Oleic acid as an antibacterial for treating eye infections

Purpose: Bacterial eye infections are routinely treated with topical antibiotics. Antibiotics carry the risk of systemic side effects which are particularly serious in children. Increasing development of antibiotics resistance calls for testing compounds that are natural, safe and can help in combating antibiotic resistance. Oleic acid is one such compound that is found in skin lipids and tears lipids. It is known to be effective against bacteria in skin infections. The purpose of this study was to test efficacy of oleic acid as an antibacterial against bacteria common in ocular surface infections. Methods: Antibacterial effects of oleic acid against ocular pathogenic bacteria (Staphylococcus aureus 31, Pseudomonas aeruginosa 19, Serratia marcescens 35, and Pseudomonas aeruginosa 20) were tested in Mueller-Hinton broth using broth dilution technique. Bacterial cells were imaged using scanning electron microscopy to observe changes in cell morphology caused by oleic acid. Results: Oleic acid inhibited growth of all bacterial isolates in a concentration-dependent manner. Percentage growth inhibition with various concentrations of oleic acid varied among bacteria but all showed complete growth inhibition in the presence of 1% oleic acid. Scanning electron microscopy showed morphological damages to bacterial cells in the presence of oleic acid. Types of damages included cellular distortions, blebs, loss of cellular content and cell lysis. Conclusions: Oleic acid is capable of preventing growth of various ocular pathogenic Gram negative and Gram positive bacteria. It can provide antibacterial defence to tears and can be used to develop lipid based treatment options for eye infections helping in reducing antibiotics usage