TABLE 4.

Characterization of in vitro bactericidal activities of JNJ-Q2 and moxifloxacin against methicillin-resistant S. aureus clinical isolates by time-kill methods

MRSA isolate	QRDR genotypeb	MIC (μg/ml)		Log10 decrease (Δlog10 CFU/ml) in viable cells recovereda at:
				2× MIC		4× MIC
		MXFg	JNJ-Q2	MXF	JNJ-Q2	MXF	JNJ-Q2
OC 11223	NDf	0.06	0.008	1.0	2.5	1.5	3.9
OC 8525d	Wild type	0.12	0.008	0.0	5.1	3.2	5.0
OC 11696d	ND	1	0.06	3.1	6.5e	3.2	6.5e
OC 12501d	ND	1	0.06	3.1	6.2e	3.2	6.2e
OC 8530d	gyrAS84L	2	0.25	>−2.0c	6.3e	2.3	6.3e
	parCI143V
OC 4222d	gyrAS84L	2	0.5	2.4	5.9	2.7	4.2
	parCS80F
OC 2838	ND	4	0.25	2.6	4.1	3.2	4.5
OC 17042d	gyrAS84L, G106D	8	0.5	0.9	3.8	1.7	3.5
	parCS80FparED432N
OC 11521d	gyrAS84L, S85P	32	1	2.0	2.3	3.4	2.3
	parCE84G

^aLog₁₀ decrease in the numbers of CFU/ml recovered at 24 h in comparison to the numbers recovered at 0 h.

^bparC and parE were used in place of the gene names grlA and grlB, respectively.

^cMoxifloxacin was not effective at suppressing the elaboration of the starting inoculum.

^dIsolates display phenotypic evidence of activated efflux, as the MICs for norfloxacin, benzalkonium chloride, and ethidium bromide were ≥4-fold lower in the presence of 20 μg/ml reserpine.

^eNo colonies were cultured from these samples, indicating sterilization.

^fND, not determined.

^gMXF, moxifloxacin.