Cold atmospheric pressure plasmas exhibit antimicrobial properties against critical bacteria and yeast species

OBJECTIVE

Cold atmospheric pressure plasmas (CAPPs) have been used to sterilise implant materials and other thermally unstable medical products and to modify chemical surfaces. This study investigates the antimicrobial effect of the gas and input power used to generate CAPPs on microorganisms causing skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Malassezia pachydermatis.

METHOD

Microorganisms were cultivated on Mueller Hinton 2 (MH2) agar plates. CAPP treatment was performed using the Plasma BLASTER MEF. To investigate the antimicrobial effects the following CAPP parameters were varied: the gas used, input power, as well as number of treatments and treatment time.

RESULTS

The antimicrobial efficacy of the CAPPs was found to increase with increasing input power and treatment time (or cycles). Furthermore the plasma generated from nitrogen is more effective than from air.

CONCLUSION

The study showed that CAPPs demonstrate strong bactericidal and fungicidal properties in vitro. The selective application of CAPPs for the treatment of wound infections may offer a promising supplementary tool alongside current therapies.

Antimicrobial impact of cold atmospheric pressure plasma on medical critical yeasts and bacteria cultures

OBJECTIVES

Plasma medicine focuses on the application of cold atmospheric pressure plasmas (CAPs) in or on the human body. So far, plasmas have been used to sterilize implant materials or other thermally unstable medical products and have been applied for chemical surface modifications. This study investigates the antimicrobial effect of physical plasmas on microorganisms which cause skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, depending on the plasma source and the kind of plasma excitation used.

MATERIALS

Microorganisms were plated onto MH2 agar plates. Plasma treatment was performed using the plasma sources BLASTER MEF and kinpen 09. To investigate the antimicrobial effects, the following plasma parameters have been varied: working gas, distance from nozzle to surface, electrical power, grid spacing of treatment lines, number of treatments and work piece velocity.

RESULTS

The generated plasmas had an antimicrobial effect that depended on the chosen plasma parameters, in particular on the process gas used, the plasma power and the number of treatments performed. Thus, different reactive species were observed by optical emission spectroscopy measurement in the generated plasmas.

CONCLUSIONS

The study showed that CAPs exhibit profound bactericidal and fungicidal properties in vitro. However, an important factor for the antimicrobial efficacy is the composition of the 'chemical soup' supplied by the CAP system which can be regulated by the process gases used.

Thymine-metal ion interactions: relevance for thymine quartet structures

Apart from their function as counter ions for the charge neutralization of nucleic acids, alkali metal ions play important roles in stabilizing particular multistranded nucleic acids, e.g. guanine quartets in telomeres and uracil (U) or thymine (T) quartets. Here X-ray crystal structure determinations of a series of alkali metal ions (Na+, K+, Rb+, Cs+) as well as of Mg2+ and H5O2+ adducts with the model bases 1-methylthymine and 1-ethylthymine are reported, which bear relevance to the question of thymine quartet (T4) geometries. The compounds isolated differ in their stoichiometries (T:M = 4:1, 2:1, 1:1), and the ways the metal ions interact with the bases. The two extremes are exclusive metal coordination to exocyclic oxygen atoms of the T bases and exclusive H bonding between M aqua cations and the bases.

Liposomal amphotericin B (AmBisome) application and hepatic microsomal enzyme function in the rat

In the present study we investigated the influence of AmBisome, a lyophilized liposomal amphotericin B formulation on various hepatic cytochrome P450-dependent mixed function oxidases, antipyrine clearance and hepatic glucose-6-phosphatase activity in rats. Animals were treated intravenously for 6 days with AmBisome (15 mg kg-1 body weight). Subsequently, the enzyme activities and cytochrome P450 concentrations were measured ex vivo in hepatic microsomes. Following AmBisome the activity of the microsomal ethoxycoumarin-O-deethylase increased significantly from 333 +/- 77 pmol mg-1 to 459 +/- 125 pmol mg-1, whereas benzpyrenhydroxylase and glucose-6-phosphatase did not change compared with the controls. Accordingly, antipyrine clearance was not affected by AmBisome treatment. Microsomal cytochrome P450 concentrations as well as total microsomal protein concentrations were not changed following treatment with AmBisome and it did not affect either serum levels of liver transaminases or bilirubin. The results show that the application of a high AmBisome dose had no adverse effects on a variety of microsomal hepatic enzymes and the antipyrine clearance in rats. Thus, it seems likely that AmBisome does not seriously impair metabolic liver function.