• Pediatric Infection and Vaccine
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• 제18권1호
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• pp.23-30
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• 2011

목 적 : A. baumannii는 원내 감염의 중요한 원인으로 다양한 감염증을 일으키고 있으며, 다양한 항생제에 대하여 내성을 가지고, 다약제 및 범약제 내성도 점차 증가하고 있어 그 중요성이 높아지고 있다. 이에 소아에서의 A. baumannii 감염 현황 및 내성 발생 현황을 알아보고자 연구를 시행하였다. 방 법: 2001년 1월 1일부터 2008년 12월 31일까지 세브란스 병원에 입원치료 하였던 19세 이하의 소아환자 중 A. baumannii가 동정된 환자 505명, 680례에 대하여 후향적 방법으로 조사하였다. 다약제 내성은 3가지 이상의 항생제 그룹에 대하여 내성을 나타내거나 carbapenem에 대하여 내성을 나타내는 경우로 정의하였고, 범약제 내성은 세브란스 병원에서 항생제 감수성을 검사하는 모든 항생제에 내성을 나타낼 경우로 정의 하였다. A. baumannii의 감염빈도 및 항생제 내성 발생 현황의 연도별 추이에 대하여 조사하였으며, 재원장소, 항생제 사용 유무, 기계 호흡유무 등에 따른 감염빈도 및 다약제, 범약제 내성 발생의 차이에 대하여 조사하였고, 이에 대해 카이제곱 검정, t-검정을 사용하여 통계적 유의성 여부를 알아보았다. 결 과 : A. baumannii 가 동정된 환자들의 기저질환은 혈액종양성 질환, 신경계 질환이 각각 208례(30.6%), 165례(24.3%)로 가장 많았으며, 만성소모성 질환이 많았다. 객담과 소변검체에서 많이 동정되었다. A. baumanii의 검출 빈도는 항생제를 사용하였던 환자들에서 78.1%로, 사용하지 않은 그룹에 비하여 더 높았다. 다약제 내성 및 범약제 내성 A. baumannii의 발생빈도는 중 환자실 재원의 경우 각각 76.4%, 38.3%였고, 기계호흡을 하였던 경우 76.8%와 38.9%로 일반병실 재원 환자 및 기계호흡을 하지 않았던 환자보다 더 높은 빈도를 보였다. 연도별 발생추이는 2001년부터 2004년까지 증가 하다가 2005년 대폭 감소하였으며 이후 다시 증가하여 2008년에는 다약제 내성균주가 63.5%, 범약제 내성균주가 48.2%에 이르렀다. 항생제 내성균의 증가는 모든계열의 항생제에서 나타나고 있으며 2008년에는 모든계열의 항생제가 50% 이상의 내성률을 나타내었다. 항생제 내성은 중환자실 재원여부, 항생제 사용 및 기계호흡 여부와 상관하여 증가하였다(P <0.0001). 결 론:소아에서의 다약제내성, 범약제내성 A. baumannii의 증가는 항생제 과다사용 및 내성 균주의 전파 때문으로 생각되며, 철저한 환경관리가 A. baumannii 감염으로의 이환 및 내성 균주 발생 방지에 중요한 역할을 함을 알 수 있었다.

• The Plant Pathology Journal
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• 제29권2호
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• pp.125-135
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• 2013

In agro-ecosystems worldwide, some of the most important and devastating diseases are caused by soil-borne necrotrophic fungal pathogens, against which crop plants generally lack genetic resistance. However, plants have evolved approaches to protect themselves against pathogens by stimulating and supporting specific groups of beneficial microorganisms that have the ability to protect either by direct inhibition of the pathogen or by inducing resistance mechanisms in the plant. One of the best examples of protection of plant roots by antagonistic microbes occurs in soils that are suppressive to take-all disease of wheat. Take-all, caused by Gaeumannomyces graminis var. tritici, is the most economically important root disease of wheat worldwide. Take-all decline (TAD) is the spontaneous decline in incidence and severity of disease after a severe outbreak of take-all during continuous wheat or barley monoculture. TAD occurs worldwide, and in the United States and The Netherlands it results from a build-up of populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent Pseudomonas spp. during wheat monoculture. The antibiotic 2,4-DAPG has a broad spectrum of activity and is especially active against the take-all pathogen. Based on genotype analysis by repetitive sequence-based-PCR analysis and restriction fragment length polymorphism of phlD, a key 2,4-DAPG biosynthesis gene, at least 22 genotypes of 2,4-DAPG producing fluorescent Pseudomonas spp. have been described worldwide. In this review, we provide an overview of G. graminis var. tritici, the take-all disease, Pseudomonas biocontrol agents, and mechanism of disease suppression.

