Table 3.

Fractional Inhibitory Concentration Index (FICI) for the combination of ZnO NPs with Meropenem, Ciprofloxacin, and Colistin.

Organism	FICI values
	Meropenem	Ciprofloxacin	Colistin
P. aeruginosa ATCC 27853	1.1 (I) ± 0.2	N/T	0.41 (S) ±  0.09
P. aeruginosa MRO-17-29	1.8 (I) ± 0.2	N/T	N/T
P. aeruginosa MRO-17-3	N/T	0.76 (A) ±  0.2	N/T
P. aeruginosa MRO-16-3	N/T	N/T	0.24 (S) ±  0.04
P. aeruginosa MRO-16-4	N/T	N/T	0.39 (S) ±  0.1
P. aeruginosa MRO-16-1	N/T	N/T	0.64 (A) ±  0.4
P. aeruginosa MRO-16-7	N/T	N/T	0.55 (A) ± 0.01

(S) Synergy, (A) Additive, (I) Indifference, (N/T) not been tested.

*FICI value interpretation: Synergy ≤ 0.5, additive > 0.5 and ≤ 1.0, Indifference > 1 and ≤ 4.0 and Antagonism > 4.0.