Killing bacteria with Plasma
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 io9.com. 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.
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!