​Efficacy of Resveratrol and Ursolic Acid on Biofilm Inhibition and Antimicrobial Resistance of Streptococcus uberis

Abstract

Background: Bovine mastitis is a multifactorial and is one of the most challenging disease. It can be caused by many different bacterial species, the most common of which are Staphylococcus species and Streptococcus species. The prevalence of different species varies temporally, geographically and also due to control measures adopted in herds. The present study is on the biofilm forming Streptococcus uberis causing mastitis and the effect of antibiofilm agents on the antimicrobial resistance of the microorganisms. Methods: The isolates were identified by Polymerase chain reaction (PCR). Two antibiofilm agents, resveratrol and ursolic acid (UA) each at two concentrations (30 μg/ml, 100 μg/ml) were used for the study. Biofilm formation and rate of biofilm inhibition was detected using quantitative microtiter plate (MTP) assay and biofilm gene (lux S) was detected using PCR. The isolates treated with antibiofilm agents were subjected to standard disc diffusion test with 7 antibiotics and the change in antibiotic resistance was studied. Result: The mean±SE values of inhibition rates of 29 S. uberis isolates by 30 μg/ml UA, 100 μg/ml UA, 30 μg/ml resveratrol, 100 μg/ml resveratrol were 33.96±3.17%, 57.40±2.8%, 31.35±3.12% and 46.28±3.47%, respectively. Biofilm inhibiting agents along with all antibiotics had reduced antimicrobial resistance by 1.5-2 times on in vitro antibiotic resistance testing by disc diffusion at 100 μg/ml concentration. The antibiofilm agents were found to be very effective to control antibiotic resistance of S. uberis from mastitic milk samples in vitro.