Pseudomonas aeruginosa is an opportunistic pathogen of humans, animals as well as of plants and the most common Gram-negative bacterium found in nosocomial infections. Pseudomonas associated biofilms are highly tolerant to lethal doses of antibiotics. Recent discoveries of quorum quenching mechanisms use quorum sensing as a potential antimicrobial target. In this review we discuss the efficacy of different antipathogenic compounds against gram-negative bacteria in general and against selected P. aeruginosa strains in particular. Several strategies for quorum quenching have recently been deployed and recommended. The first approach is the use of quorum quenching enzymes that target a broad range of AHLs. Quorum quenching enzymes such as lactonase and acylase are able to inactivate a wide range of AHLs. The second approach involves the use of different herbal extracts as quorum quenching compounds against bacterial virulence. The third approach combines the use of quorum quenching along with other supplemental treatments, such as antibiotics, to obtain a synergistic effect in which the quorum quenching compounds deliver the primary offensive capability to reduce bacterial capacity for pathogenicity and increase the susceptibility of bacteria to antibiotic treatment. The convergent approaches are discussed here to elaborate on how new as well as previously available natural compounds such as active antipathogenic compounds from garlic and other naturally occurring herbal sources can be utilized in novel ways with the help of combinatorial chemistry to meet the challenges of increasing threats from newly emergent and potent drug resistant microbes to treat compromised individuals particularly with low immunity thresholds.

Key words: Antipathogenic compounds, Pseudomonas aeruginosa, Quorum sensing inhibition