Invitro assessment of the antibacterial activity of the combinations of Methanolic Extracts of dry Mangifera indica Bark and Psydium guajava Linnaeus Leaf on Multidrug Resistant Pseudomonas aeruginosa

Abstract

Introduction; Pseudomonas aeruginosa causes infections such as endocarditis, meningitis and septicemia in humans and as well as in animals both in hospital and community settings. The high resistance and the economic burden associated with management of pseudomonal infections mean that new antimicrobial agent is urgently required to better combat this pathogen. Mango and guava plants are a good starting point for getting leads for developing new antipseudomonal agents. Objective; to assess the antibacterial activity of a combination of methanolic extracts of dry Mangifera indica bark and dry Psidium guajava Linnaeus leaves Method; the plants of interest, P. guajava and M. indica were collected fresh, washed, dried and ground and extracted using methanol as the solvent. The dilutions prepared 100mg/ml, 50mg/ml, 25mg/ml and 12.5mg/ml, 6.25mg/ml, 3.125mg/ml for P.guajava and M.indica respectively were tested for antipseudomonal activity separately to ascertain the MICs from previous studies. Then different proportions of the combination ie 50:50, 30:70, 70:30 for P. guajava and M .indica respectively were made and the MIC of most active of the combinations (70:30) was determined too on Pseudomonas aeruginosa. Colistin was used as the positive control and 10% DMSO as the negative control. The analysis was done using one- way ANOVA run in Graphpad prism ver 7.03. Results; the methanolic extracts of dry M.indica bark and P. guajava leaves showed antipseudomonal activity with MICs of 3.64mg/ml and 21.51mg/ml respectively and the combination was more active than the individual extracts (p˂0.05 & p˂0.001). The combination was found to be synergistic with FICI of 0.2434 Conclusion; these results show that; combination of mango bark and guava leaf extracts is more active on MDR P. aeruginosa than the individual extracts with synergism observed and this could be a potential new drug for treating MDR P. aeruginosa infections.