Susceptibility Assessment of Multidrug Resistant Bacteria to Natural Products

Objective: The aim of this study was to examine the effect of some natural compounds against multidrug-resistant bacteria. Methods: Forty-three bacterial strains were collected. Disc diffusion and minimum inhibitory concentration (MIC) tests were carried out for natural compounds including quercetin,Acacia nilotica,Syzygium aromaticum, andHolothuria atra. Scanning electron microscope analysis and bacterial DNA apoptosis assays were performed. Results: Staphylococcus aureusstrains were resistant to imipenim, ampicillin, and penicillin. MostEscherichia colistrains were resistant to amoxicillin, clavulanat, and ampicillin. Finally, tigecycline was effective withKlebsiella pneumoniaeand was resistant to all antibiotics. OnlyS aromaticumhad an antibacterial effect onK pneumoniae. MostS aureusstrains were sensitive toS aromaticum,A nilotica, and quercetin. All examined natural extracts had no effect onE coli.Holothuria atrahad no effect on any of the strains tested. Minimum inhibitory concentration and minimum bactericidal concentration values for examined plants againstS aureuswere 6.25 to 12, 1.6 to 3.2, and 9.12 to 18.24 mg/mL, respectively.Syzygium aromaticumwas active againstK pneumoniaewith an MIC of 12.5 mg/mL. Scanning electron microscope analysis performed after 24 and 48 hours of incubation showed bacterial strains with distorted shapes and severe cell wall damage.Syzygium aromaticum, quercetin, andA niloticashowed clear fragmentations ofS aureusDNA. Conclusions: Current findings confirmed the beneficial effect of using natural products such asclove (S aromaticum), quercetin, andA niloticaas a promising therapy to overcome multidrug resistant bacteria.