• IMMUNE NETWORK
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• v.21 no.2
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• pp.13.1-13.19
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• 2021

Macrophages are important for the first line of defense against microbial pathogens. Integrin CD11b, which is encoded by Itgam, is expressed on the surface of macrophages and has been implicated in adhesion, migration, and cell-mediated cytotoxicity. However, the functional impact of CD11b on the inflammatory responses of macrophages upon microbial infection remains unclear. Here, we show that CD11b deficiency resulted in increased susceptibility to sepsis induced by methicillin-resistant Staphylococcus aureus (MRSA) infection by enhancing the pro-inflammatory activities of macrophages. Upon infection with MRSA, the mortality of Itgam knockout mice was significantly higher than that of control mice, which is associated with increased production of TNF-α and IL-6. In response to MRSA, both bone marrow-derived macrophages and peritoneal macrophages lacking CD11b produced elevated amounts of pro-inflammatory cytokines and nitric oxide. Moreover, CD11b deficiency upregulated IL-4-induced expression of anti-inflammatory mediators such as IL-10 and arginase-1, and an immunomodulatory function of macrophages to restrain T cell activation. Biochemical and confocal microscopy data revealed that CD11b deficiency augmented the activation of NF-κB signaling and phosphorylation of Akt, which promotes the functional activation of macrophages with pro-inflammatory and immunoregulatory phenotypes, respectively. Overall, our experimental evidence suggests that CD11b is a critical modulator of macrophages in response to microbial infection.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.799-805
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• 2016

Methicillin-resistant Staphylococcus aureus (MRSA), the major causative agent of nosocomial infection, has also been reported from non-human sources. A sequence type (ST) 541 MRSA isolate designated K12PJN53 was isolated from a healthy pig in 2012. The genome of K12PJN53 consists of 44 contiguous sequences (contigs), totalling 2,880,108 bases with 32.88% GC content. Among the annotated contigs, 14, 17, and 18 contained genes related to antimicrobial resistance, adherence, and toxin genes, respectively. The genomic distance of strain K12PJN53 was close to the ST398 strains. This is the first report of the draft genome sequence of a novel livestock-associated MRSA ST541 strain.

• Clinics in Shoulder and Elbow
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• v.16 no.2
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• pp.141-147
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• 2013

A 57-year-old man who simultaneously underwent an operation for repair of rotator cuff and a revision operation for nonunion of a Pilon fracture presented with osteomyelitis of the humeral head on the $19^{th}$ day after surgery due to MRSA (Methicillin-resistant Staphylococcus aureus) infection. Infection was controlled after administration of appropriate intravenous antibiotic therapy and performance of several surgical procedures. However, devastating defects at the humeral head and the rotator cuff remained. No case of short term MRSA induced osteomyelitis has been reported.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.800-805
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• 2012

Licochalcone E was firstly isolated from licorice root in 2005, which belongs to the retrochalcone family. Studies on the biological activities of licochalcone E were in the initial stage. In the study, we demonstrated that licochalcone E has potent antimicrobial property against Staphylococcus aureus. Furthermore, via hemolysis, Western blot, and real-time RT-PCR assays, we have shown that subinhibitory concentrations of licochalcone E dose-dependently reduces the production of ${\alpha}$-toxin in both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The data suggest that licochalcone E may deserve further investigation as a potential therapeutic against S. aureus infections, or the structure of licochalcone E may be used as a basis for chemical synthesis of novel anti-S. aureus compounds.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2695-2699
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• 2011

