ANTIBACTERIAL ACTIVITIES OF LEECH SALIVARY EXTRACT-SILVER NANOPARTICLES AGAINST SOME PATHOGENIC BACTERIA

Abstract

ABSTRACT Leeches are blood sucking annelid worms that lives in fresh water habitat. Leech saliva and silver nanoparticles have both been reported to possess antibacterial activities against bacteria pathogens. The aim of this study was to determine the antibacterial activities of leech salivary extract silver nanoparticles against some pathogenic bacteria. Crude Leech salivary extract (LSE) and leech salivary extract silver nanoparticles (LSE-AgNp) were screened for antimicrobial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Klebsiella species using agar diffusion method and was compared with Augmentin (8 µg/ml). The minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) of LSE-AgNp were assayed using micro broth dilution method with tetrazolium dye as indicator. The LSE-AgNp was synthesized and then characterized by UV-Vis spectroscopy and a Zeta nanosizer. The acute and subacute toxicity of the LSE-AgNp were determined in Wister rats using Lorke’s method. The crude neat LSE was inactive on all test isolates while the LSE-AgNp was active against P. aeruginosa with zones of inhibition of 8.3 ± 0.88 mm and 12.3 ± 0.88 mm at 100 μL and 200 μL respectively. The zones of inhibition for Klebsiella spp were 12 ± 0.57 mm and 12.3 ± 0.33 mm at 100 μL and 200 μL respectively. The MIC and MBC of LSE-AgNp for P. aeruginosa and Klebsiella spp were 100 μL and 200 μL respectively. The wavelength of the LSE-Ag was at 456 nm while the size was 98.04 nm. The nanoparticles were bactericidal on the isolates. The lethal dose (LD50) of the LSE-AgNp in rats was above 5000 mg/kgbw. Oral administration of the LSE-AgNp to rats at 25 mg/kgbw, 50 mg/kgbw and 100 mg/kgbw for 21 days produced no significant (P > 0.05) change in the body weight, red blood cell indices, differential blood counts, renal function indices and liver biomarkers. The LSE-AgNp at 100 mg/kgbw increased the relative spleen weight and decreased the feed intake of treated rats when compared with the control (AgNO3 and normal saline). The results obtained suggest that the LSE-AgNp could be used in stabilizing the immune system and treating infectious diseases caused by P. aeruginosa and Klebsiella species.