Antagonistic effect of ursolic acid on Staphylococcal biofilms

Abstract

Aim:The present study was carried out to study the effect of ursolic acid (UA) as a potential anti-biofilm agent in dispersing the biofilm generated by Staphylococcus aureus isolated from milk samples of crossbred dairy cows on the day of drying. Further, in the S. aureus isolates, the presence of intracellular adherence gene locus involved in biofilm production (icaD) was investigated.Materials and Methods:A total of 50 S. aureus strains were isolated over a period of 3 months from 200 milk samples collected from crossbred dairy cows on the day of drying. These isolates were subjected for biofilm detection by Congo red agar (CRA), microtiter plate assay (MTP), and polymerase chain reaction specific for icaD gene. The antagonistic effect of biofilm formation by UA was studied using different concentrations (30 µg/ml and 60 µg/ml) of UA and compared with the control group.Results:Among the 50 S. aureus subjected for biofilm detection, 34 and 40 isolates were detected as biofilm agents by CRA and MTP methods, respectively. The in vitro studies on the effect of UA in inhibiting biofilm formation by S. aureus using MTP assay showed 71.5% and 48.6% inhibition at UA concentrations of 60 µg/ml and 30 µg/ml, respectively, with a significant difference (p<0.05) between the treated and untreated isolates, which was further evident by scanning electron microscopy. Interestingly, the isolates that were tested to be resistant through Antibiotic Sensitivity Test to commonly used antibiotics were found to be sensitive to all the tested antibiotics following UA treatment at both the tested concentrations. Furthermore, molecular detection of icaD gene for biofilm detection revealed that all the isolates that were positive by MTP had icaD gene.Conclusion:Increased incidence of biofilm agents in dairy infections must be considered as an alarming situation. UA treatment significantly enhanced the sensitivity of the microbial pathogens to commonly used antibiotics. Hence, attention must be paid toward implementation of new strategies such as therapeutic regimes with a combination of antibiotic and anti-biofilm agents for effective treatment of infections in dairy farms.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

“…UA can be used synergistically with antibiotics for enhancing their activity [31][32][33] and has proven to be an efficient agent to disperse the biofilm generated by S. aureus [34] and to inhibit the formation of biofilm by MRSA isolates [35]. Although the precise mechanisms underlying these findings are not known in detail, a study on the mode of action of UA against MRSA reported initial irreversible damage to bacterial membrane integrity, UA is considered a promising compound for cancer prevention and therapy, as it influences cell signalling pathways, inhibiting enzyme activity, inducing apoptosis, and reducing tumor growth.…”

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

“…It suggests that a combination of an antibiofilm agent along with the antibiotics may help to bring the case under control. Jyothi et al (2018) studied the antagonistic effect of UA on S. aureus biofilms using MTP assay and found 71.5% and 48.6% inhibition at UA concentrations of 60 μg/ml and 30 μg/ml respectively, they also showed that the isolates tested to be resistant through antibiotic sensitivity test to commonly used antibiotics were become sensitive to all the tested antibiotics after treatment with UA at both the tested concentrations. The S. uberis isolates treated with UA and resveratrol were more sensitive to antibiotics than untreated.…”

Anti-Planktonic and Anti-Biofilm Properties of Pentacyclic Triterpenes—Asiatic Acid and Ursolic Acid as Promising Antibacterial Future Pharmaceuticals

“…Jyothi et al [ 109 ] investigated the antibiofilm activity of UA against 50 S. aureus strains with icaD adhesion gene involved in biofilm production. Inhibition of biofilm formation was observed in 40 isolates of the analysed strains, and it was 48.6% for UA applied at a concentration of 30 mg/L and 71.5% when the UA concentration was 60 mg/L, respectively.…”