Environmental sampling articles and methods
The present invention refers to articles for collecting samples from a surface, articles for microbiological analyses of said samples, and methods of use of said articles. The articles include sample collectors, sample housings with optional barrier layers, and sample-ready reagent strips comprising hydrophilic agents to grow and detect microorganisms. The disclosure includes methods to collect, detect, and quantify microorganisms in a surface sample.
1. A method for detecting microorganisms on an environmental surface, the method comprising:
providing;
a barrier layer;
a sample-suspending medium;
a sample collector comprising a substrate with upper and lower major surfaces wherein at least one major surface is water-impervious;
a sample housing comprising:
a bottom member comprising a self-supporting substrate with upper and lower major surfaces;
a cover sheet comprising a substrate with upper and lower major surfaces wherein at least part of one major surface is coated with a cold water soluble powder including at least one gelling agent; and
a reagent strip comprising a self-supporting substrate with upper and lower major surfaces wherein at least part of one major surface is coated with a cold water soluble gelling agent and a hydrophilic agent selected from the group consisting of a nutrient for growing microorganisms, a selective agent, an indicator, and combinations of any two or more of the foregoing;
obtaining a sample on at least one major surface of the sample collector;
forming an assembly by placing the sample-collector into the sample housing with the at least one major surface comprising the sample oriented toward the cover sheet;
applying the sample-suspending medium to the sample collector major surface comprising the sample;
inserting the water-resistant barrier layer between the sample collector and the cover sheet, thereby preventing the sample-suspending medium from contacting at least a part of the cover sheet;
incubating the assembly for a period of time;
removing at least a portion of the barrier layer from the sample housing;
contacting the lower major surface of the cover sheet with the sample-suspending medium to form a hydrated gel;
placing a coated surface of the reagent strip in contact with the hydrated gel;
incubating the sample housing for a period of time; and
observing an indicator of microbial growth.
2. The method according to claim 1 , the method further comprising the step of enumerating microorganisms in the sample.
3. The method according to claim 1 , wherein observing an indicator of microbial growth comprises observing an indicator of growth of a microorganism selected from a group consisting of Listeria spp., Salmonella spp., Enterobacteriaceae, Clostridium spp., Enterococcus spp., Yersinia spp. Bacillus spp., Escherichia coli, Staphylococcus spp., and Extended-Spectrum β-Lactamase-containing microorganisms.