• Korean Journal of Microbiology
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• v.46 no.2
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• pp.192-199
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• 2010

The alone and combined effects of bacteriocin produced from Enterococcus faecalis MJ-213 and potassium sorbate against the food-borne pathogenic bacteria were studied. Bacteriocin minimal inhibitory concentration (MIC) values for Staphylococcus aureus ATCC 6538 and Salmonella enteritidis ATCC 13076 were 50 and 100 ${\mu}g$/ml, respectively. Bacteriocin (100 ${\mu}g$/ml) alone was active against S. aureus and S. enteritidis, but it was lower in antimicrobial effectiveness than the combination of bacteriocin (100 ${\mu}g$/ml) with potassium sorbate (100 ${\mu}g$/ml), which reduced initial counts (6 log cycle) of S. aureus and S. enteritidis by 1 and 3 log cycle, respectively. The bactericidal activity of bacteriocin of E. faecalis MJ-213 heated at $100^{\circ}C$ for 30 min or $121^{\circ}C$ for 15 min was markedly decreased as compared with the control. Moreover, the activity of bacteriocin was completely abolished by pepsin or protease II, but not affected by ${\alpha}$-amylase or lipase. The activity of bacteriocin adjusted to pH 6.0-8.0 showed almost the same inhibition ratio compared with the bacteriocin unadjusted pH, and though the inhibition ratio against pathogenic bacteria was reduced than the control, the bacteriocin was stable at pH 4.0 or 10.0, relatively. Furthermore, the combined treatment of bacteriocin and potassium sorbate than the alone treatment of bacteriocin significantly decreased (p<0.05) the viable cell counts of S. aureus or S. enteritidis inoculated on grind beef during storage at $4^{\circ}C$.

• Pediatric Infection and Vaccine
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• v.26 no.1
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• pp.1-10
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• 2019

Purpose: We investigated the distribution and antimicrobial resistance of pneumococcal isolates from hospitalized children at Asan Medical Center for recent 4 years, and aimed to recommend proper choice of empirical antibiotics for pneumococcal infection. Methods: From March 2014 to May 2018, children admitted to Asan Medical Center Childrens' Hospital with pneumococcal infection were subjected for evaluation of minimal inhibitory concentration (MIC) for ${\beta}-lactams$ and macrolide antibiotics. Patient's age, underlying disease, gender were retrospectively collected. Using Monte Carlo simulation model and MIC from our study, we predicted the rate of treatment success with amoxicillin treatment. Results: Sixty-three isolates were analyzed including 20.6% (n=13) of invasive isolates, and 79.4% (n=50) of non-invasive isolates; median age were 3.3 years old, and 87.3% of the pneumococcal infections occurred to children with underlying disease. Overall susceptibility rate was 49.2%, 68.2%, and 74.6% for amoxicillin, parenteral penicillin, and cefotaxime respectively. 23.8% and 9.5% of the isolates showed high resistance for amoxicillin, and cefotaxime. Only 4.8% (n=3) were susceptible to erythromycin. Monte Carlo simulation model revealed the likelihood of treatment success was 46.0% at the dosage of 90 mg/kg/day of amoxicillin. Conclusions: Recent pneumococcal isolates from pediatric patients with underlying disease revealed high resistance for amoxicillin and cefotaxime, and high resistance for erythromycin. Prudent choice of antibiotics based on the local data of resistance cannot be emphasized enough, especially in high risk patients with underlying disease, and timely vaccination should be implemented for prevention of the spread of resistant strains.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.105-111
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• 2013

The Erm family of adenine-$N^6$ methyltransferases (MTases) is responsible for the development of resistance to macrolide-lincosamide-streptogramin B antibiotics through the methylation of 23S ribosomal RNA. Recently, it has been proposed that well conserved amino acids in ErnC' located in concave cleft between N-terminal 'catalytic' domain and C-terminal 'RNA-binding' domain interacts with substrate RNA. We carried out the site-directed mutagenesis and studied the function of the ErmSF R237 mutant in vitro and in vivo. R237 amino acid residue is located in the concave cleft between two domains. Furthermore this residue is very highly conserved in almost all the Erm family. Purified mutant protein exhibited only 51% enzyme activity compared to wild-type. Escherichia coli with R237A mutant protein compared to the wild-type protein expressing E. coli did not show any difference in its MIC (minimal inhibitory concentration) suggesting that even with lowered enzyme activity, mutant protein was able to efficiently methylate 23S rRNA to confer the resistance on E. coli expressing this protein. But this observation strongly suggests that R237 of ErmSF probably interacts with substrate RNA affecting enzyme activity significantly.

