• 대한임상검사과학회지
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• 제38권3호
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• pp.166-172
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• 2006

Metallo-${\beta}$-lactamase (MBL) can hydrolyze all ${\beta}$-lactams except monobactams and frequently coexists with various antibiotic resistance genes such as aminoglycoside resistance, sulfonamide resistance gene, etc. Therefore, the effective antibiotics against infections by these bacteria are markedly limited or can't even be found. We tried to search in-vitro antimicrobial combinations with synergistic effects for a VIM-2 type MBL producing Pseudomonas aeruginosa, isolated from clinical specimen. On the selection of antibiotic combinations with synergistic effects, we performed a one disk synergy test, modified Pestel's method, in agar without aztreonam (AZT). The bacteriostatic synergistic effects of this tests were scored as $S_1$ (by susceptibility pattern in agar without antibiotics), $S_2$ (by the change of susceptibility in agar with or without antibiotics) and $S_3$ ($S_1$ + $S_2$) and was classified into weak (1 point), moderate (2 points) and strong (3 points) by $S_3$ score. Subsequently, we carried out the time-killing curve for the antibiotic combinations with the strong synergistic bacteriostatic effect. One VIM-2 type MBL producing P. aeruginosa confirmed by the PCR showed all resistance against all ${\beta}$-lactams except AZT, aminoglycoside and ciprofloxacin. In the one disk synergy test, this isolate showed a strong bacteriostatic synergistic effect for the antibiotic combination of AZT and piperacillin-tazobactam (PIP-TZP) or AZT and amikacin (AN). On the time-killing curve after six hours of incubation, the colony forming units (CFUs/mL) of this bacteria in the medium broth with both combination antibiotics were decreased to 1/18.7, 1/17.1 of the least CFUs of each single antibiotics. The triple antibiotic combination therapy including AZT, PIP-TZP and AN was shown to be significantly synergistic after 8 hrs of exposure. In a VIM-2 MBL producing P. aeruginosa with susceptibility for AZT, the triple antibiotic combination therapy including AZT, PIP-TZP and AN may be considered as an alternative antibiotics modality against the infection by some MBL type. But the antimicrobial combination therapy for many more MBL producing isolates is essential to know as soon as possible for the selection of effective treatment against the infection by this bacteria.

• Preventive Nutrition and Food Science
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• 제9권4호
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• pp.306-311
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• 2004

This study was performed to investigate the antimicrobial effects of Portulaca oleracea extracts against food-borne pathogens. First, the Portulaca oleracea was extracted with methanol at room temperature, and then further fractionated by using petroleum ether, chloroform, ethyl acetate and methanol, respectively. The antimicrobial activity of the Portulaca oleracea extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Portulaca oleracea showed the highest antimicrobial activity against Staphylococcus aureus and Shigella dysenteriae. There was also a synergistic effect of the combined extracts of Portulaca oleracea and Indigofera kirilowii as compared to each extract alone. Finally, the growth inhibition curve of ethyl acetate extracts of Portulaca oleracea against Staph­ylococcus aureus and Shigella dysenteriae was determined The ethyl acetate extract of Portulaca oleracea showed strong antimicrobial activity against Staphylococcus aureus at the concentration of 4,000 ppm. The 4,000 ppm of ethyl acetate extract from Portulaca oleracea, retarded the growth of S. aureus by more than 24 hand Shigella dysenteriae up to 12 h at $37^{\circ}C$.

• Food Science and Biotechnology
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• 제18권5호
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• pp.1263-1272
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• 2009

Danshen (Salvia miltiorrhiza Bunge) is a traditional Korean medicine that is commonly used for the treatment of inflammatory diseases such as edema, arthritis, hepatitis, and endangitis. The several extracts of danshen were tested for antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) isolated in clinic by broth microdilution method, the checkerboard, and time-kill methods to evaluate the synergistic effects of the combination of the extracts with antibiotics. The chloroform ($CHCl_3$) and n-hexane (HEX) extracts [minimum inhibitory concentration (MIC), 0.0078-0.3125${\mu}g/mL$; minimum bactericidal concentration (MBC), 0.019-0.625${\mu}g/mL$] were found to have strong antibacterial activity against MRSA. Additionally, when the $CHCl_3$ and HEX extracts were co-administered with ampicillin or oxacillin, a synergistic effect against MRSA was observed. Furthermore, a time-kill study evaluating the effects of the extracts against MRSA indicated that treatment with the $CHCl_3$ extract in combination with ampicillin or oxacillin produced rapid bactericidal activity. These results suggest that danshen extracts may have potently antimicrobial activity and thus, it can be a suitable phytotherapeutic agent for treating MRSA infections.

