Mass spectrometry (MS) in Selected Reaction Monitoring (SRM) mode is proposed for in-depth characterisation of microorganisms in a multiplexed analysis. Within 60–80 minutes, the SRM method performs microbial identification (I), antibiotic-resistance detection (R), virulence assessment (V) and it provides epidemiological typing information (T). This SRM application is illustrated by the analysis of the human pathogen Staphylococcus aureus, demonstrating its promise for rapid characterisation of bacteria from positive blood cultures of sepsis patients.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS) has been introduced in clinical routine microbiology laboratories. For the rapid diagnosis of urinary tract infections, culture-independent methods prior MALDI-mediated identification have been described. Here, we describe a comparison of three of these methods based on their performance of bacterial identification and their potential as a routine tool for microbiology labs : (i) differential centrifugation, (ii) urine filtration and (iii) a 5-h bacterial cultivation on solid culture media. For 19 urine samples, all methods were directly compared and correct bacterial species identification by MALDI was used as performance indicator. A higher percentage of correct MALDI identification was obtained after filtration (78.9 %) and the growth-based method (84.2 %) as compared to differential centrifugation (68.4 %). Additional testing of 76 mono-microbial specimens (bacteriuria > 10(5) CFU/mL) confirmed the good performance of short growth with a 90.8 % correct MALDI score, with a potentially better fit to the routine workflow of microbiology labs.

The aim of this work is to demonstrate the ability of atomic force microscopy (AFM) to detect and to quantify specific immunological reactions between antibodies and antigens, with a view to creating a very sensitive biosensor. A monolayer of antiferritin antibodies was adsorbed onto alkyl silane modified silicon oxide substrates, which were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The sensitivity limit for antibody detection was quantified by radioimmunoassay (RIA) and compared to that obtained by enzyme linked immuno sorbent assay (ELISA) and by AFM after antibody binding with colloidal gold labeled conjugates. In this latter case, substrate modification after reaction was checked by measuring the surface roughness (R rms) variations. AFM was found to be more sensitive than RIA, with a detection limit of 0.3 × 10-3 ng of antibodies per mm2. Then, the biosensor performance was investigated using ferritin solutions of various concentrations:  the antibody/antigen reaction was quantified by directly detecting the antigen and measuring surface roughness modifications. Results were compared to sandwich immunoassay techniques. Up to now, AFM has detected a minimum ferritin concentration of 0.06 μg/mL.