• Archives of Pharmacal Research
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• 제19권5호
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• pp.400-405
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• 1996

In vitro studies were conducted to dertermine the frequency rate of spontaneous resistance to LB20304 and to dertermine whether cross-resistance to other antimicrobial agents develops. In eight strains of bacteria, the frequency of mutation to LB20304 at the concentrations of four and eight times the minimal inhibitory concentration(MIC) ranaged from less than 4.0 ${\times}$ $10^{-10}$ to 2.2 $\{times}$ $10^{-10}$ . These results were similar to those founf for other new fluoroquinolones. THe development of stepwise resistance was determined by repeated subculture in broth in the presence of increasing concentration of the compounds. Exposure of bacteria to increasing concentrations of LB20304 resulted in the selection of organisms with higher MICs. There were 4- to 128-fold increases in the MIC of LB20304 for bacterial strains of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli and Pseudomonas aeruginosa. However, those strains selected after repeated exposure were well within the susceptibility range for LB20304 except for Pseudomonas aeruginosa. The resistant isolates selected with LB20304 showed cross-resistance when tested against ciprofloxacin and vice versa.

• 한국동물위생학회지
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• 제15권1호
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• pp.81-88
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• 1992

This study was conducted to determine the microorganisms inhabitating in sow genital organs and their anti-microbial drug susceptibility During the period between February, 1991 and November 1991, 128 sow genital organs were sampled at six abattoirs. Gross pathological examination and bacterial isolation and identification were performed from the genital organ. In addition, antimicrobial drug susceptibility for the major organisms isolated were examined. 1. Among the bateria isolated from normal genital organs, E. coli(30.7%) Stahylococcus spp.(29.4%), Corynebarterium pyogenes(C. pyogenes) (14.7%), Streptococcus spp.(13.3%) were most freqently isolated, whereas the genera of Klebsiella, Actinobacillus, and Serratia were detected less freqently. 2. Among the bacteria isolated from abnormal genital organs, C. pyogenes,(37.7%), Stahylococcus spp.(30.2%), Proteus spp. (26.4%) , Pasteurella spp. (18.9%) , Steptococcus spp. (9.4%) were most freqently isolated whereas the genera of Pseudomonas, Serratia and Klebsiella were detected less freqently. 3. From sow genital organs showing lesion of endometritis and purulent endometritis C. pyogenes were most freqently isolated, the isolation rate being 67.7％ and followed by Stahylococcus spp., E. coli, Proteus spp., Steptococcus spp. and Pasteurella spp. in the order. 4. Antimicrobial drug susceptibility of the major organisms showed that all the isolates were susceptible to cephalothin, ampicillin, chloramphenicol and sulfamethoxazole / trimethoprim, but resistant to penicillin and streptomycin.

• 약학회지
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• 제56권5호
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• pp.304-308
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• 2012

In vitro antibacterial activity of DW286 was tested against recently collected clinical isolates of Gram-positive strains by the two fold agar dilution method. In vivo activity of DW286 was also determined against systemic infections in mice caused by Staphylococcus aureus. DW286 showed 16~64-fold more potent in vitro activities than ciprofloxacin against Gram-positive bacteria. Against systemic infection model caused by two S. aureus strains, one being methicillin-susceptible and the other methicillin-resistant, DW286 ($ED_{50}s$, 0.16 mg/kg and 4.36 mg/kg, respectively) was more potent than gemifloxacin (1.37 mg/kg, 26.58 mg/kg, respectively).

• Archives of Pharmacal Research
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• 제19권2호
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• pp.143-147
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• 1996

LB20304 is a novel fluoroquinolone that exhibits a potent broad spectrum antibacterial activity against both gram-positve and gram-negative bacteria. The MICs (Minimal Inhibitory Concentration) of LB20304 were determined against both gram-positve and gram-negative bacteria under various conditions including several media, pHs, and inoculum concentrations. The in vitro activity of LB20304 was not significantly affected by the changes in testing conditions such as components of media and inoculum concentrations, but it was slightly reduced by acid condition. The MICs and MBCs (Minimal Bactericidal Concentration) of LB20304 against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were hardly affected by the presence of 50 % human serum, mouse serum, guinea pig serum or horse serum, and the MBCs were equal to or at most four-times higher than the MiCs. The activities of LB20304 were decreased by the presence of high concentraion of $Mg^{++}$ or human urine (pH, 5.5) in the test media. The frequencies of mutants resistant to LB20304 were similar to or lower than those found in ciprofloxacin and sparfloxacin.

