BIOMOLECULAR AND HEALTH SCIENCE JOURNAL 2020 JUNE, VOL 03 (01) ORIGINAL ARTICLE 11 Combination of Red Coconut Coir (Cocos nucifera L. var rubescens) and Linezolid on Methicillin-Resistant Staphylococcus aureus in vitro Growth Trisnawati 1 , Wiwin Retnowati 2 , Danti Nur Indiastuti 3* 1 Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia 2 Department of Microbiology, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia 3 Department of Pharmacology, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia A R T I C L E I N F O A B S T R A C T Article history: Received 13 May 2020 Received in revised form 09 June 2020 Accepted 11 June 2020 Keywords: Methicillin-Resistant Staphylococcus aureus, Cocos nucifera L. var rubescens, well-difusion test, antibacterial resistance. Introduction: Methicillin-Resistant Staphylococcus aureus (MRSA) bacterial infections may cause poor manifestations and even increase patients’ morbidity and mortality. The use of antibiotics in the management of infections remains the main therapy. However, ever-increasing antibacterial resistance has prompted researchers to fnd the solution. This study aimed to determine the efect of a combination of red coconut coir (Cocos nucifera L. var rubescens) in various concentrations and linezolid 10 µ/ml on the growth of MRSA bacteria in vitro. Methods: The antibacterial activity test method was well-difusion test. Bacteria was plated in mueller hinton agar for 24 hours at 37 o C. The treatment groups were red coconut coir extract and its combination with linezolid 10 µg/ml. The well-difusion test results were statistically analyzed with the One-Way ANOVA and Tukey HSD post-hoc tests. Results: Mean inhibitory zone diameter formed in the C. nucifera L. var rubescens extract test in various concentrations was 12.5 ± 0.36 - 16.2 ± 0.79 mm, while its combination with 10 µg/ml linezolid produced mean inhibitory zone of 15.1 ± 1.31-18.4 ± 0.46 mm. There was a signifcant diference between groups (p<0.05). Conclusion: Increasing concentration of C. nucifera L. var rubescens extract was in line with the increase of mean diameter of the inhibitory zone. Extract and antibiotic combination tests showed higher mean diameter zones than the single test of materials. The combination of extract and linezolid has the potential to synergistically prevent antibacterial resistance. © 2020 Biomolecular and Health Science Journal. Introduction Methicillin-Resistant Staphylococcus aureus (MRSA) is a strain of S. aureus that resistant to penicillin and its derivatives. This bacterium was frst discovered in 1961. 1 In general, MRSA causes nosocomial infections. 2 Another study even suggested that community-acquired MRSA infection has now become a global problem. 3 Until now, antibiotic therapy is still the main therapy in cases of infection due to bacteria so that antibacterial resistance is very likely to occur. According to WHO, antibacterial resistance can occur naturally and is accelerated by improper use in humans and animals. 4 Related research in Indonesia conducted in 2014 revealed the incidence of antibacterial resistance around 700,000 cases per year. 5 Researchers are trying to overcome this problem with new types of antibiotics as well as by combining antibiotics and plant extracts. Linezolid, a new type of antibiotic, has successfully overcome gram-positive infections in the last 10 years. The linezolid target is diferent from the previous antibiotic, which is in the 50S ribosome. 2 It also in diferent mechanism from coconut coir (Cocos nucifera L.) extract which has a target of action on cell walls. Researches stated that coconut coir can prevent the formation of bioflm, 6 growth of gram bacteria, 7 even MRSA with Minimum Inhibitory Concentration (MIC) of 156 µg/ml. 8 It is because the extract contains phenol compounds that may cause intracellular leakage and inhibit the formation of peptidoglycan. 9,10 Phenolic compound is secondary metabolite of plant which has the role as pathogen protector and plant’s self-defense. 11 Indonesia has various species and subspecies of coconut and also known as the biggest coconut producer in the world in 2014. 12 This study used *Correspondence: dantinurindiastuti@gmail.com © 2020 Biomolecular and Health Science Journal. Available at https://e-journal.unair.ac.id/BHSJ