Antibacterial activity of silver nanoparticles and selected antibiotics on streptococcus isolates and pure culture

Abstract

The objective of the current study was to synthesize, characterize, and evaluate the antibacterial activity of silver nanoparticles (AgNPs) using an environmentally friendly approach against Streptococcus. A total of 100 milk samples were collected from various sources, and the culture-based method revealed that 27 samples (27%) tested positive for Streptococcus. The average zone of inhibition for tamarind fruit extract against Streptococcus was found to be 3 mm for pure cultures and 2.04±0.16 mm for milk isolates. Similarly, the mean zone of inhibition for moringa leaf extract was 2 mm for pure cultures and 1.00±0.14 mm for milk isolates. For both pure cultures and milk isolates, the average zone of inhibition of AgNO3 solution against Streptococcus was 10 mm and 9.19±0.35 mm, respectively. The mean inhibition zone of AgNPs prepared with Moringa oleifera against Streptococcus was found to be 16 mm for pure cultures and 14.11±0.43 mm for milk isolates. On the other hand, AgNPs prepared with Tamarindus indica exhibited a mean inhibition zone of 14 mm for pure cultures and 12.19±0.46 mm for milk isolates against Streptococcus. The average inhibition zone of tetracycline against Streptococcus pure cultures and isolates was 6 mm and 4.04±0.38 mm, respectively. Ciprofloxacin displayed a mean inhibition zone of 12 mm for pure cultures and 10.30±0.40 mm for milk isolates, while Ampicillin's mean inhibition zone was 18 mm for pure cultures and 16.33±0.50 mm for milk isolates. Similarly, ceftriaxone exhibited a mean inhibition zone of 10 mm for pure cultures and 8.00±0.36 mm for milk isolates against Streptococcus.