• International Journal of Oral Biology
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• 제41권4호
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• pp.209-215
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• 2016

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.

• 약학회지
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• 제43권1호
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• pp.131-133
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• 1999

The bactericidal activities of DW-116, a new fluoroquinolone was estimated by comparing the minimal bactericidal concentrations (MBCs) of it against some Gram-positive and -negative bacterial strains with the minimal inhibitory concentrations (MICs). The MBCs against the test organisms were equal to or two times higher than MICs. The results support that the antibacterial activity of DW-116 is bactericidal.

• 한국임상수의학회지
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• 제5권2호
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• pp.73-81
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• 1988

Combinations of EDTA-Tris and gentamicin, oxytetracycline in normal bovine milk were examined for synergistic activities aganist Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium Pyogenes, Escherichia coli, Salmonella dublin, Pseudomonas aeruginosa, and proteus spp. isolated from the milk of acute clinical bovine mastitis. The results were summarized as follows: 1. The minimal inhibitory concentrations of EDTA-Tris and gentamicin, oxytetracycline on Escherichia coli, Salmonella dublin, proteus spp., Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus agalactiae were markedly reduced. 2. The significant synergistic effects observed when the microorganisms were reacted with EDTA-Tris and gentamicin, oxytetracycline. These findings were respectively verified by kinetic studies of microbial death, using one-fourth minimal inhibitory concentrations of EDTA-Tris, gentamicin, and oxytetracycline.

• 한국임상수의학회지
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• 제23권3호
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• pp.286-290
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• 2006

To find alternative agents for bovine mastitis, the extracts of 30 selected herbal medicine were screened for their antibacterial activity against mastitis pathogens. The extracts of 9 herbal medicine, Terminaliae chebula, Cinnamonum loureirii, Paeonia japonica, Inula britannica, Caesalpinia sappan(C. sappan), Salix babylonica, Alpinia katsumadai, Polygonum aviculare and Coptidis japonica showed strong antibacterial activity. Among of them, C. sappan extract was found to be the most active against all bacteria in this experiment. Methanol extract of C. sappan and brazilin, the main component of C. sappan, had inhibitory activity against a variety of pathogens, however they had less of an inhibitory effect on gram negative bacteria. Minimal inhibitory concentrations of brazilin against gram positive pathogens was lower than that of methanol extract. These results showed that the extract of C. sappan has a potential as a therapeutic agent for bovine mastitis.

• International Journal of Oral Biology
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• 제40권4호
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• pp.189-196
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• 2015

Minimal inhibitory concentration (MIC) is the lowest antibiotic concentration that inhibits the visible growth of bacteria. Sub-minimal inhibitory concentration (Sub-MIC) is defined as the concentration of an antimicrobial agent that does not have an effect on bacterial growth but can alter bacterial biochemistry, thus reducing bacterial virulence. Many studies have confirmed that sub-MICs of antibiotics can inhibit bacterial virulence factors. However, most studies were focused on Gram-negative bacteria, while few studies on the effect of sub-MICs of antibiotics on Gram-positive bacteria. In this study, we examined the influence of sub-MICs of doxycycline, tetracycline, penicillin and amoxicillin on biofilm formation and coaggregation of Streptococcus gordonii, Streptococcus mutans, Actinomyces naeslundii, and Actinomyces odontolyticus. In this study, incubation with sub-MIC of antibiotics had no effect on the biofilm formation of S. gordonii and A. naeslundii. However, S. mutans showed increased biofilm formation after incubation with sub-MIC amoxicillin and penicillin. Also, the biofilm formation of A. odontolyticus was increased after incubating with sub-MIC penicillin. Coaggregation of A. naeslundii with S. gordonii and A. odontolyticus was diminished by sub-MIC amoxicillin. These observations indicated that sub-MICs of antibiotics could affect variable virulence properties such as biofilm formation and coaggregation in Gram-positive oral bacteria.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2008년도 제49회 학술심포지움 및 국제학술대회
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• pp.65.1-65.1
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• 2008

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2008년도 제49회 학술심포지움 및 국제학술대회
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• pp.66.1-66.1
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• 2008

• 대한한의학회지
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• 제23권3호
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• pp.223-232
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• 2002

Objectives : Methicillin-resistant Staphylococcus aureus (MRSA) CCARM 3251 and S. aureusKCTC 1928 have been known to be resistant to many kinds of antibiotics. The extract of Glycyrrhizae Radix showed antibacterial activity against MRSA and antibiotics-resistant S. aureus. Methods : We examined the effects of the water-soluble extract and the methanol-soluble extract of Glycyrrhizae Radix on MRSA and antibiotic-resistant S. aureus. The methanolic extract was further fractionated with organic solvents such as hexane, chloroform, and ethyl acetate in that order. Results and Conclusions : The methanol-soluble extract of Glycyrrhizae Radix showed relatively high antibacterial activity against MRSA and antibiotic-resistant S. aureus. However, the water-soluble extract of Glycyrrhizae Radix showed no antibacterial activity against MRSA and antibiotic-resistant S. aureus. Among the fractions tested, the chloroform fraction showed the highest antibacterial activity against MRSA and antibiotic-resistant S. aureus. The methanol-soluble extract of Glycyrrhizae Radix minimal inhibitory concentrations (MICs) against MRSA and antibiotics-resistant S. aureus were $5{\;}mg/m{\ell}$ in both. The methanol-soluble extract of Glycyrrhizae Radix was separated using thin-layer chromatography and detected with UV -detector. Further study should be carried out to identify which effects cell growth inhibition of MRSA and antibiotics-resistant S. aureus.

• 약학회지
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• 제42권6호
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• pp.639-641
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• 1998

Minimal inhibitory concentrations (MICs) of Bifidobacterium spp. strains (Bifidobacterium breve K-110, B. breve K-111 and B. infantis K-525) isolated from healthy Korean against antituberculosis agents and fluoroquinolones were determined. From the MICs it was found that Bifidobacterium breve K-110, B. breve K-111 and B. infantis K-525 were susceptible to rifampicin and fluoroquinolenes and resistant to other antituberculosis agents.

• Journal of Pharmaceutical Investigation
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• 제31권1호
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• pp.1-5
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• 2001

The aggregation behavior of nystatin (NYS) in the presence of pluronic F127, triblock copolymer of poly (ethylene oxide) (PEO) and poly (propylene oxide) (PPO), was measured and correlated with hemolytic activity. Antifungal activity was also studied using Saccharomyces cerevisiae as a model strain. The critical aggregation concentrations (CAC) of the drug were 50.1, 108.0, 134.2, 154.3, and $217.9\;{\mu}M$ at 0.1%, 0.5%, 1.0%, 1.5%, and 2.0% pluronic F127 solution, respectively. The levels of NYS required to start lysis of erythrocytes were about 80, 100, 125, 150, and $200\;{\mu}M$ at 0.1%, 0.5%, 1.0%, 1.5%, and 2.0% pluronic F127 solution, respectively. It was $50\;{\mu}M$ in the absence of the polymer. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of NYS-pluronic F127 lyophilizate were same at $3\;{\mu}g/ml$, while MIC and MFC of pure NYS are $3\;{\mu}g/ml$ and $12\;{\mu}g/ml$, respectively. By modulating the aggregation behavior of NYS, pluronic F127 was able to reduce the toxicity of the drug without compromising the MIC and MFC.