Evaluation of Antibacterial and Synergistic Effects of Vitex agnus-castus Leaves Extract on Multidrug-Resistant Pseudomonas aeruginosa Isolates

Abstract

Pseudomonas aeruginosa is a common bacterium that causes diseases that are problematic to treat, its pervasiveness and contribution to increased morbidity and mortality have shown the need for developing and applying natural alternative antimicrobial medicines to control MDR bacteria. The aim of the study, the efficacy of Vitex agnus-castus leaf extract was experienced against MDR P. aeruginosa. and examining this extract’s synergistic relationship with drugs to which the target microorganisms were resistant. Sixteen isolates of P. aeruginosa were obtained from Iraqi patients admitted to the Al Kindy Teaching Hospital in Baghdad. After testing for antibiotic vulnerability on every isolate, it was found that 7 (43.75%) of the isolates were MDR. After V. agnus leaves were extracted alcoholically, active compounds were discovered by GC-MS analysis of the Vitex agnus extract. Using the microdilution broth method, the Minimum Inhibitory Concentration (MIC) of methanolic V. Agnus extract was 512 μg/mL. The antibacterial activity of plant active components that prevent bacterial growth and decrease resistance to most tested antibiotics, with the highest effect toward Ciprofloxacin and Meropenem (P-value=0.0001), may be mirrored in the antibacterial activity of the V. agnus extract (at MIC value) when studied as an antibacterial agent against MDR isolates. There was a synergistic effect of combined V. agnus extract and antibiotics against P. aeruginosa. This was estimating by the increase in diameters of fold for the inhibition zones of each antibiotic disk after a combination with Vitex extract. The maximum increase in the fold was 330% when Meropenem and V. agnus extract were combined. Combining Vitex extract with antibiotics has the potential to be beneficial as a therapeutic agent for treating bacteria and in the fight against drug-resistant P. aeruginosa.