${\beta}$ Ketoacyl acyl carrier protein synthase III (KAS III) initiates fatty acid synthesis in bacteria and is a key target enzyme to overcome the antibiotic resistance problem. In our previous study, we found flavonoid inhibitors of Enterococcus faecalis KAS III and proposed three potent antimicrobial flavonoids against Enterococcus faecalis and Vancomycin-resistant Enterococcus faecalis with MIC values in the range of 128-512 ${\mu}g/mL$ as well as high binding affinities on the order from $10^6$ to $10^7\;M^{-1}$. Using these series of flavonoids, we conducted biological assays as well as docking study to find potent flavonoids inhibitors of Staphylococcus aureus KAS III with specificities against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. Here, we propose that naringenin (5,7,4'-trihydroxyflavanone) and eriodictyol (5,7,3',4'-tetrahydroxyflavanone) are potent antimicrobial inhibitors of Staphylococcus aureus KAS III with binding affinity of $3.35{\times}10^5$ and $2.01{\times}10^5\;M^{-1}$, respectively. Since Arg38 in efKAS III is replaced with Met36 in saKAS III, this key difference caused one hydrogen bond missing in saKAS III compared with efKAS III, resulting in slight discrepancy in their binding interactions as well as decrease in binding affinities. 4'-OH and 7-OH of these flavonoids participated in hydrogen bonding interactions with backbone carbonyl of Phe298 and Ser152, respectively. In particular, these flavonoids display potent antimicrobial activities against various MRSA strains in the range of 64 to 128 ${\mu}M$ with good binding affinities.

• Journal of Korean Biological Nursing Science
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• v.21 no.4
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• pp.283-291
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• 2019

Purpose: The aim of this study was to identify awareness and competency for Multi-Drug Resistant Organisms (MDRO) infection control in nursing students with experience of clinical practice. Methods: This cross-sectional descriptive study was conducted from March 2019 to May 2019 by including 231 nursing students in four nursing schools located in Seoul, Gyeonggi-do and Chungcheongnam-do. The data were collected using self-report questionnaires. Results: The awareness and the competency for Carbapenem-Resistant Enterobacteriaceae (CRE) infection control were lower than that of Methicillin-Resistant Staphylococcus aureus (MRSA). The agreement between the awareness and the competency of MDRO infection control in participants was low with regard to isolation, contact precautions, and disinfection for MRSA. Also, it was low with respect to disinfection, isolation, contact precautions, and carrier identification for CRE. The awareness and the competency of MDRO infection control exhibited significant positive correlation. Conclusion: The infection control competency is required to prevent MDRO infection. In order to enhance the infection control competency, it is important to raise awareness about MDRO infection control by providing education based on the guidelines and the principles of infection control.

• The Korean Journal of Mycology
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• v.48 no.1
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• pp.15-27
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• 2020

In screening for antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) KCCM 40510 and Bacillus cereus KCTC 3624, NNIBRFG5039 was isolated from the air in Sangju-si, Gyeongsangbuk-do. Based on a high sequence similarity of the internal transcribed spacer (ITS) region, NNIBRFG5039 was determined to be closely related to Penicillium rubefaciens CBS 139145. The optimal media, initial pH, and temperature for mycelial growth and antimicrobial activity of P. rubefaciens NNIBRFG5039 were determined as follows: potato dextrose broth (PDB), pH 6.5, and 30℃, respectively. Under the optimal culture conditions, maximum mycelial growth (12.4 g L^-1) and antibacterial activity (7.5 mm zone of inhibition against MRSA KCCM 40510, and 5.0 mm zone of inhibition against B. cereus KCTC 3624) were observed in a 5 L stirred-tank fermenter. We also isolated the antimicrobial compound from an ethyl acetate fraction, and its chemical structure was identified as (S)-6-hydroxymellein (1) by ESI-MS, ¹H-NMR, and ¹³C-NMR. Consequently, the extract from P. rubefaciens NNIBRFG5039 may be used in functional materials for antimicrobial-related applications.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.207-214
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• 2005