• Journal of Microbiology
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• 제44권4호
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• pp.423-431
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• 2006

Among 53 Acinetobacter baumannii isolates collected in 2004, nine imipenem-resistant isolates were obtained from clinical specimens taken from patients hospitalized in Busan, Korea. Nine carbapenemase-producing isolates were further investigated in order to determine the mechanisms underlying resistance. These isolates were then analyzed via antibiotic susceptibility testing, microbiological tests of carbapenemase activity, pI determination, transconjugation test, enterobacterial repetitive consensus (ERIC)-PCR, and DNA sequencing. One outbreak involved seven cases of infection by A. baumannii producing OXA-23 ${\beta}-lactamase$, and was found to have been caused by a single ERIC-PCR clone. During the study period, the other outbreak involved two cases of infection by A. baumannii producing IMP-1 ${\beta}-lactamase$. The two clones, one from each of the outbreaks, were characterized via a modified cloverleaf synergy test and an EDTA-disk synergy test. The isoelectric focusing of the crude bacterial extracts detected nitrocefin-positive bands with pI values of 6.65 (OXA-23) and 9.0 (IMP-1). The PCR amplification and characterization of the amplicons via direct sequencing showed that the clonal isolates harbored $bla_{IMP-1}$ or $bla_{oxA-23}$ determinants. The two clones were characterized by a multidrug resistance phenotype that remained unaltered throughout the outbreak. This resistance encompassed penicillins, extended-spectrum cephalosporins, carbapenems, monobactams, and aminoglycosides. These results appear to show that the imipenem resistance observed among nine Korean A. baumannii isolates could be attributed to the spread of an IMP-lor OXA-23-producing clone. Our microbiological test of carbapenemase activity is a simple method for the screening of clinical isolates producing class D carbapenemase and/or class B $metallo-{\beta}-lactamase$, in order both to determine their clinical impact and to prevent further spread.

• Journal of Microbiology and Biotechnology
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• 제31권8호
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• pp.1060-1068
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• 2021

Community-associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is notorious as a leading cause of soft tissue infections. Despite several studies on the Agr regulator, the mechanisms of action of Agr on the virulence factors in different strains are still unknown. To reveal the role of Agr in different CA-MRSA, we investigated the LACΔagr mutant and the MW2Δagr mutant by comparing LAC (USA300), MW2 (USA400), and Δagr mutants. The changes of Δagr mutants in sensitivity to oxacillin and several virulence factors such as biofilm formation, pigmentation, motility, and membrane properties were monitored. LACΔagr and MW2Δagr mutants showed different oxacillin sensitivity and biofilm formation compared to the LAC and MW2 strains. Regardless of the strain, the motility was reduced in Δagr mutants. And there was an increase in the long chain fatty acid in phospholipid fatty acid composition of Δagr mutants. Other properties such as biofilm formation, pigmentation, motility, and membrane properties were different in both Δagr mutants. The Agr regulator may have a common role like the control of motility and straindependent roles such as antibiotic resistance, biofilm formation, change of membrane, and pigment production. It does not seem easy to control all MRSA by targeting the Agr regulator only as it showed strain-dependent behaviors.

• Genomics & Informatics
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• 제21권3호
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• pp.34.1-34.10
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• 2023

Nosocomial infections, commonly referred to as healthcare-associated infections, are illnesses that patients get while hospitalized and are typically either not yet manifest or may develop. One of the most prevalent nosocomial diseases in hospitalized patients is pneumonia, among the leading causes of mortality and morbidity. Viral, bacterial, and fungal pathogens cause pneumonia. More severe introductions commonly included Staphylococcus aureus, which is at the top of bacterial infections, per World Health Organization reports. The staphylococci, S. aureus, strain RMI-014804, mesophile, on-sporulating, and non-motile bacterium, was isolated from the sputum of a pulmonary patient in Pakistan. Many characteristics of S. aureus strain RMI-014804 have been revealed in this paper, with complete genome sequence and annotation. Our findings indicate that the genome is a single circular 2.82 Mbp long genome with 1,962 protein-coding genes, 15 rRNA, 49 tRNA, 62 pseudogenes, and a GC content of 28.76%. As a result of this genome sequencing analysis, researchers will fully understand the genetic and molecular basis of the virulence of the S. aureus bacteria, which could help prevent the spread of nosocomial infections like pneumonia. Genome analysis of this strain was necessary to identify the specific genes and molecular mechanisms that contribute to its pathogenicity, antibiotic resistance, and genetic diversity, allowing for a more in-depth investigation of its pathogenesis to develop new treatments and preventive measures against infections caused by this bacterium.