• 한국수산과학회지
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• 제41권3호
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• pp.188-192
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• 2008

Methyl gallate isolated from bark of the tree Rhus verniciflua Stokes has significant antimicrobial activity against the fish pathogenic bacteria Edwardsiella tarda and Vibrio anguillarum. To evaluate the antimicrobial activity of gallate derivatives, eight alkyl gallates were tested. Ethyl gallate and propyl gallate had the highest activities, with MICs of $15.6-31.3{\mu}g/mL$ against E. tarda. For V. anguillarum, propyl gallate and butyl gallate were highly effective, with MICs of $7.81-31.3{\mu}g/mL$. When used in combination with antibiotics, methyl gallate exhibited synergistic effects with oxytetracycline against E. tarda and with norfloxacin against V. anguillarum. These results suggest that short-chain alkyl gallates can be used as alternatives to antibiotics against the fish pathogenic bacteria.

• Natural Product Sciences
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• 제26권4호
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• pp.317-325
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• 2020

A new dimer stilbene [Monalittorin (1)] and ten known compounds [engeletin (2), aurantiamide acetate (3), lupeol (4), friedelin (5), quercetin (6), tiliroside (7), rutoside (8), astragalin (9), isoquercitrin (10) and quercimeritroside (11)] have been isolated from the leaves of Monanthotaxis littoralis (Annonaceae). The structures of these compounds were established by interpretation of their data, mainly, HR-TOFESIMS, 1-D NMR (1H and 13C) and 2-D NMR (1H-1H COSY, HSQC, HMBC and NOESY) and by comparison with the literature. The evaluation of their antimicrobial activities against three bacteria (Staphylococcus aureus ATCC 25923, Escherichia coli S2 (1) and Pseudomonas aeruginosa PA01) and three fungal strains (Candida albicans ATCC10231, Candida tropicalis PK233 and Cryptococcus neoformans H99) using broth micro dilution method, showed the largest antimicrobial activities of EtOAc fraction and compounds 1, 5, 6, 8 and 11 (MIC = 8 - 64 ㎍/mL). In addition, EtOAc fraction presented synergistic effect with Vancomycin and fluconazole against the tested microorganisms.

• Food Science and Biotechnology
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• 제15권2호
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• pp.321-323
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• 2006

A combination of thymol and sodium bisulfate was found to be an effective biocidal agent against strains of Burkholderia cepacia and of Xanthomonas maltophilia that were found in the space shuttle water system. Potassium iodide (KI), the biocidal agent used in the past, had a minimum inhibitory concentration (MIC) of 50,000 ppm against the two B. cepacia (541 STS-81 and 1119 STS-91) strains, whereas that of thymol and sodium bisulfate was 2,400 and 950 ppm, which was 21 and 53 times lower than that of KI for B. cepacia, respectively. The MIC value for the combination of thymol and sodium bisulfate was 4 times lower than that for thymol or sodium bisulfate alone against B. cepacia (541 STS-81, 1119 STS-91) or Pseudomonas cepacia (ATCC 31941). The fractional inhibitory concentration (FIC) of the combination of thymol and sodium bisulfate for all organisms tested was less than 0.5, indicating a strong synergistic effect.

• Journal of Nutrition and Health
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• 제37권8호
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• pp.655-661
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• 2004

This study was performed to investigate the antimicrobial effect of the Pulsatilla koreana extracts against food-borne pathogens. First, the Pulsatilla koreana was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Pulsatilla koreana was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Pulsatilla koreana extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Pulsatilla koreana showed the highest antimicrobial activity against Staphylococcus aureus, Salmonella enteritidis and Shigella dysenteriae. The Staphylococcus aureus and Shigella dysenteriae were inhibited by petroleum ether and chloroform extracts of Pulsatilla koreana as well as ethyl acetate extracts of Pulsatilla koreana. The synergistic effect has been found in combined extracts of Pulsatilla koreana and Portulaca oleracea as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Pulsatilla koreana against Staphylococcus aureus and Shigella dysenteriae. The ethyl acetate extract of Pulsatilla koreana showed strong antimicrobial activity against Staphylococcus aureus at the concentration of 2,000 ppm. The 2,000 ppm of ethyl acetate extract from Pulsatilla koreana retarded the growth of S. aureus more than 12 hours and Shigella dysenteriae up to 9 hours.

