• 대한한의학회지
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• 제23권3호
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• pp.223-232
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• 2002

Objectives : Methicillin-resistant Staphylococcus aureus (MRSA) CCARM 3251 and S. aureusKCTC 1928 have been known to be resistant to many kinds of antibiotics. The extract of Glycyrrhizae Radix showed antibacterial activity against MRSA and antibiotics-resistant S. aureus. Methods : We examined the effects of the water-soluble extract and the methanol-soluble extract of Glycyrrhizae Radix on MRSA and antibiotic-resistant S. aureus. The methanolic extract was further fractionated with organic solvents such as hexane, chloroform, and ethyl acetate in that order. Results and Conclusions : The methanol-soluble extract of Glycyrrhizae Radix showed relatively high antibacterial activity against MRSA and antibiotic-resistant S. aureus. However, the water-soluble extract of Glycyrrhizae Radix showed no antibacterial activity against MRSA and antibiotic-resistant S. aureus. Among the fractions tested, the chloroform fraction showed the highest antibacterial activity against MRSA and antibiotic-resistant S. aureus. The methanol-soluble extract of Glycyrrhizae Radix minimal inhibitory concentrations (MICs) against MRSA and antibiotics-resistant S. aureus were $5{\;}mg/m{\ell}$ in both. The methanol-soluble extract of Glycyrrhizae Radix was separated using thin-layer chromatography and detected with UV -detector. Further study should be carried out to identify which effects cell growth inhibition of MRSA and antibiotics-resistant S. aureus.

• 한국해양바이오학회지
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• 제9권2호
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• pp.49-57
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• 2017

We isolated marine bacterium, isolate DG-2 which produces the antibiotics against MRSA (methicillin-resistant Staphylococcus aureus). This isolate DG-2 was examined by its morphological, biochemical properties, and 16S rRNA sequencing analysis. And then, isolate DG-2 was identified to the genus Streptomyces. Therefore, this isolate was designated as Streptomyces sp. DG-2. Streptomyces sp. DG-2 grew relatively well at $25^{\circ}C$, pH 7.0, and NaCl 1.0%. For the pre-purification of the bioactive compounds, DG-2 was fermented in 30 L PPES-II medium, and the culture filtrates of DG-2 was extracted by ethyl acetate. The ethyl acetate extract of DG-2 showed the significant anti-MRSA and antibacterial activities.

• 미생물학회지
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• 제47권4호
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• pp.381-385
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• 2011

Methicillin-resistant Staphylococcus aureus (MRSA)는 화농성 질환, 균혈증을 유발하고 병원내 감염의 주요 원인균으로 알려져 있다. 병원에서의 MRSA 분리율은 점차 증가하여 80% 이상으로 보고 되고 있으며 Methicillin 뿐만 아니라 다른 항균제에도 내성을 나타냄으로 치료를 위한 항균제 사용에 제한을 받고 있다. 이에 본 연구에서는 MRSA의 정확한 판정을 통해 항생제 남용을 막고자 대부분의 병원에서 사용하는 항균제 감수성 검사법과 경제적인 면으로 인해 병원내에서 많이 사용되고 있지 않지만 정확도가 높은 mecA 유전자 검출법을 서로 비교하였다. 그 결과 대조군인 Methicillin-susceptible Staphylococcus aureus와 실험군 MRSA 20 균주를 대상으로 항균제 감수성 검사법과 mecA 유전자 PCR 검출법을 실시한 결과 MRSA 20 균주는 Oxacillin과 Cefoxitin에 모두 내성을 나타냈으나 mecA 유전자 검출에서는 20 개 중 17 개에서만 유전자가 검출되어 염기서열분석 결과 mecA 유전자임을 확인하였다. 이런 결과로 보아 mecA(-) 3 균주는 mecA 유전자의 변이로 추측할 수 있기에 임상에서의 MRSA의 판정은 항균제 디스크법과 mecA 유전자 PCR 검출법을 동시에 사용함으로 정확한 MRSA 진단에 도움을 주고자 한다.

