Cascade filtration and droplet digital detection integrated microfluidic assay enables isolating culture-free phenotypic identification of carbapenem-resistant organisms.

Carbapenem-resistant organisms (CROs) are characterized by high drug resistance, rapid transmission, and high lethality. Therefore, rapid detection for CROs is essential for appropriate applying antibiotics and implementing quarantine. Droplet digital chromogenic assays (DDCA) have been accepted as an effective means for rapid microbial detection as the small droplet volumes facilitate a significant enhancement in the local concentration of chromogenic factors and, therefore, reduce the required time of the test. Nevertheless, as their dependence on the time-consuming isolation culture, the DDCA is still associated with a long turnaround time. To overcome this limitation, we develop here a microfluidic chip-based CRO phenotypic identification method that integrates cascade filtration (CF) with DDCA (CF-DDCA). After a body fluid sample is introduced to the microfluidic chip, particles with sizes >5 µm are removed out by the primary filter, and Gram (+) cocci with sizes <1 µm removed out by the secondary filter so that only Gram (-) bacilli with sizes between 1.5 and 5 µm are selectively retained. The purified Gram (-) bacilli, along with chromogenic reagents and carbapenem antibiotics, are then subjected to the DDCA. We demonstrate that the CF can remove 99.9% of the interfering microorganisms and thus eliminates the isolating culture. Benefited from the isolating culture-free DDCA, phenotypic identification of CROs can be achieved within 3.5 h. Clinical urine sample testing shows that the sensitivity and specificity of the CF-DDCA for CRO identification are all 100%, and the total coincidence rate between CF-DDCA and the conventional assay is also 100%.

A pocket-sized device automates multiplexed point-of-care RNA testing for rapid screening of infectious pathogens.

Rapid screening of infectious pathogens at the point-of-care (POC) is ideally low-cost, portable, easy to use, and capable of multiplex detection with high sensitivity. However, satisfying all these features in a single device without compromise remains a challenging task. Here, we introduce an ultraportable, automated RNA amplification testing device that allows rapid screening of infectious pathogens from clinical samples. In this device, 3D-printed structural parts incorporated with off-the-shelf mechanic/electronic components are utilized to create an inexpensive and automated droplet manipulation platform. On this platform, a simple configuration that couples a linear displacement of the chip with a tunable magnet array allows parallel and versatile droplet operations, including mixing, splitting, transporting, and merging. By exploiting a multi-channel droplet array chip to preload necessary reagents in "water-in-oil" format, bacteria lysis, RNA extraction and amplification are seamlessly integrated and implemented by the combination of droplet operations. Furthermore, visual readout and geometrically-multiplexed quantitative detection are provided by an integrated wireless video camera-enabled wide-field fluorescence imaging. We demonstrated that this droplet-based device could have a shorter RNA extraction time (12 min) and lower detection limits for pathogenic RNA (approaching to 102 copies per reaction). We also verified its clinical applicability for the rapid screening of four sexually transmitted pathogens from urine specimens. Results show that the sample-to-answer assay could be completed in approximately 42 min, with 100% concordance with the laboratory-based molecular testing. The exhibiting features may render this microdevice an easily accessible POC molecular diagnostic platform for infectious disease, especially in resource-limited settings.

Misidentification of Burkholderia pseudomallei, China.

We report a case of melioidosis in China and offer a comparison of 5 commercial detection systems for Burkholderia pseudomallei. The organism was misidentified by the VITEK 2 Compact, Phoenix, VITEK mass spectrometry, and API 20NE systems but was eventually identified by the Bruker Biotyper system and 16S rRNA sequencing.

In Situ Li3PO4/PVA Solid Polymer Electrolyte Protective Layer Stabilizes the Lithium Metal Anode.

A lithium metal anode is regarded as the most promising anode material for the next generation of high-energy density batteries because of its high specific capacity and low reduction potential. However, dendritic deposition and severe side reactions in continuous Li plating/stripping inevitably hinder the practical application of Li metal batteries. A solid polymer electrolyte protective layer with synergistic Li3PO4/polyvinyl alcohol (PVA) features is in situ constructed on a lithium metal anode to obtain a stable interface during charge/discharge cycles. The protective layer can adapt to volume changes and inhibit lithium dendrites. The in situ reaction guaranteed the uniformity of ion transport and a tight interface between the protective layer and the lithium metal, so that the lithium deposition behavior was effectively regulated. The PP-Li anode presented a stable Li plating/stripping for 1000 h in a symmetrical cell system and exhibited an enhanced performance of the lithium titanium oxide cell. The in situ Li3PO4/PVA solid polymer electrolyte protective layer provided a promising strategy to tackle the challenges raised by the intrinsic properties of the lithium metal anode.