• Journal of Applied Biological Chemistry
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• v.66
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• pp.98-104
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• 2023

Effective and alternative strategies to control methicillin-resistant Staphylococcus aureus (MRSA) are consistently needed. Previous study presented that 7,10-epoxy-octadeca-7,9-dienoic acid (EODA) was produced from 7,10-dihydroxy-8(E)-octadecenoic acid through one-step heat treatment. Further studies confirmed that EODA was highly active against broad range of pathogenic bacteria including MRSA, promising development of a novel antibacterial agent to control MRSA. However, there are some practical huddles for industrialization of EODA, especially high cost for fine purification. To address this problem, this study was focused on determination of any changes in the antibacterial activities of EODA when used as a crude extract. As a result, any significant changes in the antibacterial activities of EODA was not detected and additional synergistic effect for commercial antibiotics on antibacterial activity was sustained as it was.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.788-797
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• 2001

The usefulness of three PCR methods were evaluated for the epidemiological typing of Staphylococcus aureus: an enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), repetitive extragenic palindromic element PCR (REP-PCR), and 16S-23S intergenic spacer PCR (ITS-PCR). The analysis was performed using a collection of S. aureus strains comprised of 6 reference and 79 isolates from patients with various diseases. Among the 85 S. aureus strains tested, 6 references and 6 isolates were found to be susceptible to methicillin, whereas the remaining 73 isolates were resistant to it. PCR methods are of special concern, as conventional phenotypic methods are unable to clearly distinguish among methicillin-resistant S. aureus (MRSA) strains. The ability of the techniques to detect different unrelated types was found to be as follows: ERIC-PCR, 19 types; REP-PCR, 36 types; and ITS-PCR, 14 types. On the basis of combining the ERIC, REP, and ITS fingerprints, the 85 S. aureus strains were grouped into 56 genetic types (designated G1 to G56). The diversities for the 85 S. aureus strains, calculated according to Simpson\`s index, were 0.88 for an ERIC-PCR, 0.93 for a REP-PCR, and 0.48 for an ITS-PCR, and the diversity increased up to 0.97 when an ERIC-PCR and REP-PCR were combined. The above discrimination indices imply that the genetic heterogeneity of S. aureus strains is high. Accordingly, this study demonstrates that DNA sequences from highly conserved repeats of a genome, particularly a combination of ERIC sequences and REP elements, are a convenient and accurate tool for the subspecies-specific discrimination and epidemiologic tracking of S. aureus.

• Natural Product Sciences
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• v.23 no.1
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• pp.5-8
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• 2017

An antimicrobial compound has been isolated from the leaves of Glochidion superbum. The compound was determined as methyl 3, 4, 5-trihydroxybenzoate (methyl gallate), based on ultraviolet (UV), infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS) analysis. The isolated compound exhibited potent antimicrobial activity against three clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) by qualitative agar disc diffusion method and quantitative broth dilution method. Agar disc diffusion was done in a dose-dependent manner for each bacterial isolate at disc potencies of 25, 50, 100, and $150{\mu}g/disc$. The zones of inhibition were on average equal to 12.27, 14.20, 15.43, and 24.17 mm respectively. The inhibition zones were compared with that of vancomycin disc at $30{\mu}g$ as a reference standard. The MIC and MBC values were $50{\mu}g/ml$ and $100{\mu}g/ml$ respectively. The results of anti MRSA activity were analyzed using one-way ANOVA with Turkey's HSD and Duncan test. In conclusion, methyl gallate which was isolated from G. superbum showed the inhibition activity against methicillin resistant S. aureus.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.775-778
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• 2010

A total of 2,858 meat samples collected during 2003-2008 in Korea were investigated, and methicillin-resistant Staphylococcus aureus (MRSA) isolates were isolated from 1.0% (9/890) of beef, 0.3% (4/1,055) of pork, and 0.3% (3/913) of chicken meat samples, respectively. MRSA isolates showed the two sequence types (STs), ST72 from beef and pork and ST692 from chicken meat. MRSA isolates from beef and pork were Panton-Valentine leukocidin-negative, staphylococcal cassette chromosome mec type IVa strain with ST72, which is the most prevalent type of communityacquired MRSA in Korea. An identical pulse-field gel electrophoresis pattern was detected among 10 of 16 MRSA isolates: 9 strains from beef (n=5) and pork (n=4) in 2008, and one strain from beef in 2005.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.784-789
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• 2016

We evaluated the synergistic antibacterial effect in combination with the chitosan-ferulic acid conjugate (CFA) and β-lactam antibiotics, such as ampicillin, penicillin, and oxacillin, against methicillin-resistant Staphylococcus aureus (MRSA) using fractional inhibitory concentration (FIC) indices. CFA clearly reversed the antibacterial activity of ampicillin, penicillin, and oxacillin against MRSA in the combination mode. Among these antibiotics, the combination of oxacillin-CFA resulted in a ΣFIC_min range of 0.250 and ΣFIC_max of 0.563, suggesting that the oxacillin-CFA combination resulted in an antibacterial synergy effect against MRSA. In addition, we determined that CFA inhibited the mRNA expression of gene mecA and the production of PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. Thus, the results obtained in this study supported the idea on the antibacterial action mechanism that oxacillin will restore the antibacterial activity against MRSA through the suppression of PBP2a production by CFA.

