• Korean Journal of Microbiology
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• v.50 no.3
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• pp.239-244
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• 2014

ErmSF is one of the four antibiotic resistance factor proteins expressed by Streptomyces fradiae, antibiotic tylosin producer, which renders $MLS_B$ (macrolide-lincosamide-streptogramin B) antibiotic resistance through dimethylating A2058 of 23S rRNA, thereby reducing the affinity of antibiotic to ribosome. Unlike other Erm proteins, ErmSF harbors long N-terminal end region. To investigate its role in enzyme activity, mutant ErmSF deleted of 1-38 amino acids was overexpressed and activity in vivo and in vitro was observed. In vitro enzymatic assay showed that mutant protein exhibited reduced activity by 20% compared to the wild type enzyme. Due to the reduced activity of the mutant protein, cells expressing mutant protein showed weaker resistance to erythromycin than cells with wild type enzyme. Presumably, the decrease in enzyme activity was caused by the hindrance in substrate binding and (or) product release, not by defect in the methyl group transfer occurred in active site.

• Journal of Korean Society of Health-System Pharmacists
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• v.35 no.4
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• pp.391-399
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• 2018

Background : The Antimicrobial Stewardship Program promotes interdisciplinary interventions and targeted recommendations for the proper utilization of antibiotics. In particular, the aim of the program is to avoid indiscriminate use of broad-spectrum antibiotics based on the documented literature on the significant impact of unsystematic usage of antibiotics on the distribution of antibiotic-resistant microorganisms. To improve the care process for pneumonia treatment using antimicrobial agents, institution-level guidelines were established and disseminated at the Seoul National University Bundang Hospital in April 2016. In this study, we evaluated changes in the physicians'antibiotic prescribing patterns both before-and after-the implementation of the guidelines. Methods : The electronic medical records of inpatients who were prescribed with one or more antibiotics in May 2014 (Group A) and May 2016 (Group B) were reviewed. Data on demographic characteristics, clinical outcomes, and antibiotic prescriptions were collected and the prescription records were compared both before- and after- the implementation of the guidelines. Results : A total of 180 patients were included in the study: 77 patients in group A and 103 patients in group B. The baseline characteristics of the patients were not significantly different between the two groups. Community-acquired pneumonia was the most common diagnosis in both the groups and the difference was not significant (68.8% vs. 67.9%; p=0.67). The type of antibiotic prescriptions used for empirical treatment was not different between the two groups. The most commonly prescribed empirical antibiotics were cephalosporins, with no significant difference (p=0.31). One of the most inappropriately used antibiotics was piperacillin/tazobactam and the rate of prescription was similar in both the groups (p=0.68). The rates of appropriate empirical selection of antibiotics remained unaltered between the two groups (67.5% vs. 71.8%; p=0.53). Conclusions : Implementation of the guidelines only exhibited no significant effect on the antibiotic prescribing patterns of physicians for the treatment of pneumonia. To improve the adequate use of empiric antibiotics, more active interventions and closer monitoring of the feedbacks should be additionally considered and evaluated in future studies.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.9
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• pp.1339-1347
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• 2008

The objective of this study was to determine the effects of green tea probiotics on growth performance, meat quality and immune response in finishing pigs, and to assess the possibility of substituting green tea probiotics for antibiotics in diets of finishing pigs. This green tea probiotics is made by mixing green tea powder and excipients (defatted rice bran and wheat bran) and fermenting the mixture with beneficial bacteria. A total of 90 crossbreed "Landrace$\times$Yorkshire" finishing pigs with an average body weight of $72.5{\pm}2.5kg$ were assigned to 5 dietary treatments in a completely randomized design. Each treatment had 3 replications with 6 pigs per replication. The five dietary treatments were control, antibiotic (0.003% chlortetracycline added) and 0.1, 0.5 and 1.0% of green tea probiotics. There were no significant differences in final body weight, daily weight gain, daily feed intake and feed conversion ratio in the green tea probiotics and antibiotic treatments (p>0.05). Crude protein content was significantly increased in the 0.1 and 1.0% green tea probiotics treatment groups (p<0.05) and there was no significant difference in crude fat content of the meat among the treatments. The TBA value of meat was significantly lowered with 0.5 and 1.0% green tea probiotics treatments compared to that of controls and statistically similar to the antibiotic treatment after 3 weeks of storage (p<0.05). The growth of spleen cells stimulated with Con A (0.1 and $1.0{\mu}g/ml$) was significantly increased with 1.0% green tea probiotics treatment compared to that of the control treatment (p<0.05). The growth of spleen cells stimulated with LPS (1.0, 3.0 and $10{\mu}g/ml$) was significantly increased in the 0.5% green tea probiotics group compared to the antibiotic group (p<0.05). In Con A ($1.0{\mu}g/ml$) medium, IL-6 production of spleen cells was significantly increased with 1.0% green tea probiotics treatment compared to that of the control (p<0.05). In LPS ($10.0{\mu}g/ml$) medium, TNF-${\alpha}$ production of spleen cells increased significantly in all green tea probiotics treatment groups compared to that of the control (p<0.05). Finally it can be summarized that addition of green tea probiotic has a positive effect similar to antibiotic and 0.5% is the suitable dietary supplementation dose for finishing pig production.

