• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.375-380
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• 1986

Thirty-one strains of Pseudomonas aeruginosa were submitted to the synergistic activity test of amikacin(AK) and gentamicin(GM) combined with moxalactam(MX), ceftizoxime(CTZ) or cefoperazone(CFZ). The minimal inhibitory concentrations(MICs) of each drug and drugs combined in various ratios were measured by checkerboard dilution method. The synergism was determined through analysing the MIC distribution curve on isobologram and calculating the fractional inhibitory concentration index(FICI). MICs of GM, AK, MX, CFZ and CTZ against the 31 tested strains were distributed from $12.5{\mu}g/ml$ to $800{\mu}g/ml$, from $0.8{\mu}g/ml$ to $25{\mu}g/ml$, from $3.1{\mu}g/ml$ to $50{\mu}g/ml$, from $3.1{\mu}g/ml$ to $400{\mu}g/ml$, and from $12.5{\mu}g/ml$ to $100{\mu}g/ml$, respectively. The rate synergism of each drug combination by means of FICl was 45.5% in GM-MX, 36.4% in GM-CFZ, 63.6% in GM-CTZ, 48.6% in AK-MX, 35.3% in AK-CFZ, and 35.7% in AK-CTZ combination. Thus, it is suggested that Pseudomonas aeruginosa may effectively be inhibited by various aminoglycoside and cephalosporin combinations.

• The Journal of Internal Korean Medicine
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• v.19 no.2
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• pp.300-316
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• 1998

The various oriental herbal medicines, which have usually been used for treatment of reducing fever, purging intense heat and detoxication, were screened to determine the antibacterial activity and the minimal inhibitory concentration against antibiotics-resistant Staphylococcus aureus. The results obtained were as follows: 1. Among the 23 oriental medicines tested, the water-soluble extract of Coptis japonica showed very excellent antibacterial activity against antibiotics-sensitive and -resistant S. aureus. A little activity was found in the extracts of Scutellaria baicalensis, Eriobotrya japonica and Prunus mume against antibiotics-sensitive S. aureus and in that extracts of P. mume, Schizandra chinensis and S. baicalensis against antibiotics-resistant S. aureus. When C japonica was used, the high antibacterial activity was shown against Bacillus subtilis and other extracts showed a little or no antibacterial activity against B. subtilis and E. coli as a control. 2. The highest antibacterial activities against antibiotics-resistant S. aureus were found in the ethanol-soluble extract of C japonica. Other ethanol-soluble extracts of S, baicalensis, S. chinensis and P. mume showed a little activity against both antibiotics-sensitive and antibiotics-resistant S. aureus. 3. Among the medicinal herbs tested, the water- and ethanol extracts of C. japonica showed very excellent antibacterial activity against the pathogenic S. aureus and both Escherichia coli and Bacillus subtilis used as a control. 4. When the water-soluble extracts of C. japonica and S. baicalensis, minimal inhibitory concentrations (MICs) against antibiotics-sensitive S. aureus were $20mg/m{\ell}\;and\;30mg/m{\ell}$, respectively. The MICs of the ethanol-soluble extracts of C. japonica and P. scabriosaefolia were $7.5mg/m{\ell}\;and\;12mg/m{\ell}$, respectively. 5. For the MICs against antibiotics-resistant S. aureus, the water-soluble extracts of C. japonica and P. mume showed $15mg/m{\ell}\;and\;10mg/m{\ell}$, respectively. The MICs of the ethanol-soluble extracts of C. japonica and P. mume were $13mg/m{\ell}\;and\;20mg/m{\ell}$, respectively. As a result, the highest antibacterial activity was found in both water- and ethanol-soluble extracts of C. japonica against antibiotics-resistant S. aureus. And the water- and ethanol-soluble extracts of S. baicalensis, S. chinensis and P. mume showed comparatively high antibacterial activities against both antibiotics-sensitive and -resistant S. aureus.

