• Clean Technology
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• v.29 no.2
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• pp.135-144
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• 2023

Pseudomonas aeruginosa and Staphylococcus aureus are the two most frequently encountered pathogens responsible for chronic wound infections, often coexisting in such cases. These infections exhibit heightened virulence compared to single infections, leading to unfavorable patient outcomes. The interaction among microorganisms within polymicrobial infections has been shown to exacerbate disease progression. Polymicrobial infections, prevalent in various contexts such as the respiratory tract, wounds, and diabetic foot, typically involve diverse microorganisms, with Pseudomonas aeruginosa and Staphylococcus aureus being the most commonly identified pathogens. This study aimed to compare the growth patterns of bacteria under a concentration gradient of toxic chemicals, focusing on a Gram-negative strain of Pseudomonas aeruginosa and a Gram-positive strain of Staphylococcus aureus. The minimum inhibitory concentration (MIC), which signifies the concentration at which bacterial growth is inhibited, was determined by performing broth microdilution and assessing the bacteria's growth curves. The growth curves of both Pseudomonas aeruginosa and Staphylococcus aureus were confirmed, and the exponential growth phases were applied to calculate the doubling times of bacteria. The MIC value for each toxic chemical was determined through broth microdilution. These results allowed for the identification of disparities in growth rates between Gram-positive and Gram-negative bacteria, as well as differences in resistance to individual toxic substances. We expect that this approach has a strong potential for further development towards the innovative treatment of bacteria-associated infections.

• Korean Journal of Veterinary Service
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• v.36 no.4
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• pp.297-301
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• 2013

The present study was to investigate anti-microbial effects of curcumin on major bacterial pathogens for farmed fish, such as Aeromonas hydrophila, A. salmonicida subsp. masoucida, A. salmonicida subsp. salmonicida, Edwardsiella tarda, Vibrio vulnificus, V. paraheamolyticus using disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. In disc diffusion test, curcumin exhibited concentration-dependent antimicrobial activities to all bacteria pathogens used in the study. Antimicrobial effects of curcumin was found differently depending on bacterial species when determined by MIC or MBC tests. For examples, E. tarda and A. hydrophila was respectively the most sensitive bacterium for bacteriostatic and bacteriocidal effect of curcumin. Collectively, curcumin could be a potential natural drug for controlling pathogenic bacteria in the aquaculture industry.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.564-568
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• 2007

In this study, the ethanolic extracts of 40 species of traditional herbal medicines were examined for their antimicrobial activities against Clostridium difficile. Among the 43 screened traditional herbal medicines, Achyranthes Japonica Nakai (AJN), Siegesbeckia glabrescens Makino, and Phelloedendron amurense Ruprecht showed antimicrobial activities greater than 90% at a concentration of 500 ppm. According to the minimum inhibitory concentration (MIC) test the ethyl acetate soluble fraction of the AJN ethanolic extracts (AJNEA) showed the highest growth inhibitory activity against C. difficile, with a MIC of $625{\mu}g/mL$. In addition, the effect of AJNEA on the growth of lactic acid bacteria was investigated. AJNEA did not inhibit the growth of the tested Bifidobacterium spp. or Lactobacillus spp., with the exception of B. longum, Streptococcus thermophilus, and L. helveticus. These results indicate that AJNEA can be utilized as a potential antimicrobial agent against C. difficile related disease.

• Journal of Pharmacopuncture
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• v.22 no.1
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• pp.49-54
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• 2019

Objective: Antibiotic resistance is a global health problem and threatens health of societies. These problems have led to a search for alternative approaches such as combination therapy. The aim of the present study was to investigate the effect of caffeine and omeprazole in combination with gentamicin or ciprofloxacin against standard and clinically resistant isolates of Staphylococcus aureus and Escherichia coli. Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of different agents against bacterial strains were determined. The interaction of non- antibiotic drugs with gentamicin and ciprofloxacin was studied in vitro using a checkerboard method and calculating fraction inhibitory concentration index (FICI). Verapamil as efflux pump inhibitor was used to evaluate the possible mechanism of bacterial resistance to antibiotics. Results: The MIC and MBC values of gentamicin against bacterial strains were in the range of $20-80{\mu}g/ml$ and $40-200{\mu}g/ml$, respectively. Caffeine and omeprazole had no intrinsic inhibitory activity against tested microorganisms. However, upon combination of caffeine with antibiotics, the synergistic effects were observed. Verapamil was able to reduce the MIC values of gentamicin (4 folds) only in some bacterial strains. Conclusion: These findings indicated that caffeine was effective in removing bacterial infection caused by S. aureus and E. coli. The relevant mechanisms of antibiotic resistance were not related to the drug efflux.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.872-881
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• 2012

