WO2016112878A1

WO2016112878A1 - Electronic germicidal device

Info

Publication number: WO2016112878A1
Application number: PCT/CZ2015/000002
Authority: WO
Inventors: Mojmír ČERMÁK
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-01-12
Filing date: 2015-01-12
Publication date: 2016-07-21
Anticipated expiration: 2017-07-12

Abstract

In the electronic germicidal device comprising a source of pulsed voltage and a pair of electrodes to be applied on the treated tissue the electrodes (8, 9) placed on a plastic film form at least partially a system of parallel or concentric lines with opposite polarity of the neighbouring electrodes (8, 9).

Description

Electronic Germicidal Device

BACKGROUND OF THE INVENTION

The invention relates to an electronic germicidal device comprising a source of pulsed voltage and a pair of electrodes applied on the treated tissue.

Secondary healing of wounds is a frequent complication occurring in all surgical fields. Especially diabetes brings about development of poorly healing skin defects, usually complicated by infection. Another problem is represented by infected decubiti in immobile patients, infected varicose ulcers as well as infected common injuries. Wound infections prolong hospitalisation, force the patients to pay long-term periodic visits to outpatient surgeries with painful dressing changes and use of often high doses of antibiotics.

Electrical therapy uses various types of electric currents improving blood circulation in tissues, releasing muscle tension or on the other hand strengthening the muscles. Galvanic therapy currently offers a whole range of therapeutic methods using electrical current in various forms - direct current, alternating current of low or medium frequency or high-frequency current with pulses of various shapes. Galvanic therapy is therefore indicated for treatment of diseases of the mobile apparatus, especially in the case of chronic and degenerative diseases, post-operative conditions, traumatic conditions, chronic gynaecological and urological inflammations, diseases of digestive and respiratory tracts, dermatological diseases and many more. Generally speaking electric therapy is basically used for treatment of deep tissues in cases of problems of other than bacterial origin.

New uses of galvanic therapy are proposed in JP 2007068748. The patent application describes a device for antibacterial treatment of burns or surgical wounds by ions of silver and electrical stimulation. The device comprises a source of pulsed voltage connected to two separate electrodes made of very pure silver and placed on the patient 's body in a distance from each other, with one of them directly placed on the treated site. Disadvantages of this device include a relatively low efficiency as a consequence of the mutual distance of the electrodes and also high costs of the electrode manufacture. Thus, it is desirable to provide an efficient electronic germicidal device whose price will not considerably increase costs of treatment even with disposable contact parts.

SUMMARY OF THE INVENTION

The present invention provides an improved electronic germicidal device comprising a source of pulsed voltage and a pair of electrodes to be applied on the treated tissue, wherein the electrodes placed on a plastic film form at least partially a system of parallel or concentric lines, with opposite polarity of the neighbouring electrodes.

The distance between the electrodes is the beneficial 0.1 to 1.5 mm.

In another beneficial embodiment of the invention the electrode system is a printed circuit applied on a plastic film.

The electrodes may be covered with a silver or gold layer for increased antibacterial effect.

Input voltage of the electrodes is single-phase substantially rectangular-shaped DC pulsed voltage ranging between 2 V and 12 V with the frequency range from 40 Hz to 200 Hz.

To prevent clogging the electrodes are adapted to polarity alternation in an interval of 1 to 30 seconds.

In the basic embodiment the plastic film with the electrodes is made for single use.

The objects and advantages of the present invention will be more apparent upon reading the following detailed description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the power source for the electrodes and

FIGs. 2 to 4 show three different embodiments of the electrode system on the plastic film. DESCRIPTION OF PREFFERRED EMBODIMENTS

