• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.653-659
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• 2016

The purpose of the study is to investigate the correlation between the amount of antimicrobial agent (Defined Daily Dose, DDD) and antimicrobial resistance rate (%). The treatment of infectious diseases is becoming increasingly difficult, due to the increase in the number of multi-drug resistant bacteria, making it a clinically significant problem. Among the various factors, antimicrobial abuse is a major cause of antimicrobial resistance. The study was conducted on inpatients in a secondary university hospital in the central region utilizing the hospital's computerized statistical data and microbiological program of laboratory medicine from January 2010 to December 2014 pertaining to the dose of antimicrobial drugs for Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli strains isolated from blood culture. We analyzed the antimicrobial resistance rate per dose with the Pearson correlation coefficient. A significant (positive?) correlation was detected between the cefepime dose and the resistance of E. coli (P<0.033; r=0.907), while a significant negative correlation was found between the tobramycin dose and the resistance of E.coli. (P<0.028; r=-0.917). The aminoglycoside resistance of A. baumannii showed a significant negative correlation (P<0.048; r=-0.881), and the aminoglycoside resistance of E. coli showed a significant negative correlation as well (P<0.001; r=-0.992). In conclusion, the amount of antimicrobial agent (Defined Daily Dose, DDD) (is partly related to) the bacterial strain and its antimicrobial resistance rate (%).

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.803-811
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• 2014

Concerns over drug-resistant bacteria have stimulated interest in developing alternative methods to control bacterial infections. Endolysin, a phage-encoded enzyme that breaks down bacterial peptidoglycan at the terminal stage of the phage reproduction cycle, is reported to be effective for the control of bacterial pathogenic bacteria. Bioinformatic analysis of the SPN9CC bacteriophage genome revealed a gene that encodes an endolysin with a domain structure similar to those of the endolysins produced by the P1 and P22 coliphages. The SPN9CC endolysin was purified with a C-terminal oligo-histidine tag. The endolysin was relatively stable and active over a broad temperature range (from $24^{\circ}C$ to $65^{\circ}C$). It showed maximal activity at $50^{\circ}C$, and its optimum pH range was from pH 7.5 to 8.5. The SPN9CC endolysin showed antimicrobial activity against only gram-negative bacteria and functioned by cutting the glycosidic bond of peptidoglycan. Interestingly, the SPN9CC endolysin could lyse intact gram-negative bacteria in the absence of EDTA as an outer membrane permeabilizer. The exogenous lytic activity of the SPN9CC endolysin makes it a potential therapeutic agent against gram-negative bacteria.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.376-381
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• 1998

Xanthomonas campestris pv. glycines 8ra causes bacterial pustule disease on susceptible soybean leaves and produces a bacteriocin, named glycinecin, against related bacteria such as Xanthomonas campestris pv. vesicatoria. The antimicrobial activity of the glycinecin was effective to most tested Xanthomonas species. X. c. pv. glycines 8ra was able to produce the glycinecin in liquid media as well as solid media. Maximal productivity of glycinecin was obtained at 3$0^{\circ}C$ in the early stationary phase of growth of the X. c. pv. glycines 8ra. The production of glycinecin was not dependent on the initial inoculum level but on cell density. Glycinecin was very sensitive to proteolytic enzymes such as trypsin and proteinase K but resistant to DNase and RNase. The culture supernatant of X. c. pv. glycines 8ra retained some of its antimicrobial activity after 15 min at 6$0^{\circ}C$. It is stable at wide range of pH. The glycinecin showed the bactericidal activity after the adsorption of the glycinecin to the sensitive bacterial cell.

• Korean Journal of Veterinary Research
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• v.49 no.2
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• pp.113-119
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• 2009

Atrophic rhinitis (AR) is the one of important respiratory diseases and causes severe economic losses in pig industry. Severe attempts have been made to reduce the economic losses by preventing the disease. One of the methods is the spraying of antibiotics into nasal cavity of piglets. Recently, the efficacy of the spraying with kanamycin and gentamicin was reduced in the Korean swine industry. Therefore, the preventive methods have been required to be changed based on the antimicrobial susceptibility profiles of causative agents of swine AR. Based on the current situations of this disease, Bordetella (B.) bronchiseptica and Pasteurella (P.) multocida 4D were isolated from pigs with clinical signs of AR. The isolation rates of B. bronchiseptica and P. multocida 4D were 58.5% and 32.9%, respectively. In the antimicrobial susceptibility test, the bacteria were resistant to kanamycin and gentamicin which have been used as the spraying agents, but they were susceptible to amikacin. A new spraying agent was developed using amikacin using ${\beta}$-glucan and yakbaltag as supplementary agents. Field efficacy of the agent was carried out with different schedule. The results from this study suggested that the newly developed spraying agents might be helpful to prevent AR in swine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.918-926
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• 2021

We isolated 28 Vibrio vulnificus strains from seawater and fisheries and investigated the positive rate of eight virulence genes. Additionally, we evaluated the susceptibility of these strains to 25 antimicrobials. The positive rates of fur, vvhA, tcp, rtxA, vcgC, viuB, vvp, and acfA were 100, 92.9, 92.9, 67.9, 64.3, 25.0, 14.3, and 7.1%, respectively. A disk diffusion susceptibility test revealed that, all the investigated strains had the highest resistance to amoxicillin and oxacillin, followed by that to streptomycin (96.4%), cefoxitin (92.9%), clindamycin (82.1%), amikacin (67.9%), vancomycin (46.4%), nalidixic acid (7.1%), penicillin G (7.1%), and ampicillin (3.6%). Moreover, they were susceptible to 10 other antimicrobials, including cefotaxime, chloramphenicol, erythromycin, gentamicin, and rifampicin. Notably, amoxicillin, oxacillin, and streptomycin had average minimum inhibitory concentrations of 132.6, 603.4, and 23.1 ㎍/mL against V. vulnificus, respectively. These observations provide new insights regarding the necessity for sanitation of commercial fisheries and can potentially, help reduce the risk posed by fisheries contaminated with bacteria resistant to antimicrobials.

