Antimicrobial peptides effectively kill a broad spectrum of Listeria monocytogenes and Staphylococcus aureus strains independently of origin, sub-type, or virulence factor expression

Table 4 Virulence assessment of the S. aureus strain collection

Strain	Hemolysis	Staph. kin.	Catalase	Carotenoid	Enterotoxin				TSST-1	C. elegans	Blood
					A	B	C	D
8325-4	+++	- ^a	++	+	-	-	-	-	-	184	2.4 × 10⁸
Sa113	-	-	++	++	-	-	-	-	-
ΔmprF	-	-	++(+)	++	-	-	-	-	-
ΔdltA	-	-	+(+)	+	-	-	-	-	-
14943	-	-	++(+)	+++	+++	-	-	-	+++	157	7.6 × 10⁸
15033	++	-	+++	+++	-	+++	-	-	-
B31369	++	-	++(+)	+++	-	+++	-	-	-	140	1.1 × 10⁸
796	(+)	-	++(+)	+++	-	-	-	-	-	223	2.5 × 10⁸
J15033	(+)	-	++	+++	-	-	-	-	-
2148-jvi	-	-	++(+)	++	-	-	-	-	-	256	3.0 × 10⁶
K3-B2	+	-	++	++	-	-	-	-	-	225	3.4 × 10⁷
B29997	(+)	-	++(+)	+++	-	-	-	-	-
KES439	(+)	-	++	++	-	-	-	-	-
KES626	+++	- ^a	++(+)	+	-	-	-	-	-	118	1.0 × 10⁹
KES735	(+)	-	++	+++	-	-	-	-	-
KES855	++	-	++	++	-	-	-	-	-

^a A clearing zone on both plates with and without added serum indicate a high production of proteases.
Tests include hemolytic activity, staphylokinase activity, catalase activity, carotenoid production and production of exotoxins. A sub-selection of strains were tested for their killing kinetics against C. elegans (time to 50% mortality, h) and their ability to survive and grow in human whole blood (cell density after 24 h, CFU/ml).

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