Killing bacteria with Plasma

Set phasers for "bacteriocidal," Mr. Spock!

We’re one step closer to the future this morning, with this news article published in the Journal of Physics, as seen on the blog Researchers in Australia and China have described an inexpensive electronic mechanism for eliminating antibiotic resistant bacteria. The handheld device is powered by a 12 V battery, and generates a cold atmospheric-pressure plasma jet (CAPP), which has been shown previously to be effective at killing microorganisms. The previous devices which have been constructed all utilize an external power supply to generate a plasma torch; this is the first one that is portable, and can presently be constructed with about $100 in materials.

The researchers grew Enterococcus faecalis in culture on slides to promote the growth of biofilms. Organisms that grow in biofilms present a significant issue for health care settings, as they are more resistant to both chemical (antiseptics and disinfectants) and physical (scrubbing) methods for removal. Consequently, they are frequent causes of nosocomial infections in patients. They found that treatment of biofilms could result in complete killing of the entire community of microorganisms could be accomplished within 5 minutes.

Green picture: pre-treatment
Red picture: post-treatment

Data from the manuscript is shown in the figure to the left: biofilms, both pretreatment and posttreatment were examined by fluorescence microscopy. They utilized a set of dyes for microscopy, one that only stained living cells and turned them green, and one that stained only dead cells and turned them red. The relative amounts of each color then could be used as an indicator of the viability of the biofilm by confocal laser scanning microscopy, a type of light-based microscope that allows the researcher to move down through layers of a biological sample.

As is apparent in the bottom panel, all layers of the Enterococcus biofilm are dead following treatment. The researchers also indicate that the biofilms that were treated were among the thickest ones tested with this technology, at over 25 micrometers thick. And as seen in the image at the top, the plasma torch is safe to touch. Stick one of these on a toothbrush for me!


About ycpmicro

My name is David Singleton, and I am an Associate Professor of Microbiology at York College of Pennsylvania. My main course is BIO230, a course taken by allied-health students at YCP. Views on this site are my own.

Posted on April 7, 2012, in Strange but True and tagged , , . Bookmark the permalink. 6 Comments.

  1. now this is interesting or should I say… just what the doctor ordered (or perhaps, needed).

    • It really does seem truly portable, which will allow it to be brought into many settings that might preclude a larger, tethered apparatus. Plus, physical methods for microbial control (like application of heat) will prevent development of resistance that currently is such a significant issue in health care settings with chemical methods for control.

  2. That last sentence of this blog is what I started thinking at the beginning, after reading a few sentences and thought I was way off base. I was thinking this could be really useful for dentists too, to aid in the removal of plaque from their patient’s teeth, not just useful for microbiologists killing micoorganisms. Has the aspect of any long term side effects due to using the CAPP directly on skin, repeatedly over an extended period of time been studied? If it can be constructed using only $100 worth of materials, maybe YCP should invest in a few of these for the upper level science labs who study biofilms! =)

    • I think that would be one of the first uses of such a device. One of the commenters on the link I provided up above recalled an anecdotal story about a similar device being proposed to clean out dental cavities without drilling, prior to implanting fillings. Certainly would reduce the pain quotient of dental visits. This Wikipedia link summarizes some of the current thinking about using this.

  3. This device would be able to clean a dental cavity without drilling? How would that process work… the biofilm and the plaque have already done their damage by the tooth’s evident decay.

    • I think that it is designed to replace the traditional dental drill, which is used to remove bacterial material from the cavity prior to filling. If the plasma device can spot sterilize the region without drilling, it may be less painful.

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