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Clinical diagnostics in routine microbiology still mostly relies on bacterial growth, a time-consuming process that prevents test results to be used directly as key decision-making elements for therapeutic decisions. There is some evidence that Raman micro-spectroscopy provides clinically relevant information from a limited amount of bacterial cells, thus holding the promise of reduced growth times and accelerated result delivery. Indeed, bacterial identification at the species level directly from micro-colonies at an early time of growth (6 h) directly on their growth medium has been demonstrated. However, such analysis is suspected to be partly destructive and could prevent the further growth of the colony needed for other tests, e.g. antibiotic susceptibility testing (AST) . In the present study, we evaluated the effect of the powerful laser excitation used for Raman identification on micro-colonies probed after very short growth times. We show here, using envelope integrity markers (Syto 9 and Propidium Iodide) directly on ultra-small micro-colonies of a few tens of Escherichia coli and Staphylococcus epidermidis cells (3 h growth time), that only the cells that are directly impacted by the laser lose their membrane integrity. Growth kinetics experiments show that the non-probed surrounding cells are sometimes also affected but that the micro-colonies keep their ability to grow, resulting in normal aspect and size of colonies after 15 h of growth. Thus, Raman spectroscopy could be used for very early (< 3 h) identification of grown micro-organisms without impairing further antibiotics susceptibility characterization steps [ABSTRACT FROM AUTHOR]

Abstract: In the framework of a French Joint program COVADIS, an innovative system is developed for the simultaneous detection of benzene, toluene and xylenes in indoor air. The present work is focused on the benzene and xylene detection. The detection is based on absorbance measurements over the 250nm-300nm spectral range with a cooled and uncooled spectrophotometer. The prototype includes an exposure chamber, which contains five sensors. The sensors are nanoporous disks, whose pore sizes are tailored to efficiently entrap the targeted pollutants. 20ppb of benzene and 10ppb of m-xylene have been successfully detected within 40min of exposure. [Copyright &y& Elsevier]