  Acinetobacter baumannii is a typically short, almost round, rod-shaped
(coccobacillus) Gram-negative bacterium. It can be an opportunistic pathogen in
humans, affecting people with compromised immune systems, and it is becoming
increasingly important as a hospital-associated (nosocomial) infection. It has
also been isolated from environmental soil and water samples. In this work,
unlike conventional medical methods like antibiotics, the influence of
atmospheric-pressure cold plasma on this bacterium is evaluated by means of a
colony count technique and scanning electron microscopy. The plasma used here
refers to streamers axially propagating into a helium channel penetrating the
atmospheric air. The plasma is probed with high resolution optical emission
spectroscopy and copious reactive species are unveiled under low-temperature
conditions. Based on the experimental results, post-treatment (delayed)
biochemical effects on Acinetobacter baumannii and morphological modifications
appear dominant, leading to complete deactivation of this bacterium.
