automated and manual extraction proved reliable, and thus a potential efficient alternative for the diagnosis of suspected COVID-19 in developing countries. Resumen La escasez mundial de reactivos para la extracción de ácidos nucleicos y la detección molecular de SARS-CoV-2 requiere de nuevas estrategias de mayor rendimiento para el diagnóstico de casos sospechosos de COVID-19, especialmente en países que necesitan aumentar su capacidad diagnóstica. La detección de ácidos nucleicos en muestras agrupadas o pool testing se ha utilizado ampliamente como una estrategia costo-efectiva para el VIH, hepatitis B, hepatitis C e influenza. Adicionalmente, los protocolos que no requieren extracción de ARN aparecen como una opción para la detección de SARS-CoV-2. En este trabajo, presentamos los resultados de una estrategia detección de SARS-CoV-2 en muestras agrupadas, que incluye diferentes métodos de extracción de ARN que puede ser una estrategia atractiva para los países en desarrollo. La agrupación de 5 muestras mostró variaciones CT en el rango de 1,0 a 4,5 unidades, con una baja probabilidad de obtener falsos negativos, a diferencias de los resultados agregando muestras agrupadas directamente en la reacción de amplificación de SARS-CoV-2. En conclusión, la agrupación de muestras nasofaríngeas, demostró ser un método confiable y, por lo tanto, una alternativa para aumentar el rendimiento en el diagnóstico de COVID-19 para países en desarrollo.

Optimizing RT-PCR detection of SARS-CoV-2 for developing countries using pool testing.

The global shortage of reagents and kits for nucleic acid extraction and molecular detection of SARS-CoV-2 requires new cost-effective strategies for the diagnosis of suspected COVID-19 cases, especially in countries that need to increase detection capacity. Pooled nucleic acid testing has been extensively used as a cost-effective strategy for HIV, HepB, HepC and influenza. Also, protocols dispensing of RNA extraction appears as an attractive option for detection of SARS-CoV-2. In this study, we found that pooling of 5 samples showed that CT variations were in the range of 1.0-4,5 units, with less likelihood of a false negative result. Results of the sample without nucleic acid ex-traction, was unsatisfactory, with a significant increase in CT values, and thus for risk of a false negative result. In conclusion, pooling nasopharyngeal samples with both automated and manual extraction proved reliable, and thus a potential efficient alternative for the diagnosis of suspected COVID-19 in developing countries.