Quorum Sensing Inhibitors as Anti-Biofilm Agents

Abstract

Biofilms are microbial sessile communities characterized by cells that are attached to a substratum or interface or to each other, are embedded in a self-produced matrix of extracellular polymeric substances and exhibit an altered phenotype compared to planktonic cells. Biofilms are estimated to be associated with 80% of microbial infections and it is currently common knowledge that growth of micro-organisms in biofilms can enhance their resistance to antimicrobial agents. As a consequence antimicrobial therapy often fails to eradicate biofilms from the site of infection. For this reason, innovative anti-biofilm agents with novel targets and modes of action are needed. One alternative approach is targeting the bacterial communication system (quorum sensing, QS). QS is a process by which bacteria produce and detect signal molecules and thereby coordinate their behavior in a cell-density dependent manner. Three main QS systems can be distinguished: the acylhomoserine lactone (AHL) QS system in Gram-negative bacteria, the autoinducing peptide (AIP) QS system in Gram-positive bacteria and the autoinducer-2 (AI-2) QS system in both Gram-negative and -positive bacteria. Although much remains to be learned about the involvement of QS in biofilm formation, maintenance, and dispersal, QS inhibitors (QSI) have been proposed as promising antibiofilm agents. In this article we will give an overview of QS inhibitors which have been shown to play a role in biofilm formation and/or maturation.

Microbial biofilm in human health - an updated theoretical and practical insight

“…QS operates through a wide range of signals such as: Oligopeptides (5-10 amino acid cyclic thiolactone), N-acyl homoserine lactones (AHLs), Furanosyl borate (Autinducer-2, AI-2), Hydroxyl-palmitic acid methylester, and Methyl dodecanoic acid. QS inhibition is referred to inhibiting signal synthesis or direct degradation of the signal, inhibition of binding of the signal molecule to the receptor and/or inhibition of the signal transduction cascade (29).…”

Sexually transmitted infections: challenges ahead

“…Effectiveness of chlamydia screening in clinical trials 307 The rationale for chlamydia screening is that testing should detect asymptomatic infections in 308 women before they cause PID or other reproductive complications; if a large enough 309 proportion of the population can be screened, reduced incidence and prevalence of infection 310 ought to further prevent reproductive complications indirectly by reducing exposure to 311 infection. 91 …”

Current Research Approaches to Target Biofilm Infections.

“…Regarding natural products, previous reviews have described the antibiofilm properties of plant extracts, such as garlic and cranberries, halogenated furanones isolated from the red algae Delisea pulchra, salicylic acid and cinnamaldehyde, among others (53,54). The polyphenolic compound tannic acid found in tea was shown to van 55).…”

“…Quorum sensing (QS) signaling systems are responsible for the coordination of gene expression at a bacterial community level, which includes controlling the expression of virulence factors, as well as influencing the formation of biofilms (19,54). Many natural products act as quorum sensing inhibitors, and therefore have beneficial effects towards reducing biofilm formation (54).…”