Decontamination of Nosocomial Bacteria IncludingClostridium difficileSpores on Dry Inanimate Surface by Cold Atmospheric Plasma

Abstract

Microbial control is important to prevent nosocomial infections. Cold atmospheric plasma (CAP) is studied as an alternative disinfectant for dry surfaces. Bacterial endospores including Clostridium difficile and vegetative bacteria including Enterococcus faecium are treated on carriers, considering European testing standards. CAP reduces the spore load (106 cfu) by at least 3 log10 as required, independent from the bioburden (≤10 min treatments). Only a 2 log10 reduction is achieved with vegetative bacteria due to multilayer formation resulting from a higher required load (108 cfu). However, densities <10−7 cfu cm−2 enable disinfection by CAP. Elemental mapping identified other influencing burden. Overall, this study demonstrates possibilities and limitations of CAP treatment for disinfecting purposes.

Plasma Medicine: A Field of Applied Redox Biology

“…Regardless of the specific mode of action, early experimental evidence on microbicidal plasma effects on heat or radiation-sensitive material surfaces spurred further efforts to investigate plasma effects on contaminated or infected tissue. Several in vitro studies on effective inactivation of clinically relevant microorganisms and viruses have produced promising results (51)(52)(53)(54)(55)(56)(57)(58). The first clinical investigations on antiseptic plasma effects on tissue and wounds that followed have shown rather modest microbial reduction rates (59)(60)(61)(62)(63).…”

Evolutionary clade affects resistance of Clostridium difficile spores to Cold Atmospheric Plasma

“…Previous studies have demonstrated the sporicidal effect of plasma produced in air with surface discharge 30 and a compressed air jet 31 to decontaminate C. difficile spores. The ability of a helium/oxygen atmospheric pressure plasma jet to deactivate C. difficile spores has also been demonstrated 32 , whilst a separate study found helium/oxygen plasma ineffective against C. difficile spores 33 .…”

“…A clean dry environment provided the greatest reduction in spores and shortest D value (0.4 minutes), compared to dried albumin (D value = 1.7 minutes) and C. difficile spores suspended in water (D value = 1.8 minutes). The observation that organic matter increases spore survival to plasma exposure has previously been reported by Klampf et al ., 2014, where they assessed a surface micro-discharge against C. difficile endospores in the presence of 0.03% albumin 30 . The presence of organic matter is known to attenuate the efficacy of medical device disinfection 42 and is an important consideration when assessing plasma for high level disinfection.…”

“…Spore suspensions were centrifuged at 3000 × g for 4 minutes and resuspended in an aqueous Bovine Serum Albumin, BSA, (Sigma Aldrich Corp.) solution at 0.03% (w/v) 30 . 100 μl aliquots of this BSA supplemented spore suspension were dispensed, with continuous mixing, into wells of a 96-well Nunc TM microtitre plate and left to air dry overnight in a fume cabinet (Holliday Fielding Hocking Ltd.).…”

Application of High Pressure with Homogenization, Temperature, Carbon Dioxide, and Cold Plasma for the Inactivation of Bacterial Spores: A Review

“…Reduction of 3 log units were achieved for all spore tested, being C. difficile more efficiently inactivated (after 1 min of treatment) than the other spores (both after 2.5 min of treatment). In addition, the authors analyzed the morphology of the examinated spores and no significant changes were observed (Klämpfl and others ). In another study, different strains of C. difficile spores were exposed to cold atmospheric pressure using a mixture of helium and oxygen as a carrier gas.…”