Antibacterial activity of silver nanoparticles synthesized from leaf extracts of Aloe vera against Klebsiella pneumoniae isolated from Oreochromis niloticus

Abstract

The increasing use of natural products for preventing and treating bacterial diseases offers significant benefits, particularly for individuals in low socioeconomic settings within urban and rural communities. This study investigated the antibacterial activity of aqueous Aloe vera extract against Klebsiella pneumoniae isolated from Oreochromis niloticus. Aloe vera was collected from a household garden in Keffi Metropolis, and silver nanoparticles (Ag-NPs) were synthesized from its aqueous extract using silver nitrate (AgNO₃). Characterization of the Ag-NPs revealed dominant functional groups, including alcohols and alkenes, with an average particle size of 50-80 nm, determined using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The antibacterial efficacy of Ag-NPs, alone and in combination with meropenem, was evaluated against carbapenemase-producing K. pneumoniae isolates using the agar dilution method. Additionally, biofilm formation, inhibition, and dissolution were assessed using the microtiter plate method. At 80% of the minimum inhibitory concentration (MIC), Ag-NPs achieved biofilm inhibition rates ranging from 96.75% to 96.79% and biofilm dissolution rates between 0.0% and 8.7%. The findings demonstrate that synthesized Ag-NPs possess significant antibacterial and antibiofilm activities, which were further enhanced when combined with meropenem, exhibiting synergistic effects against K. pneumoniae.