• Korean Journal of Microbiology
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• v.42 no.1
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• pp.54-58
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• 2006

Dried roots of Paeonia japonica were extracted with dichloromethane, methanol and water aerially. Silica gel column chromatography and thin layer chromatography were used to separate the fractions with antimicrobial activities, and mass spectrometry was used to determine the mass. Dichloromethane extract showed the highest antimicrobial activity. Dichloromethane extract from Paeonia japonica could be a candidate for a new antimicrobial agent against MRSA.

• Biomedical Science Letters
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• v.16 no.4
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• pp.331-339
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• 2010

This study aims to evaluate the effect of Photodynamic Therapy (PDT) against methicillin-resistant Staphylococcus aureus with high-level mupirocin resistance (Hi-Mup MRSA). To examine the antimicrobial effect of photogem-mediated PDT against Hi-Mup MRSA, CFU quantifications, bacteria cell viability tests, and disk diffusion antimicrobial susceptibility tests were evaluated. In addition, one of PDT mechanisms was investigated by accumulating photogem ($10\;{\mu}g/ml$) in Hi-Mup MRSA. Photogem-mediated PDT properly inhibited the colony formation of Hi-Mup MRSA. Viable bacteria decreased greatly after a PDT application with photogem $10\;{\mu}g/ml$ at energy density $15\;J/cm^2$. The diameter of the inhibition zone around susceptible disks increased after PDT. In addition, we confirmed the accumulation of photogem in bacteria through fluorescent images. These results demonstrated that excellent photosensitization of Hi-Mup MRSA can be achieved using photogem with 630 nm LED irradiation. Thus, PDT may make survival Hi-Mup MRSA inactive.

• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.212-213
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• 2023

Once known as a major community-genotype, sequence type (ST) 72 methicillin-resistant Staphylococcus aureus (MRSA) strains have been increasingly identified in hospital-associated infections in Korea. Here, we report the complete genome sequence of SA520 isolated from a patient in Korea.

• Biomedical Science Letters
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• v.30 no.1
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• pp.32-35
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• 2024

In vitro antimicrobial activities of hot water extracts of Chamaecyparis obtuse, for methicillin-resistant Staphylococcus aureus (MRSA) was compared to commonly used conventional antimicrobial agents. All MRSA was susceptible to linezolid or vancomycin, but also to erythromycin. MIC range and MIC₉₀ to erythromycin, clindamycin, levofloxacin, tetracycline for MRSA were each 4 ㎍/mL, 2 ~ >128 ㎍/mL, ≤0.06 ~ >128 ㎍/mL, 0.25 ~ >128 ㎍/mL, 0.25~64 ㎍/mL and 4 ㎍/mL, .128 ㎍/mL, >128 ㎍/mL, >128 ㎍/mL, 64 ㎍/mL. The hot water extracts of leaf of C. obtuse had the lowest MIC range, MIC₅₀, and MIC₉₀ (0.125 µL/mL) for the MRSA tested, and it was possible more potent than various conventional antimicrobial agents. Screen antibacterial drug candidate with high antibacterial activity such as derivatives of C. obtuse leaf extract such as terpinen-4-ol or using combined therapy with commercialized antibacterial agents will likely be helpful in treating refractory MRSA infections.

• Korean Journal of Veterinary Service
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• v.33 no.3
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• pp.233-240
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• 2010

Methicillin-resistant coagulase-negative staphylococci (MRCNS) were isolated from the respiratory sites of chickens in 4 farms and slaughter house located in Chungnam provinces. Isolation of coagulase-negative staphylococci (CNS) was positive for 61 (26.6%) of the 229 chickens tested, and isolation of MRCNS was positive for 17 (27.9%) of the isolated CNS. A total of 17 MRCNS isolates were selected and subjected to identification. Of the 17 MRCNS isolates selected, 6 were identified as Staphylococcus cohnii, 2 as S. saprophyticus, 3 as S. simulans, 3 as S. lentus, 2 as S. carnosus, and 1 as S. xylosus. The MRCNS isolates were resistant to many beta-lactam antibiotics, and some isolates were also resistant to macrolide and aminoglycoside antibiotics. The mecA gene was detected in some isolates of each MRCNS strains. The mecA-positive isolates were classified into five staphylococcal cassette chromosome mec (SCCmec). SCCmec types I to IV were detected in isolates from chickens.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.229-237
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• 2018

Identification of antibiotic resistant bacteria isolated from animals is necessary for seeking a proper treatment and for preventing the spread of the bacteria among animals. Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is of worldwide concern in veterinary medicine. This study was conducted to investigate the antimicrobial susceptibility of Staphylococcus pseudintermedius (S. pseudintermedius) isolated from dogs and cats. Out of the total number of 150 specimens, 35 isolates (23.3％) were identified as S. pseudintermedius when tested by MALDI-TOF MS (Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectroscopy). Among them, 5 isolates (14.3%) were the case of MRSP. In the results of the antimicrobial susceptibility test, the isolates of S. pseudintermedius were susceptible to amikacin (100%), cephalothin (100%), vancomycin (100%), amoxicillin (85.7%), oxacillin (85.7%), enrofloxacin (82.8%), chloramphenicol (80%). On the other hand, they were resistant to penicillin (71.4%), tetracycline (48.6%), ampicillin (37.1%), kanamycin (31.5%), erythromycin (31.4%), respectively.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1288-1294
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• 2021

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-O-galloyl-glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and β-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

• Biomedical Science Letters
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• v.14 no.4
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• pp.269-274
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• 2008

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens. It is associated with hospitals is now being isolated in the community. The aim of this study was to evaluate the antibacterial effect of photodynamic therapy using Photogem and 630 nm LED on MRSA and methicillin-sensitive Staphylococcus aureus (MSSA). The broth cultured MRSA and MSSA incubated with various concentrations of Photogem (500,50,5 and $0.5{\mu}g/mL$) for 4 h. Then 630 nm LED was given at $9\;J/cm^2$, $20{\mu}l$ of the exposed bacteria solution was inoculated onto agar plate. Plates were incubated for 24 hand colonies were counted. The PDT group was effective in killing MRSA and MSSA at the Photogem dose of $50{\mu}g/mL$. But MSSA is more sensitive than MRSA in photodynamic effect. Other groups (light only, sensitizer only, or no treatment) observed no bacterial cell killing. These results raise the possibility of using PDT with or without antimicrobial drugs to eradicate MRSA and MSSA. In order to confirm this result, we need to further study bacterial death mechanism and in vivo study.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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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.

• Biomedical Science Letters
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• v.27 no.4
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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.