An exemplary embodiment of an electronic germicidal device comprises a source of pulsed voltage shown in FIG. 1 known from prior art and a pair of electrodes implemented as a printed circuit applied on a plastic film, see FIGs. 2 to 4. The source comprises a power input device 1 , working within the range of up to 12 V with current limitation by max. 1.8 A, a frequency generator 2 connected to it that can be regulated within the range of 40 to 200 Hz and a power amplifier 3, to which the electrode power input cables 4 are connected. The source is provided with alternative power inputs either from an 11 .4 V accumulator 5 with the capacity of 3500 mAh with a connected 220/1 1.4 V charger 6, or from a 220/12 V mains adaptor 7. The pulsed voltage source is connected to electrodes 8, 9 placed on a plastic film and making a system of parallel lines with opposite polarities of the neighbouring electrodes 8, 9. The distance between the electrodes 8, 9 in the case of the described embodiment is 0.25 mm. The electrodes 8, 9 are galvanised with a silver layer to increase the antibacterial effect. The electrodes 8, 9 are supplied with rectangular-shaped single-phase pulsed 3.8 V voltage with the frequency of 112 Hz. Polarity of the electrodes 8, 9 alternates in a 10 s interval. The plastic film with the electrodes 8, 9 is disposable. FIGs. 2 to 4 document straight and circular shapes of the parallel or concentric electrodes 8, 9, respectively. However, the solution according to the present invention may also be implemented with a system of line electrodes with any progress if they remain at least partly parallel.

The skin serves as the basic barrier protecting the body against bacterial infections. Where this barrier is weakened by an injury (wounds, burns) or circulation insufficiencies (decubiti, varicose ulcers) bacteria may more easily penetrate to the tissues of the damaged site which may considerably increase overall risk of infection. The danger of future infection, in addition to the nature of the damage to this basic barrier, may also be affected by the types and numbers of microorganisms colonising the respective skin defect. The most frequently occurring bacteria colonising poorly healing dermal tissue include the gram-positive bacterium Staphylococcus aureus and the gram-negative bacteria Pseudomonas aeruginosa, Klebsiella pneumoniae,

Acinetobacter baumannii, Escherichia coli and others. Factors assisting infection prevention include timely surgical treatment locally administered and prophylactic antibiotics and intensive anti-inflammatory measures. In the case of older processes a bacterial bio plastic film may develop with increased resistance against antibiotics and antiseptics. Healing may further be complicated by infections caused by resistant hospital-borne strains (nosocomial infections) such as the methici!lin-resistant S. aureus (MRSA), extended-spectrum beta-lactamases (ESBL) forming gram-negative bacteria and vancomycin-resistant enterococci (VRE).

Nosocomial strains may be resistant to an extent making finding an appropriate and efficient antibiotic very difficult. That is why there is the worldwide trend towards search for efficient alternatives allowing for addressing these situations. One of these solutions may be treatment of the infected skin defects by temporary bandage with electrodes according to the present invention.

Antibacterial effects of the invented device have been laboratory tested by the Institute of infectious Diseases and Microbiology of the University of Veterinary and Pharmaceutical Sciences in Brno.

Collected strains of the following bacterial cultures have been used for the experiments:

Pseudomonas aeruginosa, Staphylococcus aureus, methicillin-resistant isolate of S. aureus (MRSA), Acinetobacter, Escherichia coli (ATTC) and vancomycin-resistant Enterococcus faecalis (VRE) individually kept in cryo-protective medium at - 80°C. Before use the strains were inoculated on maso-peptone agar ( PKA) or Mc Conkey agar (Oxoid, VB), incubated at 37°C for 18-24 hours and then incubated under the same conditions at least once again.

The quantity of the culture corresponding to 3 to 4 colonies was swabbed by a sterile swab and transferred to a test tube filled with 2 ml of sterile distilled water.

Turbidity was measured with a photometer and the inoculum was adjusted to the required value of 0.5 degrees of the McFarland turbidity scale. The initial inoculum was diluted in the ratio of 1 :100 by pipetting 30 μΙ of the suspension with 0.5 turbidity to a test tube filled with 3 ml buffered saline and profoundly homogenized. This inoculum with the number of cells corresponding roughly to 10⁶ CFU/ml was then used for the experiments. First of all the antibacterial effect of the device was subject to qualitative testing:

100 μ! of the suspension of the relevant bacterial strain with the density of 10⁶ CFU/ml was transferred onto the surface of pre-dried MPKA agar and spread across the whole surface of the substrate. After a short drying period the surface of the inoculated MPKA was covered with a plastic film with a system of electrodes and adhesion of the plastic film was assured. The electrodes were powered with 6 V with decreasing intensity from 1400 to 200 mA for 30 or 60 minutes.

