Combined  Antibacterial Activity of Bacteriophages and Extract of Caesalpinia decapetala and Parrotiopsis jacquemontiana Against Pseudomonas aeruginosa and Staphylococcus aureus

Background: Emergence of antimicrobial resistance is one of the most burning issue which is being faced by mankind. Rate of discovery of new antibiotic has reduced tremendously. Already available antibiotics are almost inactive against many bacterial species like P. aeruginosa and MDR strains of S. aureus. To combat this problem researchers are looking for alternatives. phytotherapy and phage therapy are two potential candidates as alternative to synthetic antibiotics. Material &Methods: In this study aqueous extracts of C. decapetala and P. jacquemontiana were prepared. Phytochemical analysis and antibacterial activity of extracts was examined. Spot assay was done to assess the lytic activity of bacteriophages. Combined effect of extract and bacteriophages was examined using mixture of specific concentration of extract and bacteriophages. Results: Phytochemical screening revealed the presences of phenols, phlobatanins, and terpenoids in the extracts. Well diffusion assay indicated that stem extracts of both species exhibited notably stronger antibacterial activity compared to root extracts. Specifically, the stem extract of C. decapetala showed highest antibacterial activity against S. aeruginosa (SA3320) achieving a zone of inhibition of 15mm followed by stem extract of P. jacquemontiana against. In contrast lowest activity was exhibited by root extract of P. jacquemontiana against P. aureus PA2. The synergistic study result showed that the stem extracts of both P. jacquemontiana C. decapetala exhibits inhibitory activity against the bacteriophages MDR S. aureus (SA3320) and P. aeruginosa(PA2) and the combine effect of phages and extracts was less than that of their individual activities. Conclusion: combined application of plant extract and bacteriophage against the selected MDR strains resulted in a 60-70% reduction in the zone of inhibition compared to their individual activities. Suggesting a strong antagonistic interaction between the two agents.