In vitro antibacterial activity of crude extracts of 9 selected medicinal plants against UTI causing MDR bacteria

Abstract

Urinary tract infection (UTI) has become a more grievous problem today, due to multidrug resistance of infecting Gram-positive (GP) and Gram-negative (GN) bacteria, sometimes even with multiple infections. This study examines effectivity of 9 tropical flowering plants (Anogeissus acuminata, Azadirachta indica, Bauhinia variegata, Boerhaavia diffusa, Punica granatum, Soymida febrifuga, Terminalia chebula, Tinospora cordifolia and Tribulus terrestris) for possible use as source of antimicrobials for multidrug resistant (MDR) bacteria, along with main-stream antibiotics. Pathogenic bacteria were isolated from urine samples of patients attending and admitted in the hospital. Antibiograms of 11 isolated bacteria (GPs, Enterococcus faecalis and Staphylococcus aureus; and GNs, Acinetobacter baumannii, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris and Pseudomonas aeruginosa) were ascertained by the disc-diffusion method, and antibacterial effectivity of plant extracts was monitored by the agar-well diffusion method. Isolated bacteria were floridly MDR to most antibiotics of the day. Methanol extracts of 9 plants were used, and extracts of 3 plants, A. acuminata, P. granatum and S. febrifuga at least caused 25–29mm as the maximum size of zone of inhibition on bacterial lawns. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of methanol extracts of 9 plants were recorded. The methanol extract of A. acuminata had 0.29mg/ml as the lowest MIC value and 0.67mg/ml as the lowest MBC value, against MDR S. aureus, signifying effectivity; but, it had the highest MIC value of 3.41mg/ml. and the highest MBC value of 4.27mg/ml for most other MDR bacteria including E. coli. Qualitative phytochemical analysis was done for these 9 plants and information on leading phytochemicals was presented retrieved from PubChem database. Thus, three effective-most plants in controlling MDR-UTI bacteria in vitro were A. acuminata, P. granatum and S. febrifuga, which can be promoted as complementary medicine.