Sensitive and rapid determination of antimicrobial susceptibility

• US 7,687,239 B2
• Filed: 07/08/2004
• Issued: 03/30/2010
• Est. Priority Date: 07/12/2003
• Status: Active Grant

• Current Assignee: Accelerate Diagnostics, Inc.
• Original Assignee: Accelrs Technology Corporation
• Inventors: Buttry, Daniel A., Saavedra, Steven Scott, Metzger, Steven W., Howson, David C., Goldberg, David A.
• Primary Examiner(s): Lam; Ann Y
• Application Number:
  US10/888,828
• Publication Number:
  US 20050048599A1
• Time in Patent Office: 2,091 Days
• Field of Search: 436/514, 436/518, 436/517, 435/287.1, 435/4, 435/7.2, 435/7.42, 435/283.1, 435/287.3, 422/50, 422/55
• US Class Current: 435/7.2
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: C12Q 1/18 Testing for antimicrobial activity of a material
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: G01N 33/561 Immunoelectrophoresis
• CPC Class Codes: G01N 33/569 for microorganisms, e.g. protozoa, bacteria, viruses

Abstract

The present invention relates to moving microorganisms to a surface, where they are grown in the presence and absence of antimicrobials, and by monitoring the growth of the microorganisms over time in the two conditions, their susceptibility to the antimicrobials can be determined. The microorganisms can be moved to the surface through electrophoresis, centrifugation or filtration. When the movement involves electrophoresis, the presence of oxidizing and reducing reagents lowers the voltage at which electrophoretic force can be generated and allows a broader range of means by which the target can be detected. Monitoring can comprise optical detection, and most conveniently includes the detection of individual microorganisms. The microorganisms can be stained in order to give information about their response to antimicrobials.

Claims

1. A system for detecting a first type of viable microorganism in a solution, comprising:

a chamber comprising a first electrophoresis electrode and a second electrophoresis electrode on opposing walls of the chamber, wherein the electrodes are configured to cause said microorganism to migrate toward said first electrode when a potential is applied between the electrodes;

an input port configured to transport said solution into the chamber between the electrodes;

an output port configured to transport said solution out of said chamber;

a first capture surface disposed on said first electrode, said capture surface comprising a plurality of first capture agents that bind to said first type of viable microorganism, wherein a viable microorganism is a microorganism that engages in growth and division;

an electrode controller operably linked to the first and second electrodes, said controller configured to control the potential between the first and second electrodes;

an optical detector configured to detect the quantity of said first type of viable microorganism bound to the first capture agents; and

a storage controller that stores the quantity of the first type of viable microorganism as determined by the optical detector.

2. The system of claim 1, wherein the first type of microorganism is selected from the group consisting of Pseudomonas, Stenotrophomonas, Acinetobacter, Enterobacter, Escherichia, Klebsiella, Proteus, Serratia, Haemophilus, Streptococcus, Staphylococcus, Enterococcus, Mycobacterium, Candida, Aspergillus and Neisseria.

3. The system of claim 1, further comprising the solution, wherein the solution comprises an oxidizing agent.

4. The system of claim 3, wherein a reduced product of the oxidizing agent comprises the reducing agent.

5. The system of claim 3, wherein the oxidizing agent is selected from the set consisting of benzoquinone, a dithiol, a ketone, a ferrocinium, a ferricyanide, dihydroascorbate, oxidized glutathione, oxidized methyl viologen, water, and a halogen.

6. The system of claim 1, further comprising the solution, wherein the solution comprises an oxidizing agent.

7. The system of claim 6, wherein water is an oxidizing agent.

8. The system of claim 6, wherein the reducing agent is selected from the set consisting of dithiothreitol, dithioerythritol, a dithioalkane, a dithioalkene, a thioalkane, a thioalkene, a thiol, a hydroquinone, an alcohol, a ferrocene, a ferrocyanide, ascorbate, glutathione, methyl viologen, water, and a halide.

9. The system of claim 1, wherein the conductivity of the solution is less than 100 microSiemens/cm.

10. The system of claim 1, wherein the conductivity of the solution is less than 10 microSiemens/cm.

11. The system of claim 1, wherein the solution comprises a zwitterionic buffer.

12. The system of claim 1, further comprising a concentrator disposed before the input port that concentrates the first type of microorganisms in the solution.

13. The system of claim 12, wherein the concentrator comprises a centrifuge.

14. The system of claim 12, wherein the concentrator comprises ion exchange particles.

15. The system of claim 1, wherein the optical detector is configured to detect the first type of microorganism by a method selected from set consisting of light scattering imaging, brightfield imaging, darkfield imaging, phase imaging, fluorescence imaging, upconverting phosphor imaging, quantum dot imaging, chemiluminescence imaging.

16. The system of claim 15, wherein the optical detector is further configured to determine the position of at least a portion of said first type of microorganisms on said capture surface.

