RESUMO
BackgroundSince the beginning of the pandemic, clinicians and researchers have been searching for alternative tests to improve screening and diagnosis of SARS-CoV-2 infection (Y. Yang et al., medRxiv 2020; W. Wang et al., 2020.3786; A Senok et al., Infect Drug Resist 2020). Currently, the gold standard for virus identification is the nasopharyngeal (NP) swab (N. Sethuraman et al., JAMA 2020; A.J. Jamal et al Clinical Infect Disease 2021). Saliva samples, however, offer clear practical and logistical advantages (K.K.W To et al, Clinical Microb and Infect; A.L. Wylle et al. N Engl J Med 2020; N. Matic et al, Eur J Clin 2021) but due to lack of collection, transport, and storage solutions, high-throughput saliva-based laboratory tests are difficult to scale up as a screening or diagnostic tool (D. Esser et al., Biomark Insights 2008; E. Kaufman et al., Crit Rev Oral Biol Med2002). With this study, we aimed to validate an intra-laboratory molecular detection method for SARS-CoV-2 on saliva samples collected in a new storage saline solution, comparing the results to NP swabs to determine the difference in sensitivity between the two tests. MethodsIn this study, 156 patients (cases) and 1005 asymptomatic subjects (controls) were enrolled and tested simultaneously for the detection of the SARS-CoV-2 viral genome by RT-PCR on both NP swab and saliva samples. Saliva samples were collected in a preservative and inhibiting saline solution (Biofarma Srl). Internal method validation was performed to standardize the entire workflow for saliva samples. ResultsThe identification of SARS-CoV-2 conducted on saliva samples showed a clinical sensitivity of 95.1% and specificity of 97.8% compared to NP swabs. The positive predictive value (PPV) was 81% while the negative predictive value (NPV) was 99.5%. Test concordance was 97.6% (Cohens Kappa=0.86; 95% CI 0.81-0.91). The LoD of the test was 5 viral copies for both samples. ConclusionsRT-PCR assays conducted on a stored saliva sample achieved similar performance to those on NP swabs and this may provide a very effective tool for population screening and diagnosis. Collection of saliva in a stabilizing solution makes the test more convenient and widely available; furthermore, the denaturing properties of the solution reduce the infective risks belonging to sample manipulation.
RESUMO
Mass screening aimed at detecting, in asymptomatic subjects, the presence of SARS-CoV-2 is considered a strategic measure for the control of the present pandemic. It allows virus carriers to be identified and quarantined, thus preventing local spread and protecting vulnerable individuals. Although the screening strategy should be determined by the epidemiological situation, the size of the population that can be screened is indeed limited by the availability of resources. Here we present the implementation of an 8-sample pool strategy that relies on protocols, reagents and equipment currently used in clinical diagnostics. The method permitted to identify, with 100% sensitivity, specificity and accuracy, samples with low viral load, being the limit of detection of 11 viral copies extracted from the equivalent of 133l of nasopharyngeal sample-pool. When the protocol has been applied, as a proof of principle, in a real population of 3592 consecutive nasopharyngeal swabs collected by healthcare providers in asymptomatic subjects, 20 positive pools were detected and in 100% of cases the positive specimens identified. Considering these performances, the 8-sample pool will allow, in populations with an expected positive rate of less than 1%, reducing costs by at least 80%, being a suitable method for a sustainable mass screening strategy in a population of asymptomatic subjects.
RESUMO
ABSTRACT: Despite the fact that cold storage and modified atmosphere techniques have already been studied for fresh cut Star fruit, little has been done considering the whole fruit. Besides that, each cultivar has its peculiarities, so the efficiency of combined postharvest treatments should be studied. The objective of this study was to evaluate the effect of polyvinyl chloride (PVC), 8.5 µm thick and low-density polyethylene (LDPE), 33 µm thick associated with cold storage (10 ± 1 °C and 5 ± 1 °C / 85 ± 5% RH) on the conservation of 'Malasia' Star fruit. Storage at 25 oC maintained Star fruit overall quality, regardless of the film type, up to four days. The weight loss was higher in fruit packed with PVC, but this fact was not noticed by the sensory analysis. The storage in 5 and 10 oC did not caused chilling injury but fruit presented retention of yellow color development and firmness reduction; these aspects were positively assessed by the sensory analysis. The film type did not influence the conservation of the fruit. The storage at 5 and 10 °C, regardless of the package film, prolonged 'Malasia' star fruit shelf life up to 16 days, followed by two days at 25 °C.
RESUMO: Apesar das técnicas de armazenamento refrigerado e atmosfera modificada já terem sido estudadas para carambolas processadas, pouco foi feito considerando a fruta inteira. Além disso, cada cultivar possui peculiaridades, dessa forma a eficiência dos tratamentos pós-colheita combinados deve ser estudada. O objetivo deste trabalho foi avaliar o efeito do cloreto de polivinila (PVC), 8,5 µm de espessura e polietileno de baixa densidade (PEBD), 33 µm de espessura associados ao armazenamento refrigerado (10 ± 1 °C e 5 ± 1 °C / 85 ± 5% de UR) na conservação da carambola Malasia. O armazenamento a 25 °C manteve a qualidade da carambola, independentemente do tipo de filme, até quatro dias. A perda de massa foi maior nos frutos embalados em PVC, mas esta não foi percebida pela análise sensorial. As temperaturas de armazenamento de 5 e 10 °C não causaram dano de frio, mas os frutos apresentaram retenção no desenvolvimento da coloração amarela e na redução da firmeza; esses aspectos foram avaliados positivamente na análise sensorial. O tipo de filme não influenciou a conservação do fruto. O armazenamento a 5 e 10 °C, independente do filme da embalagem, prolongou a vida útil da carambola 'Malasia' até 16 dias, seguido por dois dias a 25 °C.
