Effect of Carnosic acid and swimming and twitching motilities, pyocyanin virulence factor production and antibiotic susceptibility in Pseudomonas aeruginosa PAO1

ELEONORA MENGONI; OMAR PIVETTA; EDUARDO CAFFERATA; SILVIA MORENO; ADRIAN VOJNOV

Rosario- santa Fé

Congreso; SAMIGE; 2008

Pseudomonas aeruginosa is a Gram-negative, rod-shaped, motile bacterium that contains a single flagellum and type IV pilus, all usually located at the same pole. It is a highly versatile organism that survives in a wide variety of environments, and causes diseases in insects, plants, and animals. In humans, it is an opportunistic pathogen causing a variety of infections in immunocompromised hosts such as patients with cystic fibrosis, burns, cancer, and those requiring extensive stays in intensive care units. Antibiotic resistance of P. aeruginosa has been partially attributed to active efflux pumps that remove antimicrobial coumpounds. Furthermore P. aeruginosa is capable of forming biofilms on severals surfaces as a survival strategy. Bacterial biofilms are defined as highly structured, surface-attached communities of cells encased within a self-produced extracellular polymeric matrix. P. aeruginosa biofilm is a contributing factor in the persistent because show a higher degree of resistance to host immune responses and antimicrobial treatments compared with planktonic cells. The initial stages of P. aeruginosa biofilm formation require flagellar motility and type IV pili-mediated twitching for surface attachment and microcolony aggregation. P. aeruginosa also produces a large number of toxic exoproducts, including proteases, rhamnolipids, and pyocyanin (PCN). PCN is a blue pigment and contributes to the ability of P. aeruginosa to persist in the lungs of cystic fibrosis patients and interferes with mammalian cell functions. The aim of the present study was to evaluate the action of carnosic acid (CA), a natural compound found in plants like Rosmarinus officinalis and Salvia officinalis, on swimming and twitching motilities and PCN production in PAO1 strain. CA was also evaluated alone and in combination with tobramycin on the growth of PAO1. The results of this study shown that, swimming and twitching motilities were affected strongly at sub-MICs of CA. The effect on PCN production by supplementing the growth medium with different concentration of CA, repressed its expression in dose-dependent manner without affecting the growth rate. The action of tobramicyn was increased when CA was adding to culture media. This will suggest a synergistic effect. Therefore CA exerts unfavorable in vitro effects on P. aeruginosa PAO1. Taken together the attenuation of bacterial virulence factor, enhancements of tobramicyn action and decreased the motility of P. aeruginosa by CA may be helpful like a new drug and will help the host to eradicate P. aeruginosa more readily.