The inhibitory effect of the Klebsiella pneumoniae ATCC 13883 strain caused by the hexane extract of Halimeda discoidea (Nor Afifah et al., 2010) was further evaluated by means of the microscopy view and its growth curves. The morphological changes of the K. pneumoniae ATCC 13883 cells were observed under the scanning electron microscope (SEM) and transmission electron microscope (TEM) after they were treated at minimum inhibitory concentration (MIC; 0.50 mg/ml) (Nor Afifah et al., 2010) for 12, 24, and 36 h. The results showed the severity of the morphological deteriorations experienced by the treated cells. The killing curve assay was performed for 48 h at three different extract concentrations (1/2 MIC, MIC, and 2 MIC). An increase in the extract concentration of up to 2 MIC value did significantly reduce the number of cells by approximately 1.9 $log_{10}$, as compared with the control. Identification of the potential compounds of the extract responsible for the antibacterial activity was carried out through the gas chromatography-mass spectrum (GC-MS) analysis of the active subfraction, and the compound E-15-heptadecenal was identified and suggested as the most potential antibacterial compound of this extract. The subsequent cellular degenerations showed by the data might well explain the inhibitory mechanisms of the suggested antibacterial compound. All of these inhibitory effects have further proven the presence of an antibacterial compound within H. discoidea that can inhibit the growth of K. pneumoniae ATCC 13883.

• Journal of fish pathology
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• v.35 no.1
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• pp.47-56
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• 2022

Lincomycin as one of the lincosamides antibiotics have been mainly used in human and livestock fields, but have not been used in aquaculture. In this study, the distribution of minimum inhibitory concentration (MIC) values against lincomycin and the detection of the macrolide-lincosamide-streptogramin (MLS) resistance gene were confirmed in bacterial pathogens isolated from cultured olive flounder (Paralichthys olivaceus). Of the 107 strains isolated from Jeju, 36 strains of Gram-positive bacteria and 71 strains of Gram-negative bacteria were identified. Most of Streptococcus spp. was found to have a MIC value of less than or equal to 0.5 ㎍/mL, and Edwardsiella piscicida was found to have a MIC value higher than 1,024 ㎍/mL. V. harveyi and V. alginolyticus mostly showed MIC values of 256 ㎍/mL, but V. scophthalmi displayed values of 8~64 ㎍/mL. In the detection of MLS resistance gene, erm(B) was detected in 9 strains of Streptococcus spp., and erm(A) was confirmed in one strain.

• YAKHAK HOEJI
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• v.43 no.2
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• pp.221-227
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• 1999

The fungistatic and fungicidal activities of amphotericin B, fluconazole, miconazole, econazole, and 5-fluorocytosine against Saccharomyces cerevisiae were estimated in the presence of 1/2 minimum inhibitory concentration (MIC) and 1/2 minimum fungicidal concentration (MFC) of polygodial, respectively. Among them, the antifungal activities of miconazoles by polygodial was still shown against several yeast-like fungi including Candida albicans, Candida utilis, Cryptococcus neoformans, except for Candida krusei. The combination of polygodial with imidazole drugs against Saccharomyces cerevisiae was further examined using the macrobroth dilution checkerboard method. The fractional inhibitory concentration (FIC) and the fractional fungicidal concentration (FFC) index between polygodial and miconazole were 0.16 and 0.19, while the combination of polygodial with econazole exhibited the FIC index of 0.19 and the FFC of 0.25, respectively. These results suggest that polygodial and the imidazoles on the fungistatic and fungicidal action are highly synergistic.

• YAKHAK HOEJI
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• v.43 no.2
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• pp.228-232
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• 1999

The combination effect of anethole with amphotericin B, fluconazole, miconazole, or 5-fluorocytosine was investigated against Saccharomyces cerevisiae. When combined with $\frac{1}{2}$ minimum inhibitory concentration (MIC) or $\frac{1}{2}$ minimum fungicidal concentration (MFC) of anethole, the antifungal activities of fluconazole and 5-fluorocytosine were not changed, but the fungistatic and the fungicidal activities of miconazole were increased 64-fold, respectively. In the case of amphotericin B, the fungistatic activity was increased 2-fold, while the fungicidal activity was decreased 2-fold. The combination effect of anethole with miconazole or amphotericin B was also investigated at the various concentrations using the macrobroth dilution checkerboard method. The fractional inhibitory concentration (FIC) and the fractional fungicidal concentration (FFC) index between B exhibited the FIC index of 8.25 and the FFC of 32.06, respectively. Thus, it is analyzed that the combination of anethole with miconazole or amphotericin B on the antifungal action shows synergism and antagonism, respectively.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.1006-1009
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• 2002

The biological activities of farnesoic acid derivatives against pathogenic fungi and bacteria were investigated. Farnesoic acid and its derivatives showed growth inhibitory activities against various bacteria. Among the compounds tested, geranylgeranoic acid (3) had potent antibacterial activity against Salmonella typhimurium, Proteus vulgaris, and Bacillus subtilis with minimum inhibitory concentration (MIC) in the range of $6.25-12.5{\mu}g/ml$. On the other hand, amide derivatives of farnesoic acid showed some antifungal activities. In particular, 3,7,11-trimethyl-dodeca-2,6,10-trienoic acid amide (5a) had a potent antifungal activity against Aspergillus niger, Candida albicans, and Trichophyton sp. with MIC in the range of $6.25-12.5{\mu}g/ml$.

• Food Science and Biotechnology
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• v.15 no.2
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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.