Evaluation of the analytical performance of the 15-minute point-of-care DASH™ SARS-CoV-2 RT-qPCR test.

Accurate and timely diagnosis for COVID-19 diagnosis allows highly effective antiviral medications to be prescribed. The DASH™ Rapid PCR System is a sample-to-answer point-of-care platform combining state-of-the-art PCR kinetics with sequence specific hybridization. The platform's first assay, the DASH™ SARS-CoV-2/S test for anterior nares direct swab specimens, received FDA Emergency Use Authorization in March 2022 for point-of-care use. Here we report the analytical characteristics of the assay including limit of detection, dynamic range, and robustness of SARS-CoV-2 variant detection. The limit of detection was determined by testing swabs contrived with one hundred copies of wild type or Omicron BA.5 virus and detecting 20/20 and 19/20, respectively. The dynamic range was assessed with contrived swabs containing 102-106 copies; the log-linear relationship between Cq and copy input was plotted, and the qPCR efficiency calculated from the slope of the line was 101.4%. Detection of seven SARS-CoV-2 variants was demonstrated.

Taxonomic characterization of Pseudomonas hygromyciniae sp. nov., a novel species discovered from a commercially purchased antibiotic.

In an attempt to identify novel bacterial species, microbiologists have examined a wide range of environmental niches. We describe the serendipitous discovery of a novel gram-negative bacterial species from a different type of extreme niche: a purchased vial of antibiotic. The vial of antibiotic hygromycin B was found to be factory contaminated with a bacterial species, which we designate Pseudomonas hygromyciniae sp. nov. The proposed novel species belongs to the P. fluorescens complex and is most closely related to P. brenneri, P. proteolytica, and P. fluorescens. The type strain Pseudomonas hygromyciniae sp. nov. strain SDM007T (SDM007T) harbors a novel 250 kb megaplasmid which confers resistance to hygromycin B and contains numerous other genes predicted to encode replication and conjugation machinery. SDM007T grows in hygromycin concentrations of up to 5 mg/mL but does not use the antibiotic as a carbon or nitrogen source. While unable to grow at 37°C ruling out its ability to infect humans, it grows and survives at temperatures between 4 and 30°C. SDM007T can infect plants, as demonstrated by the lettuce leaf model, and is highly virulent in the Galleria mellonella infection model but is unable to infect mammalian A549 cells. These findings indicate that commercially manufactured antibiotics represent another extreme environment that may support the growth of novel bacterial species. IMPORTANCE Physical and biological stresses in extreme environments may select for bacteria not found in conventional environments providing researchers with the opportunity to not only discover novel species but to uncover new enzymes, biomolecules, and biochemical pathways. This strategy has been successful in harsh niches such as hot springs, deep ocean trenches, and hypersaline brine pools. Bacteria belonging to the Pseudomonas species are often found to survive in these unusual environments, making them relevant to healthcare, food, and manufacturing industries. Their ability to survive in a variety of environments is mainly due to the high genotypic and phenotypic diversity displayed by this genus. In this study, we discovered a novel Pseudomonas sp. from a desiccated environment of a sealed antibiotic bottle that was considered sterile. A close genetic relationship with its phylogenetic neighbors reiterated the need to use not just DNA-based tools but also biochemical characteristics to accurately classify this organism.