• Korean Journal of Poultry Science
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• v.12 no.2
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• pp.89-95
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• 1985

Two experiments were undertaken to study the growth promoting effect of Spiramycin and Virginiamycin at the level of 5ppm each. In the first experiment, 180 day - old male broiler chickens (Maniker parent stock) were divided into 18 groups of 10 birds each. Six groups were placed on one of the three experimental diets (Nonmedicated control, Spiramycin supplemented diet and Virginiamycin supplemented diet). Basal diet of Experiment 1 contained 21.9% crude protein and 3159kcal /kg diet. Second experiment employed same treatments as were used in the Experiment 1. Ninety male and 90 female day-old broiler chickens(Maniker commercial) were grouped by 10 birds of sane sex in each and assigned to 3${\times}$2 factorial design. Basal diet of Experiment 2 contained 19.95% crude protein and 2931kcal/kg diet. Chicks were fed for six weeks in battery with raised floor and kept further for metabolic trials. The results of feeding trials showed that there were no statistically significant differences between treatments in weight gain, feed intake, feed efficiency and mortality. However, birds fed Antibiotic B supplemented diet grew approximately 3% more than the control in Experiment 1 and than those fed Antibiotic A supplemented diet in Experiment 2. Feed efficiency was also improved by supplementing Antibiotic B in both experiments. There were significant(P〈0.01) differences between sexes in growth rate, feed intake and feed efficiency. Birds fed Antibiotic B supplemented diet of Experiment 1 showed significantly (P〈0.01) greater availability for crude fat than those fed other diets. Birds fed Antiobiotic A supplemented diet in Experiment 1 showed significantly (P〈0.05) lower availability of crude fiber than those of other treatments. Weight of small intestine of birds fed Antibiotic B tended to be heavier than those fed other diets.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.102.1-102
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• 2003

A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens (Siegesbeckia pubescens Makino；Family：Compositae) in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bacterial strain was identified as Pseudomonu aureofaciens. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antibiotic activity was found from the culture filtrate of TSB(tryptic soy broth) and its active compounds were quantitatively bound to XAD adsorber resin. The antibiotic spectrum was broad and growth of C. orbiculare and F. oxysporum, B. cinerea were inhibited at very low concentration. The chemical data from various chromatographic procedures showed that active fraction consisted of at least two phenazine derivatives. However, the metabolites had no inhibitory effect on Pythium ultimum which was reported to be sensitive to phenazine antibiotics. The compounds responsible for the activity are now under investigation.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1226-1231
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• 2014

The rare actinomycete Pseudonocardia autotrophica was previously shown to produce a solubility-improved toxicity-reduced novel polyene compound named $\underline{N}ystatin$-like $\underline{P}seudonocardia$ $\underline{P}olyene$ (NPP). The low productivity of NPP in P. autotrophica implies that its biosynthetic pathway is tightly regulated. In this study, $wblA_{pau}$ was isolated and identified as a novel negative regulatory gene for NPP production in P. autotrophica, which showed approximately 49% amino acid identity with a global antibiotic down-regulatory gene, wblA, identified from various Streptomycetes species. Although no significant difference in NPP production was observed between P. autotrophica harboring empty vector and the S. coelicolor wblA under its native promoter, approximately 12% less NPP was produced in P. autotrophica expressing the wblA gene under the strong constitutive $ermE^*$ promoter. Furthermore, disruption of the $wblA_{pau}$ gene from P. autotrophica resulted in an approximately 80% increase in NPP productivity. These results strongly suggest that identification and inactivation of the global antibiotic down-regulatory gene wblA ortholog are a critical strategy for improving secondary metabolite overproduction in not only Streptomyces but also non-Streptomyces rare actinomycete species.

