TABLE 1.

Summary of in vitro time-kill assays of oritavancin combinations against S. aureus isolates

Agenta	MSSA ATCC 29213					VISA NRS402					VRSA VRS5
	Concn (μg/ml)b	Fold MIC in combinationc	Δlog CFU at 24 h vsd:			Concn (μg/ml)	Fold MIC in combination	Δlog CFU at 24 h vs:			Concn (μg/ml)	Fold MIC in combination	Δlog CFU at 24 h vs:
			C	A	I			C	A	I			C	A	I
ORI	0.031	0.5	−0.34	NAe	NA	0.50	0.5	−3.5/−2.5g	NA	NA	0.13	0.5	−0.70	NA	NA
GEN	0.25	0.5	−0.81	−7.3	−3.8	0.13	0.25	−0.21	−2.9	−3.1	0.25	0.5	−0.18	−6.2	−3.9
LZD	1	0.5	−0.64	−1.2	2.5	0.25	0.25	−0.94	−4.1	−3.2	1	0.5	−0.57	−6.2	−3.9
MOX	0.063	1	−1.5	−6.3	−3.5	NDf	ND	ND	ND	ND	ND	ND	ND	ND	ND
RIF	0.008	1	−5.9	−2.3	−3.8	ND	ND	ND	ND	ND	0.002	0.5	−0.88	−4.2	−2.1

^aAbbreviations: ORI, oritavancin; GEN, gentamicin; LZD, linezolid; MOX, moxifloxacin; RIF, rifampin.

^bConcentration of the antimicrobial agent tested as a single agent and used in combination in the time-kill assay.

^cMultiple of the broth microdilution MIC (determined as per the CLSI guidelines) of oritavancin or other agent used in combination.

^dValues presented are the log₁₀ change in CFU (a negative value indicates a decrease) at 24 h for the single agent relative to the growth control (C) or for the combination of the indicated agent with oritavancin relative to the most active agent of the combination (A) or the inoculum (I). Values shown are the means of duplicate determinations from a representative experiment repeated at least three times.

^eNA, not applicable.

^fND, not determined since inherent resistance or nonsusceptibility to the combination agent precluded testing in combination with oritavancin.

^gThe value after the slash is for oritavancin used in combination with linezolid.