Microbial detection and quantification

• US 20060134728A1
• Filed: 04/28/2005
• Published: 06/22/2006
• Est. Priority Date: 12/16/2003
• Status: Active Grant

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: MacDonald, John Gavin, Martin, Stephanie M., Lye, Jason
• Granted Patent: US 7,399,608 B2
• Time in Patent Office: Days
• US Class Current: 435/34
• CPC Class Codes: C12Q 1/04 Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor C12Q1/6897 takes precedence
• CPC Class Codes: C12Q 1/06 Quantitative determination
• CPC Class Codes: Y10T 442/2566 Organic solvent resistant [e.g., dry cleaning fluid, etc.]

Abstract

A method for semi-quantitatively or quantitatively detecting the presence of a microbe in a sample is provided. The method utilizes a test dye that undergoes a detectable color change in the presence of one or more microbes. For example, in one embodiment, the test dye is a solvatochromic dye (e.g., Reichardt'"'"'s dye) that responds to differences in polarity between microbe components (e.g., cell membrane, cytoplasm, etc.) and the environment outside the cell. Alternatively, other mechanisms may be wholly or partially responsible for the interaction between the dye and the microbe, such as acid-base reactions, redox reactions, and so forth. Regardless, the color of the test dye may be compared to the color of a control dye, wherein the color of the control dye corresponds to a known microbe concentration.

Claims

1. A method for semi-quantitatively or quantitatively detecting the presence of a microbe in a sample, the method comprising:

contacting a test dye with the sample so that the test dye undergoes a detectable color change; and

thereafter, comparing the color of the test dye to the color of a control dye, wherein the color of the control dye corresponds to a known microbe concentration.

2. The method of claim 1, wherein the color of the test dye is compared to the color of a plurality of control dyes, wherein the control dyes each have a color corresponding to different known microbe concentrations.

3. The method of claim 1, further comprising measuring the color intensity of the test dye, the control dye, or both.

4. The method of claim 3, wherein the color intensity of the test dye is proportional to the concentration of the microbe within the test sample.

5. The method of claim 3, further comprising generating a detection curve by plotting the color intensity of a dye for a plurality of known microbe concentrations.

6. The method of claim 5, further comprising correlating the color intensity of the test dye to a microbe concentration on the detection curve.

7. The method of claim 3, wherein an optical reader is employed to measure color intensity.

8. The method of claim 1, wherein a substrate defines a detection zone containing the test dye and a control zone containing the control dye.

9. The method of claim 8, wherein the substrate is a film, paper, nonwoven fabric, woven fabric, knitted fabric, foam, or combinations thereof.

10. The method of claim 8, wherein the substrate is a porous membrane of a lateral flow device.

11. The method of claim 1, wherein the microbe is a bacteria, virus, or fungi.

12. The method of claim 1, wherein the test dye and control dye are formed from the same type of dye.

13. The method of claim 1, wherein the test dye, the control dye, or both are solvatochromic dyes.

14. The method of claim 1, wherein the test dye, the control dye, or both are a merocyanine dye.

15. The method of claim 14, wherein the merocyanine dye has the following structure:

16. The method of claim 1, wherein the test dye, the control dye, or both are a zwitterionic dye.

17. The method of claim 16, wherein the zwitterionic dye is an N-phenolate betaine dye.

18. The method of claim 16, wherein the zwitterionic dye is Reichardt'"'"'s dye.

19. The method of claim 16, wherein the zwitterionic dye has the following structure:

20. The method of claim 1, wherein the color change occurs in less than about 5 minutes.

21. The method of claim 1, wherein the color change occurs in less than about 1 minute.

22. A method for semi-quantitatively or quantitatively detecting the presence of a microbe in a sample, the method comprising:

contacting a solvatochromic test dye with the sample so that the test dye undergoes a detectable color change; and

thereafter, comparing the color of the test dye to the color of a plurality of solvatochromic control dyes, wherein the control dyes each have a color corresponding to different known microbe concentrations.

23. The method of claim 22, further comprising measuring the color intensity of the test dye and control dyes.

24. The method of claim 23, further comprising generating a detection curve by plotting the color intensity of the control dyes versus microbe concentration.

25. The method of claim 24, further comprising correlating the color intensity of the test dye to a microbe concentration on the detection curve.

26. The method of claim 22, wherein a substrate defines a detection zone containing the test dye and a control zone containing the control dyes.

27. The method of claim 22, wherein the test dye and control dyes are merocyanine dyes, N-phenolate betaine dyes, or combination thereof.

28. The method of claim 22, wherein the test dye and control dyes are Reichardt'"'"'s dye.

29. A substrate for semi-quantitatively or quantitatively detecting the presence of a microbe in a sample, the substrate defining a detection zone and a control zone, wherein a test dye is contained within the detection zone that is capable of undergoing a detectable color change in the presence of the microbe, and wherein a plurality of control dyes are contained within the control zone, the color of each control dye corresponding to a different known microbe concentration.

30. The substrate of claim 29, wherein the test dye, the control dye, or both are solvatochromic dyes.

31. The substrate of claim 29, wherein the test dye, the control dye, or both are a merocyanine dye, N-phenolate betaine dye, or combination thereof.

32. The substrate of claim 29, wherein the test dye, the control dye, or both are Reichardt'"'"'s dye.