• Clinical and Experimental Pediatrics
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• v.49 no.3
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• pp.235-241
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• 2006

Streptococus pneumoniae is an important cause of invasive infections as well as non-invasive infections such as acute otitis media and sinusitis both in children and adults. Resistance of S. pneumoniae to multiple antimicrobials is increasing and poses therapeutic challenges, and prevention became more important. 23-valent polysaccharide vaccine has been used for the last several decades, but is not effective in children <2 years of age, the highest risk group of invasive diseases. Recently, a 7-valent pneumococcal protein conjugate vaccine(PCV) which is effective in infants and young children has been developed. The efficacy of PCVs against invasive pneumococcal disease and pneumonia is well established and is documented in several well-conducted studies. However, the effect of PCVs on otitis media is less obvious and more complex. PCVs clearly reduce diseases caused by vaccine-type(VT) pneumococci, but replacement of VT serotypes by non-VT serotypes in nasopharyngeal carriage of S. pneumoniae is responsible for the increase in acute otitis media caused by non-VT serotypes. Three years after introduction of PCV in the US, some increase of invasive infections with serotype 19A possibly due to serotype switching within certain vaccine type strains has been noted. Since most antibiotic-resistance in S. pneumoniae is confined to VT serotypes, vaccine use also reduces antibiotic resistance. With development of PCV, there was a great advance in the prevention of pneumococcal diseases, but replacement with potential virulent organisms and development of antibiotic resistance in non-VT pneumococci is a possibility that needs careful monitoring.

• BMB Reports
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• v.33 no.1
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• pp.49-53
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• 2000

PMAP-23 is a 23-residue antimicrobial peptide derived from porcine myloid cells. In order to investigate the effects of two Pro residues at positions 12 and 15 of PMAP-23 on antibiotic activity, two analogues in which Ala was substituted for Pro residue at position 12 or 15 were synthesized. $Pro^{12}{\rightarrow}Ala$ (PMAPl) or $Pro^{15}{\rightarrow}Ala$(PMAP2) substitution in PMAP-23 caused a significant reduction on antitumor and phospholipid vesicle-disrupting activities, but did not cause a significant effect on antibacterial activity. PMAP-23 displayed the type I ${\beta}-turn$ structure with a negative ellipticity at near 205 om in SDS micelle, whereas PMAP1 and PMAP2 had a somewhat ${\alpha}-helical$ propensity in TFE solution, as compared to PMAP-23. These results suggest that two Pro residues of positions 12 and 15 in PMAP-23 play important roles in the formation of ${\beta}-turn$ structure on lipid membrane and its ${\beta}-turn$ structure may be essential for antibiotic activity including phospholipid vesicle-disrupting property.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.659-664
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• 2010

The present study was to investigate the effect of the transition from conventional to organic dairy farming on the antimicrobial resistant pattern of pathogens in milk. A farm with tie-stall management, with an average herd size of 20 milking cows, was selected based on the owner' willingness to accept, for at least 6 months, the highly restricted protocol developed in this study. Comparisons of bacterial isolates and antimicrobial susceptibilities before changing to an organic farm system (BEFORE) and for 6 months after (AFTER) operating the experimental organic farm system were performed by Fisher's Exact Chi-square tests. Significant levels were defined at p<0.05. During the AFTER period, average frequency of antibiotic treatment was decreased from more than 3 cases/month to less than 1 case/month during which the antibiotic use was authorized only by the veterinarian. In total, 92 and 70 quarter milk samples from 24 and 18 cows during BEFORE and AFTER, respectively, were included in the study. Overall, isolates ranged from a non-resistant level for cephazolin to a very high resistant level to streptomycin (64.71% to 95.45%). Percentages of antimicrobial resistant isolates during BEFORE were significantly higher than during AFTER for ampicillin (43.48% and 5.88%, respectively) and streptomycin (95.45% and 64.71%, respectively). In conclusion, percentages of antimicrobial resistant isolates were decreased after 6 months of operating as an organic farm system.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.473-478
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• 2007

Antibiotic composite was synthesized by coprecipitation of silver nitrate into hydroxyapatite. Adsorbed amount of silver ion was examined by the variation of concentration of silver nitrate, temperature, pressure and curing time. Optimum condition for silver-hydroxyapatite adsorption could be achieved. Physical and chemical characteristic properties of synthesized silver-hydroxyapatite were tested by ICP-MS, SEM-EDAX, DSC and XRD. Antibiotic properties for gram positive staphylococcus aureus (ATCC 6538) and gram negative escherichia coli (ATCC 25922) were tested by shake flake method.