• Korean Journal of Food Science and Technology
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• v.49 no.2
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• pp.146-150
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• 2017

Staphylococcus aureus is a pathogenic bacterium that causes food poisoning, exhibits a strong capacity to form biofilm, and is highly resistant to antimicrobial agents. The purpose of this study was to investigate the antimicrobial characteristics of corosolic acid against S. aureus. S. aureus showed high susceptibility to corosolic acid in a concentration-dependent manner. The minimum inhibitory concentration and colony-forming ability determined by the broth microdilution method showed that corosolic acid had strong antimicrobial activity against the bacteria. The diameters of the inhibition zone and numbers of colony forming units at each concentration of corosolic acid were also measured. In addition, corosolic acid displayed potent biofilm inhibition activity against S. aureus at concentrations below its minimum inhibitory concentration. These results suggest that corosolic acid can be used to effectively prevent biofilm formation by S. aureus, thereby making S. aureus more susceptible to the action of antimicrobials.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1457-1466
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• 2012

Antimicrobial peptides (AMPs) exert antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and viruses by various mechanisms. AMPs commonly possess particular characteristics by harboring cationic and amphipathic structures and binding to cell membranes, resulting in the leakage of essential cell contents by forming pores or disturbing lipid organization. These membrane disruptive mechanisms of AMPs are possible to explain according to the various structure forming pores in the membrane. Some AMPs inhibit DNA and/or RNA synthesis as well as apoptosis induction by reactive oxygen species (ROS) accumulation and mitochondrial dysfunction. Specifically, mitochondria play a major role in the apoptotic pathway. During apoptosis induced by AMPs, cells undergo cytochrome c release, caspase activation, phosphatidylserine externalization, plasma or mitochondrial membrane depolarization, DNA and nuclei damage, cell shrinkage, apoptotic body formation, and membrane blebbing. Even AMPs, which have been reported to exert membrane-active mechanisms, induce apoptosis in yeast. These phenomena were also discovered in tumor cells treated with AMPs. The apoptosis mechanism of AMPs is available for various therapeutics such as antibiotics for antibiotic-resistant pathogens that resist to the membrane active mechanism, and antitumor agents with selectivity to tumor cells.

• Journal of Microbiology and Biotechnology
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• v.32 no.11
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• pp.1416-1426
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• 2022

The need to discover new types of antimicrobial agents has grown since the emergence of antibiotic-resistant pathogens that threaten human health. The world's oceans, comprising complex niches of biodiversity, are a promising environment from which to extract new antibiotics-like compounds. In this study, we newly isolated Pseudomonas sp. NIBR-H-19 from the gut of the sea roach Ligia exotica and present both phenotypes and genomic information consisting of 6,184,379 bp in a single chromosome possessing a total of 5,644 protein-coding genes. Genomic analysis of the isolated species revealed that numerous genes involved in antimicrobial secondary metabolites are predicted throughout the whole genome. Moreover, our analysis showed that among twenty-five pathogenic bacteria, the growth of three pathogens, including Staphylococcus aureus, Streptococcus hominis and Rhodococcus equi, was significantly inhibited by the culture of Pseudomonas sp. NIBR-H-19. The characterization of marine microorganisms with biochemical assays and genomics tools will help uncover the biosynthesis and action mechanism of antimicrobial metabolites for development as antagonistic probiotics against fish pathogens in an aquatic culture system.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.71-78
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• 2002

With the incidence of antibiotic resistant bacteria there is increasing interest in natural products such as herb extract and probiotics to control antibiotic resistant bacteria. This study was focused on the determination of antimicrobial activity of Opuntia ficus-indica var. saboten against Salmonella enetrica serovar Enteritidis (S. enterifidis), S. enterica serovar Typhimurium (S. Typhimurium) DT 104 and Escherichia coli 0157:H7. Though bactericidal effect of 0. ficus-indica var. saboten was not observed, it had significant inhibitory activity against Salmonella spp. and E. coli O157:H7 on the Moulter Hinton agar containing its solution dissolved in deionized water. To investigate the antimicrobial activity in vivo, mice were challenged with 5. Typhimurium DT104 (3.7$\times$108 cfu/mouse) after pre-feeding 0. ficus-indica var. saboten solution. The fecal shedding of S. Typhimurium DT104 was more dramatically decreased and not detectable in feces and intestines 3 days after challenge in mice fed with 0. ficus-indica var. saboten. Antibody responses of the intestinal IgA were also significantly increased in mice fed with 0. ficus-indica var. saboten. These findings suggest that Opuntia ficus-indica var. saboten decreased the shedding of S. Typhimurium DT104 in vitro and also in the gastrointestinal tract in mice. In addition, administration of the product might enhance the mucosal immune response against S. Typhimurium DT 104. In conclusion, Opuntia ficus-indica var. saboten might be useful to control antibiotic resistant bacteria in vivo and in vitro.