Chapter 6 - Assessment of the Inhibitory Potency of Antibiotics by MRI

Abstract

This chapter evaluates the application of magnetic resonance imaging (MRI) to assess the inhibitory potency of antibiotics in bacterial cultures. MRI allows for in vivo investigations in animal models and human subjects and although it is routinely used to monitor disease progression in patients, its applications for evaluation of drugs are rare. Large-scale assessment of the inhibitory potency of antibiotic substances may provide a novel approach to identifying drug candidates. High-throughput screening requires parallelization of the detection method, which is limited with established procedures. MRI is non-invasive and the measurement does not interfere with the cultures nor does it require separate excitation or detection for the individual samples. It allows for identification of growth inhibition in bacterial cultures by measurement of the transverse relaxation time. Physical parameters that are typically measured by MRI and related to physiological or pathological events in humans or animals cannot be directly translated into experiments with bacterial cultures. Under reasonable growth conditions, bacteria are dilute in the medium. Therefore, the parameter spin density, which directly translates into water content, is not appropriate for cultures. The measurement may be extended to investigate 10,000 samples simultaneously, opening a new dimension in throughput compared with conventional methods.