Antibacterial activity of chlorhexidine alone and in combination with metronidazole, Punica granatum, and Curcuma longa against Porphyromonas gingivalis: an in vitro study

BACKGROUND: The aim was to evaluate the antibacterial activity of 0.2% chlorhexidine (CHX) alone and in combination with metronidazole, Punica granatum extract, and Curcuma longa extract against Porphyromonas gingivalis. MATERIALS AND METHODS: An in vitro experimental study was performed using P. gingivalis strain ATCC 33277. Bacteria were cultured under anaerobic conditions. Ten experimental groups were evaluated: 0.2% CHX, 0.5% metronidazole, 100% P. granatum extract, 0.1 and 1.0% C. longa extracts, their respective combinations with 0.2% CHX, and distilled water. Antibacterial activity was assessed using an agar-well diffusion assay, and the diameter of the bacterial growth inhibition zone was measured in millimeters. Statistical significance was established at P < 0.05. RESULTS: The combination of 0.2% CHX and 0.5% metronidazole demonstrated the greatest antibacterial activity, producing the largest inhibition zone (21.67 ± 1.60 mm). This value was significantly greater than those observed for CHX alone (16.44 ± 1.09 mm, P < 0.01), P. granatum combined with CHX (18.11 ± 0.11 mm, P < 0.01), 0.1% C. longa combined with CHX (18.89 ± 0.40 mm, P < 0.01), and 1.0% C. longa combined with CHX (18.40 ± 0.62 mm, P < 0.01). Among the individual agents, 100% P. granatum extract demonstrated the greatest antibacterial activity (20.67 ± 0.00 mm), whereas metronidazole alone, both C. longa extracts, and the negative control produced no measurable inhibition zones. CONCLUSIONS: The combination of CHX and metronidazole exhibits the strongest antibacterial activity, whereas P. granatum extracts demonstrate substantial antibacterial activity against P. gingivalis.