Microbial detection system and methods
The disclosure provides culture devices and methods for a microorganism in a sample. The devices include a base member, a cover sheet, an adhesive layer coupled to the base member or the cover sheet, and a cold water-soluble gelling agent disposed on the base member; wherein the devices are substantially optically transmissive when the gelling agent is hydrated with a clear liquid. Methods of use include detecting or enumerating microorganisms. The methods further provide for detecting a microorganism by detecting the presence or size of an abiogenic gas bubble in a culture device.
1. A method for detecting the presence or absence of an aerobic or a facultatively anaerobic microorganism in a sample, comprising:
providing a sample and a culture device comprising a base member, a cover layer, and a hydrogel comprising a plurality of abiogenic gas bubbles disposed there between;
wherein the culture device comprises an outermost first major surface and an outermost second major surface;
wherein the hydrogel defines a growth area;
wherein providing the culture device comprises providing a thin film culture device that includes a dry, cold water-soluble gelling agent and wherein the method further comprises hydrating the gelling agent with an aqueous liquid;
inoculating the growth area of the device with the sample at a first point in time;
incubating the device for a period of time;
illuminating the growth area with a light source;
observing an abiogenic gas bubble in the hydrogel in the growth area at a second point in time;
observing the growth area with regard to the size or absence of the abiogenic gas bubble at a third point in time, wherein the third point in time occurs after the second point in time;
comparing observations of the growth area at two points in time; and
detecting the presence or absence of an aerobic or a facultatively anaerobic microorganism in the growth area at a third point in time;
wherein detecting the presence or absence of an aerobic or a facultatively anaerobic microorganism comprises observing an indication of growth;
wherein observing an indication of growth comprises detecting a diminution or absence of the abiogenic gas bubble in the hydrogel at the third point in time;
wherein detecting the diminution or absence of the abiogenic gas bubble in the hydrogel at the third point in time indicates the presence of an aerobic or a facultatively anaerobic microorganism in the sample.
2. The method of claim 1 , wherein illuminating the growth area comprises illuminating the growth area with the light source positioned facing the first major surface of the culture device.
3. The method according to claim 2 , wherein observing an indication of growth comprises observing the growth area from a position facing the first major surface of the culture device.
4. The method of claim 1 , wherein observing an indication of growth comprises observing the growth area from an observation position facing the first major surface of the culture device.
5. The method of claim 1 , wherein illuminating the growth area comprises illuminating the growth area with the light source positioned facing the second major surface of the culture device.
6. The method of claim 1 , overlapping at least a portion of the growth area of the culture device, the second major surface of the culture device comprises a contrast layer.
7. The method of claim 6 , wherein observing an indication of growth comprises observing the growth area from a position facing the second major surface of the culture device.
8. The method of claim 1 , wherein detecting the presence or absence of a microorganism comprises detecting and differentiating two or more types of microorganisms.
9. The method of claim 1 , wherein detecting the presence or absence of a microorganism further comprises:
providing an imaging system; and
obtaining an image of the growth area of the culture device;
wherein observing an indication of growth comprises displaying, printing, or analyzing the image of the growth area.