Automated and rapid identification of multidrug resistant Escherichia coli against the lead drugs of acylureidopenicillins, cephalosporins, and fluoroquinolones using specific Raman marker bands.

A Raman-based, strain-independent, semi-automated method is presented that allows the rapid (<3 hours) determination of antibiotic susceptibility of bacterial pathogens isolated from clinical samples. Applying a priori knowledge about the mode of action of the respective antibiotic, we identified characteristic Raman marker bands in the spectrum and calculated batch-wise weighted sum scores from standardized Raman intensity differences between spectra of antibiotic exposed and nonexposed samples of the same strains. The lead substances for three relevant antibiotic classes (fluoroquinolone ciprofloxacin, third-generation cephalosporin cefotaxime, ureidopenicillin piperacillin) against multidrug-resistant Gram-negative bacteria (MRGN) revealed a high sensitivity and specificity for the susceptibility testing of two Escherichia coli laboratory strains and 12 clinical isolates.

Simple Ciprofloxacin Resistance Test and Determination of Minimal Inhibitory Concentration within 2 h Using Raman Spectroscopy.

Resistant bacteria are spreading worldwide, which makes fast antibiotic susceptibility testing and determination of the minimal inhibitory concentration (MIC) urgently necessary to select appropriate antibiotic therapy in time and, by this, improve patient's outcome and, at the same time, avoid inappropriate treatment as well as the unnecessary use of broad spectrum antibiotics that would foster further spread of resistant bacteria. Here, a simple and fast Raman spectroscopy-based procedure is introduced to identify antimicrobial susceptibilities and determine the MIC within only 2 h total analysis, marking a huge time savings compared to established phenotypic methods nowadays used in diagnostics. Sample preparation is fast and easy as well as comparable to currently established tests.

On-chip spectroscopic assessment of microbial susceptibility to antibiotics within 3.5 hours.

In times of rising antibiotic resistances, there is a high need for fast, sensitive and specific methods to determine antibiotic susceptibilities of bacterial pathogens. Here, we present an integrated microfluidic device in which bacteria from diluted suspensions are captured in well-defined regions using on-chip dielectrophoresis and further analyzed in a label-free and non-destructive manner using Raman spectroscopy. Minimal sample preparation and automated sample processing ensure safe handling of infectious material with minimal hands-on time for the operator.

Single cell analysis in native tissue: Quantification of the retinoid content of hepatic stellate cells.

Hepatic stellate cells (HSCs) are retinoid storing cells in the liver: The retinoid content of those cells changes depending on nutrition and stress level. There are also differences with regard to a HSC's anatomical position in the liver. Up to now, retinoid levels were only accessible from bulk measurements of tissue homogenates or cell extracts.

Rapid, culture-independent, optical diagnostics of centrifugally captured bacteria from urine samples.

This work presents a polymeric centrifugal microfluidic platform for the rapid and sensitive identification of bacteria directly from urine, thus eliminating time-consuming cultivation steps. This "Lab-on-a-Disc" platform utilizes the rotationally induced centrifugal field to efficiently capture bacteria directly from suspension within a glass-polymer hybrid chip. Once trapped in an array of small V-shaped structures, the bacteria are readily available for spectroscopic characterization, such as Raman spectroscopic fingerprinting, providing valuable information on the characteristics of the captured bacteria.

Combined dielectrophoresis-Raman setup for the classification of pathogens recovered from the urinary tract.

Rapid and effective methods of pathogen identifications are of major interest in clinical microbiological analysis to administer timely tailored antibiotic therapy. Raman spectroscopy as a label-free, culture-independent optical method is suitable to identify even single bacteria. However, the low bacteria concentration in body fluids makes it difficult to detect their characteristic molecular fingerprint directly in suspension.