Performance of Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) Targeting the RNA Polymerase Gene for the Direct Detection of SARS-CoV2 in Nasopharyngeal Swabs.

In 2020, a global pandemic caused by SARS-CoV-2 was declared. Different institutes proposed diagnostic molecular methods to detect the virus in clinical samples. This study aims to validate and standardize the use of a loop-mediated isothermal amplification (LAMP)-based methodology targeting the viral RP gene, as a faster and low-cost diagnostic method for SARS-CoV-2 infections. The results obtained with RT-LAMP (Reverse Transcriptase) were compared to the results of real-time polymerase chain reaction (RT-PCR) to assess its sensitivity and specificity. In total, 115 samples (nasopharyngeal samples) were used for detecting SARS-CoV-2 by RT-LAMP, with 43 positives and 72 negatives. The study showed a positive predictive value (PPV) of 90.7% and a negative predictive value (VPN) of 100%. The LAMP assay also demonstrated a high sensitivity of 90.7% and a specificity of 100% (confidence interval 77.9-97.4%) when using the lower detection limit of 40 copies/µL. The RT-LAMP described here has the potential to detect even the new variants of SARS-CoV-2, suggesting that it may not be significantly affected by gene mutations. The RT-LAMP targeting the RP viral region is faster and less expensive than other molecular approaches, making it an alternative for developing countries.

Bactéria cromogênica associada a manchas negras / Black-spotted chromogenic bactéria

Objetivos: Este trabalho tem como objetivo avaliar a associação das bactérias Prevotella Melaninogênica e Actinomyces ao biofilme escuro em dentes permanentes. Relato de Caso: Um paciente apresentou manchas enegrecidas ao longo do contorno cervical dos dentes foi convidado a participar do presente estudo. Foi coletado com o auxílio de uma cureta estéril, uma parte deste biofilme que transferido para um eppendorff contendo soro fisiológico. O material coletado foi agitado em um Vórtex por 15 segundos e em seguida, inoculadas em 100 microlitros (µl) da solução em um meio de ágar sangue suplementado com Canamicina 5%, seguido de cultivo por 72 horas. A partir do crescimento bacteriano, as mesmas foram isoladas em ágar macconkey, chocolate e sangue em anaerobiose. Em seguida foram realizados testes de bioquimismo, utilizando-se os meios MIO (motilidade, indol e ornitina), citrato, TSI (triplo açúcar com ferro) e LIA (ágar lisina com ferro). Conclusão: Através das características clínicas associadas ao bioquimismo empregado nos testes, podemos concluir que a bactéria que está associada as manchas negras presentes no paciente é do gênero prevotella spp(AU)

Objectives: This study aims to evaluate the association of Prevotella Melaninogenic and Actinomyces bacteria with dark biofilm in permanent teeth. Case Report: A patient with black spots along the cervical contour of the teeth was invited to participate in the present study. After its clarification and acceptance, completing the IC, was collected with the aid of a sterile curette, a part of this biofilm that was inserted into an eppendorff containing saline. The collected material was vortexed for 15 seconds and then inoculated into 100 microliters (µl) of the solution in a 5% kanamycin supplemented blood agar medium, followed by cultivation for 72 hours. From bacterial growth, they were isolated on macconkey agar, chocolate and anaerobic blood. Biochemical tests were then performed using MIO (motility, indole and ornithine), citrate, TSI (triple sugar with iron) and LIA (iron lysine agar) media. Conclusion: Through the clinical characteristics associated with the biochemism employed in the tests, we can conclude that the bacteria that is associated with black spots present in the patient is of the genus prevotella spp(AU)