• Archives of Pharmacal Research
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• v.26 no.5
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• pp.389-393
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• 2003

The essential oils from Cedrus atlantica, Styrax tonkinensis, Juniperus communis, Lavandula angustifolia, Melaleuca alternifolia, Pelargonium graveolens, Pogestemon patchouli and Rosmarinus officinalis were analyzed by GC-MS. Antifungal activities of the oils were investigated by disk diffusion assay and the broth dilution method against Aspergillus niger and A. flavus. The effects of geraniol and the essential oil fraction from P. graveolens on the antifungal activity of amphotericin Band ketoconazole were examined using a checkerboard microtiter assay against both Aspergillus fungi. Most of the tested essential oils, with the exception of C. atlantica, J. communis, and P. patchouli, significantly inhibited growth of A. niger and to a lesser extent that of A. fIavus, with MICs (minimal inhibitory concentrations) in the range 0.78-12.5 mg/mL. The essential oil fraction of P. graveolens and its main components, geraniol and citronellol, exhibited additive effects with amphotericin B and with ketoconazole against both Aspergillus species, resulting in fractional inhibitory concentration (FIC) indices ranging from 0.52 to 1.00.

• Natural Product Sciences
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• v.13 no.2
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• pp.164-168
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• 2007

To investigate natural antibiotics from plant essential oils and to evaluate their synergism with current antimicrobial drugs in inhibiting antibiotic-resistant strains of Streptococcus pneumoniae. The minimal inhibitory concentrations (MICs) of eleven plant essential oils and their main components were established for two antibiotic-susceptible and two antibiotic-resistant strains of S. pneumoniae, using broth microdilution tests. Potential synergism with oxacillin, norfloxacin, or erythromycin was evaluated using a checkerboard microtitre assay. Among the tested oils, Mentha piperita oil and its main component, menthol, exhibited the strongest inhibitory activities against all of the tested strains. The activity of antibiotics against antibiotic-resistant strains of S. pneumoniae was enhanced significantly by combination with Mentha piperita oils and its main component, menthol. In conclusion, the combination Mentha piperita essential oil or menthol with antibiotics could be used to reduce the effective dose of antibiotic and to modulate the resistance of S. pneumoniae strains.

• Journal of Microbiology
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• v.38 no.4
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• pp.265-269
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• 2000

Iron increased the susceptibilities of clinical isolates Pseudomonas aeruginosa to quinolones. In the presence of iron, increased susceptibilities to ofloxacin were observed in twenty-six out of thirty isolates and with no change in four isolates. In the case of norfloxacin, iran increased susceptibilities of twelve isolates but did not render any change in eighteen isolates. In the case of ciprofloxacin, iron decreased the MICs (Minimal Inhibitory Concentration) of twenty isolates, increased the MIC of one isolate, and did net change the MICs of nine isolates. To find out how iron increased susceptibility to ofloxacin, bacterial cells were grown in Muller Hinton (MH) media and succinate minimal media (SMM) to induce iran acquisition systems and the intracellular ofloxacin concentrations were assayed in the presence of iron. The addition of iron to the media decreased the MICs of cells whether they were grown in MH or SMM. Siderophores, carbonyl cyanide m-chlorophenylhydrazone (an inhibiter of proton motive force), and ouabain (an inhibitor of ATPase) did not decrease the effect of iron. Results suggested that the increase in the intracellular ofloxacin concentration by iron is accomplished not by decreasing the efflux but by increasing the of ofloxacin permeability.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.161-165
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• 2003

Ornithobacterium rhinotracheale (OR) is a recently described gram-negative rod-shaped bacterium associated with respiratory tract infection in poultry. In order to investigate current occurrence of OR infection and to evaluate antibiotic susceptibility, the prevalence of OR antibody in domestic chickens were examined and the minimal inhibitory concentrations(MICs) of 8 antibiotics for 11 OR isolates was determined. All isolates tested were mostly susceptible to three antibiotics, ampicillin (MICs ranging from 0.38 ${\mu}g$/ml to 2 ${\mu}g$/ml), tetracycline (MICs 0.094～3 ${\mu}g$/ml) and doxycycline (MICs 0.047～4 ${\mu}g$/ml) but resistant to genatmicin. Ciprofloxacin, norfloxacin, enrofloxacin, and ofloxacin gave most isolates inhibition only in case of a higher concentration (MICs ranged in most cases from 3 ${\mu}g$/ml to 48 ${\mu}g$/ml). Out of 188 chicken flocks including broilers, broiler breeders, and layers, seropositive flock to OR were detected in 5 broilers (4%), 17 broiler breeders (50%), and 16 layers (55.2%), using commercial OR enzyme-linked immunosorbent assay(ELISA) kits. It suggested that OR infection was widespreaded in poultry farms in Korea.

