Table 4.

Δlog₁₀ colony changes of P. aeruginosa and E. coli strains obtained by the time-kill assay, after 24 h treatment with A22, antibiotics alone in relation to the initial inoculum or their combinations in relation to the initial inoculum and the most active agent.

Strains	Monotherapy, combinations	Fold MIC in monotherapy, combination	Colony changes (Δlog10 cfu/mL) at 24 h		Interaction
			vs. initial inoculum	vs. most active agent
P. aeruginosa	A22	0.5	+2.88	—	(⦰)
	CAZ	0.5	+3.92	—	(⦰)
	MERO	0.5	+4.2	—	(⦰)
	GEN	0.5	+3.18	—	(⦰)
	CIP	0.5	+1.64	—	(⦰)
	A22 + CAZ	0.5	−3.59	−6.47	Bactericidal/synergism
	A22 + MERO	0.5	−3.84	−6.72	Bactericidal/synergism
	A22 + GEN	0.5	−4.01	−6.89	Bactericidal/synergism
	A22 + CIP	0.5	−4.29	−6.12	Bactericidal/synergism
E. coli	A22	1	−0.98	—	Bacteriostatic
	AZM	1	+3.53	—	(⦰)
	CFX	1	+3.9	—	(⦰)
	A22 + AZM	1	−4.63	−3.68	Bactericidal/synergism
	A22 + CFX	1	−4.66	−3.7	Bactericidal/synergism

Antibiotics abbreviations: azithromycin (AZM), cefoxitin (CFX), ceftazidime (CAZ), ciprofloxacin (CIP), gentamicin (GEN), meropenem (MERO); +: increase growth; −: decrease growth; bacteriostatic, bactericidal: <3log₁₀ and ≥3log₁₀ reduction in cfu/mL, respectively, relative to the initial inoculum at 24 h; synergism: ≥2log₁₀ reduction in cfu/mL relative to the most active agent of the combination at 24 h; (⦰): no effect.