17. The system of claim 15, wherein the detector is configured to detect the first type of microorganism by averaging the signal of a portion of the surface of said first electrode.

18. The system of claim 15, wherein the optical detector comprises a camera.

19. The system of claim 18, wherein the field of view corresponding to each pixel of said camera comprises a long axis that is less than 2 microns.

20. The system of claim 18, wherein the field of view corresponding to each pixel of said camera comprises a long axis that is less than 0.5 microns.

21. The system of claim 1, wherein an electrode selected from the set consisting of the first electrode and second electrode is optically transparent.

22. The system of claim 1, wherein the first electrode comprises gold, and the optical detector is configured to detect said first type of microorganism by surface plasmon resonance.

23. The system of claim 1, wherein the solution further comprises a second type of microorganism, wherein the optical detector is capable of distinguishing the first type of microorganism from the second type of microorganism.

24. The system of claim 23, further comprising:

a first tag linked to the first type of microorganism; and

a second tag linked to the second type of microorganism;

wherein the optical detector is capable of distinguishing the first tag and the second tag.

25. The system of claim 24, wherein the optical detector is configured to measure the quantity and location of the first and second tags.

26. The system of claim 24, wherein the first capture agent comprises an antibody that binds to the first type of microorganism.

27. The system of claim 24, wherein the optical detector is configured to count the quantity of the first and second tags.

28. The system of claim 23, wherein the optical detector is configured to distinguish first and second types of microorganisms by electrophoresis.

29. The system of claim 1, wherein the first capture agent comprises a polyelectrolyte.

30. The system of claim 29, wherein the polyelectrolyte comprises a polycationic polymer.

31. The system of claim 30, wherein the polycationic polymer comprises amine moieties.

32. The system of claim 1, wherein the solution further comprises a second type of microorganism, wherein the second type of microorganism does not bind to the first capture agent.

33. The system of claim 32, wherein the first capture agent is selected from the set consisting of antibody and aptamer.

34. The system of claim 32, further comprising a second capture agent bound to the first electrode, wherein the second capture agent is capable of binding the second type of microorganism, and

wherein the optical detector can detect the quantity of the second type of microorganism bound to the second capture agent,

wherein the optical detector is configured to distinguish the first type of microorganism from the second type of microorganism by whether a microorganism binds to the first capture agent or the second capture agent.

35. The system of claim 32, wherein the first capture agent further comprises a polymer selected from a set consisting of polyethylene glycol and polyacrylamide.

36. The system of claim 32, further comprising a third electrode co-planar with the first electrode, wherein a second capture agent capable of binding the second type of microorganism is bound to said third electrode, and wherein a first potential difference between the first electrode and the second electrode and a second potential difference between the third electrode and the second electrode can be independently controlled by the electrode controller.

37. The system of claim 1, wherein the optical detector is configured to distinguish living microorganisms from dead microorganisms.

38. The system of claim 37, wherein the chamber further comprises a stain selected from the set consisting of antibodies, lectins, mortal stain and vital stain.

39. The system of claim 1, wherein the chamber is configured to provide conditions conducive to growing said first type of microorganism.

40. The system of claim 39, wherein the chamber comprises heat regulation components capable of keeping the chamber at a temperature between 34 and 40 degrees Centigrade.

41. The system of claim 39, wherein system is further configured to provide growth medium through the input port.

42. The system of claim 41, wherein the growth medium has a conductivity of less than 1 milliSiemens/cm, and the electrode controller maintains a potential of greater than 100 mV between the first electrode and the second electrode.

43. The system of claim 39, wherein the optical detector is configured to measure the growth difference between said the first type of microorganism at a first time and a second time.

44. The system of claim 43, wherein the growth conditions further comprise an anti-microorganisms agent.

45. The system of claim 44, wherein the optical detector is capable of distinguishing living and dead microorganisms stained with a stain selected from the set consisting of mortal stain and vital stain.

46. The system of claim 43, wherein the antimicroorganism agent is selected from the set consisting of cephalosporins, penicillins, carbapenems, monobactams, beta-lactams, beta-lactamase inhibitors, fluoroquinolones, macrolides, ketolides, glycopeptides, aminoglycosides, fluoroquinolones, and rifampin.

47. The system of claim 39, wherein the optical detector is configured to count the growth difference between said first type of microorganism at a first time and a second time.

48. The system of claim 1, wherein the optical detector is configured to count the quantity of the first type of microorganism.

49. The system of claim 1, wherein the optical detector is configured to count individual binding events.

50. The system of claim 1, wherein the potential between the first and second electrode is less than 2 volts.

51. The system of claim 1, wherein the potential difference is measured relative to a third reference electrode.

52. The system of claim 1, wherein the storage controller is configured to determine the number of individual microorganisms.

53. The system of claim 1, wherein the storage controller is configured to determine morphology.

54. The system of claim 1, wherein the chamber is configured to move in a horizontal direction.