TREATING BACTERIA WITH ELECTRIC FIELDS

• US 20110137229A1
• Filed: 12/02/2010
• Published: 06/09/2011
• Est. Priority Date: 02/17/2000
• Status: Active Grant

• Current Assignee: Novocure GmbH (NovoCure Limited)
• Original Assignee: NovoCure Limited
• Inventors: Palti, Yoram, Giladi, Moshe
• Granted Patent: US 8,447,395 B2
• Time in Patent Office: Days
• US Class Current: 604/20
• CPC Class Codes: A61B 18/04 by heating by applying electromagnetic radiation A61B18/18; hyperthermia using electric or magnetic fields, radiation or ultrasound A61N
• CPC Class Codes: A61N 1/0428 Specially adapted for iontophoresis, e.g. AC, DC or including drug reservoirs
• CPC Class Codes: A61N 1/205 for promoting a biological process
• CPC Class Codes: A61N 1/30 Apparatus for iontophoresis, i.e. transfer of media in ionic state by an electromotoric force into the body, or cataphoresis
• CPC Class Codes: A61N 1/32 alternating or intermittent currents applying electric fields by inductive or capacitive coupling A61N1/40; microwave apparatus A61N5/02
• CPC Class Codes: A61N 1/326 for promoting growth of cells, e.g. bone cells
• CPC Class Codes: A61N 1/40 Applying electric fields by inductive or capacitive coupling microwave apparatus A61N5/00; Applying radio-frequency signals
• CPC Class Codes: C12N 13/00 Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves

Abstract

Cells that are in the process division are vulnerable to damage by AC electric fields that have specific frequency and field strength characteristics. The selective destruction of rapidly dividing cells can therefore be accomplished by imposing an AC electric field in a target region for extended periods of time at particular frequencies with particular filed strengths. Some of the cells that divide while the field is applied will be damaged, but the cells that do not divide will not be harmed. This selectively damages rapidly dividing cells like bacteria, but does not harm normal cells that are not dividing. Since the vulnerability of the dividing cells is strongly related to the alignment between the long axis of the dividing cells and the lines of force of the electric field, improved results can be obtained when the field is sequentially imposed in different directions.

Claims

1. A method of selectively destroying or inhibiting the growth of bacteria located within a target region of a patient, comprising the steps of:

administering, to the patient, an antibiotic against the bacteria, so that a therapeutically effective dose arrives in the target region;

capacitively coupling an AC electric field into the target region of the patient while the therapeutically effective dose is present at the target region, wherein the electric field has frequency characteristics that correspond to a vulnerability of the bacteria, wherein the electric field is strong enough to damage, during cell division, a significant portion of the bacteria whose long axis is generally aligned with the lines of force of the electric field, and wherein the electric field leaves non-dividing cells located within the target region substantially unharmed; and

repeating the coupling step until a therapeutically significant portion of the bacteria die,

wherein the strength of the electric field in at least a portion of the target region is between 2 V/cm and 100 V/cm.

2. The method of claim 1, wherein the strength of the electric field in at least a portion of the target region is between 5 V/cm and 20 V/cm.

3. The method of claim 1, wherein the strength of the electric field in at least a portion of the target region is between 10 V/cm and 17 V/cm.

4. The method of claim 3, wherein the frequency of the electric field is between 5 MHz and 20 MHz

5. The method of claim 3, wherein the frequency of the electric field is about 10 MHz.

6. The method of claim 1, wherein the electric field has a first orientation during a first interval of time and a second orientation during a second interval of time, wherein at least a portion of the first interval of time and the second interval of time are mutually exclusive.

7. The method of claim 6, wherein the first orientation is generally perpendicular to the second orientation.

8. A method of selectively destroying or inhibiting the growth of bacteria located within a target region, comprising the steps of:

capacitively coupling an AC electric field into the target region, wherein the frequency of the electric field is between 5 MHz and 20 MHz, wherein the strength of the electric field in at least a portion of the target region is between 2 V/cm and 100 V/cm, wherein the electric field has frequency characteristics that correspond to a vulnerability of the bacteria, wherein the electric field is strong enough to damage, during cell division, a significant portion of the bacteria whose long axis is generally aligned with the lines of force of the electric field, and wherein the electric field leaves non-dividing cells located within the target region substantially unharmed; and

repeating the coupling step until a therapeutically significant portion of the bacteria die.

9. The method of claim 8, further comprising the step of delivering an antibiotic to the target region so that a therapeutically effective dose of the antibiotic is present in the target region while the coupling step is performed.

10. The method of claim 8, wherein the strength of the electric field in at least a portion of the target region is between 5 V/cm and 20 V/cm.

11. The method of claim 8, wherein the strength of the electric field in at least a portion of the target region is between 10 V/cm and 17 V/cm.

12. The method of claim 8, wherein the frequency of the electric field is about 10 MHz.

13. The method of claim 8, wherein the electric field has a first orientation during a first interval of time and a second orientation during a second interval of time, wherein at least a portion of the first interval of time and the second interval of time are mutually exclusive.

14. The method of claim 13, wherein the first orientation is generally perpendicular to the second orientation.

15. An apparatus for selectively destroying or inhibiting the growth of bacteria located within a target region of a patient, the apparatus comprising:

a first pair of insulated electrodes, wherein each of the electrodes has a surface configured to facilitate capacitive coupling of an electric field into the patient'"'"'s body; and

an AC voltage source operatively connected to the electrodes;

wherein the AC voltage source and the electrodes are configured so that, when the electrodes are placed against the patient'"'"'s body and the AC voltage source is activated, an AC electric field is capacitively coupled into the target region of the patient via the electrodes,

wherein the frequency of the electric field is between 5 MHz and 20 MHz, wherein the strength of the electric field in at least a portion of the target region is between 2 V/cm and 100 V/cm, wherein the imposed electric field has frequency characteristics that correspond to a vulnerability of the bacteria, wherein the electric field is strong enough to damage, during cell division, a significant portion of the bacteria whose long axis is generally aligned with the lines of force of the electric field, and wherein the electric field leaves non-dividing cells located within the target region substantially unharmed.

16. The apparatus of claim 15, wherein the strength of the electric field in at least a portion of the target region is between 5 V/cm and 20 V/cm.

17. The apparatus of claim 15, wherein the strength of the electric field in at least a portion of the target region is between 10 V/cm and 17 V/cm.

18. The apparatus of claim 15, wherein the frequency of the electric field is about 10 MHz.

19. The apparatus of claim 15, wherein the surface of each of the electrodes is insulated from the AC voltage source by a thin dielectric coating that has a very high dielectric constant.

20. The apparatus of claim 15, further comprising:

a second pair of insulated electrodes, each having a surface configured to facilitate capacitively coupling of an electric field into the patient'"'"'s body; and

a switching mechanism that alternately applies the output of the AC voltage source to either (a) the first pair of electrodes or (b) the second pair of electrodes.

21. The apparatus of claim 20, wherein the first pair of electrodes is oriented with respect to the second pair of electrodes so that the field that is coupled into the patient when the AC voltage is applied to the first pair of electrodes is roughly perpendicular to the field that is coupled into the patient when the AC voltage is applied to the second pair of electrodes.

22. The apparatus of claim 20, wherein the surface of each of the electrodes is insulated from the AC voltage source by a thin dielectric coating that has a very high dielectric constant.