• Journal of Life Science
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• v.18 no.8
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• pp.1083-1089
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• 2008

We investigated the molecular epidemiological characteristic of methicillin resistant Staphylococcus aureus (MRSA) strains isolated from stool samples in Busan from 2004 to 2006. Among 142 isolates of S. aureus, 49 isolates (34.5%) were confirmed as MRSA. With the antimicrobial susceptibility tests, 37 isolates (75.5%) showed multiple resistance to more than 10 antibiotics, but all isolates were sensitive to vancomycin. All of MRSA had enterotoxin A in 30.6%, B 4.1%, C 8.3%, D, C/G, A 2.0% and None 51%. PFGE of SmaI-digested chromosomal DNA was performed on 49 sporadic MRSA isolates. Restriction fragment patterns consisted of 8 to 14 fragments ranged in size from 48.5 to 630.5 kbp. We could divided the isolates into 7 groups ($I{\sim}VII$) by analyzing PFGE patterns. Group I subdivided as 2 subgroups and 17 (34.7%) strains belong to the group I. Dendrogram of PFGE patterns showed that MRSA strains in Busan were heterogeneous but we could find out minor homogeneity in hospital.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.694-705
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• 2017

The aim of this study was to isolate and identify marine bacterium with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity, and to purify the anti-MRSA compound, as well as to determine its activity and synergistic effects. Among the marine bacteria isolated in this study, the YJ-1 isolate had the strongest anti-MRSA activity. The YJ-1 isolate was identified on the basis of its biochemical characteristics and an analysis of 16S rRNA gene sequences. The YJ-1 isolate showed over 99.2% homology with Pseudomonas stutzeri, and was designated as a Pseudomonas sp. YJ-1. The optimal culture conditions were $25^{\circ}C$ and initial pH 7.0. For the purification of the anti-MRSA compounds, the YJ-1 was cultured in Pa PES-II medium, and the culture filtrates were extracted by ethyl acetate, hexane, and 80% MeOH. The 80% MeOH fraction was separated by a $C_{18}$ ODS column, silica gel chromatography and a reverse phase HPLC, to yield three anti-MRSA agents, the MR1, MR2, and MR3 compounds. When the MR1 compound of $250{\mu}g\;mL^{-1}$ concentration was applied to the MRSA cells, over 95% of bacterial cells was killed within 48 hr. Compared with vancomycin and ampicillin, the MR1 compound showed significant anti-MRSA activity. In addition, the anti-MRSA activity was increased by dose and time dependent manners. Furthermore, the combination of an MR1 compound with vancomycin produced a more rapid decrease in the MRSA cells than did the MR1 compound alone. Taken together, our results suggest that the Pseudomonas sp. YJ-1 and its anti-MRSA compounds could be employed as a natural antibacterial agent in MRSA infections.

• Tuberculosis and Respiratory Diseases
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• v.75 no.2
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• pp.75-78
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• 2013

Methcillin-resistant Staphylococcus aureus (MRSA) has emerged as an important cause of community-acquired infections, which has been recently designated as community-associated (CA) MRSA. Panton-Valentine leukocidin (PVL)-negative multilocus sequence type 72 (ST72)-staphylococcal cassette chromosome mec (SCCmec) type IV has been reported as the predominat CA-MRSA strain in Korea and is commonly associated with skin and soft tissue infections in addition to healthcare-associated pneumonia. However, community-acquired pneumonia (CAP) for this strain has not yet been reported. We hereby report two cases of CAP caused by PVL-negative ST72-SCCmec type IV strain in patients who had no risk factors for MRSA acquisition. While CA-MRSA infections are not yet prevalent in Korea, our cases suggest that CA-MRSA should be considered in cases of severe CAP, especially for cases associated with necrotizing pneumonia.

• Fisheries and Aquatic Sciences
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• v.3 no.3_4
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• pp.217-221
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• 2000

In previous study, marine actinomycetes producing the antibiotics were investigated to invent new antibiotics from east coast of Korea. The optimum growth conditions of Streptomyces sp. NS 13239 were $28^{\circ}C$, pH 7.0 and $3\%$ of NaCl concentration in various media. Streptomyces sp. NS 13239 showed strong antimicrobial activity against gram-positive bacteria, specially Methicillin resistant Staphylococcus aureus (MRSA), but just weak antimicrobial activity against yeasts and mold. On the other hand, it did not show antimicrobial activity against gram-negative bacteria. The optimum conditions for producing antibiotics were almost consistent with optimum growth conditions except carbon source and nitrogen source.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.391-399
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• 2011

Free fatty acids (FFAs) are known to have bacteriocidal activity and are important components of the innate immune system. Many FFAs are naturally present in human and animal skin, breast milk, and in the bloodstream. Here, the therapeutic potential of FFAs against methicillin-resistant Staphylococcus aureus (MRSA) is demonstrated in cultures and in mice. Among a series of FFAs, only oleic acid (OA) (C18:1, cis-9) can effectively eliminate Staphylococcus aureus (S. aureus) through cell wall disruption. Lauric acid (LA, C12:0) and palmitic acid (PA, C16:0) do not have this ability. OA can inhibit growth of a number of Gram-positive bacteria, including hospital and community-associated MRSA at a dose that did not show any toxicity to human sebocytes. The bacteriocidal activities of FFAs were also demonstrated in vivo through injection of OA into mouse skin lesions previously infected with a strain of MRSA. In conclusion, our results suggest a promising therapeutic approach against MRSA through boosting the bacteriocidal activities of native FFAs, which may have been co-evolved during the interactions between microbes and their hosts.