Antimicrobial effect of copper alloys on Acinetobacter species isolated from infections and hospital environment

Abstract

BackgroundAn increased proportion of Gram-negative bacteria have recently been reported among etiologic agents of infection. In Poland, Acinetobacter baumannii is a big problem for hospitals, especially intensive care units. Touch surfaces made from materials with antimicrobial properties, especially copper alloys, are recommended as a supplementary method of increasing biological safety in the hospital environment.Aim of the studyThe objective of this study is to determine the susceptibility to selected copper alloys of three clinical Acinetobacter baumannii strains, one Acinetobacter lwoffi and an A. pittii strain isolated from the hospital environment.Material and methodThe modification of the Japanese Standard, which the ISO 22196:2011 norm was used for testing antimicrobial properties of CuZn37, CuSn6 and CuNi18Zn20 and Cu-ETP and stainless steel as positive and negative control, respectively.ResultsThe highest cidal efficiency, expressed as both time and the degree of reduction of the initial suspension density, against all of the tested Acinetobacter strains was found for ETP copper. But, the results of our study also confirmed effective activity (bacteriocidal or bacteriostatic) of copper alloys selected for the study, contrary to the stainless steel. The reduction in bacterial suspension density is significantly different depending on the strain and copper alloy composition.ConslusionsThe results of our study confirmed the effective antibacterial activity of copper and its selected alloys against clinical Acinetobacter baumannii and Acinetobacter lwoffii strains, and Acinetobacter pittii strain isolated from the hospital environment.

Copper-Polyurethane Composite Materials: Particle Size Effect on the Physical-Chemical and Antibacterial Properties

“…The cell density was expressed as Log 10 of the colony-forming units per mL (Log 10 CFU/mL) and the average values and standard deviations were then calculated and plotted using Prim 7 (GraphPad, San Diego, CA, USA). A bacteriostatic effect was considered to have occurred when the decrease in the inoculum was >2 Log 10 and <3 Log 10 and a bactericidal effect was considered to have occurred when the cell density decrease was ≥3 log 10 [ 13 , 14 , 15 ].…”

Brass Alloys: Copper-Bottomed Solutions against Hospital-Acquired Infections?

“…For example, within the Acinetobacter genus, the reduction in Acinetobacter lwoffii counts on brass obtained after a 5 h exposure were lower (around 99% reduction) than those obtained for Acinetobacter pittii and most A. baumannii strains (99.9% reduction and above) [ 60 ]. At the species level, one XDR A. baumannii strain count was unchanged after a 5 h exposure to brass, while the two other A. baumannii strains (1 MDR and 1 XDR) registered a count reduction of at least 99.9% [ 60 ]. Similarly, out of three MRSA strains, two were readily eradicated from the surface of brass while only a one log (90%) reduction was registered for the third one after a 6 h exposure [ 54 ].…”

“…The antibacterial efficacy is usually assessed after a time of exposure to the copper-containing surface using reduction in bacterial counts either compared to the initial inoculum and/or to the counts obtained on a control surface deprived of antibacterial properties such as glass, plastic or stainless steel (Figure 2). These tests were first held on food pathogens and collection strains susceptible to antibiotics [51][52][53], but publications soon moved on to report significant reductions in bacterial counts on copper and copper alloy surfaces for a range of multidrug-resistant (MDR) bacteria and/or bacteria originating from clinical settings [32,[54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69]. Indeed, the importance of testing clinical strains to evaluate whether any co-selected, cross-selected and/or co-regulated resistance between copper and antibiotics and/or detergent-disinfectants could occur soon appeared as mandatory [62].…”

Evaluation of copper alloys for reducing infection by methicillin resistant Staphylococcus aureus and vancomycin resistant Enterococcus faecium in intensive care unit and in vitro

“…Cu99 showed a bactericidal effect of less than 1 hour for MRSA, 2 hours for P. aeruginosa and exhibited a closer bactericidal range effect against A. baumannii . Rozanska et al [ 15 ] showed antimicrobial effect of copper alloys on Acinetobacter species isolated from infections and hospital environment. And the results of the study confirmed effective activity (bacteriocidal or bacteriostatic) of copper alloys [ 15 ].…”