In vitro antibacterial and antibiofilm activity of selected medicinal plants and spices extracts against multidrug resistant Pseudomonas aeruginosa

Abstract

Pseudomonas aeruginosa is a human opportunistic pathogen known to build biofilm and is able to proliferate within the biofilm. Antibacterial substances are of natural origin, and it is thought that their influences on the environment are important and can be used as biological control agents. In the present study, multi-drug resistant and the high yielding biofilm Pseudomonas aeruginosa strains have been isolated from the hospital waste. Multi-drug resistance pattern was studied with disc diffusion assay using commercially available antibiotic discs. Ten isolates were multi-drug resistant among eighteen isolates. Modified crystal violet staining method was performed to know the ability of biofilm formation by isolated strains. All of the isolates were able to form biofilm except one. Antibiofilm and Antimicrobial activity of medicinal plants Centella asiatica (Thankuni), Mentha spicata (Mentha), Azadirachta indica (Neem), Psidium guajava (Guava) and spices Syzygium aromaticum (Cloves), Cinnamomum zeylanicum (Cinnamon) extracts were studied with modified crystal violet biofilm assay and Well diffusion assay respectively. Both Methanol and ethyl acetate extract of guava leaf showed lowest antibacterial activity against all selected isolates. MIC values were determined for each extracts and it was ranged from 500 µg mL-1 to 2000 µg mL-1. Methanol and ethyl acetate extract of Cinnamon, Neem and Mentha showed high antibiofilm activity suggested that these extracts might act as a potential antibiofilm agent against Pseudomonas aeruginosa. Despite of the fact that the extracts were not pure compounds, antimicrobial activity as well as antibiofilm activity were observed. This recommends the potency of these extracts and could be a target for further research to search antibiofilm bioactive compound for therapeutic uses.