• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.328-333
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• 1999

Susceptibility of 61 strains of Helicobacter pylori to metronidazole was examined by both the disk diffusion method using a cut-off of 15㎜ for resistance and the E test with a cut-off of 8㎎/l. The MIC/sub 50/ and MIC/sub 90/ by the E test were 2 ㎎/l and 256㎎/l, respectively. Metronidazole resistance was found in 22 (36％) out of the 61 H. pylori strains by the E test and in three additional strains by the disk diffusion method. Amongst the latter three isolates, the MICs by the E test were 4 ㎎/l, 6㎎/l, and 6㎎/l, respectively. These figures are one log₂ or half log₂ dilution lower than the cut-off of 8㎎/l recommended as resistance for the E test. All 22 metronidazole resistant H. pylori isolates by the E test that were subjected to random amplified polymorphic DNA (RAPD) fingerprinting showed different DNA fingerprints. Interestingly, >90％ of resistant isolates possess two common DNA bands of 0.4 and 0.9 kb. This study demonstrates that the results of the disk diffusion method for testing H. pylori susceptibility to metronidazole correlates well with that of the E test. The criteria for interpretation need to be internationally standardized so that the results from different centers can be compared.

• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.235-242
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• 1999

We investigated the growth-inhibitory mechanism of Helicobacter pylori by omeprazole (OMP) and its activated sulfenamide (OAS). Using dithiothreitol (DTT) and 5,5'-dithio-bis[2-nitrobenzoic acid] (DTNB; Ellman's reagent), we first determined the relationship between the binding capacity of these compounds to H. pylori membrane and its significance to membrane P-type ATPase activity. After incubation of the intact H. pylori cells with either OMP or OAS, the residual quantity of free SH-groups on the cell membrane was measured, and, the resulting values were plotted as a function of time. From this experiment, we found that there was a considerable difference in the membrane-binding rates between OMP and OAS. At neutral pH, the disulfide bond formation on H. pylori membrane was completed within 2 min of incubation of the intact cells with OAS. By OMP, however, it was gradually formed, exceeding 10 min of incubation for completion, whereby, the extent of P-type ATPase inhibition appeared to be proportional to the disulfide forming rate. From this data, it was suggested that the disulfide formation might directly affect enzyme activity. Since OMP per se cannot yield a disulfide bond with cysteine, it is predicted that the enzyme inactivation must be caused by the OAS form. Accordingly, we postulated that, under the neutral pH, OMP could be converted to OAS in the course of transport. By extrapolating the inhibitory slopes, we could evaluate K₁ values, relating to their minimal inhibitory concentrations (MICs) for H. pylori growth. In these MIC ranges, H. pylori uptake or vesicular export of nutrients such as peptides were totally prohibited, but their effect in Escherichia coli were negligible. From these observations, we strongly suggest that the P-type ATPase activity is essential for the survival of H. pylori cells in particular.

• 동의생리병리학회지
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• 제17권2호
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• pp.574-579
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• 2003

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important hospital and community pathogens. Therefore, new agents are needed to treat the MRSA. In the present study, we investigated antimicrobial activity of ethyl acetate, methanol, and water extracts of Curcuma longa L. (C. longa) aganist clinical isolates of MRSA. The ethyl acetate extract of C. long a demonstrated a higher antibacterial activity than the methanol extract or water extract. Since the ethyl acetate extract was more active than other extracts, we examined whether ethyl acetate extract may restore the antibacterial activity of β-lactams and alter the adhesion and invasion of MRSA to human mucosal fibroblasts (HMFs). In the checkerboard test, ethyl acetate extract of C. longa markedly lowered the MICs of ampicillin and oxacillin against MRSA. In the bacterial adhesion and invasion assay, MRSA intracellular invasion were notably decreased in the presence of 0.125 - 2 mg/ml of C. longa extract compared to the control group. These results suggest that ethyl acetate extract of C. longa may have antibacterial activity and the potential to restore the effectiveness of β-lactams against MRSA, and inhibit the MRSA adhesion and invasion to HMFs.

