Inactivation of bacterial and viral biothreat agents on metallic copper surfaces

Abstract

In recent years several studies in laboratory settings and in hospital environments have demonstrated that surfaces of massive metallic copper have intrinsic antibacterial and antiviral properties. Microbes are rapidly inactivated by a quick, sharp shock known as contact killing. The underlying mechanism is not yet fully understood; however, in this process the cytoplasmic membrane is severely damaged. Pathogenic bacterial and viral high-consequence species able to evade the host immune system are among the most serious lethal microbial challenges to human health. Here, we investigated contact-killing mediated by copper surfaces of Gram-negative bacteria (Brucella melitensis, Burkholderia mallei, Burkholderia pseudomallei, Francisella tularensis tularensis and Yersinia pestis) and of Gram-positive endospore-forming Bacillus anthracis. Additionally, we also tested inactivation of monkeypox virus and vaccinia virus on copper. This group of pathogens comprises biothreat species (or their close relatives) classified by the Center for Disease and Control and Prevention (CDC) as microbial select agents posing severe threats to public health and having the potential to be deliberately released. All agents were rapidly inactivated on copper between 30 s and 5 min with the exception of B. anthracis endospores. For vegetative bacterial cells prolonged contact to metallic copper resulted in the destruction of cell structure.

Antibacterial effect and mechanism of high-intensity 405±5nm light emitting diode on Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus under refrigerated condition

“…ROS generated by the LED illumination may interact directly with unsaturated fatty acids in bacterial membranes and start lipid peroxidation, probably resulting in decreasing their membrane fluidity and then changing membrane components as well as disrupting membrane bound proteins [32]. Similar results were also obtained by Bleicher et al [29] who reported that the cytoplasmic membrane damage was observed in Yersinia pestis and Burkholderia strains by metallic copper surfaces due to oxidative damage.…”

“…The LIVE/DEAD staining of SYTO®9 and propidium iodide (PI) bound to nucleic acid is able to distinguish between damaged and intact bacterial membranes. Green fluorescing SYTO®9 (485/500 nm) penetrates the cytoplasmic membranes of both intact and damaged cells due to low molecular weight (~10 Da), while red fluorescing PI (490/635 nm) of higher molecular weight (668 Da) is only able to enter the damaged cytoplasmic membranes, resulting in a reduction in the intensity of SYTO®9 when two stains coexist within the cell [29][30][31]. In this study, healthy and non-illuminated cells exposed to 10°C for 7.5 h revealed green fluorescent signal of SYTO®9, whereas some LED-illuminated cells showed red fluorescence (Fig.…”

Killing of bacteria by copper, cadmium, and silver surfaces reveals relevant physicochemical parameters

“…9,[23][24][25] On the other hand, differences in killing rates due to different bacterial strains are comparatively smaller: >10 7 cfu of five different bacterial biothreat agents were all killed in 0.5-5 min on copper in dry plating experiments. 28 Similarly, >10 7 cfu of five clinical isolates of methicillin-resistant bacteria were killed in 60-270 min, and in another study, >99% of ten clinical isolates were all killed in 2 h in wet plating on copper. 29,30 We here chose E. coli as the model organism because it has been used in many fundamental studies on contact killing.…”

Contact killing and antimicrobial properties of copper

“…In addition, the inactivation of monkeypox and vaccinia viruses have also been demonstrated on copper surfaces (Bleichert et al 2014).…”