Figure 4.

Quorum-sensing circuits of ESKAPE pathogens. All ESKAPE pathogens have been reported to have well-organized quorum-sensing circuits influencing their virulence and the ability to form biofilms. Four pathogens among the six, Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, and Enterobacter sp., involve LuxS system in altering antibiotic susceptibility and forming biofilms. More often than not, multiple quorum-sensing networks are involved in the biofilm formation process of these organisms. For instance, Pseudomonas aeruginosa is found to have a LasI–LasR system, RhII–RhIR system, and Quinolone and IQS systems in place to aid biofilm formation at various levels, including host tissue invasion and degradation. Similarly, the AbaI/AbaR system of Acinetobacter baumannii aids in its motility apart from contributing toward biofilm formation. Created with BioRender.com.