The antimicrobial effects of helium and helium–air plasma on Staphylococcus aureus and Clostridium difficile

Abstract

Significance and Impact of the Study: Many bacterial causes of healthcare infection can survive in the inanimate environment for lengthy periods and be transmitted to patients. Furthermore, current methods of environmental decontamination such as detergents, chemical disinfectants or gaseous fumigation are suboptimal for a variety of reasons. We assessed the efficacy of helium and helium-air plasma as a decontaminant and demonstrated a significant reduction in bacterial counts of Staphylococcus aureus on a glass surface. Atomic force microscopy morphologically confirmed the impact on bacterial cells. This approach warrants further study as an alternative to current options for hospital hygiene. AbstractHealthcare-associated infections (HCAI) affect 5-10% of acute hospital admissions. Environmental decontamination is an important component of all strategies to prevent HCAI as many bacterial causes survive and persist in the environment, which serve as ongoing reservoirs of infection. Current approaches such as cleaning with detergents and the use of chemical disinfectant are suboptimal. We assessed the efficacy of helium and helium-air plasma in killing Staphylococcus aureus and Clostridium difficile on a glass surface and studied the impact on bacterial cells using atomic force microscopy (AFM). Both plasma types exhibited bactericidal effects on Staph. aureus (log3Á6 ->log7), with increased activity against methicillin-resistant strains, but had a negligible effect on Cl. difficile spores (<1log). AFM demonstrated cell surface disruption. The addition of air increased the microbicidal activity of the plasma and decreased the exposure time required for an equivalent log reduction. Further evaluation of cold plasma systems is warranted with, for example, different bacteria and on surfaces more reminiscent of the health care environment as this approach has potential as an effective decontaminant.

Potential Applications of Non-thermal Plasma in Animal Husbandry to Improve Infrastructure

“…This fungicidal property of NTP also suggests its usefulness in decontaminating animal farms. The antibacterial efficacy of NTP has been further confirmed by several groups (4,30,(38)(39)(40). NTP has been found to have antibacterial effects on a variety of bacteria (41,42), on ESKAPE pathogens in the environment (17), on multi-drugresistant bacteria in surface environments (43).…”

“…To date, NTP has been identified as an effective, low-cost and non-toxic way to decontaminate surfaces, instruments and confined environments (15,16,29). It has been shown that NTP produced from single-jet system eradicates vegetative bacteria from different surfaces (16,30) and NTP from multi-jet system is capable of reducing surface pathogens such as methicillin-resistant staphylococcus aureus, Clostridium difficile, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii (16). Furthermore, other studies have also demonstrated the successful decontamination of surfaces and instruments from these pathogenic organisms by NTP treatment (6,15).…”

Cold atmospheric pressure plasma and decontamination. Can it contribute to preventing hospital-acquired infections?

“…All of these tests were completed on cells air-dried on glass slides. 87 To evaluate the efficacy of a CAPP, however, we selected surface materials routinely found in the clinical environment, including marmoleum flooring, polyurethane mattress fabric, polypropylene plastic, powdercoated mild steel, and stainless steel. All surfaces were inoculated with MRSA, ESBL E. coli, vancomycin-resistant Enterococcus faecalis, and Acinetobacter baumannii and treated for periods of 30, 60, and 90 s. The optimum antimicrobial activity of the air plasma in this study was observed after 90 s, producing reductions of 3e5 log 10 for MRSA, 2e5 log 10 for VRE, 2e3 log 10 for E. coli and 1.7e3 log 10 for A. baumannii, all of which were air-dried on each test surface.…”

Detecting Clostridium difficile Spores from Inanimate Surfaces of the Hospital Environment: Which Method Is Best?

“…C. difficile colonization increases with the length of hospital stay following environmental exposure to spores or contact with an infected person (3). Contamination and survival of C. difficile spores on hospital inanimate surfaces have been reported (4, 5) and shown to be associated with cross-transmission (6-8).Inactivation and eradication of Clostridium difficile spores are a challenge, and several relatively new techniques have been investigated, such as hydrogen peroxide vapor, UV radiation, or gaseous plasma systems (5,6,9,10). Validation of such techniques should use optimal recovery methods to better quantify bacterial spore killing or eradication.…”

“…Inactivation and eradication of Clostridium difficile spores are a challenge, and several relatively new techniques have been investigated, such as hydrogen peroxide vapor, UV radiation, or gaseous plasma systems (5,6,9,10). Validation of such techniques should use optimal recovery methods to better quantify bacterial spore killing or eradication.…”