Induction kinetics of the Staphylococcus aureus cell wall stress stimulon in response to different cell wall active antibiotics

Table 2 MIC values and summary of induction kinetics characteristics of different antibiotics

Antibiotic	MIC^a	Fold MIC decrease in BB255ΔVraR^b	Lag before induction^c	Maximum induction^d	Time point of maximum induction^e	Concentration dependence^f	OD/CFU/ml as % of control^g
Fosfomycin	0.5	2x	30	high	120	high (29.5)	47/10
D-Cycloserine	12	none	10	medium	60	high (25.5)	56/36
Bacitracin	32	10x	none	medium	60	low (1.5)	26/9
Tunicamycin	8	4x	10	high	120	medium (3.0)	38/9
Flavomycin	4	16x	none	high	60	low (1.6)	41/25
Vancomycin	1.3	2x	none	low	120	medium (12.6)	100/100
Oxacillin	0.2	none	none	high	120	high (19.1)	74/20
Daptomycin	0.25	2x	none	low	120	medium (14.1)	85/75
Lysostaphin	0.065	2x	none	low	10	medium (11.3)	11/6
Teicoplanin	0.5	10x	none	medium	60	medium (7.5)	91/83

^aDetermined in μg/ml for BB255 psas016-luc+. ^bDifference in MIC values of BB255/BB255ΔVraR. ^cEarliest time point at which induction was detected (min). ^dInduction levels were scored as: high (> 40'000 RLU); medium (>10'000 - < 40'000); low (< 10'000). ^eTime taken for maximum induction to be reached after antibiotic addition (min). ^fThe ratio of maximal induction levels measured at 5x MIC/0.2x MIC, scored as: high (> 15); medium (>2 - < 15); low (< 2). ^gOD and CFU/ml values after treatment with antibiotics (1x MIC) for 120 min, expressed as a percentage of the values from untreated cell.

ISSN: 1471-2180