The antibacterial biofilm activity of metal-doped mullite ceramics against pathogenic bacteria

Bacterial biofilms are densely packed microorganisms surrounded by secreted polymers responsible for many chronic infectious diseases as well as for contamination of clinical and industrial environments. The aim of this study was to assess the potential antimicrobial activity of zinc-, copper- and silver-doped mullite ceramics disks against biofilm producing clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis,Streptococcus mutans and Pseudomonas aeruginosa. It also aimed to compare their effect in preventing the initial bacterial adhesion and the accumulation and maturation of biofilm on the disk surfaces. The antibacterial activities of the metal-doped mullites against biofilm were found dependent on mineral concentration and the incubation time. Silver-mullite disks showed high potential for controlling early and late biofilms against the studied microorganisms. Copper-mullite disks had exerted better activity in reducing theP. aeruginosa adherence and biofilm growth as compared with the Gram positive bacteria. However, these disks failed to show antibacterial activity against S. mutansplanktonic or biofilm grown after 24 h incubation. Interestingly, zinc-mullite disks enhanced the growth of S. aureus and S. epidermidis in suspension or biofilm.