• Korean Journal Plant Pathology
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• v.2 no.2
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• pp.89-95
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• 1986

The five short-chain fatty acids such as isobutyric(C-4), butyric(C-4), isovaleric(C-5), valeric(C-5) and caproic (C-6) acids obtained from the extract of common purslane showed wide antifungal spectra against spore germination and mycelial growth of the twenty five phytopathogenic fungi tested in vitro, although there were differences in antifungal potency among them. The antifungal potency of each fatty acid varied significantly against different fungi in spore germination and mycelial growth. The seventeen fungi used for spore germination test and the sixteen fungi used for mycelial growth test can be divided into three groups depending upon differences in minimal inhibitory concentration of each fatty acid for them, respectively. Caproic acid was significantly more toxic to germination than to mycelial growth of the test fungi, while the other four fatty acids did not show such a significant differences in toxicity with a few of exceptions as shown in valerie acid. The longer the chain-length of fatty acid was, the higher the antifungal potency was shown. The normal fatty acids such as butyric and valerie acid were more toxic than their isomers to spore germination and mycelial growth of the test fungi. Each fatty acid was more toxic to spore germination of obligate parasites and some of facultative parasites, and mycelial growth of facultative parasites than to spore germination and mycelial growth of saprophytes, respectively.

• Korean Journal of Medicinal Crop Science
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• v.16 no.5
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• pp.320-325
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• 2008

Machilus thunbergii has been showed relation to antimicrobial activity on minimal inhibitoty concentration (MIC) and colony forming inhibitory activity (CFIA) test, so that can be used to food preservatives for green vegetable. Nanoparticles has been made of edible materials. 80% of the nanoparticles has been characterized by image analyser and electron microscopy, showing in the range under 300 nm diameter. The sprayed nanoparticles remained on the surface of chicon even after washing by dilution water, then activate biological activities for storage of chicon with storing and releasement system of extracts. Chicon treated nanoparticle has been kept fresh condition about 2 months longer than 3 weeks of the non-treated control. It can be tell that treatment with nanoparticle of M. thunbergii extracts extends storage time of chicon possibly by inhibition of ethylene production through efficiency control on cell breathing.

• The Plant Pathology Journal
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• v.28 no.1
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• pp.32-39
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• 2012

Efficacy of different control methods was evaluated for disease management of tomato bacterial wilt caused by $Ralstonia$ $solanacearum$. All six chemical pesticides applied to the bacterial suspension showed $in$ $vitro$ bactericidal activities against $R.$ $solanacearum$. Minimal inhibitory concentrations (MICs) of copper hydroxide (CH), copper hydroxide-oxadixyl mixture (CH+O), and copper oxychloride-dithianon mixture (CO+D) were all 200 ${\mu}g/ml$; MIC of copper oxychloride-kasugamycin (CO+K) mixture was 100 ${\mu}g/ml$; MICs of both streptomycin- validamycin (S+V) and oxine copper-polyoxine B mixture (OC+PB) were 10 ${\mu}g/ml$. Among these chemical pesticides, treatment of the detached tomato leaves with the 5 pesticides (1 mg/ml), except for OC+PB delayed early wilting symptom development caused by the bacterial inoculation ($10^6$ and $10^7$ cfu/ml). Four pesticides, CH, CH+O, CO+K and S+V, showed disease protection in pot analyses. Six plant essential oils, such as cinnamon oil, citral, clove oil, eugenol, geraniol and limonene, differentially showed their antibacterial activities $in$ $vitro$ against $R.$ $solanacearum$ demonstrated by paper disc assay. Among those, cinnamon oil and clove oil exert the most effective activity for protection from the wilt disease caused by the bacterial infection ($10^6$ cfu/ml). Treatment with cinnamon oil and clove oil also suppressed bacterial disease by a higher inoculum concentration ($10^7$ cfu/ml). Clove oil could be used for prevention of bacterial wilt disease of tomato plants without any phytotoxicity. Thus, we suggest that copper compounds, antibiotics and essential oils have potency as a controlling agent of tomato bacterial wilt.

• Korean Journal of Veterinary Research
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• v.29 no.4
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• pp.493-501
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• 1989

