In-vitro and in-vivo antibacterial effect of five different sizes of silver nanoparticles (Ag-NPs) in Labeo rohita

Abstract

The present study evaluated the efficacy of silver nanoparticles (Ag-NPs) on in-vitro antimicrobial activity via a battery of tests and in-vivo antimicrobial activity against E. tarda in Indian Major Carp, Labeo rohita. In-vitro antibacterial tests showed that Ag-NPs in the smaller size range exhibit better antibacterial activity as compared to larger size Ag-NPs. For in-vivo testing, fishes were challenged with E. tarda @ 6.7×104/100μl. The infected fishes were treated with 5 different sizes of Ag-NPs (27 nm, 46.1 nm, 71 nm, 96 nm and 103 nm) by 3 different routes of administration, i.e. by injection, feed and immersion @ 3.6 mg/kg body weight, 4.5 mg/kg body weight and 0.2 mg/litre, respectively, for 21 days. The in-vivo test showed that significantly higher protection was achieved in treatment with 27 nm Ag-NPs followed by 71 nm and 46.1 nm Ag-NPs. The 3 routes of administration increased the survival rate of L. rohita by 31%, 5% and 18%, respectively. Hence, it can be concluded that with further evaluation, nanoparticle based treatment technologies could overcome threats of multi-drug resistance syndrome either as an alternative or as supplementary to antibiotic therapy.