TABLE 3.

Changes in bacterial densities at multiple time points observed over 96 hours in the in vitro pharmacodynamic model

Isolate and drug treatment	Time to 99.9% kill (h)	Changes in bacterial density (CFU/g) at:
		4 h	24 h	48 h	72 h	96 h
MRSA 494
Daptomycin 6 mg/kg alone	32	−1.49	−2.31	−6.85	−7.06	−6.64
In combination with:
Gentamicin q8h	24	−1.49	−6.56a	−7.14	−7.36	−7.36
Gentamicin q8h (3 doses)	24	−1.64	−6.41a	−7.17	−7.17	−7.17
Gentamicin q24h	4	−3.78a	−6.64a	−7.12	−7.28	−7.28
Gentamicin q24h (1 dose)	4	−4.49a	−6.67a	−7.47	−7.47	−7.47
Daptomycin 8 mg/kg alone	24	−2.16	−5.85	−7.39	−7.39	−7.39
In combination with:
Gentamicin q8h	24	−2.39	−7.13b	−7.42	−7.42	−7.42
Gentamicin q8h (3 doses)	24	−2.42	−6.74b	−6.83	−7.06	−7.06
Gentamicin q24h	4	−6.21a	−7.31b	−7.31	−7.31	−7.31
Gentamicin q24h (1 dose)	4	−6.46a	−6.92b	−7.19	−7.19	−7.19
Vancomycin alone	NAc	−0.02	−0.49	−0.51	−2.36	−2.89
In combination with:
Gentamicin q8h	72	−0.54	−0.77	−2.23a	−3.87b	−4.95a
Gentamicin q8h (3 doses)	NA	−0.40	−0.65	−0.86	−2.59	−2.91
Gentamicin q24h	24	−1.73	−3.07a	−4.82a	−6.86a	−7.16a
Gentamicin q24h (1 dose)	32	−1.89b	−2.86a	−3.43a	−4.64a	−5.79a
MSSA 1199
Daptomycin 6 mg/kg alone	24	−2.13	−3.17	−6.13	−6.42	−6.82
In combination with:
Gentamicin q8h	24	−1.87	−5.86a	−7.38b	−7.38	−7.38
Gentamicin q8h (3 doses)	24	−1.89	−5.99a	−7.38b	−7.38	−7.08
Gentamicin q24h	4	−3.53b	−6.87a	−7.32b	−7.32	−7.32
Gentamicin q24h (1 dose)	4	−3.17b	−6.49a	−7.33b	−6.88	−6.80
Daptomycin 8 mg/kg alone	8	−2.99	−5.63	−6.63	−7.36	−7.10
In combination with:
Gentamicin q8h	4	−3.23	−7.06	−7.36	7.36	7.36
Gentamicin q8h (3 doses)	4	−3.74	−6.60	−7.46	7.46	7.16
Gentamicin q24h	4	−4.75b	−7.16b	−7.28	7.28	7.28
Gentamicin q24h (1 dose)	4	−4.29b	−6.73b	−7.31	7.31	7.31
Vancomycin alone	NA	−0.13	−0.17	−0.29	0.52	0.87
In combination with:
Gentamicin q8h	NA	−0.38	−1.37b	−1.31b	2.40b	2.73b
Gentamicin q8h (3 doses)	NA	−0.30	−1.42b	−1.27	1.52	1.28
Gentamicin q24h	72	−1.27	−1.32b	−1.81b	3.17a	4.34a
Gentamicin q24h (1 dose)	80	−1.11	−1.50b	−1.31	2.20b	3.20a

^aEnhancement in kill observed with combination.

^bImprovement in kill observed with combination.

^cNA, not applicable.