To characterize the genotypic traits of clinical methicillin-resistant Staphyiococus aureus (MRSA) isolates (n=49), major virulence-associated genes were detected by using PCR-based methods. All the MRSA isolates possessed coagulase gene and showed four polymorphism types [500bp ($6{\%}$),580bp ($27{\%}$), 660bp ($65{\%}$) and 740bp ($2{\%}$)] due to variable numbers of tandem repeats present within the gene. The four or five different loci of hemolysin gene family were dominant in the MRSA isolates,25 of which($51{\%}$) possessed a combination of hla / hlb / hld/ hlg / hlg-2 genes as the most prevalent type. The prevalence of enterotoxin genes was varied among the MRSA isolates. sea and seb genes were detected from all the MRSA isolates. But sei, tsst-1, seg, sec, and seh genes were detected from 31 ($63{\%}$), 16 ($33{\%}$), 14 ($29{\%}$), 8 ($16{\%}$), and 5 ($10{\%}$) isolates, respectively. sed and sej genes were detected from 1 ($2{\%}$) isolate, respectively. see, eta, and etb genes were not detected at all. sea / seb genes were co-detected from 11 ($23{\%}$) isolates, sea / seb / sei genes from 9 ($19{\%}$) isolates, and sea / seb / seg / sei / tsst-1 genes from 5 ($10{\%}$) isolates. Other genes were co-detected with below $10{\%}$ frequencies.

• Journal of Preventive Medicine and Public Health
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• v.45 no.3
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• pp.174-180
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• 2012

Objectives: An ambulance can be a potential source of contagious or droplet infection of a community. We estimated the prevalence of positive carriage of tuberculosis (TB), methicillin-resistant $Staphylococcus$ $aureus$ (MRSA), and vancomycin-resistant $Enterococci$ (VRE) in patients transported by ambulance. Methods: This was a retrospective observational study. We enrolled all patients who visited a tertiary teaching hospital emergency department (ED). Blood, sputum, urine, body fluid, and rectal swab samples were taken from patients when they were suspected of TB, MRSA, or VRE in the ED. The patients were categorized into three groups: pre-hospital ambulance (PA) group; inter-facility ambulance (IA) group; and non-ambulance (NA) group. Adjusted odds ratio (OR) and 95% confidence intervals (CI) were calculated using a multivariable logistic regression model for the prevalence of each infection. Results: The total number of patients was 89206. Of these, 9378 (10.5%) and 4799 (5.4%) were in the PA and IA group, respectively. The prevalence of TB, MRSA, and VRE infection were 0.3%, 1.1%, and 0.3%, respectively. In the PA group, the prevalence of TB, MRSA, and VRE were 0.3%, 1.8%, and 0.4%. In the IA group, the prevalence of TB, MRSA, and VRE were 0.7%, 4.6%, and 1.5%, respectively. The adjusted ORs (95% CI) of the PA and IA compared to the NA group were 1.02 (0.69 to 1.53) and 1.83 (1.24 to 2.71) for TB, 2.24 (1.87 to 2.69) and 5.47 (4.63 to 6.46) for MRSA, 2.59 (1.78 to 3.77) and 8.90 (6.52 to 12.14) for VRE, respectively. Conclusions: A high prevalence of positive carriage of TB, MRSA, and VRE in patients transported by metropolitan ambulances was found.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.456-464
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• 2005

Antimicrobial drug-resistance is natural response to antimicrobial stress based on selection, which weakens chemotherapy effect. Introduction of large numbers of chemotherapeutic agents to clinical practice has generated strains of microorganisms that survive and multiply in vivo with high-drug concentrations. Methicillin-resistant Staphylococcus aureus (MRSA), bacteria found in normal daily life, can be easily ingested through milk vegetables, and meats, etc. MRSA emerged in many port of the world, increasing complex clinical problems. Therefore, new agents are needed to treat MRSA. Glycyrrhiza uralensis was extracted using 80% MeOH to investigate its antimicrobial activity against MRSA stains KCCM 11812, 40510, and 40512 through bacterial measurement, disc diffusion, and O.D. methods, MIC values, MRSA gene expression investigation, and scanning electron microscope observation. Results revealed MecA, Mecl, MecRI, and FemA were the most highly manifested MRSA genes. Methanolic extract of G. uralensis significantly inhibited MRSA and thus could be used in development of antibacteria.