• 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.

• 한국축산식품학회지
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• 제40권3호
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• pp.401-414
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• 2020

The emergence and persistence of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in livestock animals have been reported as a potential risk factor for transmission to humans. In this study, we investigated the nationwide prevalence and characteristics of MRSA and MSSA in the Korean beef production system, including retail markets, slaughterhouses, and cattle farms. From a total of 1,285 samples, only 5 MRSA strains were isolated: from a farmer (1 ST72 MRSA), a carcass sample from a slaughterhouse (1 ST72 MRSA), and beef cattle (3 ST5 MRSA). In addition, 11 MSSA strains were isolated from beef cattle (n=3), humans (1 farmer, 1 slaughterhouse worker, and 4 retail market workers), and carcass samples (n=1) and slaughterhouse environment (n=1). Although the prevalence of MRSA and MSSA in beef cattle was much lower than that reported in pigs, 5/5 MRSA and 2/11 MSSA strains displayed multiple drug resistance (MDR) phenotypes. Unlike the swine-associated MRSA, no correlation was found between tetracycline/zinc resistance and MDR phenotype. However, MRSA strains had an identical set of staphylococcal enterotoxins and exhibited enhanced levels of resistance to antimicrobial peptides (PMAP-36 and LL-37) compared to the MSSA strains. In conclusion, continued and systemic surveillance of livestock, meat products, and humans in close contact with livestock/meat products is necessary to prevent the transmission of MRSA and MSSA to humans.

• 생명과학회지
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• 제21권2호
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• pp.257-264
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• 2011

2009년 7월부터 12월까지 순천 소재 한 병원에 내원한 환자의 검체로부터 methicillin 내성 Staphylococcus aureus (MRSA) 75균주와 methicillin 감수성 S. aureus (MSSA) 24균주를 분리하였다. 분리균의 항생제 감수성 조사는 디스크 확산법을 사용하여 측정하였다. 분리균의 독소 유전자 보유는 multiplex PCR을 이용하여 장독소(enterotoxin; SE), 독성 쇼크 증상 독소 1(toxic shock syndrome toxin-1; TSST-1), 피부박탈성 독소(exfoliative toxin; ET) 및 백혈구 용해 독소(Panton-Valentine leukocidin; PVL) 유전자를 검출하였다. 분리된 MRSA 60개 균주는 1개 혹은 2개의 독소 유전자를 가지고 있으며, 22.7%의 균주가 seb, sec, seg, sei와 tst 유전자를 동시에 보유하고 있었으며 18.7%는 sec, seg, sei와 tst 유전자를 동시에 보유하고 있었다. 백혈구 용해독소를 암호하는 pvl 유전자는 검출되지 않았다. MRSA는 sec, seg, sei와 tst 유전자 보유에 높은 상관성을 보였다. MRSA 균주들은 erythromycin (분리균의 89%), gentamicin (70.7%), ciprofloxacin (69.3%), clindamycin (61.3%)과 tetracycline (58.7%)에 내성이 높은 반면, MSSA 균주들은 erythromycin를 제외한 다른 항생제에는 민감하였다. 독소 유전자 seb, sec와 tst는 tetracycline 내성과 높은 상관관계가 있었다.

• 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.

• 한국환경보건학회지
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• 제39권5호
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• pp.447-455
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• 2013

Objectives: This study aims to understand the concentration, diversity, and antibiotic characteristics of staphylococci present in the indoor air of child-care facilities. Methods: Air sampling was performed from October 2012 to January 2013 in 120 child-care facilities in Seoul, Korea. Methicillin-resistant bacteria were selected from the total obtained airborne bacteria and subjected to 16S rRNA analysis for methicillin-resistant staphylococcal species determination. Identified staphylococcal strains were tested for resistance to a range of antibiotics. Results: Average total airborne bacterial concentration was $508.9{\pm}246.3CFU/m^3$. Indoor concentration of total airborne bacteria had a significant positive correlation with the $CO_2$ concentration in the child-care facilities. Methicillin-resistant staphylococci were present in 13.3% of the child-care facilities studied. A total of four species (S. epidermidis, S. cohnii, S. saprophyticus, S. sp.) and 55 strains were identified from the indoor air of the child-care facilities. Staphylococcus cohnii was the most common species (54.5%), followed by S. epidermidis (38.2%). All of the isolated staphylococcal strains exhibited high resistance to oxacillin, erythromycin, mupirocin, and ceftizoxime. Especially, S. saprophyticus strains showed more multidrug resistance to oxacillin, vancomycin, clindamycin, erythromycin, lincomycin, ceftizoxime, mupirocin, and tetracycline than did other species. Conclusion: The results of this study showed that a monitoring system for multidrug-resistant bacteria is needed in facilities for children, as the community-associated infections of these bacteria are increasing.