• 동아시아식생활학회지
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• 제15권2호
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• pp.182-187
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• 2005

This study was performed to investigate the antimicrobial effect of the Viscum album var. coloratum extracts against food-borne pathogens. First, the Viscum album var. coloratum was extracted with methanol at room temperature and the fractionation of the methanol extracts was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol, respectively. The antimicrobial activity of the Viscum album var. coloratum extracts was determined by using a paper disc method against food-borne pathogens and food spoilage bacteria. The petroleum ether extracts of Viscum album var. coloratum showed the highest antimicrobial activity against Bacillus cereus and Shigella dysenteriae. Synergistic effect in inhibition was observed when Viscum album var. coloratum extract was mixed with Perillae folium extract as compared with each extract alone. Finally, the growth inhibition curves were determined by using petroleum ether extracts of Viscum album var. coloratum against Bacillus cereus and Shigella dysenteriae. The petroleum ether extract of Viscum album var. coloratum had strong antimicrobial activity against Bacillus cereus at the concentration of 5,000 ppm. At this concentration, the growth of Bacillus cereus was retarded more than 24 hours and up to 12 hours for Shigella dysenteriae. In conclusion, the petroleum ether extracts of Viscum album var. coloratum inhibit efficiently Bacillus cereus and Shigella dysenteriae.

• 한국미생물·생명공학회지
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• 제52권1호
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• pp.24-36
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• 2024

This study determines the combinatorial effect of enterocin MSW5 and five essential oils (EOs- Thymus vulgaris, Cymbopogon martini, Origanum vulgare, Cinnamomum zeylanicum, and Cymbopogon citrus) against Staphylococcus aureus, Listeria monocytogenes, and Salmonella Typhimurium. The Minimum Inhibitory Concentration of each antimicrobial agent was determined. The MIC of enterocin MSW5 against test pathogens was in the following order: S. aureus (0.362 ± 0.01), S. Typhimurium (0.362 ± 0.05 mg/ml), L. monocytogenes (0.725 ± 0.08 mg/ml). Among all EOs, maximum activity was observed in the case of C. zeylanicum against S. aureus (78.12 ± 0.04 ppm), S. Typhimurium (78.12 ± 0.08 ppm), and L. monocytogenes (39.00 ± 0.05 ppm). Further, the checkerboard assay was used to determine the synergistic effect between antimicrobial agents and enterocin MSW5 in combination with C. zeylanicum has shown significant synergism with the Fraction Inhibitory Concentration index (0.372) against test pathogens. Additionally, individual EOs and enterocin MSW5 have shown anti-biofilm activity, whereas their combined use has shown more significant antibiofilm activity. The maximum anti-biofilm activity was observed with the combination of enterocin MSW5 and O. vulgares against S. aureus (92.86 ± 0.06%) and S. Typhimurium (73.63 ± 0.23%) and a combination of enterocin MSW5 and C. citrus against L. monocytogenes (87.84 ± 0.15%). Therefore, combinations of antimicrobial compounds can control the growth of foodborne pathogens better than the individual agent.

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.730-739
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• 2022

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of de novo development of new antibiotics. Thymol is a key component of the essential oil of plants in the Thymus and Origanum genera. Despite the absence of antimicrobial potency, thymol is known to inhibit MRSA biofilm formation. However, the anti-MRSA activity of thymol analogs is not well characterized. Here, we assessed the antimicrobial activity of several thymol derivatives and found that 4-chloro-2-isopropyl-5-methylphenol (chlorothymol) has antimicrobial activity against MRSA and in addition it also prevents biofilm formation. Chlorothymol inhibited staphyloxanthin production, slowed MRSA motility, and altered bacterial cell density and size. This compound also showed a synergistic antimicrobial activity with oxacillin against highly resistant S. aureus clinical isolates and biofilms associated with these isolates. Our results demonstrate that chlorinated thymol derivatives should be considered as a new lead compound in anti-MRSA therapeutics.