• 한국자원식물학회지
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• 제31권6호
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• pp.719-724
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• 2018

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for a number of infections in humans that are difficult to treat, and as a result, is a substantial contributor to morbidity and mortality. In the present study, in search of natural products capable of inhibiting this multidrug-resistant bacterium, we investigated the antimicrobial activity of Lysimachia clethroides Duby root. The antibacterial activities of EtOH extract of Lysimachia clethroides Duby root and its n-hexane, EtOAc, n-BuOH and water fractions were evaluated against 15 strains of methicillin-resistant staphylococcus aureus (MRSA) and 1 standard methicillin-susceptible S. aureus (MSSA) strain by using the minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test. Antimicrobial activity of n-hexane fraction of Lysimachia clethroides Duby root was remarkable. Against the 16 strains, the minimum inhibitory concentrations (MICs) were in the range of $31.25-62.5{\mu}g/ml$ and FICI values for n-hexane fraction of Lysimachia clethroides Duby root+AM and n-hexane fraction of Lysimachia clethroides Duby root+OX were checkerboard method performed using the MRSA, MSSA and one clinical isolate strains via MICI 0.12-1 and 0.25-0.75, showing the increase of synergistic effect. When combined together, these antibiotic effects were dramatically increased. These effective combinations could be new promising agents in the management of MRSA.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.698-705
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• 2023

Rapid diagnosis of methicillin-resistant Staphylococcus aureus (MRSA) is essential for guiding clinical treatment and preventing the spread of MRSA infections. Herein, we present a simple and rapid MRSA screening test based on the aggregation effect of mannose-binding lectin (MBL)-conjugated gold nanoparticles (AuNP), called the MRSA probe. Recombinant MBL protein is a member of the lectin family and part of the innate immune system. It can recognize wall teichoic acid (WTA) on the membrane of MRSA more specifically than that of methicillin-sensitive Staphylococcus aureus (MSSA) under optimized salt conditions. Thus, the MRSA probe can selectively bind to MRSA, and the aggregation of the probes on the surface of the target bacteria can be detected and analyzed by the naked eye within 5 min. To demonstrate the suitability of the method for real-world application, we tested 40 clinical S. aureus isolates (including 20 MRSA specimens) and recorded a sensitivity of 100%. In conclusion, the MRSA probe-based screening test with its excellent sensitivity has the potential for successful application in the microbiology laboratory.

• 대한의생명과학회지
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• 제27권4호
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• pp.195-207
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• 2021

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen capable of causing human diseases, such as soft tissue infection, bacteremia, endocarditis, toxic shock syndrome, pneumonia, and sepsis. Although the incidence rate of diseases caused by MRSA has declined in recent years, these diseases still pose a clinical threat due to their consistently high morbidity and mortality rates. However, the role of virulence factors in staphylococcal infections remains incompletely understood. Methicillin resistance, which confers resistance to all β-lactam antibiotics in cellular islets, is mediated by the mecA gene in the staphylococcal cassette chromosome mec (SCCmec). Differences in SCCmec types and differences in their sizes and structures serve epidemiological purposes and are used to differentiate between hospital-associated (HA)-MRSA and community-associated (CA)-MRSA. Some virulence factors of S. aureus are also providing a distinction between HA-MRSA and CA-MRSA. These factors vary depending on the presence of toxins, adhesion, immune evasion, and other virulence determinants. In this review, we summarized an overview of MRSA such as resistance mechanisms, SCCmec types, HA- and CA-MRSA, and virulence factors that enhance pathogenicity or MRSA epidemiology, transmission, and genetic diversity.

