Sub-lethal concentration of a colloidal nanosilver formulation (Silversol®) triggers dysregulation of iron homeostasis and nitrogen metabolism in multidrug resistant Pseudomonas aeruginosa

Table 2 Silver pre-treatment modulates bacterial susceptibility to some antibiotics

Antibiotic	Concentration (µg/disc)	Zone of inhibition		% Difference
Antibiotic	Concentration (µg/disc)	Control (Mean ± SD)	Experimental (Mean ± SD)	% Difference
Imipenem	10	29 ± 2.82	30.5 ± 0.70	Non-significant
Ciprofloxacin	5	40 ± 4.24	39.5 ± 6.36
Tobramycin	10	29.5 ± 0.70	29 ± 2.82
Moxifloxacin	5	35.5 ± 0.70	33 ± 2.82
Ofloxacin	5	34 ± 0	34.5 ± 3.53
Sparfloxacin	5	33 ± 1.4	31 ± 5.65
Levofloxacin	5	38 ± 1.41	36.5 ± 2.12
Norfloxacin	10	34.5 ± 0.70	33.5 ± 2.12
Co-Trimoxazole	25	R	R
Nalidixic acid	30	15 ± 10.6	15.5 ± 0.70
Augmentin	30	R	10.5 ± 0.70	Resistance reversal
Gatifloxacin	5	34.65 ± 0.49	34 ± 1.41	Non-significant
Amikacin	30	22 ± 1.41	21.5 ± 0.70	Non-significant
Streptomycin	25	13 ± 0	18 ± 1.41	38.46*
Ceftriaxone	30	25.5 ± 2.12	23.5 ± 3.53	Non-significant
Cefpodoxime	10	25 ± 0	25.5 ± 0.70
Colistin	10	21.7 ± 0.7	22 ± 0.6
Kanamycin	30	18.2 ± 1.06	21 ± 1.41
Gentamicin	10	21.5 ± 0.7	2.05 ± 0.7
Ticarcillin	75	26.7 ± 1.06	25.5 ± 0.7

Antibiotic susceptibility profile of the bacterium was generated using the antibiotic discs- Icosa G-I Minus (HiMedia, Mumbai), through disc diffusion assay performed as per NCCLS guidelines. The zones of inhibition were measured and the interpretation (S - sensitive, I - intermediate, R - resistant) was drawn as per zone size interpretative chart provided by the manufacturer. *p < 0.05

ISSN: 1471-2180