Oscillometric instrument for the Non-invasive detection of low-level microbial Activity. Part 2: growth characteristics, detection Limits and impedimetric assays

Instrument performance and application was evaluated with a variety of microbial suspensions. Data were compared with those obtainable from current commercial apparatus in terms of resolution and detection times. Trials with growing and non-growing cultures indicated periodic synchronous ion exchange processes. Media composition, particularly salt and nutrient ratios, remain crucial to early and rapid detection of viable microbial activity at low concentrations. With appropriate conditions very significant improvements in detection times with typical detection thresholds of 300 min for start concentrations of 10 2 are shown. It is concluded that with regard to resolution and stability, the system out-performs current systems and is superior in terms of potential test costs, sample handling and sample transport.