• 한국수산과학회지
• /
• 제52권6호
• /
• pp.587-595
• /
• 2019

Eighty-three Vibrio parahaemolyticus isolates from surface seawater in Gomso Bay on the west coast of Korea, and commercial fisheries from Gunsan fisheries center were analyzed for the presence of virulence genes and susceptibility to 30 different antimicrobials. All 83 isolates were examined for the presence of two virulence genes (tdh or trh) using polymerase chain reaction; however, neither gene was found in any of the isolates. A disk diffusion susceptibility test, showed that all of the strains studied were resistant to clindamycin, oxacillin, ticarcillin, and vancomycin, and also revealed varying levels of resistance to ampicillin (98.8%), penicillin G (95.2%), streptomycin (20.5%), cefoxitin (14.5%), amikacin (6.0%), cephalothin (4.8%), and erythromycin (3.6%). However, all of the strains were susceptible to 19 other antimicrobial agents, including cefepime, cefotaxime, chloramphenicol, gentamycin, nalidixic acid, sulfamethoxazole/trimethoprim, and trimethoprim. All 83 isolates (100%) were resistant to five or more classes of antimicrobials, and two strains exhibited resistance to ten antimicrobial agents. The average minimum inhibitory concentrations against V. parahaemolyticus of clindamycin, oxacillin, ticarcillin, and vancomycin were 55.9, 98.3, 499.3, and 44.3 ㎍/mL, respectively. These results provide new insight into the necessity for seawater sanitation in Gomso Bay and commercial fisheries, and provide evidence to help reduce the risk of contamination by antimicrobial-resistant bacteria.

• Mycobiology
• /
• 제38권4호
• /
• pp.328-330
• /
• 2010

In this study, we demonstrate that equol has fungicidal activities against Candida albicans. The minimum inhibitory and minimum fungicidal concentrations of equol against C. albicans were 516 and $1,032{\mu}M$, respectively. Two separate viability assays found that equol changed the integrity of the C. albicans cell membrane, possibly by formation of membrane lesions. Scanning electron microscopy demonstrated ultrastructural changes.

• 한국약용작물학회지
• /
• 제22권6호
• /
• pp.504-509
• /
• 2014

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of brazilein (BRZ) isolated from Caesalpinia sappan L. (Leguminosae) against 8 different strains of Staphylococcus aureus (S. aureus). New antimicrobial activity was found using the minimum inhibitory concentrations (MICs), broth dilution as well as checkerboard method. Against the 8 strains, the minimum inhibitory concentrations of BRZ were in the range of $62.5-500{\mu}g/mL$. From those results we performed the checkerboard test to determine the synergism of BRZ in combination with Hygromycin-b (HgB) against 4 strains. The combined activity of BRZ and HgB against 4 strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.18-0.5. The effect of BRZ with HgB was found to be synergistic. We found that BRZ reduced the MICs of HgB. BRZ and HgB could lead to the development of new combination antibiotics against MRSA infection.

• Archives of Pharmacal Research
• /
• 제28권8호
• /
• pp.897-901
• /
• 2005

The in vitro inhibitory activities of essential oils from Thymus magnus and T. quinquecostatus as well as their main constituents were evaluated against susceptible and resistant species of Streptococcus pneumoniae, Staphylococcus aureus, Salmonella enteritidis, and Salmonella typhimurium. Notably, the essential oil fraction of T. magnus and its main components displayed significant inhibitory action against both antibiotic-susceptible and resistant strains of S. pneumoniae, S. aureus, and S. typhimurium with minimum inhibitory concentrations (MICs) ranging from 0.125 to 8 mg/mL. The differential MIC values imply that the oil fraction and its main components exhibit distinct patterns of activity against the tested bacterial species. Moreover, the disk diffusion test revealed that the inhibitory activities of oil fraction and components were dose-dependent. Data from the checkerboard titer test confirmed synergism between the antibiotic, norfloxacin, and T. magnus oil or thymol, particularly against the resistant strains of S. aureus.

• 생약학회지
• /
• 제36권3호통권142호
• /
• pp.252-256
• /
• 2005

The in visto inhibitory activities of essential oils of the Rosmarinus officinalis as well as its main constituents were evaluated against antibiotic-susceptible and -resistant strains of Staphylococcus aureus, streptococcus pneumoniae, Salmonella enteritidis and S. typhimurium. The essential oil fraction of R. officinalis and its main components, 1,8-cineole and camphor, exhibited significant inhibitory activities against most of the tested strains in this study, with MICs(minimum inhibitory concentrations) racing from 0.5mg/ml to 16mg/ml. The total oil fraction showed higher activity than its main components, 1,8-cineole and camphor against S. aureus strains. No remarkable differences were evident between MICs of the susceptible and resistant strains of S. aureus. Among the tested strains, S. pneumoniae CCARM 3523, the resistant strain to norfloxacin, oxacillin and erythromycin exhibited significantly lower sensitivity to the tested oils than antibiotic-susceptible strain. The oils revealed mostly higher inhibitory activity against S. typhimurium than against S. enteritidis.

