Quorum sensing in Gram-negative pathogens, a fresh look

Quorum sensing is the cell-density dependent bacterial communication system. A number of Gram-negative bacteria have been reported to use quorum sensing to regulate their various traits including virulence. In this review, we focus on Quorum sensing in Gram-negative human pathogens and ways to contain pathogens by utilizing the QS phenomena. Bacteria prefer quorum sensing to regulate their pathogenesis-related factors. Many signal molecules and receptors are reported as part of quorum sensing system and interestingly single bacterium may use multiple quorum sensing systems. They are used for intra-genus, intra-species and/or inter-species communications. In this review, a detailed account of quorum-sensing systems reported in Pseudomonas aeruginosa, Vibrio cholerae as well as E. coli, Salmonella, Burkholderia cepacia complex, Stenotrophomonas maltophilia, Acinetobacter baumannii are presented. Antimicrobial-resistance in Gram-negative human pathogens is increasing continuously. Understanding the quorum sensing system in pathogens can help to develop novel strategies to control their infections. Targeting the signal molecules to quench the quorum sensing and in turn stopping pathogens, is an interesting and upcoming area in antimicrobial research. In present study, a preliminary in-silico analysis has also been done to look for activity of an enzyme AHL lactonase that can degrade AHL (quorum sensing signal). Results were compared to published articles. This aspect is discussed in later part of the review.