Concerted dispersion of Staphylococcus aureus biofilm by bacteriophage and 'green synthesized' silver nanoparticles.

Staphylococcal biofilms predominantly cause persistent nosocomial infections. The widespread antibiotic resistance followed by its ability to form biofilm in biological and inert surfaces often contributes to major complications in patients and veterinary animals. Strategic importance of bacteriophage therapy against critical staphylococcal infections had been predicted ever since the advent of antibiotic resistant staphylococcal strains. The significance of metal nanoparticles in quenching biofilm associated bacteria was previously reported. In this study, we demonstrate a concerted action of 'green synthesized' silver nanoparticles and bacteriophages in removing pre-formed Staphylococcus aureus biofilms from an inert glass surface in a time dependent manner. Our results demonstrate, for the first time, the rapid co-operative dispersion of the bacterial biofilm. In addition, the synergistic activity of the nanoparticles and bacteriophages causes the loss of viability of the biofilm entrapped bacterial cells thus preventing establishment of a new infection and subsequent colonization. This work further opens up a platform for the combinational therapeutic approach with a variety of nanoparticles and bacteriophages against mono or poly bacterial biofilm in environmental, industrial or clinical settings.

Microscopic analysis of the inhibition of staphylococcal biofilm formation by Escherichia coli and the disruption of preformed staphylococcal biofilm by bacteriophage.

The formation of bacterial biofilms is a severely encountered problem in clinical and industrial settings. Most of the naturally occurring bacterial strains are capable of forming mono or mixed biofilms. In this study, we evaluated the potentiality of three clinically relevant species in forming mono and mixed biofilms over glass surface. In addition, we also appraised the efficiency of bacteriophages in alleviating preformed mono and mixed biofilm. Our initial study focused on the ability of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa in forming biofilm on glass cover slip. All the three strains were able to form mono biofilm, although at varying intensities. Interestingly, E. coli inhibited the formation of S. aureus biofilm in a mixed culture. Specific bacteriophages ɸ44AHJD and ɸX174 completely disrupted S. aureus and E. coli preformed biofilm structure after 72 hr of incubation. However, addition of either of the bacteriophage to the mixed E. coli-S. aureus promoted the formation of biofilm by the alternate strain that was not affected by the phage. Our findings elicit the potentiality of common bacterial strains in forming biofilms on smooth glass surface. In addition, these results are very promising for the development of effective drugs using intact bacteriophages for the removal of complicated bacterial biofilms formed in clinically relevant glass surfaces. The observations further complemented the earlier finding of competitive inhibition of S. aureus biofilm development by E. coli.