• International Journal of Oral Biology
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• v.42 no.3
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• pp.123-128
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• 2017

Recurrent aphthous stomatitis (RAS) is a common oral mucosal disorder for which no curative treatment is available. We previously reported that decreased Streptococcus salivarius and increased Acinetobacter johnsonii on the oral mucosa are associated with RAS risk. The purpose of this study was to identify antibiotics that selectively inhibit A. johnsonii but minimally inhibit oral mucosal commensals. S. salivarius KCTC 5512, S. salivarius KCTC 3960, A. johnsonii KCTC 12405, Rothia mucilaginosa KCTC 19862, and Veillonella dispar KCOM 1864 were subjected to antibiotic susceptibility test using amoxicillin, cefotaxime, gentamicin, clindamycin, and metronidazole in liquid culture. The minimal inhibitory concentration (MIC) was defined as the concentration that inhibits 90% of growth. Only gentamicin presented a higher MIC for A. johnsonii than MICs for S. salivarius and several oral mucosal commensals. Interestingly, the growth of S. salivarius increased 10~200% in the presence of sub-MIC concentrations of gentamicin, which was independent of development of resistance to gentamicin. In conclusion, gentamicin may be useful to restore RAS-associated imbalance in oral microbiota by selectively inhibiting the growth of A. johnsonii but enhancing the growth of S. salivarius.

• Mycobiology
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• v.29 no.1
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• pp.11-14
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• 2001

A preparation of water soluble components(EA) was made from carpophores of Elfvingia applanata(Pers.) Karst and its in vitro antibacterial activity on a number of bacterial species was examined by macrobroth dilution assay. Among 16 species of bacteria tested, the most potent antibacterial activity was observed against Staphylococcus epiderrnidis and Proteus vulgaris, of which MICs were 1.25 mg/ml. To investigate the antibacterial effects in combinations of EA with quinolone antibiotics, such as ciprofloxacin, enoxacin, lomefloxacin, norfloxacin, and ofloxacin, the fractional inhibitory concentrations(FICs) and the fractional inhibitory concentration indices(FICIs) for four bacterial strains were determined by macrobroth dilution checkerboard assay. Combinations of EA and quinolones exhibited either additive or indifferent effects of antibacterial activity in most instances. However, both synergistic and antagonistic effects were not observed in any cases.

• Korean Journal of Plant Resources
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• v.29 no.6
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• pp.699-703
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• 2016

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical and an urgent problem worldwide. Few new drugs are available against MRSA, because MRSA has the ability to acquire resistance to most antibiotics, which consequently increases the cost of medication. In the present study, the antibacterial activity of Hydnocarpi Semen was investigated. The most effective method is to develop antibiotics from the natural products without having any toxic or side effects. Therefore, there is a need to develop alternative antibacterial drugs for the treatment of infectious diseases. Five Clinical isolates (MRSA) were obtained from five different patients at Wonkwang University Hospital (Iksan, South Korea). The Other 2 strains were ATCC 33591 (Methicillin-resistant strain) and ATCC 25923 (Methicillin-susceptible strain). Antibacterial activity (Minimal Inhibitory Concentrations, MICs) was determined by broth dilution method, disk diffusion method, MTT test, and checkerboard dilution test. Antibacterial activity of n-hexane fraction was remarkable, and had a MICs ranging from $31.25-125{\mu}g/m{\ell}$. FICI values for HFH+AM and HFH+OX were 0.13-0.19 and 0.04-0.29, showing the increase of synergistic effect. When combined together, these antibacterial effects were dramatically increased.

• Natural Product Sciences
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• v.13 no.4
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• pp.342-346
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• 2007

The antimicrobial activity of the essential oil from Pelargonium graveolens and its effects when it was combined with current antibiotics against antibiotic-resistant strains of Streptococcus pneumoniae were evaluated. The minimal inhibitory concentrations (MICs) of the essential oil fraction and the main components of this plant were determined for two antibiotic-susceptible and two antibiotic-resistant strains of S. pneumoniae using broth microdilution tests. The combined effects of the oil with erythromycin, norfloxacin, or oxacillin were evaluated using a checkerboard microtitre assay. The combination of the oil fraction of P. graveolens, or its main component, together with the antibiotics tested significantly lowered the MICs of the antibiotics against all of the tested strains with fraction inhibiting concentration indices (FICs) ranging from 0.16 to 1.50. In particular, the activity of norfloxacin against all of the tested strains of S. pneumoniae was enhanced significantly by combination with citronellol. In conclusion, the combination of P. graveolens oil with antibiotics could be used to reduce the effective dose of antibiotic and to modulate the resistance of S. pneumoniae strains.