Antibacterial activities of Macrotermes bellicosus metabolitemediated silver nanoparticles against isolates from patients with diabetic foot infection

Abstract

ABSTRACT Diabetic foot infections (DFI) are commonly refered to a breech in the skin epithelium involving the distal to the ankle joints in a person suffering from diabetes mellitus.The antibacterial activity of crude extract and extract mediated silver nanoparticles of Macrotermes bellicosus (Soldier termites) were investigated against isolates from patients with diabetic foot infection using agar diffusion method. Extraction of powdered insect gave rise to crude ethanol extract, n-hexane (Eh), ethylacetate (Eoac) and (Ee), aqueous (Eaq) fractions. Cyanides, saponins, phytates, phenols, flavonoids, alkaloids, tannins and proteins were detected in the crude extract and fractions. Treatment of extract and fractions with silver nitrate (2mM) produced a dark-brown spherical and aggregated shaped nanoparticles with absorbance peaks from lowest to highest nm (390, 395, 400 and 410 nm). The Eaoc-AgNPs at 200mg/ml produced zones of inhibition of 16.00 ±1.00, 6.47 ± 0.58 and 30.67 ± 2.08 mm against P.aeruginosa, S. pyogenes and K. pneumoniae respectively. The MIC of Eoac-AgNPs for P.aeruginosa, S. pyogenes and K. pneumoniae was at 6.25, 1.25 and 25.0 mg/ml respectively while the MBC was at 12.5, 50.0 and 6.25 mg/ml. The Eoac-AgNPs was bacteriocidal on the test isolates. There was significant (P≤0.05) wound closure observed in rats (groups 1-6) treated with Eoac-AgNPs from day 0 (1.23± 0.12-1.27±0.30 mm) to day 14 (0.67±0.25-0.33±0.10 mm) compared to group 7 (diabetes + wound only) at 1.13±0.21 mm. Treatment of rats with ointment showed wound healing characterized by the presence of collagen, granulation tissues, few inflammatory cells and complete epitelialization. The application of Eoac-AgNPs ointment on the rats did not produce allergic reactions, dermatitis or death. These findings showed that M.bellicosus could be useful in treating infected ulcer.