Rapid antimicrobial susceptibility testing (AST) is urgently needed for treating infections with appropriate antibiotics and slowing down the emergence of antibiotic-resistant bacteria. Here, a phenotypic platform that rapidly produces AST results by femtosecond stimulated Raman scattering imaging of deuterium oxide (D 2 O) metabolism is reported. Metabolic incorporation of D 2 O into biomass in a single bacterium and the metabolic response to antibiotics are probed in as short as 10 min after culture in 70% D 2 O medium, the fastest among current technologies. Single-cell metabolism inactivation concentration (SC-MIC) is obtained in less than 2.5 h from colony to results. The SC-MIC results of 37 sets of bacterial isolate samples, which include 8 major bacterial species and 14 different antibiotics often encountered in clinic, are validated by standard minimal inhibitory concentration blindly measured via broth microdilution. Toward clinical translation, stimulated Raman scattering imaging of D 2 O metabolic incorporation and SC-MIC determination after 1 h antibiotic treatment and 30 min mixture of D 2 O and antibiotics incubation of bacteria in urine or whole blood is demonstrated.

The widespread use of antibiotics has significantly increased the number of resistant bacteria, which has also increased the urgency of rapid bacterial detection and profiling their antibiotic response. Current clinical methods for antibiotic susceptibility testing (AST) rely on culture and require at least 16 to 24 h to conduct. Therefore, there is an urgent need for a rapid method that can test the susceptibility of bacteria in a culture-free manner. Here we demonstrate a rapid AST method by monitoring the glucose metabolic activity of live bacteria at the single-cell level with hyperspectral stimulated Raman scattering (SRS) imaging. Using vancomycin-susceptible and -resistant enterococci E. faecalis as models, we demonstrate that the metabolic uptake of deuterated glucose in a single living bacterium can be quantitatively monitored via hyperspectral SRS imaging. Remarkably, the metabolic activity of susceptible bacteria responds differently to antibiotics from the resistant strain within only 0.5 h from the addition of antibiotics. Therefore, bacterial susceptibility and the minimum inhibitory concentration (MIC) of antibiotics can be determined within one cell cycle. Our metabolic imaging method is applicable to other bacteria species including E. coli, K. Pneumoniae, and S. aureus as well as different antibiotics, regardless of their mechanisms of inhibiting or killing bacteria.

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With the development and rising of antimicrobial resistance, rapid and effective killings of bacteria are urgently needed, especially for antibiotic-resistant bacteria and bacterial biofilms that are usually hard to be treated with conventional antibiotics. Here, a rapid and broad-spectrum antibacterial strategy is demonstrated through photothermal ablation with MXene and light. Ti 3 C 2 MXenes, when combined with 808 nm light, show significant antibacterial effects in just 20 min. The antibacterial strategy is effective to 15 bacterial species tested, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). In addition, the rapid antibacterial strategy works for MRSA biofilms, by damaging the structures as well as killing bacteria in biofilms. Furthermore, the investigation of the antibacterial mechanisms shows that Ti 3 C 2 with light kills bacteria mainly physically through inserting/contact and photothermal effect. This work broadens the potential applications of MXene and provides a way to eradicate bacteria and biofilms physically, without the likelihood of resistance development.

RNAs have diverse structures that include bulges and internal loops able to form tertiary contacts or serve as ligand binding sites. The recent increase in structural and functional information related to RNAs has put them in the limelight as a drug target for small molecule therapy. In addition, the recognition of the marked difference between prokaryotic and eukaryotic rRNA has led to the development of antibiotics that specifically target bacterial rRNA, reduce protein translation and thereby inhibit bacterial growth. To facilitate the development of new antibiotics targeting RNA, we here review the literature concerning such antibiotics, mRNA, riboswitch and tRNA and the key methodologies used for their screening.

An experimental and numerical study was developed for the unsteady phenomena at off-design conditions of a diffuser pump. Unsteady pressure measurements were made downstream of the impeller, and the pressure fluctuations were analyzed using the ensemble averaging technique as well as the statistical and chaotic time series analysis. The unsteady flow was classified into five ranges as a result of the statistical and chaotic time series analysis. And a two-dimensional vortex method was employed to investigate the unsteady flow structure due to the interaction between impeller and diffuser vanes in a diffuser pump at various off-design conditions. The numerical results of unsteady flow at a partial discharge range (approximately 83% of the rated flow rate) show an asymmetrical separation bubble near the pressure surface of the impeller vane. The intermittence of the separation bubble may be the main factor to cause the unstable characteristics of the test diffuser pump. The calculated unsteady flow at the lower partial discharge range (50% of the rated flow rate) presents a rotating stall in the impeller passage as well as in the diffuser passage, which can be main cause of unstable characteristics there.

Candida albicans is the single most prevalent cause of fungal bloodstream infections worldwide causing significant mortality as high as 50 percent. This high mortality rate is, in part, due to the inability to initiate an effective antifungal therapy early in the disease process. Mortality rates significantly increase after 12 hours of delay in initiating the appropriate antifungal therapy following a positive blood culture. Early administration of appropriate antifungal therapy is hampered by the slow turnovers of the conventional antimicrobial testing techniques, which require days of incubation. To address this unmet need, we explored the potential of employing stimulated Raman scattering (SRS) imaging to probe for metabolic differences between fluconazole-susceptible and -resistant strains at a single cell level in search of a metabolic signature. Metabolism is integral to pathogenicity. Since only a few hours are needed to observe a full metabolic cycle in C. albicans, metabolic profiling provides an avenue for rapid antimicrobial susceptibility testing. C-H frequency (2850 cm) SRS imaging revealed a substantial difference in lipogenesis between the fluconazole-susceptible and -resistant C. albicans. Exposure to fluconazole, an antimicrobial drug that targets ergosterol biosynthesis, only affected the lipogenesis in the susceptible strain. These results show that single cell metabolic imaging via SRS microscopy can be used for rapid detection of antimicrobial susceptibility.

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