• 생명과학회지
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• 제25권1호
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• pp.29-36
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• 2015

천연의 붉은 색소인 prodigiosin은 Serratia marcescens에 의해서 생산되며 이는 pyrrolylpyrromethane 골격으로 구성되어 있다. 이 색소는 그 분자가 가진 특성 때문에 넓은 범위에서 활용되고 있다. 또한 항암제, 면역억제제, 항진균제, 살조제 등 다양한 분야의 효과가 보고되소 있다. Methicillin-resistant Staphylococcus aureus (MRSA)는 세계적으로 가장 주요한 원내 감염균으로써, 미국에서 해마다 HIV로 사망하는 수보다 더 많은 사망률을 보이고 있다. 그러므로 MRSA에 대한 새로운 치료제의 개발이 매우 중요하며 급박한 문제이다. 본 연구에서는 중증오염도를 가진 하천수로부터 Serratia sp. PDGS 120915를 분리하였으며 항 MRSA 활성을 가진 prodigiosin에 대하여 연구하였다. 본 연구를 위하여 HPLC를 이용하여 물질을 정제하였으며, 분리된 물질의 항 MRSA 활성을 확인하였다. Prodigiosin의 MRSA에 대한 최소억제농도(Minimal inhibitory concentration; MIC)는 $32{\mu}g/ml$이었으며, 분할저해농도(Fractional inhibitory concentration; FIC)는 ampicillin과 penicillin에서 상승작용이 있는 것으로 나타났다.

• 한국축산식품학회지
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• 제37권4호
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• pp.502-510
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• 2017

This study investigated bacterial growth-inhibitory effect of 69 therapeutic herbal plants extracts on 9 bacterial strains using a disc diffusion assay. Especially, the antimicrobial activity of Psoraleae semen, which showed different activity on pathogenic Gram-positive and Gram-negative bacteria, was evaluated by MIC (minimal inhibition concentration) and biofilm formation assay. The effect of Psoraleae semen extract on bacterial cell membranes was examined by measurement of protein leakage (optical density at 280 nm) and scanning electron microscope (SEM). No clear zone was formed on discs containing Gram-negative bacteria, but Gram-positive bacteria exhibited clear zones. The MICs of Psoraleae semen extract were $8{\mu}g/mL$ for Streptococcus mutans, and $16{\mu}g/mL$ for Enterococci and Staphylococcus aureus. In addition, biofilm formation was inhibited at concentration $8-16{\mu}g/mL$. Protein leakage values and SEM images revealed that cell membranes of Gram-positive bacteria were impaired following exposure to the extract. Further, the extract inhibited the growth of Listeria monocytogenes in sausages. These results indicate that Psoraleae semen extract could be utilized as a natural antimicrobial agent against Gram-positive bacteria.

• 한국동물위생학회지
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• 제40권3호
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• pp.219-225
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• 2017

This study was investigated the synergistic effects from the combination of cefalexin and gentamicin (CCG) against Staphylococcus spp. isolated from bovine milk. Minimum inhibitory concentrations (MICs) and fractional inhibitory concentration (FIC) index were determined for 16 bacteria from 13 bovine farms in Gyeongsangnam province by the National Committee for Clinical Laboratory Standards broth microdilution procedure. Antimicrobial agents tested included cefalexin, gentamicin and CCG. Against Staphylococcus spp. tested, the MIC ranges of cefalexin, gentamicin and CCG were 0.25~1.0, 0.5~0.125 and $0.06{\sim}0.125{\mu}g/mL$, respectively. In addition, the FIC index ranges of CCG against most of the isolates was 0.28~0.43 and the FIC index of CCG against 2 strains of Staphylococcus haemolyticus (S. haemolyticus) was 0.59. In conclusion, CCG has a high antibacterial activity against Staphylococcus isolates, then the combination may be applied for the treatment of bovine mastitis caused by Staphylococcus spp.

• 한국어병학회지
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• 제22권1호
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• pp.1-7
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• 2009

과산화수소의 이스라엘잉어에 대한 급성독성 시험을 실시하여 반수치사농도 ($LC_{50}$)를 구하고 기생충 제거 효과와 살균력을 조사하였다. 이스라엘잉어 (평균체중 0.44 g)는 80 $\mu\ell/\ell$에서 24시간 동안 폐사가 발생하지 않았으며 24시간 $LC_{50}$은 148.9 $\mu\ell/\ell$ 이었다. 이스라엘잉어 (평균 체중 0.1 g)에 기생된 트리코디나는 40 $\mu\ell/\ell$의 과산화수소로 1회 약욕 하였을 때 모두 제거되었다. 30종의 어병 임상균주를 사용하여 시험한 결과, 과산화수소에 대한 어병 세균의 최소억제 농도는 거의 40 $\mu\ell/\ell$보다 낮았으며 과산화수소에 의한 세균 증식 억제 효과를 확인 할 수 있었다.

