Table 6.

Single and combined efficacy of AgNPs and antibiotics against MDR Pseudomonas aeruginosa.

ZOI (mm) of antibiotics in combination with AgNPs	Pseudomonas aeruginosa
Piperacillin/tazobactam (A) (100 µg)	18 ± 0.5
AgNP	13 ± 0.6
Piperacillin/tazobactam + AgNP (B)	31 ± 1.4
Fold increase of inhibition zone areab	1.97 (72.2%)
Cefoxitin (A) (30 µg)	18 ± 0.3
AgNP	13 ± 0.5
Cefoxitin + AgNP (B)	30 ± 1.0
Fold increase of inhibition zone areab	1.8 (66.6%)
Amikacin (A) (30 µg)	16 ± 0.7
AgNP	13 ± 0.6
Amikacin + AgNP (B)	25 ± 1.3
Fold increase of inhibition zone areab	1.4 (56.2%)
Aztreonam (A) (10 µg)	14 ± 0.4
AgNP	13 ± 0.2
Aztreonam + AgNP (B)	23 ± 1.5
Fold increase of inhibition zone areab	1.7 (64.2%)
Meropenem (A) (10 µg)	12 ± 1
AgNP	13 ± 0.5
Meropenem + AgNP (B)	22 ± 1
Fold increase of inhibition zone areab	2.3 (83.3%)
Imipenem (A) (10 µg)	10 ± 1.5
AgNP	13 ± 0.5
Imipenem + AgNP (B)	20 ± 1.5
Fold increase of inhibition zone areab	3.0 (100%)
Gentamicin (A) (10 µg)	8 ± 0.1
AgNP	13 ± 0.4
Gentamicin + AgNP (B)	17 ± 0.5
Fold increase of inhibition zone areab	3.5 (112.5%)
Ciprofloxacin (A) (5 µg)	8 ± 1.2
AgNP	13 ± 0.6
Ciprofloxacin + AgNP (B)	16 ± 0.1
Fold increase of inhibition zone areab	3.0 (100%)
Cefoperazone/sulbactam (A) (75–10 µg)	8 ± 0.5
AgNP	13 ± 1.3
Cefoperazone/sulbactam + AgNP (B)	14 ± 0.4
Fold increase of inhibition zone areab	2.1 (75%)
Ceftazidime (A) (30 µg)	0a
AgNP	13 ± 0.3
Ceftazidime + AgNP (B)	14 ± 1.2
Fold increase of inhibition zone areab	0.15 (133.3%)

Rank order is indicated by Alphabets. Vertically, the ranking is linked to combinations of antibiotics against bacterial isolates; horizontally, the ranking is of bacterial isolates with respect to sensitivity to antibiotic amalgamation (P, 0.05). ^aDisc diameter (6 mm) was employed for calculation of fold increase in absence of bacterial growth inhibition zone³⁴. ^bFold increase of inhibition zone area = (B² − A²)/A²

$\text{As}\%\text{synergism}=\left(\text{B}-\text{A}\right)/\text{A}\times 100$^.

AgNP silver nanoparticles.