Antagonistic effect of ursolic acid on Staphylococcal biofilms.

Y Narasimha Reddy,M A Hannan Umair,K Dhanalakshmi,Kalyani Putty,J Shiva Jyothi

doi:10.14202/vetworld.2018.1440-1444

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.

Highlights

Biofilm, referred to as slime, is an extracellular polymeric conglomeration of DNA, proteins, and polysaccharides and is a significant problem in the medical, food, and marine industries often leading to substantial economic and health problems [1,2]
Among the 50 S. aureus subjected for biofilm detection, 34 and 40 isolates were detected as biofilm agents by Congo red agar (CRA) and microtiter plate assay (MTP) methods, respectively
The in vitro studies on the effect of ursolic acid (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

Summary

Introduction

Referred to as slime, is an extracellular polymeric conglomeration of DNA, proteins, and polysaccharides and is a significant problem in the medical, food, and marine industries often leading to substantial economic and health problems [1,2]. The microbial community of a biofilm is complex and highly resistant to antibiotics, posing a challenge of persistent infections despite antimicrobial therapies [3]. The ability of Staphylococcus species to produce biofilm is one of the primary reasons for treatment failure and recurrent infections of mammary gland [4]. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

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