<i>Iv vitro</i> synergistic antimicrobial interactions between the extract of <i>Azadirachta indica</i> and antibiotics against <i>Bacillus subtilis</i>

This study aims to investigate the in vitro antimicrobial interactions between crude aqueous extract of Azadirachta indica and standard antibiotics, including ciprofloxacin, and norfloxacin. Using checkerboard techniques with Bacillus subtilis as the test microorganism, the synergistic effect of Azadirachta indica and antibiotics (ciprofloxacin and norfloxacin), was determined. The checkerboard assay presented FIC indices indicative of synergy, particularly notable with the combination of A. indica extract and the antibiotics. Specifically, with the 4:6, 8:2, and 9:1 ratios of ciprofloxacin and 1.9 to 9:1 of norfloxacin. These results suggest a potentiation of antibacterial effects when the plant extract is used in conjunction with conventional antibiotics. The synergistic interaction could potentially reduce the required doses of antibiotics, thereby minimizing side effects and the risk of antibiotic resistance.