Filtration method for detecting microbial contamination

A method for detecting contaminants in a medium suspected of containing such contaminants, the method comprising the consecutive steps of:

• a) passing a known volume of said medium through a filter from an influent side to an effluent side in a filter device thereby concentrating the contaminants on the influent side of the filter in the filter device;
• b) contacting the influent side of the filter in the filter device with a liquid vehicle containing at least one substrate, wherein said at least one substrate through interaction with an enzyme characteristic of the contaminants produces a detectable moiety;
• c) allowing the substrate to interact with the contaminants on the influent side of the filter in the filter device for a period of time between 5-minutes to 24-hours, which is sufficient to allow the detectable moiety to be detected in the liquid vehicle;
• d) evacuating the liquid vehicle from the influent side of the filter by forcing the liquid vehicle through to the effluent side of the filter;
• and
• e) performing a quantitative or qualitative detection of the detectable moiety in the liquid vehicle evacuated in step d and correlating the detection of the moiety to the amount or presence of contaminants in the sample.