Table 5.

Summary of the quorum-sensing inhibition methods employed against the ESKAPE organisms and their impact on pathogenicity.

Organism name	Method of disruption of quorum-sensing mechanism	Further details	Targeted quorum sensing system	Major parameters analyzed	Observations	References
Enterococcus sp.	Gene knockout	Long flanking homology (LFH) PCR was used to generate deletion mutants	LuxS/AI-2	Proliferation ability after deletion	No significant effect	(Yang et al., 2018)
				Biofilm-forming ability	Decreased
	Chemical inhibitor	Siamycin I	fsr system	Growth of the microbe	Decreased	(Nakayama et al., 2007)
				Gelatinase activity	Decreased
				GBAP production	Decreased
				Biofilm-forming ability	Decreased
Staphylococcus aureus	Gene knockout and chemical inhibitor	RIP	agr system	Biofilm-forming ability	Decreased	(Balaban et al., 2007)
Klebsiella pneumoniae	Chemical Inhibitor	2′-Hydroxycinnamic acid and 3-methyl-2(5H)-furanone	C6-AHL system	Biofilm-forming ability	Decreased	(Cadavid and Echeverri, 2019)
				Adherence	Decreased
	Gene knockout	“Gene Gorging” method followed by allelic replacement with a kanamycin resistance-encoding gene (Km) was used to generate deletion mutants	LuxS/AI-2 system	Biofilm-forming ability	Decreased	(Chen L et al., 2020)
				Ability to synthesize lipopolysaccharide (wzm)	Decreased
				Ability to synthesize polysaccharide (pgaA), which is involved in the synthesis of porin	Increased
				Ability to synthesize type 3 fimbriae (mrkA)	No significant effect
Acinetobacter baumannii	Chemical Inhibitor	Chloroquine, Levamisole, Propranolol, Erythromycin, and Azithromycin	Aba1/AbaR system	Biofilm-forming ability	Decreased	(Seleem et al., 2020)
				Twitching and swarming motilities	Decreased
				Ability to produce proteolytic enzymes	Decreased
				Resistance to oxidative stress	Decreased
	Gene knockout	Cloned plasmid pMo130v was used to generate ΔabaI deletion mutants encompassing regions of the A1S_0109 gene	Aba1/AbaR system	Biofilm-forming ability	Decreased	(Mayer et al., 2020)
				Surface associated motility	Decreased
Pseudomonas aeruginosa	Chemical inhibitor	Catechin-7-xyloside (C7X), sappanol and butein	LasR system	Biofilm-forming ability	Decreased	(Zhong et al., 2020)
				Ability to generate pyocyanin	Decreased
				Ability to generate rhamnolipids	Decreased
				Ability to generate elastin	Decreased
	Gene knockout and Chemical Inhibitor	Quercetin	LasI system	Biofilm-forming ability	Decreased	(Ouyang et al., 2020)
				Adhesion	Decreased
				Swarming motility	Decreased
			RhlI system	Biofilm-forming ability	No direct effect
			LasI/RhlI system	Biofilm-forming ability	Decreased
				Adhesion	Decreased
				Swarming motility	Decreased
Enterobacter sp.	–	–	–	–	–	–

"-" denotes insufficient information.