• 한국임상약학회지
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• 제23권1호
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• pp.20-25
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• 2013

Background & Objectives: Burn injury mortality and septic complication are frequent and well-known in burned pediatric patients. The overuse of antibiotics is the base for development of wound infection by resistant microorganisms as well as opportunist agents. Methods: We have carried out a study of the bacterial profile and antimicrobial resistance clinically important bacteria isolated from burn wound infections in children patients. The most common isolate from burn wound cultures was Pseudomonas aeruginosa (26.8%), followed by Staphylococcus aureus (25.4%), Acinetobacter baumannii (12.7%), coagulase negative staphylococcus (12.0%), Enterococcus faecium (7.7%), Escherichia coli (4.9%), Enterococcus faecalis (3.7%), Burkholderia cepacia (3.0%), Enterobacter cloacae (2.3%) and Klebsiella pneumonia (2.3%). Colistin was very significantly effective drug in gram negative organism, such as Pseudomonas aeruginosa and Acinetobacter baumannii. Results & Conclusion: The resistance rates were 65% and 98% to piperacillin, 63% and 97% to ceftazidime, 28% and 50% to levofloxacin. The most effective antibiotic in gram positive organism, such as Staphylococcus aureus, coagulase negative staphylococcus were moxifloxacin. The resistance rates were 83% and 64% to ciprofloxacin, 80% and 17% to clindamycin.

• 한국식물병리학회지
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• 제14권2호
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• pp.177-183
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• 1998

A DNA fragment which is involved in tolassin production was cloned to obtain a molecular marker of Pseudomonas tolaasii, a casual agent of bacterial brown blotch disease of oyster mushroom (Pleurotus ostreatus). Tolaasin is a lipodepsipeptide toxin and known as a primary disease determinant of the P. tolaasii. It is responsible for formation of white line in agar when P. tolaasii were cultured against white line reacting organisms (WLROs). White line negative mutants (WL-) were generated by conjugation between rifampicin resistant strain of P. tolaasii and E. coli carrying suicidal plasmid pSUP2021 : : Tn5. The ability of tolaasin production of the WL- mutants was examined by hemolysis test, pathogenicity test, and high pressure liquid chromatography (HPLC) analysis of culture filtrate. All of the WL- mutants were lost the ability of tolaasin production (Tol-). Genomic library of the Tol- mutant was constructed in pLAFR3 and the cosmid clone containing Tn5 was selected. DNA fragment fro franking region of Tn5 was cloned from the plasmid and used as a probe in Southern blot. DNA-DNA hybridization with the probe to total DNA from group of bacteria ecologically similar to P. tolaasii including WLORs, fluorescent Pseudomonads isolated from oyster mushroom, P. agarici, P. gingeri, and some of other species of Psedomonas showed that some of the tested bacteria do not have any hybridized band and others have bands sowing RFLP. The cloned DNA fragment or its nucleotide sequence will be useful in detection and identification of the P. tolaasii.

• Biodesign
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• 제6권4호
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• pp.96-99
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• 2018

The gram-positive bacterium Staphylococcus aureus is a common cause of abscesses, sinusitis and food poisoning. The emergence of antibiotic-resistant strains has caused significant clinical issues worldwide. The HslU-HslV complex was first identified as a prokaryotic homolog of eukaryotic proteasomes. HslU is an unfoldase that mediates the unfolding of the substrate proteins, and it works with the protease HslV in the complex. To date, the protein complex has been mostly studied in gram-negative bacteria. In this study, we report the purification and crystallization of the full-length HslU from S. aureus. The crystal diffracted X-rays to a $3.5{\AA}$ resolution, revealing that the crystals belong to space group $P2_1$, with unit cell parameters of a = 166.5, b = 189.6, $c=226.6{\AA}$, and ${\beta}=108.1^{\circ}$. We solved the phage problem by molecular replacement using the structure of HslU from Haemophilus influenzae as a search model. The cell content analysis with this molecular replacement solution revealed that 24 molecules are contained in the asymmetric unit. This structure provides insight into the structural and mechanistic difference of the HslUV complex of gram-positive bacteria.

