TABLE 1.

Zone of inhibition (mm) of different antibiotics against bacteria in the absence and in the presence of AgNPs (30 μg/well).

Antibiotics	E. coli*			P. aeruginosa*			S. aureus*
	A	B	C	A	B	C	A	B	C
Streptomycin	7	21	8.00	8	14	2.06	9	15	1.78
Rifampicin	8	19	4.64	8	9	0.27	8	32	15.00
Chloramphenicol	8	22	6.56	7	9	0.65	7	20	7.16
Novobiocin	7	22	8.88	8	10	0.56	6	24	15.00
Ampicillin	8	14	2.06	7	8	0.31	8	29	12.14

All the experiments were performed in triplicate, and standard deviations were negligible. Fold increases (C) for different antibiotics against three bacterial pathogens were calculated as (B² – A²)/A², where A, B are the inhibition zones in mm for antibiotic only and antibiotic in combination with AgNPs, respectively. In the absence of bacterial growth inhibition zones, the well diameters (6 mm) were used to calculate the fold increase (C). *P < 0.05; the mean difference in the synergy is significant among the bacteria at the 0.05 level by two factor ANOVA.