Comparison of the antibacterial effect of a copper-coated surface on Staphylococcus epidermidis and Pseudomonas putida in different physiological states

Abstract

The antimicrobial effect of Cu is dependent on several factors, including the physiological state of test-cultures. The present study aimed to compare the antibacterial effect of the newly developed Cu-coated surface, using bacterial cultures of Staphylococcus epidermidis and Pseudomonas putida harvested at exponential (6h) and stationary (24h) phases of growth as well as from a colony. Growth kinetics and cell morphology were characterised for each culture. The colony forming units log reduction values for a Cu-coated surface for cultures at exponential, stationary phase, and from a colony were 1.08, 2.85, and 2.14, respectively, for S. epidermidis, while 1.57, 3.95, and 3.14, respectively, for P. putida. The Cu-coated surface reduced the signal of ATP bioluminescence in both S. epidermidis and P. putida, with the more pronounced inhibition being for the cells at exponential and stationary phase of growth. The data indicated that bacterial cultures at the early exponential stage of growth are more resistant towards antimicrobial surfaces than cells at the stationary phase of growth and from a colony. This fact is of great importance for estimating the efficiency of antimicrobial coatings.