Development of a rapid phenotypic test on a microfluidic device for carbapenemase detection using the chromogenic compound nitrocefin

Nanoplasmonic Rapid Antimicrobial-Resistance Point-of-Care Identification Device: RAPIDx

The emergence of antibiotic resistance has become a global health crisis, and everyone must arm themselves with wisdom to effectively combat the "silent tsunami" of infections that are no longer treatable with antibiotics. However, the overuse or inappropriate use of unnecessary antibiotics is still routine for administering them due to the unavailability of rapid, precise, and point-of-care assays. Here, a rapid antimicrobial-resistance point-of-care identification device (RAPIDx) is reported for the accurate and simultaneous identification of bacterial species (genotype) and target enzyme activity (phenotype). First, a contamination-free active target enzyme is extracted via the photothermal lysis of preconcentrated bacteria cells on a nanoplasmonic functional layer on-chip. Second, the rapid, precise identification of pathogens is achieved by the photonic rolling circle amplification of DNA on a chip. Third, the simultaneous identification of bacterial species (genotype) and target enzyme activity (phenotype) is demonstrated within a sample-to-answer 45 min operation via the RAPIDx. It is believed that the RAPIDx will be a valuable method for solving the bottleneck of employing on-chip nanotechnology for antibiotic-resistant bioassay and other infectious diseases.

High-Throughput, Quantitative Screening of Quorum-Sensing Inhibitors Based on a Bacterial Biosensor

Quorum sensing (QS) is a cell-cell communication mechanism by which bacteria synchronize social behaviors such as biofilm formation and virulence factor secretion by producing and sensing small molecular signals. Quorum quenching (QQ) by degrading signals or blocking signal transmissions has become a promising strategy for disrupting QS and preventing bacterial infection and biofilm formation. However, studies of high-throughput screening and identification approaches for quorum-sensing inhibitors (QSIs) are still inadequate. In this work, we developed a sensitive, high-throughput approach for screening QSIs based on the bacterial biosensor strain Agrobacterium tumefaciens N5 (pBA7P), which contains a traG gene promoter induced by QS signals fused with a promoterless β-lactamase gene reporter. Using this approach, we identified 31 QQ bacteria from ∼2000 soil bacterial isolates, some belonging to the genera Bosea, Cupriavidus, and Flavobacterium that have not been reported previously as QQ bacteria. We also identified four QS inhibitory compounds and one QS signal analogue from ∼5000 small-molecule compounds, which profoundly affected the expression of QS-regulated genes and phenotypes of the pathogenic bacteria. This high-throughput screening system is effective and sensitive for screening of both QQ microbes and small molecules, enabling the discovery of a wide variety of biocompatible compounds.

Nanotechnology Approaches for Rapid Detection and Theranostics of Antimicrobial Resistant Bacterial Infections

As declared by WHO, antimicrobial resistance (AMR) is a high priority issue with a pressing need to develop impactful technologies to curb it. The rampant and inappropriate use of antibiotics due to the lack of adequate and timely diagnosis is a leading cause behind AMR evolution. Unfortunately, populations with poor economic status and those residing in densely populated areas are the most affected ones, frequently leading to emergence of AMR pathogens. Classical approaches for AMR diagnostics like phenotypic methods, biochemical assays, and molecular techniques are cumbersome and resource-intensive and involve a long turnaround time to yield confirmatory results. In contrast, recent emergence of nanotechnology-assisted approaches helps to overcome challenges in classical approaches and offer simpler, more sensitive, faster, and more affordable solutions for AMR diagnostics. Nanomaterial platforms (metallic, quantum-dot, carbon-based, upconversion, etc.), nanoparticle-based rapid point-of-care platforms, nano-biosensors (optical, mechanical, electrochemical), microfluidic-assisted devices, and importantly, nanotheranostic devices for diagnostics with treatment of AMR infections are examples of rapidly growing nanotechnology approaches used for AMR management. This review comprehensively summarizes the past 10 years of research progress on nanotechnology approaches for AMR diagnostics and for estimating antimicrobial susceptibility against commonly used antibiotics. This review also highlights several bottlenecks in nanotechnology approaches that need to be addressed prior to considering their translation to clinics.