Antibacterial activity of selected plant extracts against multidrug-resistant Acinetobacter baumannii
Acinetobacter baumannii, a multidrug-resistant Gram-negative bacterium, is increasingly recognized as an oral pathogen. With rising resistance to available antibiotics, plant-derived alternatives are gaining attention. This study aimed to evaluate the antibacterial activity of extracts of Mimusops elengi seed, Aloe barbadensis gel, and root extracts of Cocos nucifera, Areca catechu, and Piper nigrum against A. baumannii. Plant extracts were tested individually as well as in different combinations to evaluate the synergistic activity. Dental plaque samples were collected and cultured in nutrient media, and pure colonies of bacterial isolates were identified based on morphology. Based on the occurrence frequency, the isolated Morphotype A, was used for Anti-Bacterial Susceptibility Testing (ABST) via the disk diffusion method. The identity of the bacterium was confirmed by 16S rRNA gene sequencing. Crude plant extracts were prepared using methanol and subjected to ABST, individually and in combinations (1:1:1 ratio). Two, 0.2 % chlorhexidine containing mouthwashes (Positive) and sterile distilled water (Negative) were used as controls. According to ABST results, A. catechu (13.573 ± 0.0200 mm) and C. nucifera (13.108 ± 0.0366 mm) extracts showed moderate inhibition, while M. elengi showed slightly higher inhibition (14.500± 0.0643 mm). Aloe barbadensis showed the least zone of inhibition (9.017 ± 0.0328 mm), whereas P. nigrum had no effect. The combination of extracts (15.853 ± 0.0288 mm) and chlorhexidine mouthwashes (15.028 ± 0.0413 mm, 15.815 ± 0.0683 mm) also produced comparable inhibition zones, with no statistically significant difference (p > 0.05). The antibacterial activity of the combined extracts did not significantly differ from the individual effects of A. catechu or C. nucifera. Overall, M. elengi seed, A. catechu, C. nucifera root, and A. barbadensis gel extracts exhibited notable antibacterial activity against A. baumannii, individually as well as in combinations, highlighting their effectiveness as plant-based alternatives for combating A. baumannii infections.