A total of 108 strains of C jejuni isolated from pigs and chickens were examined for the susceptibility to 10 antimicrobial agents and normal sera of cattle, sheep, guinea pigs and chickens. Minimal inhibitory concentration(MIC) ranges of antimicrobial agents to C jejuni isolates were $${\leq_-}1.56$$ to $${\geq_-}100{\mu}g/ml$$ for erythromycin, rifampin, streptomycin and tetracycline, 50 to $${\geq_-}100{\mu}g$$ for cephalothin, $${\leq_-}1.56$$ to $50{\mu}g$ for ampicillin, $${\leq_-}1.56$$ to $25{\mu}g$ for kanamycin and nalidixic acid, $${\leq_-}1.56$$ to $12.5{\mu}g$ for chloramphenicol and gentamicin. Resistance rates of C jejuni were showed to in order of rifampin(84.7%), tetracycline(56.2 %), erythromycin(17.1%) and ampicillin(3.8%), all of the strains were sensitive to chloramphenicol, gentamicin and kanamycin, and the incidence rates of resistant C jejuni were highly frequent in pig isolates than chicken isolates. The drug resistance patterns of 87 chicken isolates C jejuni to 9 antimicrobial drugs were showed 12 patterns, and Sm Ra Tc(24.1%), Sm Ra(21.8%) and Ra Tc(14.9%) were relatively common, and also 21 pig isolates were showed 6 patterns and Em Sm Ra Tc(57.1%) were most frequent. The majority of the isolates showed multiple drug resistance. Bactericidal activity of 10% normal sera from healthy animals were examined for 60min at $37^{\circ}C$. C jejuni were decreased from 0.4 to 1.0 ${\log}_{10}$(p<0.01), and serum susceptibility were high in order of guinea pig, sheep, chicken and cattle sera. Serum sensitivity of C jejuni Ch-39 strain in increased serum concentation up to 10, 20, 40 and 80% were highly significant. In the normal animal serum, the number of Ch-39 strain were decreased from $1.8{\times}10^4/ml$ to $2.7{\times}10^3/ml$ after 60 min incubation(p<0.01), but the numbers were decreased to $6.6{\times}10^3/ml$ in the heat inactivated normal serum for 30 min at $56^{\circ}C$. Bactericidal activity was restored in the heat inactivated normal serum after the serum of complement source was added.

• The Journal of Internal Korean Medicine
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• v.36 no.2
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• pp.165-179
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• 2015

Objectives: This experiment investigated the antimicrobial activity of Hwangryunheadok-tang and extracts of Scutellariae radix , Phellodendri cortex , Coptis rhizome , and Gardenia jasminoides against Salmonella typhimurium . Methods: After spreading S. typhimurium on a bacterial culture medium plate, antimicrobial activity was tested by dripping diluted Hwangryunheadok-tang or extracts of Scutellariae radix , Phellodendri cortex , Coptis rhizome , or Gardenia jasminoides (80 μl, diluted 100, 50, 10, and 1%) onto the plate, followed by culture for 16 to 72 hours. The minimal inhibitory concentration (MIC) was tested by dripping the minimum dilution that showed antimicrobial activity (80, 60, 40, and 20 μl) and measuring the density. The antimicrobial activity of Hwangryunheadok-tang and four extracts showed continuous antibacterial activity against S. typhimurium throughout the experiment. Result: 1. S. typhimurium . (Standard Microorganism, ATCC) 1) The Hwangryunheadok-tang and extracts of Scutellariae radix , Phellodendri cortex , and Coptis rhizome showed antibacterial activity in the undiluted solutions and in 50% dilutions. Gardenia jasminoides extract showed potency only in the undiluted solution. The antimicrobial potency of the undiluted solution was increased when the volume of inoculation was increased, but no difference was noted when the culture time was extended. All the extracts showed antimicrobial potency against S. typhimurium . 2. S. typhimurium isolated from diarrhea patients 1) When compared to the standard microorganism experiment on S. typhimurium , the MICs of the five extracts were increased. However, whereas the antimicrobial potency of doxycycline was lost entirely against bacteria isolated from patients with diarrhea, the antimicrobial potency of all the extracts was diminished but did not disappear. 2) The antimicrobial activity of Hwangryunheadok-tang and four extracts was continuous even when the culture time was extended to 16, 24, and 72 hours. Conclusions: The Hwangryunheadok-tang and four kinds of extracts have antimicrobial activity against S. typhimurium . Comparison of a standard microorganism with S. typhimurium isolated from diarrhea patients showed that the antimicrobial activity of all the extracts was better than that of antibiotics. Further studies should focus on the value and benefits of Hwangryunheadok-tang , and the four kinds of extracts as clinical treatments.

• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.389-397
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• 2010

This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

• Journal of Yeungnam Medical Science
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• v.8 no.1
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• pp.53-62
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• 1991

Experiments were performed in mice(Balb/C) to support the basic efficacy of the human immunoglobulin (IgG) preparation. The antibacterial activity of IgG purified from human sera was examined with or without the quinolone agent, ciprofloxacin(CPFX), against Pseudomonas aeruginosa isolated from clinical specimens. Results were as follows: Antibacterial activities in terms of the percentage of survivors, after administration of Ps. aeruginosa into mouse intraperitoneal cavity were in the following order, single IgG group, CPFX administration after IgG pretreatment group, IgG and CPFX combined administration group and CPFX alone group. The number of living bacteria was monitored in blood and liver tissue of mice infected with Ps. aeriginosa and treated by IgG administration. The increase of living bacteria in liver was more drastic than that in blood. Leukocytosis was observed in mice injected with IgG, excluding those only with ciprofloxacin, after 8 hours of administration to see a decrease to normal number of bacteria after 18 hours. No significant difference was noticed between pretreatment group and post treatment group. In vitro susceptibility test of IgG against Ps. aeruginosa, minimal inhibitory concentration(MIC) was $250{\mu}g/ml$, resistant to IgG, regardless of a combined administration with CPFX. In vitro test revealed that the IgG itself did not have anti-Ps. aeruginosa activity.