US 9,850,457 B2Granted

Microbial growth detector

AssigneeNeogen Corporation

InventorsRonald Waldo Sarver, Jr., Alexandr Y. Kariagin, Christine Claire Cooper, Susan Teruko McDougal

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Abstract

The disclosure generally relates to a test device that detects microorganism growth by detecting a gas metabolite (e.g., carbon dioxide) produced during the growth of bacteria or other microorganism in a tested sample. The test device can contain a culture growth media separated from a detection area by a gas-permeable membrane. The gas-permeable membrane permits carbon dioxide to permeate into the detection area. The detection area includes a solidified mixture of pH indicators and a gelling agent in the form of a semi-permeable matrix. The optical properties, including the absorbance of light at various wavelengths, of the detection solution change with alterations in carbon dioxide concentration. This test device can then be placed in an incubation and optical detection instrument to monitor changes in optical properties of the detection are induced during microorganism growth in the culture medium.

Claims38

Dependent claims

An apparatus for detecting carbon dioxide, the apparatus comprising:

(a) a vessel comprising a wall, the wall defining (i) a detection region in the vessel and (ii) a growth region in the vessel;
(b) a semi-permeable matrix disposed in the detection region of the vessel, the matrix comprising a pH indicator distributed throughout the matrix;
(c) a gas-permeable membrane comprising a silicone polymer selected from the group consisting of room-temperature-vulcanized silicone, high-temperature-vulcanized silicone, ultraviolet-vulcanized silicone, and combinations thereof disposed inside the vessel, the gas-permeable membrane covering the semi-permeable matrix and defining a boundary between the detection region and the growth region of the vessel;
and
(d) optionally, a culture medium disposed in the growth region of the vessel, the culture medium being capable of supporting the growth of a microorganism;
wherein:
(i) the gas-permeable membrane and the semi-permeable matrix are permeable to carbon dioxide, thereby permitting diffusive transport of carbon dioxide present in the growth region to the detection region;
(ii) the gas-permeable membrane is impermeable to liquid and solid materials present in the growth region;
(iii) the gas-permeable membrane is substantially free of any pH indicators present in the semi-permeable matrix;
(iv) the wall of the vessel is at least partially transparent in the detection region;
and
(v) the semi-permeable matrix is permeable to liquids, but the presence of the gas-permeable membrane prevents the passage of liquids from the growth region to the detection region of the vessel.

9 more elements

A method of making an apparatus for detecting carbon dioxide, the method comprising:

(a) providing a vessel comprising a wall, the wall defining (i) a detection region in the vessel and (ii) a growth region in the vessel, wherein the detection region of the vessel contains a semi-permeable matrix disposed in the detection region of the vessel, the matrix comprising a pH indicator distributed throughout the matrix;
(b) applying a gas-permeable membrane precursor comprising a mixture comprising (i) a silicone prepolymer, (ii) a silicone crosslinking agent, and (iii) a curing catalyst in liquid form to an exposed surface of the semi-permeable matrix;
and
(c) curing the gas-permeable membrane precursor, thereby forming a gas-permeable membrane in the vessel, the gas-permeable membrane covering the semi-permeable matrix and defining an interface between the detection region and the growth region of the vessel;
wherein:
(i) the gas-permeable membrane and the semi-permeable matrix are permeable to carbon dioxide, thereby permitting diffusive transport of carbon dioxide present in the growth region to the detection region;
(ii) the gas-permeable membrane is impermeable to liquid and solid materials present in the growth region;
(iii) the wall of the vessel is at least partially transparent in the detection region;
and
(iv) the semi-permeable matrix is permeable to liquids, but the presence of the gas-permeable membrane prevents the passage of liquids from the growth region to the detection region of the vessel.

