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, , , and . Scanning electron microscope analysis and bacterial DNA apoptosis assays were performed.

Results: strains were resistant to imipenim, ampicillin, and penicillin. Most strains were resistant to amoxicillin, clavulanat, and ampicillin. Finally, tigecycline was effective with and was resistant to all antibiotics. Only had an antibacterial effect on . Most strains were sensitive to , , and quercetin. All examined natural extracts had no effect on . had no effect on any of the strains tested. Minimum inhibitory concentration and minimum bactericidal concentration values for examined plants against were 6.25 to 12, 1.6 to 3.2, and 9.12 to 18.24 mg/mL, respectively. was active against with 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. , quercetin, and showed clear fragmentations of DNA.

Conclusions: Current findings confirmed the beneficial effect of using natural products such as , quercetin, and as a promising therapy to overcome multidrug resistant bacteria.