Table 3.

Predictors of responses to doripenem-colistin during time-kill experiments in vitro^a

Factor	P value for doripenem-colistin at 24 h
	Level of killing			Extent of synergy
	Univariate analysis	Multivariate analyses		Univariate analysis	Multivariate analyses
log2 doripenem MIC	0.52	0.06	0.057	0.004	0.44	0.42
log2 colistin MIC	0.53	0.81	0.68	0.89	0.64	0.64
log10 KPC expression	0.32	0.40	Not included	0.94	0.87	Not included
Absence of ins aa134-135 GD or IS5 mutation	0.006	0.002	0.002	0.0004	0.04	0.037

^aUnivariate and multivariate analyses were performed using linear-regression and multiple-linear-regression models, respectively. Factors included in the multivariate analyses were those found significant by the univariate analyses or those that would be feasible as real-time tests in clinical microbiology laboratories. Multivariate analyses were performed including and excluding log₁₀ KPC expression. Boldface numbers represent significant P values at the level of <0.05.