• 셀메드
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• 제4권1호
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• pp.5.1-5.8
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• 2014

Healthcare-associated infection represents a frequent cause of mortality that increases hospital costs. Due to increasing microbial resistance to antibiotics, it is necessary to search for alternative therapies. Consequently, novel alternatives for the control of resistant microorganisms have been studied. Among them, plant antimicrobial protein presents enormous potential, with flowers being a new source of antimicrobial molecules. In this work, the antimicrobial activity of protein-rich fractions from flower tissues from 18 different species was evaluated against several human pathogenic bacteria. The results showed that protein-rich fractions of 12 species were able to control bacterial development. Due its broad inhibition spectrum and high antibacterial activity, the protein-rich fraction of Hibiscus rosa-sinensis was subjected to DEAE-Sepharose chromatography, yielding a retained fraction and a non-retained fraction. The retained fraction inhibits 29.5% of Klebsiella pneumoniae growth, and the non-retained fraction showed 31.5% of growth inhibition against the same bacteria. The protein profile of the chromatography fractions was analyzed by using SDS-PAGE, revealing the presence of two major protein bands in the retained fraction, of 20 and 15 kDa. The results indicate that medicinal plants have the biotechnological potential to increase knowledge about antimicrobial protein structure and action mechanisms, assisting in the rational design of antimicrobial compounds for the development of new antibiotic drugs.

• 생명과학회지
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• 제24권6호
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• pp.700-706
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• 2014

본 연구에서는 anthracycline 계열 항암항생제인 doxorubicin의 암세포 전이 억제 여부를 LNCap 전립선 암세포를 이용하여 이동성 및 침윤성 억제 효능 측면에서 조사하였다. 본 연구의 결과에 의하면 doxorubicin은 LNCap 세포의 이동성과 침윤성을 현저하게 억제시켰으며, matrix metalloproteinase (MMP)-2 및 -9의 발현과 활성을 저해함과 동시에 tissue inhibitor of metalloproteinase (TIMP)-1 및 -2의 발현은 증가시켰다. Doxorubicin은 또한 tight junctions (TJs)의 전기적 저항성을 증대시켰으며, 이는 TJs의 주요 구성인자인 claudin family 인자들의 발현 억제와 연관성이 있었다. 따라서 LNCap 세포에서 doxorubicin에 의한 전이의 억제에는 최소한 TJ의 견고성 증대와 MMPs의 활성 억제가 관여할 것으로 추정된다.

• Animal Bioscience
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• 제35권10호
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• pp.1461-1478
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• 2022

The maintenance of poultry gut health is complex depending on the intricate balance among diet, the commensal microbiota, and the mucosa, including the gut epithelium and the superimposing mucus layer. Changes in microflora composition and abundance can confer beneficial or detrimental effects on fowl. Antibiotics have devastating impacts on altering the landscape of gut microbiota, which further leads to antibiotic resistance or spread the pathogenic populations. By eliciting the landscape of gut microbiota, strategies should be made to break down the regulatory signals of pathogenic bacteria. The optional strategy of conferring dietary fibers (DFs) can be used to counterbalance the gut microbiota. DFs are the non-starch carbohydrates indigestible by host endogenous enzymes but can be fermented by symbiotic microbiota to produce short-chain fatty acids (SCFAs). This is one of the primary modes through which the gut microbiota interacts and communicate with the host. The majority of SCFAs are produced in the large intestine (particularly in the caecum), where they are taken up by the enterocytes or transported through portal vein circulation into the bloodstream. Recent shreds of evidence have elucidated that SCFAs affect the gut and modulate the tissues and organs either by activating G-protein-coupled receptors or affecting epigenetic modifications in the genome through inducing histone acetylase activities and inhibiting histone deacetylases. Thus, in this way, SCFAs vastly influence poultry health by promoting energy regulation, mucosal integrity, immune homeostasis, and immune maturation. In this review article, we will focus on DFs, which directly interact with gut microbes and lead to the production of SCFAs. Further, we will discuss the current molecular mechanisms of how SCFAs are generated, transported, and modulated the pro-and anti-inflammatory immune responses against pathogens and host physiology and gut health.