Piper nigrum seeds inhibit biofilm formation in Pseudomonas aeruginosa strains

Frequent occurrence of antibiotic resistant biofilm forming Pseudomonas aeruginosa infections have become global concern due to the failure of available measures to treat these pathogens. This study was designed to investigate the effect of Piper nigrum extract on Pseudomonas aeruginosa biofilms and its antiquorum sensing (QS) activity.

Antibiotic susceptibility of P. aeruginosa isolates was tested by Kirby-Bauer disc diffusion method. Effect of P. nigrum extract on biofilm formation was evaluated using crystal violet assay. Anti-QS studies were undertaken using biosensor strain Chromobacterium violaceum CVO26 and CV ATCC12472.

The clinical strains of P. aeruginosa used in the study were resistant to most of the antibiotics, except for imipenem. P. nigrum methanol extract inhibited biofilm formation in a concentration dependent manner in all these strains. 50% inhibition of biofilm was achieved at a concentration of 100μg/mL. Anti-QS activity of the extract was evidenced by the significant inhibition of violacein production.

P. nigrum extract exhibited significant biofilm inhibitory and anti-QS activity on the tested organisms, thereby indicating its probable use as a potential alternative therapeutic to complement the existing antibiotic regimen.