The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus (SARS-CoV)-2, is rapidly spreading and severely straining the capacities of public health communities and systems around the world. Therefore, accurate, rapid, and robust diagnostic tests for COVID-19 are crucial to prevent further spread of the infection, alleviate the burden on healthcare and diagnostic facilities, and ensure timely therapeutic intervention. To date, several detection methods based on nucleic acid amplification have been developed for the rapid and accurate detection of SARS-CoV-2. Despite the myriad of advancements in the detection methods for SARS-CoV-2, rapid sample preparation methods for RNA extraction from viruses have rarely been explored. Here, we report a rapid COVID-19 molecular diagnostic system that combines a self-powered sample preparation assay and loop-mediated isothermal amplification (LAMP) based naked-eye detection method for the rapid and sensitive detection of SARS-CoV-2. The self-powered sample preparation assay with a hydrophilic polyvinylidene fluoride filter and dimethyl pimelimidate can be operated by hand, without the use of any sophisticated instrumentation, similar to the reverse transcription (RT)-LAMP-based lateral flow assay for the naked-eye detection of SARS-CoV-2. The COVID-19 molecular diagnostic system enriches the virus population, extracts and amplifies the target RNA, and detects SARS-CoV-2 within 60 min. We validated the accuracy of the system by using 23 clinical nasopharyngeal specimens. We envision that this proposed system will enable simple, facile, efficient, and inexpensive diagnosis of COVID-19 at home and the clinic as a pre-screening platform to reduce the burden on the medical staff in this pandemic era.

The spin-column system for the isolation of nucleic acids (NAs) from multiple samples presents the inconvenience of repeated experimentation, time-consumption, and the risk of contamination in the process of the spin-column exchange. Herein, we propose a convenient and universal assay that can be used to diagnose multiple pathogens using a multi-sample preparation assay. The multi-sample preparation assay combines a 96-well filter/membrane plate, a bio-micromaterial lattice-like micro amine-functional diatomaceous earth (D-APDMS), and homobifunctional imidoesters (HI) for the processing of pathogen enrichment and extraction for multiple samples simultaneously. The purity and quantity of the extracted NAs from pathogens (E. coli and Brucella) using the proposed assay is superior to that of the commercialized spin-column kit. The assay also does not require the replacement of several collection tubes during the reaction processing. For the multi-sample testing, we used as many as six samples simultaneously with the proposed assay. This assay can simultaneously separate up to 96 NAs from one plate, and the use of multichannel pipettes allows faster and simpler experimentation. Therefore, we believe it is a convenient and easy process, and can be easily integrated with other detection methods for clinical diagnostics.

Background: Scrub typhus is commonly misdiagnosed because of nonspecific clinical features and limited data on the performance of diagnostic tests. This study aimed to evaluate the accuracy of commercially available serological and molecular assays for diagnosing scrub typhus. Methods: Adult patients with suspected scrub typhus who visited a tertiary-care hospital in South Korea from July 2022 to December 2024 were prospectively enrolled. Scrub typhus was confirmed by either a positive real-time polymerase chain reaction (PCR) result for Orientia tsutsugamushi or a ≥ four-fold increase in the O. tsutsugamushi-specific total immunoglobulin (Ig) antibody titer on an immunofluorescence assay (IFA). The diagnostic performances of the serial IFA, an immunochromatography-based rapid diagnostic test (ICT), and multiplex real-time PCR targeting the groEL and 47-kDa genes were compared. Results: Among 159 patients, 81 had scrub typhus and 78 did not. The sensitivity and specificity were 64% and 100% for the serial IFA, 75% and 91% for the ICT, and 95% and 100% for multiplex PCR, respectively. The area under the curve was significantly higher for the ICT (0.819) than for the acute-phase IFA (0.743, p = 0.02). Conclusions: Multiplex real-time PCR provided rapid and highly accurate confirmation of scrub typhus, and an acute-phase ICT may be an alternative to a single acute-phase IFA for early clinical decision-making.