Quorum Sensing: A New Target for Anti-infective Drug Therapy

Quorum sensing (QS) is “a cold conversation” between inter- and cross-kingdom species that facilitates microbes to communicate through signalling molecules like autoinducer-2 (AI-2), acyl-homoserine lactones (AHLs) and autoinducing peptides (AIPs), which leads to biofilm formation and virulence factor secretion, ultimately causing severe infections in the host. Emerging evidence reveals that owing to the overuse of antibiotics and other antimicrobials, bacteria have evolved to become drug resistant and now constitute a serious danger to human health. Targeting QS is one such alternative that opened promising avenues in treating several treatment-resistant infections. Because QS controls gene expression, biofilm development and virulence factors excretion of the microbe, it has become rational that targeting these areas may enable us to effectively treat chronic infections and drug-resistant microbes. Anti-QS agents, anti-virulence and anti-biofilm drugs in combination with regular antibiotics have been extremely promising in treating several infections. In addition, the degradation of AHL signalling molecules using enzymes has been a valuable approach in quenching the QS signalling systems of microbes. This chapter discusses the mechanisms of QS development in Gram-positive and Gram-negative bacteria, strategies to target QS systems, biofilm formation, virulence factor secretion, the combination of these anti-QS agents with standard antibiotics and their significance in anti-infective drug therapy.