• Toxicological Research
• /
• 제27권1호
• /
• pp.31-36
• /
• 2011

The methanol extract of 12 medicinal plants were evaluated for its antibacterial activity against Gram-positive (5 strains) and Gram-negative bacteria (10 strains) by assay for minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC). The antibacterial activity was determined by an agar dilution method (according to the guidelines of Clinical and Laboratory Standard Institute). All the compounds (12 extracts) of the 8 medicinal plants (leaf or root) were active against both Gram-negative and Gram-positive bacteria. Gram-negative showed a more potent action than Gram positive bacteria. The MIC concentrations were various ranged from $0.6\;{\mu}g/ml$ to $5000\;{\mu}g/ml$. The lowest MIC ($0.6\;{\mu}g/ml$) and MBC ($1.22\;{\mu}g/ml$) values were obtained with extract on 4 and 3 of the 15 microorganisms tested, respectively.

• 약학회지
• /
• 제43권2호
• /
• pp.228-232
• /
• 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.

• 한국식품영양과학회지
• /
• 제27권2호
• /
• pp.232-238
• /
• 1998

To developed natural food preservatives, ethanol and water extracts were prepared from the defatted camellia(Camellia japonica L.) seeds. Antimicrobial activities were examined against 14 microorganisms which were food borne pathogens and/or food poisoning microorganisms and food-related bacteria and yeasts. Ethanol extract showed antimicrobial activities against several microorganisms tested, but not on lactic acid bactria. Especially, minimum inhibitory concentrations(MIC) for yeasts were as low as 1mg/ml. Water extract exhibited antimicrobial activities for the yeasts tested, but almost bacteria were not observed. The ethanol extract was fractionated in the order of hexane, chloroform, ethylaetate and butanol fractions to test antimicrobial activity. The strongest activity for the tested yeasts were found in the butanol fractions, but bacteria were chloroform fraction. Hansenula anomala treated with ethanol were observed by scanning electron micrograph, and the results exhibited morphological changes, including the irregularly contracted cell surface and expanded ellipsoidal shape.

• Journal of Veterinary Science
• /
• 제23권3호
• /
• pp.48.1-48.12
• /
• 2022

Background: The poor intracellular concentration of enrofloxacin might lead to treatment failure of cow mastitis caused by Staphylococcus aureus small colony variants (SASCVs). Objectives: In this study, enrofloxacin composite nanogels were developed to increase the intracellular therapeutic drug concentrations and enhance the efficacy of enrofloxacin against cow mastitis caused by intracellular SASCVs. Methods: Enrofloxacin composite nanogels were formulated by an electrostatic interaction between gelatin (positive charge) and sodium alginate (SA; negative charge) with the help of CaCl₂ (ionic crosslinkers) and optimized by a single factor test using the particle diameter, zeta potential (ZP), polydispersity index (PDI), loading capacity (LC), and encapsulation efficiency (EE) as indexes. The formation mechanism, structural characteristics, bioadhesion ability, cellular uptake, and the antibacterial activity of the enrofloxacin composite nanogels against intracellular SASCVs strain were studied systematically. Results: The optimized formulation was comprised of 10 mg/mL (gelatin), 5 mg/mL (SA), and 0.25 mg/mL (CaCl₂). The size, LC, EE, PDI, and ZP of the optimized enrofloxacin composite nanogels were 323.2 ± 4.3 nm, 15.4% ± 0.2%, 69.6% ± 1.3%, 0.11 ± 0.02, and -34.4 ± 0.8 mV, respectively. Transmission electron microscopy showed that the enrofloxacin composite nanogels were spherical with a smooth surface and good particle size distributions. In addition, the enrofloxacin composite nanogels could enhance the bioadhesion capacity of enrofloxacin for the SASCVs strain by adhesive studies. The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibitory concentration, and minimum biofilm eradication concentration were 2, 4, 4, and 8 ㎍/mL, respectively. The killing rate curve had a concentration-dependent bactericidal effect as increasing drug concentrations induced swifter and more radical killing effects. Conclusions: This study provides a good tendency for developing enrofloxacin composite nanogels for treating cow mastitis caused by intracellular SASCVs and other intracellular bacterial infections.

• Natural Product Sciences
• /
• 제7권4호
• /
• pp.114-119
• /
• 2001

The effect of Rhinacanthus nasutus leaf extract on the growth of dermatophytes had been investigated. In vitro the extract exhibited high activity against various species of dermatophytes (Trichophyton mentagrophytes var. mentagrophytes, T. mentagrophytes var. interdigitale, T. rubrum, Microsporum canis and M. gypseum). The minimal inhibitory concentration (MIC) values of the extract revealed that all the dermatophytes tested had MIC values of 13.6 mg/ml. The extract exhibited fungistatic activity at lower concentrations $({\leq}13.6\;mg/ml\;or\;below\;the\;MIC\;value)$ and fungicidal activity at higher concentrations $({\geq}13.6\;mg/ml$\;or\;above\;the\;MIC\;value)$. The results suggested that the extract acted on the cell wall of the dermatophytes which subsequently leading to the formation of cytopathological and membrane structural degeneration and finally leading to cell lysis and death.