Table 1.

Summary of bacterial resistance mechanisms to CAMPs

Mechanism of resistance	Product name/gene	Organism	Virulence of the mutant	Reference
CAMP binding and inactivation	Staphylokinase	S. aureus	↑ systemic infection	[122, 123]
	SIC	S. pyogenes	↓ systemic infection	[32]
CAMP proteolytic cleavage	V8 protease	S. aureus	ND	[34]
	Aureolysin	S. aureus	ND	[34]
	ZapA	P. mirabilis	↓ colonization of urinary tract	[35, 124]
	Streptopain SpeB	S. pyogenes	ND	[35, 125]
	Elastase LasA	P. aeruginosa	↓ chronic infection in rat	[35, 126, 127]
Capsular polysaccharides	PIA, PGA	S. epidermidis	↓virulence	[38–40, 128, 129]
	Capsule synthesis gene cluster	N. meningitidis	↓virulence	[130–132]
		K. pneumoniae	↓ virulence in murine model of pneumonia	[133–135]
Surface charge neutralization		S. aureus	↓ virulence in mouse, ↓ virulence in rabbit model of endocarditis	[53, 54, 136]
d-alanine modification of teichoic acids	dltABCD	S. pyogenes	ND	[58, 137]
		L. monocytogenes	↓ mouse model of infection	[55]
		L. reuteri	↓ colonization of mouse	[69]
l-Lysine modification of PG	mprF	S. aureus	↓ virulence in mouse model of infection	[53, 85, 138]
			↓ virulence rabbit model of endocarditis
Lipid A modifications Aminoarabinose Ethanolamine	pmrAB, pmrE, pmrFHIJKL pmrC,	S. enterica ser. typhimurium	↓ virulence in mice	[98, 100, 139, 140]
Decrease in membrane fluidity
Modification of lipid A acylation	pagP, pagL,	S. enterica ser. typhimurium	No phenotype	[141, 142]
Production of carotenoids	crtOPQMN	S. aureus	↓virulence in subcutaneous abscess model	[143–145]
Presence of efflux pumps	qacA	S. aureus	ND	[16, 119, 146]
CAMP expulsion	mtrCDE	N. gonorrhoeae	↓ virulence in murine model of infection	[117, 147, 148]

↑ increased virulence, ↓ decreased virulence or virulence attenuated, ND not determined