Antibiotic-resistant bacteria are becoming more common around the world each day. Terrestrial actinomycetes are the major sources of known antibiotics. However, the number of new antibiotics found in terrestrial soils has fallen dramatically over the last 20 years. | JOURNAL OF SCIENCE OF HNUE DOI Chemical and Biological Sci. 2015 Vol. 60 No. 9 pp. 112-118 This paper is available online at http IDENTIFICATION OF Streptomyces sp. QN63 AGAINST ANTIBIOTIC-RESISTANT Staphylococcus aureus Duong Minh Lam Truong Thi Chien and Tran Thi Thuy Faculty of Biology Hanoi National University of Education Abstract. Antibiotic-resistant bacteria are becoming more common around the world each day. Terrestrial actinomycetes are the major sources of known antibiotics. However the number of new antibiotics found in terrestrial soils has fallen dramatically over the last 20 years. Marine environments and mangroves are seen as untapped environments which have high potential for new drug discovery. Actinomycetes strain QN63 was isolated from sediment collected in a mangrove environment in Yen Hung District Quang Ninh Province and it has been found to inhibit antibiotic-resistant Staphylococcus aureus. Morphological and molecular identification shows that QN63 is a strain of Streptomyces shenzhenensis. The identification of this strain and the published results of its antibiotic properties suggest that S. shenzhenensis QN63 might be effective in treating infections caused by antibiotic resistant Staphylococcus aureus. Keywords Streptomyces sp. QN63 Streptomyces shenzhenensis Staphylococcus aureus antibiotic resistant mangroves. 1. Introduction Methicillin Resistant Staphylococcus aureus-MRSA has become universal problem as it resists almost every antibiotic that has been used to kill it including vancomycin. Twenty-five years ago in 1991 more than a half of the S. aureus strains isolated in the United States of America USA were found to be capable of resisting penicillin methicillin tetracycline and erythromycin 1 . Vancomycin was the only antibiotic that was effective against S. aureus at that time. However in 1996 a vancomycin-resistant S. aureus strain at the concentration of 4 - 8 µg mL was found in .