Detection of first generation environmental sourced microbes in an environmentally-derived sample

#This invention relates to the detection of microbes in an environmental sample such as water, food, or the like. More particularly, this invention, relates to the detection of a target microbe through the use of a testing medium which medium contains a nutrient which can be significantly metabolized only by the target microbe during log phase of growth in the medium, and which, once metabolized, releases a moiety which alters a characteristic of the sample. The medium is thus a “specific medium” in that it will support growth in log phase of only the target microbes, rather than a general medium which will also support growth in log phase of microbes other than the target microbes. The medium also contains a growth accelerant for the target microbes to boost them through log phase and into log phase during the testing procedure. The microbes which this technique can detect are first generation environmental sample-sourced organisms.

#In order to detect microbial pathogens in specimens, whether of human, animal or environmental origin, the following general procedure is commonly used: the target (and other) microbes in the specimen are, in the prior art, inoculated with the specimen into a culture medium in which they are provided with all the nutrients they require for growth. The specimen may be an untreated natural sample, or it may be a sample which has been pre-treated as, for example, by membrane filtration. The culture medium has the nutrients and other selective chemicals such as antimetabolites or antibiotics, which are selectively active against microbes other than the target microbes. The culture medium is a “general medium”, even with the selective chemicals, in that it supports the growth of both target microbes and related microbes and thus is only partially specific to the target microbes.

#The culture medium, which may be a water solution or a water gel, is sterilized to rid it of any contaminating microbes which may be present in the medium and which could, therefore, interfere with the analysis. The culture medium must be refrigerated and packaged in such a way to avoid contamination after manufacture.

#Streptococcus faecalis is a microbe found to be a cause of urinary tract infection. It is the major bacterium sought out in swimming water.

#The nutrient-indicator is a substrate of the enzyme L-pyronidonyl aminopeptidase. If one wishes to determine the presence of Streptococcus faecalis by a color change, the nutrient-indicator molecule can be orthonitrophenyl-B-L-pyronidonyl (yellow); B-napthalamide-B-L-pyronidonyl (purple); alpha-napthol-B-L-pyronidonyl (red); or methylumbilliferyl-B-L-pyronidonyl (fluorescent).

#The nutrient-indicator serves as the essential source of carbon. The rest of the medium is tailored so that each ingredient provides a requirement for S. faecalis.