Silver Inhibits the Biofilm Formation of <i>Pseudomonas aeruginosa</i>

Abstract

Biofilm is the assemblage of microbial cells that are irreversibly associated with biotic and abiotic surfaces and is usually enclosed in the self secreted extracellular polymeric substances (EPS). The presence of EPS in biofilm makes the microbial population resistance against antibiotics and other drugs. Biofilms are considered as a serious challenge to pharmaceutical industries because most of the microbial diseases are now associated with biofilm. In this context, we have addressed the biofilm potentialities of Pseudomonas aeruginosa , which has been found to be associated with several deadly diseases including septicemia, urinary tract infections, and gastrointestinal infections, and wherein biofilm plays a crucial role in pathogenesis. Since silver had been used globally for a long time for treating a wide range of illnesses from burn wounds, typhoid, and anthrax to bacterial conjunctivitis in newborns, but its antibiofilm activity is still unknown. Thus, in this current study, we have tried to examine the antibiofilm potentiality of silver against the biofilm of Pseudomonas aeruginosa . Our result showed that silver exhibited considerable antimicrobial property against Pseudomonas aeruginosa where the minimum inhibitory concentration (MIC) was found at 25 μg/ml. Biofilm inhibition by silver against Pseudomonas aeruginosa was then evaluated by crystal violet (CV) staining, estimation of total biofilm protein and microscopy based microbial adherence test using the sub MIC doses of silver. The results showed that all the tested sub MIC doses of silver exhibited considerable antibiofilm activity against P. aeruginosa , wherein the maximum biofilm attenuation was showed by a silver concentration of 20 μg/ml . We also observed that all these sub MIC doses of silver neither interfere with the growth cycle of the bacteria nor affect the cell viability but only attenuates biofilm formation property of the bacteria. The current study deciphers a new axis in biofilm biology where a metal like silver can inhibit the formation of biofilm markedly. Thus, the knowledge gathered in this study may help the pharmaceutical sector to design combinatorial drug where silver could be an important partner to reduce the load of pathogenesity caused by biofilm.