• 한국양봉학회지
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• 제34권2호
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• pp.131-136
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• 2019

Recently, number of honeybees (Apis mellifera) has visibly decreased because they are vulnerable to some diseases like American foulbrood disease. American foulbrood disease, which is caused by Paenibacillus larvae, is emerged as great cause of decrease in number of honeybees. After antibiotic-resistant strain emerged, it is now more difficult to treat those pathogens successfully. Researches on finding alternative antibacterial compound are ongoing. In this study, we examined the antibacterial effect of honokiol on P. larvae. Honokiol showed great antibacterial effect with minimum inhibitory concentration of 12.5 ㎍/mL and minimum bactericidal concentration of 50 ㎍/mL. An agar diffusion test also confirmed the anti-Paenibacillus larvae activity of honokiol with an inhibitory zone of 9±0.5 mm. Since honokiol is known to interact membrane of some bacteria, we measured 260 nm absorbing particles, which could be induced by leakage of cells, and confirmed that the leakage of P. larvae occurred in dose-dependent manners. However, result of crystal violet assay suggested that honokiol has only mild anti-biofilm formation effect on P. larvae, which means honokiol controls the bacteria by inducing the bursting of membrane. Finally, an additive effect of honokiol with tetracycline and terramycin was found using a checkerboard assay with a fractional inhibitory concentration index value of 0.5.

• 대한약침학회지
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• 제26권1호
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• pp.53-59
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• 2023

Objectives: The most prominent microorganisms that cause hospital infections and acquire antibiotic resistance are Staphylococcus aureus and Pseudomonas aeruginosa. The present study aimed to compare the phenolic and flavonoid compounds of various Allium ampeloprasum and Allium porrum extracts and evaluate the antibacterial effects of these extracts against these two microorganisms. Methods: The total phenolic and flavonoid contents of the acetone, methanol, aqueous, and hexane leeks extracts from A. ampeloprasum and A. porrum were measured. The antibacterial activity of these extracts against S. aureus and P. aeruginosa was tested using the disk diffusion method for 24, 48, and 72 hours. Further, the minimum inhibitory concentrations and the minimum bactericidal concentrations of these extracts for these two bacteria were evaluated and compared with those of common antibiotics. Results: The aqueous extracts showed the highest phenolic and flavonoid contents and at concentrations of 35 and 40 mg per disk, showed the most antibacterial activity against S. aureus and P. aeruginosa; P. aeruginosa showed more sensitivity to the aqueous extracts than S. aureus. Conclusion: Aqueous A. ampeloprasum and A. porrum extracts may prevent the growth of hospital pathogens, especially P. aeruginosa; our findings will aid the discovery of new antimicrobial substances against antibiotic-resistant bacteria.

• Journal of Animal Science and Technology
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• 제66권1호
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• pp.57-78
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• 2024

In a global context, bacterial diseases caused by pathogenic bacteria have inflicted sustained damage on both humans and animals. Although antibiotics initially appeared to offer an easy treatment for most bacterial infections, the recent rise of multidrug-resistant bacteria, stemming from antibiotic misuse, has prompted regulatory measures to control antibiotic usage. Consequently, various alternatives to antibiotics are being explored, with a particular focus on bacteriophage (phage) therapy for treating bacterial diseases in animals. Animals are broadly categorized into livestock, closely associated with human dietary habits, and companion animals, which have attracted increasing attention. This study highlights phage therapy cases targeting prominent bacterial strains in various animals. In recent years, research on bacteriophages has gained considerable attention, suggesting a promising avenue for developing alternative substances to antibiotics, particularly crucial for addressing challenging bacterial diseases in the future.