7 more elements

A method of detecting carbon dioxide, comprising:

(a) providing an apparatus including (A) a vessel comprising a wall, the wall defining (i) a detection region in the vessel and (ii) a growth region in the vessel;
(B) a semi-permeable matrix disposed in the detection region of the vessel, the matrix comprising a pH indicator distributed throughout the matrix;
(C) a gas-permeable membrane comprising a silicone polymer selected from the group consisting of room-temperature-vulcanized silicone, high-temperature-vulcanized silicone, ultraviolet-vulcanized silicone, and combinations thereof disposed inside the vessel, the gas-permeable membrane covering the semi-permeable matrix and defining a boundary between the detection region and the growth region of the vessel:
and (D) optionally, a culture medium disposed in the growth region of the vessel, the culture medium being capable of supporting the growth of a microorganism;
wherein:
(1) the gas-permeable membrane and the semi-permeable matrix are permeable to carbon dioxide, thereby permitting diffusive transport of carbon dioxide present in the growth region to the detection region:
(ii) the gas-permeable membrane is impermeable to liquid and solid materials present in the growth region;
(iii) the gas-permeable membrane is substantially free of any pH indicators present in the semi-permeable matrix;
(iv) the wall of the vessel is at least partially transparent in the detection region;
and (v) the semi-permeable matrix is permeable to liquids, but the presence of the gas-permeable membrane prevents the passage of liquids from the growth region to the detection region of the vessel:
wherein the culture medium is present in the growth region of the vessel;
(b) inserting a sample to be tested into the culture medium at a first time (t1);
(c) sealing the vessel with the inserted sample;
(d) monitoring the detection region at a second time (t2>t1) to detect changes in color of the pH indicator in the semi-permeable matrix;
and
(e) correlating a change in the color of the pH indicator between the first time and the second time with a presence of carbon dioxide in the detection region.

13 more elements

A method of detecting a metabolic product gas of a microorganism, comprising:

(a) providing an apparatus (A) a vessel comprising a wall, the wall defining (i) a detection region in the vessel and (ii) a growth region in the vessel;
(B) a semi-permeable matrix disposed in the detection region of the vessel, the matrix comprising a gas indicator distributed throughout the matrix;
(C) a gas-permeable membrane comprising a silicone polymer selected from the group consisting of room-temperature-vulcanized silicone, high-temperature-vulcanized silicone, ultraviolet-vulcanized silicone, and combinations thereof disposed inside the vessel, the gas-permeable membrane covering the semi-permeable matrix and defining a boundary between the detection region and the growth region of the vessel;
and (D) optionally, a culture medium disposed in the growth region of the vessel, the culture medium being capable of supporting the growth of a microorganism;
wherein:
(i) the gas-permeable membrane and the semi-permeable matrix are permeable to a metabolic product gas of microorganism growth, thereby permitting diffusive transport of the gas present in the growth region to the detection region;
(ii) the gas-permeable membrane is impermeable to liquid and solid materials present in the growth region;
(iii) the wall of the vessel is at least partially transparent in the detection region;
and (iv) the semi-permeable matrix is permeable to liquids, but the presence of the gas-permeable membrane prevents the passage of liquids from the growth region to the detection region of the vessel;
(b) inserting a sample to be tested into the culture medium at a first time (t1);
(c) sealing the vessel with the inserted sample;
(d) monitoring the detection region at a second time (t2>t1) to detect changes in color of the gas indicator in the semi-permeable matrix;
and
(e) correlating a change in the color of the gas indicator between the first time and the second time with a presence of a metabolic product gas of microorganism growth in the detection region.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/928,960Filed 23 Dec 2010 · us provisional application
Priority: 5 May 2010
Published: US 2011/0275112 A110 Nov 2011
Granted: 26 Dec 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

C12M 23/22
Constructional details, e.g. recesses, hinges: transparent or translucent parts
C12M 23/24
Constructional details, e.g. recesses, hinges: gas permeable parts
C12M 41/26
Means for regulation, monitoring, measurement or control, e.g. flow regulation: of pH
C12M 41/34
Of concentration: of gas