Then the treated surface of the MPKA agar was printed on sterile filtration paper and the print was transferred onto sterile MPKA. The inoculated media were incubated at 37°C for 18 to 24 hours. A control sample was made for each such sample by treatment with the same inoculum and application of the same plastic film with electrodes but without powering with electric current. On the following day the results were documented with a digital camera and evaluated. The whole process was repeated once again following the identical procedure.

Result of visual evaluation: when compared to the control samples the cultures of MRSA, Pseudomonas aeruginosa, Acinetobacter calcoaceticus, E. coli and VRE showed a significant decrease in the bacterial culture density after incubation at 37°C for 18-24 hours.

On the basis of these results semi-quantitative evaluation of the effect was performed on a model muscle tissue of domestic pig (Sus scrofa domesticus).

100 μΙ of the suspension of the bacterial strains of Pseudomonas aeruginosa, ATCC and S. aureus MRSA with the density of 10^s CFU/ml was transferred on the surface of a muscle block and spread across an area corresponding to the size of the electrode-covered surface. Following short-term drying of the inoculum the plastic film with the electrodes was applied on the muscle surface and pressed in to imitate tissue bandage. The electrodes were connected for 30 minutes to a DC source with the voltage of 6 V and decreasing intensity from 1400 to 200 mA. The same muscle block covered with the identical inoculum but untreated with electric current was used as control.

The muscle blocks exposed to the effect of electric current and the control blocks were individually sampled and the number of viable bacteria on the muscle surface was measured. The test surface was swabbed with a steriie cotton wool swab in two directions and the swabbed material was transferred to 1ml of buffered saline (PBS). The obtained suspension was subject to ten-fold dilution. Twenty micro-litres were repeatedly inoculated by spreading on the surface of MPKA and MacConkey agar (MCA) to find out the number of survived bacterial cells. Following sample incubation under the abovementioned conditions the obtained colonies were counted and recalculated to the test surface of the muscle.

The processing of the swabs from the test and the control samples of contaminated muscle tissue by cultivation and recalculation revealed that the MRSA culture was completely devitalised on the test muscle sample (0 CFU of MRSA ml), while the control sample count was 1 x 10^s CFU of MRSA/ml.

In the case of the Pseudomonas aeruginosa culture the test sample count was 75 CFU of P. aeruginosafm\, while the control sample count was 2.75 x 10⁵ CFU of P. aeruginosa.

Thus under laboratory conditions the invented device showed significant antibacterial effects qualifying it for subsequent clinical verification studies.

Claims

1. An electronic germicidal device comprising a source of pulsed voltage and a pair of electrodes for application on the treated tissue, wherein the electrodes (8, 9) placed on a plastic film form at least partially a system of parallel or concentric lines with opposite polarity of the neighbouring electrodes (8, 9).

2. The device of claim 1 , wherein the distance between the electrodes (8. 9) is 0.1 to 1.5 mm.

3. The device of claims 1 or 2, wherein the system formed by the electrodes (8, 9) is a printed circuit applied on a plastic film.

4. The device of claims 1 to 3, wherein the electrodes (8, 9) are covered with a silver or gold layer.

5. The device of claims 1 to 4, wherein the input voltage of the electrodes (8, 9) is single-phase substantially rectangular-shaped DC pulsed voltage ranging between 2 V and 12 V with the frequency range from 40 Hz to 200 Hz.

6. The device of claims 1 to 5, wherein the electrodes (8, 9) are adapted to polarity alternations in the interval of 1 to 30 s.

7. The device of claim , wherein the plastic film with the electrodes (8, 9) is disposable product.