• 한방안이비인후피부과학회지
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• 제17권3호
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• pp.26-32
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• 2004

Objective: The aim of this work is to investigate the antibacterial activity of the essential oil obtained from Artemisia lavandulaefolia (A. lavandulaefolia), as the development of microbial resistance to antibiotics make it essential to constantly look for new and active compounds effective against pathogenic bacteria. Method: The aerial parts of A. lavandulaefolia (1 kg) were subjected to steam distillation for 3 h, using a modified Clevenger type apparatus in order to obtain essential oil. Diethyl ether was the extracting solvent kept at 25?. The essential oil were analyzed by gas chromatography (GC) and gas chromatography／mass spectrometry (GC／MS). The essential oil and the composition were tested for antimicrobial activities against 15 different genera of oral bacteria. Ninety-nine compounds accounting for 94.74$\%$<／TEX> of the oil were identified. The main compounds in the oil were 1,8-cineole (5.63$\%$), yomogi alcohol (4.49$\%$), camphor (4.92$\%$), a-caryophyllene (16.10$\%$), trans-a-famesene (5.09$\%$), a-terpineol (3.91$\%$), borneol (5.27$\%$), cis-chrysanthenol (6.98$\%$), and a-humulene oxide (3.33$\%$). The essential oil and its compounds were tested for antimicrobial activity against 10 different genera of oral bacteria. Conclusion: The essential oil of A. lavandulaefolia exhibited considerable inhibitory effects against all obligate anaerobic bacteria (MICs, 0.025 - 0.05 ㎎／ml) tested, while their major compounds demonstrated various degrees of growth inhibition

• 한국동물위생학회지
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• 제33권1호
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• pp.59-66
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• 2010

This study was carried out to investigate the characters of Listeria monocytogenes isolated from food, animal feces, dry cattle food, and the environment in Seoul and Kyonggi province during the period from 1998 to 2003. Serotyping of 70 L. monocytogenes isolates was performed according to the manufacturer's instruction. Minimum inhibitory concentrations (MICs) were determined by the microdilution method according to the guidelines of the Clinical and Laboratory Standards Institute. All the isolates were tested against 20 antimicrobial agents. The serotypes of the 70 L. monocytogenes isolates were 1/2c (62.8%), 1/2a (20%) and 1/2b (17.2%). Of the 70 L. monocytogenes isolates, 67.1%, 57.1%, 11.4%, 5.7%, 2.8%, 1.4% and 1.4% were resistant to tetracycline (Te), minocycline (Mi), norfloxacin (Nor), ciprofloxacin (Cip), neomycin (N), chloramphenicol (C) and cephalothin (Cf), respectively. However, all isolates were 100% sensitive to antibiotics such as amikacin, ampicillin, erythromycin, gentamycin, imipenem, kanamycin, ofloxcin, streptomycin, penicillin, trimethoprim, trimethoprim/sulfamethoxazole, tobramycin, and vancomycin. Multiple resistance patterns of the isolates were observed in TeMiNor Cip (1.4%), TeMiNor (7.1%), TeMiCip (2.9%), TeMiN (1.4%) and TeMi (44.3%). The results of this study indicate that many L. monocytogenes isolates are resistant to antimicrobial agents including Te and Mi. The possibility that the isolates could increasingly acquire multiple antimicrobial resistant properties cannot be precluded.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1848-1852
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• 2008

Salmonella remains a primary cause of food poisoning worldwide, and massive outbreaks have been witnessed in recent years. Therefore, this study investigated the antimicrobial activity of methyl gallate (MG), which exhibited good antibacterial activity ($MIC=3.9-125{\mu}g/ml$) against all the bacterial strains tested. In a checkerboard dilution test, MG markedly lowered the MICs of ciprofloxacin (CPFX) against Salmonella. The combined activity of CPFX and MG against Salmonella resulted in fractional inhibitory concentrations (FICs) ranging from 0.0037 to 0.015 and from 0.24 to $7.8{\mu}g/ml$, respectively. Meanwhile, the FIC index ranged from 0.31-0.37, indicating a marked synergistic relationship between CPFX and MG against Salmonella. Time-kill assays also showed a decrease in the CFU/ml between the combination and the more active compound. Therefore, this study demonstrated that MG and CPFX can act synergistically in inhibiting Salmonella in vitro.