Method: BiSubsal NPs were synthesized by the laser ablation technique and dissolved in sterile water. Ten different concentrations of the nanoparticles (from 0.5 to 100 %) were tested with pure cultures of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. For the experiments using Bismuth subsalicylate, a 102/mL suspension of pure cultures of each strain was plated on agar plates containing 60%, 30% and 10% of the compound. Plates were incubated at 35°C during 3 days and the number of colony forming units were determined by visual examination of the bacterial growth.
Result: BiSubsal-NPs were effective against E. coli and P. aeruginosa at the highest concentrations tested (90 and 100%), while S. aureus and S. epidermidis did not show the same sensitivity. However, when Bismuth subsalicylate was dissolved in the agar plates, a higher sensitivity of the microorganisms was observed, a complete inhibition of the growth of the four strains was obtained at the 60% concentration. Even more, no colonies of E. coliwere detected in any of the concentration tested.
Conclusion: Bismuth subsalicylate seems to have less antibacterial activity in nanoparticles compared with the normal salt.