A method for detecting Listeria species on an environmental surface, the method comprising: providing, a sample collector (110, 210, 610, 710, 810) with upper and lower major surface, wherein at least one major surface of the sample collector is water-impervious, wherein the sample collector is for use in sampling an environmental surface or patient surface; a sample suspending medium and a reagent strip (580, 680); wherein the reagent strip comprises a self-supporting substrate (582, 682) with upper and lower major surfaces wherein at least part of one major surface is coated with a dry coating that includes a hydrophilic agent (586, 686) comprising a nutrient for growing microorganisms, an indicator, and a cold water soluble gelling agent; a sample housing (360, 460) comprising a bottom member (350, 450) comprising a self-supporting water impervious substrate (352, 452) with upper and lower major surfaces; a cover sheet (330, 430) comprising a substrate (332, 432) with upper and lower major surfaces wherein at least part of the lower major surface is coated with an adhesive layer and a cold water soluble powder including at least one gelling agent is adhered to the adhesive layer 334; and a barrier layer (370, 470, 870); obtaining a sample on at least one major surface of the surface of the sample collector (110, 210, 610, 710, 810); placing the sample collector (110, 210, 610, 710, 810) into the sample housing (360, 460); hydrating the sample or the reagent strip (580, 680) with the sample suspending medium; and contacting the reagent strip (580, 680) and the sample. providing, a sample collector (110, 210, 610, 710, 810) with upper and lower major surface, wherein at least one major surface of the sample collector is water-impervious, wherein the sample collector is for use in sampling an environmental surface or patient surface; a sample suspending medium and a reagent strip (580, 680); wherein the reagent strip comprises a self-supporting substrate (582, 682) with upper and lower major surfaces wherein at least part of one major surface is coated with a dry coating that includes a hydrophilic agent (586, 686) comprising a nutrient for growing microorganisms, an indicator, and a cold water soluble gelling agent; a sample housing (360, 460) comprising a bottom member (350, 450) comprising a self-supporting water impervious substrate (352, 452) with upper and lower major surfaces; a cover sheet (330, 430) comprising a substrate (332, 432) with upper and lower major surfaces wherein at least part of the lower major surface is coated with an adhesive layer and a cold water soluble powder including at least one gelling agent is adhered to the adhesive layer 334; and a barrier layer (370, 470, 870); a sample collector (110, 210, 610, 710, 810) with upper and lower major surface, wherein at least one major surface of the sample collector is water-impervious, wherein the sample collector is for use in sampling an environmental surface or patient surface; a sample suspending medium and a reagent strip (580, 680); wherein the reagent strip comprises a self-supporting substrate (582, 682) with upper and lower major surfaces wherein at least part of one major surface is coated with a dry coating that includes a hydrophilic agent (586, 686) comprising a nutrient for growing microorganisms, an indicator, and a cold water soluble gelling agent; a sample housing (360, 460) comprising a bottom member (350, 450) comprising a self-supporting water impervious substrate (352, 452) with upper and lower major surfaces; a cover sheet (330, 430) comprising a substrate (332, 432) with upper and lower major surfaces wherein at least part of the lower major surface is coated with an adhesive layer and a cold water soluble powder including at least one gelling agent is adhered to the adhesive layer 334; and a barrier layer (370, 470, 870); obtaining a sample on at least one major surface of the surface of the sample collector (110, 210, 610, 710, 810); placing the sample collector (110, 210, 610, 710, 810) into the sample housing (360, 460); hydrating the sample or the reagent strip (580, 680) with the sample suspending medium; and contacting the reagent strip (580, 680) and the sample.