• 대한의생명과학회지
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• 제25권1호
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• pp.75-82
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• 2019

We developed the multiplex LAMP assay using 16S rRNA, femA and mecA genes for direct detection of the methicillin resistance in Staphylococci from positive blood culture. To simultaneously recognize Staphylococci genus, S. aureus and methicillin resistance, three sets of six primers for 16S rRNA, femA and mecA were designed, respectively. The performance of LAMP assay was affirmed using VITEK system for the phenotypic methods of identification and for oxacillin and cefoxitin antimicrobial susceptibility. The optimal condition for LAMP assay was obtained under $64^{\circ}C$ for 50 min. The detection limit was determined to be of 20 copies and CFU/reaction ($10^4CFU/mL$). For clinical application of comparison with phenotypic methods, the sensitivity and specificity of the LAMP with femA gene for detecting S. aureus was 95.31% and 100%, respectively. The sensitivity and specificity of the LAMP with mecA gene for detecting methicillin resistance was 98.46% and 100%, respectively. The multiplex LAMP assay with femA and mecA gene successfully detected all of MRSA (38 isolates) isolates from 103 Staphylococci in blood cultures. The LAMP assay developed in this study is sensitive, specific, and of excellent agreement with the phenotypic methods.

• Journal of Oral Medicine and Pain
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• 제45권1호
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• pp.17-21
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• 2020

Osteomyelitis of the jaw infected with Coagulase-Negative Staphylococci (CNS) is rarely reported in the Oral and Maxillofacial Region. Staphylococcus is a part of the normal body flora, but it may be cause severe infections and CNS are often described as the important pathogens in nosocomial infections. Although many studies on prevalence and antibiotics of Staphylococcus aureus have been done, but many of these studies focus only on Methicillin-resistant S. aureus and not on methicillin-resistant coagulase-negative Staphylococci (MRCNS). There was a less study about CNS or MRCNS infections in the Oral and Maxillofacial Region. This report describes a case of a 41-year-old male patient who developed osteomyelitis caused by MRCNS on condyle after open reduction and internal fixation and suggests guideline for the prevention of postoperative infection and appropriate recommendation for treatment and control.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제23권2호
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• pp.180-184
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• 2001

MRSI is the staphylococcal infection having resistance to the methicillin which is semisynthetic penicillinase-resistant agents against penicillinase. These infections are very difficult to treat because they have resistance to almost every antibiotics except for vancomycin. We experienced MRSE(methicilline-resistant staphylococcal epidermis) infected 56 years old man who developed 2 months after arthroplasty for TMJ ankylosis and MRSA(methicilline-resistant staphylococcal aureus) infected 59 years old man who was performed arthroplasty far traumatic TMJ disc displacement.

• 대한의생명과학회지
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• 제16권4호
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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.

• 생약학회지
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• 제53권2호
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• pp.87-95
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• 2022

Methicillin resistance Staphylococcus aureus (MRSA) is a gram-positive bacterium, the most commonly isolated bacterial human pathogen. JiYu-san is one of the natural products used to treat diseases in the folk recipe. In this study, we investigated the antimicrobial activity of EtOH 70% extracts of JiYu-san (JYS) against MRSA. The antibacterial activity of JYS against MRSA strain was evaluated using minimum inhibitory concentration (MIC), checkerboard dilution test, and time-kill assay. The effect of JYS on the immune mechanism of MRSA was confirmed through cell membrane permeability tests and energy metabolism tests, and the antibacterial activity mechanism was performed using qRT-PCR and western blot. As a result, in the antibacterial test of JYS, the MIC was measured to be 1.9~1000 ㎍/mL, and synergistic or showed a partial synergistic effect. In addition, JYS showed antibacterial activity in a combination test with DCCD or TX-100. In a study on the mechanism of action of antibacterial activity, it was found that JYS suppressed MRSA resistance genes and proteins. These results suggest that JYS has antibacterial activity and provides great potential as a natural antibiotic by modulating the immune mechanism against MRSA.