• 대한임상검사과학회지
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• 제44권3호
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• pp.118-123
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• 2012

Nosocomial infection and community-acquired infection with Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), has become a strong concern in human body sites and related effects. The aim of this study is investigate the isolation rate of MRSA from nasal cavity inferior regions and cellular phones to assess the risk factor of nosocomial infection and community-acquired infection. 34.7% and 37.2% isolates were MRSA from the nasal cavity inferior regions and cellular phones according to a Mannitol salt agar (added oxacillin $6{\mu}g/mL$) culture and PCR according to S. aureus specific 16S rRNA and mecA primers. Thus, the distribution of S. aureus and the isolation rate of MRSA represent a very high risk factor regards nosocomial infection and community-acquired infection.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.251-256
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• 2011

We screened for antibacterial substances against methicillin-resistant Staphylococcus aureus (MRSA). Methanolic extract of Eisenia bicyclis exhibited anti-MRSA activity according to a disk diffusion assay. To identify the active compound(s), the methanolic extract was further fractionated using hexane, dichloromethane, ethyl acetate, and n-butanol. The ethyl acetate-soluble fraction showed both the greatest anti-MRSA activity and the highest polyphenol content. The minimum inhibitory concentrations of the ethyl acetate fraction ranged from 32 to 64 ${\mu}g$ per mL against methicillin-susceptible S. aureus and MRSA strains. High-performance liquid chromatography analysis revealed that both the methanolic extract and the ethyl acetate soluble fraction contained sizeable quantities of dieckol, which is a known anti-MRSA compound. Thus, these data strongly suggest that the anti-MRSA activity of E. bicyclis may be mediated by phlorotannins such as dieckol.

• 대한의생명과학회지
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• 제11권4호
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• pp.525-531
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• 2005

Staphylococcus aureus is a major cause of nosocomial infections and is one of the most commonly isolated bacterial species in the hospital and continues to be an important pathogen in both community and hospital-acquired infection. Methicillin resistant S. aureus (MRSA), which is associated with hospitals is now being isolated in the community. The purpose of this study is to investigate the carrier rate of S. aureus in the community, antibiotic resistance patterns of the organism, detection of MRSA and mecA gene in MRSA. Ninety strains $(46.4\%)$ of S. aureus were isolated from the nasal specimens of 194 elementary school students. Eighty-nine strains $(98.9\%)$ of 90 S. aureus were resistant to penicilin, 36 strains $(40.0\%)$ to erythromycin, 14 strains $(15.6\%)$ to fusidic acid, 11 strains $(12.2\%)$ to gentamycin, 9 strains $(10.0\%)$ to tobramycin, 5 strains $(5.6\%)$ to oxacillin, 4 strains $(4.4\%)$ to clindamycin, 2 strains $(2.2\%)$ to tetracycline, 1 strains $(1.1\%)$ to fosfomycin. None of $90(0\%)$ S. aureus isolates was resistant to ciprpfloxacin, trimethoprim/sulfamethoxazole, levofloxacin, linezolid, moxifloxacin, nitrofurantoin, norfloxacin, rifampicin, quinupristin/dalfopristin, teicoplanin, and vancomycin. Five strains $(5.6\%)$ of 90 S. aureus isolates were MRSA. The mecA gene was detected from five MRSA strains by PCR.

• Journal of Microbiology
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• 제45권4호
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• pp.350-357
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• 2007

This study was conducted in an effort to evaluate the antimicrobial activity and antibiotic-resistant gene regulation from Saliva miltiorrhiza Bunge on methicillin-resistant Staphylococcus aureus (MRSA). A variety of solvent fractions and methanol extracts of S. miltiorrhiza Bunge were tested in order to determine its antimicrobial activities against S. aureus and MRSA. As a result, the hexane fraction of S. miltiorrhiza Bunge evidenced the highest levels of antimicrobial activity against S. aureus and MRSA. The MICs of the hexane fraction against various MRSA specimens were $64. The hexane fraction evidenced inhibitory effects superior to those of the chloroform fraction. The results showed inhibition zones of hexane (16 mm) and chloroform (14 mm) fractions against MRSA KCCM 40511 at $1,000{\mu}g/disc$. The hexane and chloroform fractions inhibited the expression of the resistant genes, mecA, mecR1, and femA in mRNA. Moreover, the results of Western blotting assays indicated that the hexane and chloroform fractions inhibited the expression of the resistant protein, PBP2a. These results reveal that the hexane and chloroform fractions of S. miltiorrhiza Bunge may prove to be a valuable choice for studies targeted toward the development of new antimicrobial agents.