• 한국축산식품학회지
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• 제32권1호
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• pp.91-97
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• 2012

식중독균의 항생제 내성은 주요 식품 안전 이슈로, 적절한 안전관리 옵션을 도출하기 위해서는 항생제 내성균의 노출평가가 필수적이다. 이에 식품섭취에 의한 항생제 내성균의 인체노출 정도를 평가하고자 확률노출모델을 이용하여 돈육식품 중 항생제 내성 S. aureus 및 생성 독소의 식이노출을 추정하였다. 시판 돈육 제품에서 S. aureus를 분리하고 주요 항생제에 대한 내성율을 분석한 결과 124개 시료에서 분리된 30주의 S. aureus는 penicillin과 ampicillin에 대해 각각 76.7%와 70.0%의 내성을 보였다. Oxacillin 내성은 6.7%였으며 vancomycin에 대해서는 내성을 나타내지 않았다. 가장 내성율이 높은 penicillin 내성 S. aureus를 대상으로 원료 중 오염도, 항생제 내성율, 작업지침 준수여부 등 변수를 이용한 집단급식 조리 돈육 불고기 섭취에 대한 확률노출평가 모델을 시뮬레이션한 결과, 조리 전 또는 서빙 전 단계에서 돈육 중 내성균의 추정 오염도는 평균 0.3 Log CFU/g이며, 보수적인 접근인 95% percentile값의 경우도 penicillin 내성 S. aureus의 알려진 독소 생성 수준보다 낮았다. 이 결과는 현재 주어진 조건에서 돈육조리식품 섭취에 의한 항생제 내성 S. aureus의 인체노출가능성이 낮으며 돈육조리식품 섭취에 의하여 penicillin 내성 S. aureus이 생성하는 독소에 노출될 가능성은 매우 낮음을 시사한다. 그러나 원료의 오염도, 조리 중 온도, 시간관리가 준수되지 않을 경우 식중독이 발생할 가능성은 증가할 수 있으므로 작업지침 등을 준수해야 할 것이다.

• 대한치과보철학회지
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• 제41권2호
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• pp.207-222
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• 2003

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex ; tissue stimulation, skin allergy, hypersensitivity cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Niresistance in oral microorganisms. The present study was undertaken to check whether use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral environment. Bacteria were isolated from the gingival crevicular fluid on the patients wearing Ni-Cr prosthesis. The isolated bacteria were tested fir their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several biochemical, molecular-biological tests. Performed tests were : measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy prosthesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergoviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistance to several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin, However, all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggests that there is no homology between the previously known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA of Enterococcus faecalis.

• 대한본초학회지
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• 제30권5호
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• pp.15-21
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• 2015

Objectives : Methicillin-resistantStaphylococcus aureus(MRSA) is a human pathogen. New antibacterial agents are needed to treat MRSA-related infections. This study investigated the antibacterial activity of EtOH 70% extracts ofTonghyeonipal-dan(THD) which prescription is composed of oriental medicine against MRSA.Methods : The antibacterial activity of THD was evaluated against MRSA strains by using the Disc diffusion method, broth microdilution method, Checkerboard dilution test, and Time-kill test; its mechanism of action was investigated by bacteriolysis, detergent or ATPase inhibitors were used.Results : The minimum inhibitory concentration (MIC) of THD is 1,000~2,000 μg/mL against MRSA. In the checkerboard dilution test, fractional inhibitory concentration index (FICI) of THD in combination with antibiotics indicated synergy or partial synergism againstS. aureus. Furthermore, a time-kill assay showed that the growth of the tasted bacteria was considerably inhibited after 24 h of treatment with the combination of THD with selected antibiotics. For measurement of cell membrane permeability, THD 500 μg/mL along with concentration of Triton X-100 (TX) and Tris-(hydroxymethyl) aminomethane (TRIS) were used. In the other hand, N,N-dicyclohexylcarbodimide (DCCD) and Sodium azide (NaN3) were used as an inhibitor of ATPase. TX, TRIS, DCCD and NaN3 cooperation againstS. aureusshowed synergistic action.Conclusions : Accordingly, antimicrobial activity of THD was affected by cell membrane and inhibitor of ATPase were assessed. These results suggest that THD has antibacterial activity, and that THD extract offers great potential as a natural antibiotic against MRSA.

• 대한한방부인과학회지
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• 제19권4호
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• pp.33-46
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• 2006

Purpose : This study was conducted to investigate effects of 7 herbs among medicinals resolving dampness with aroma on vaginal microorganisms. Methods : Staphylococcus aureus, Methicillin- resistant Staphylococcus aureus, Candida albicans and Gardnerella vaginalis were used for vaginal pathogenic microorganisms. Lactobacillus gasseri, Streptococcus spp. and Escherichia coli HB101 were used for vaginal flora. Medicinals resolving dampness with aroma, Pogostemonis Herba, Amomi Cardamomi Fructus, Amomi Semen, Atractylodis Rhizoma, Ammomi Tsao-ko Fructus, Alpiniae Katsumadaii Semen and Magnoliae Cortex were used in this study. In vitro antimicrobial activities were observed by optical density and colony test. Results : The optical density showed that Alpiniae Katsumadaii Semen and Magnoliae Cortex among medicinals resolving dampness with aroma had antimicrobial effects on pathogenic vaginal microorganisms (Methicillin-resistant Staphylococcus aureus). Pogostemonis Herba, Ammomi Tsao-ko Fructus had antimicrobial effects on Gardnerella vaginalis. The colony test showed that Alpiniae Katsumadaii Semen, Magnoliae Cortex among medicinals resolving dampness with aroma had antimicrobial effects on Methicillin-resistant Staphylococcus aureus. Pogostemonis Herbs, Alpiniae Katsumadaii Semen had antimicrobial effects aganist Gardnerella vaginalis. The optical density showed that Magnoliae Cortex among medicinals resolving dampness with aroma had antimicrobial effect on normal vaginal microorganisms (Streptococcus spp.). The colony test showed that medicinals resolving dampness with aroma had no antimicrobial effect on normal vaginal microorganisms. Conclusion : From this study, we could suggest that Pogostemonis Herba, Ammomi Tsao-ko Fructus, Alpiniae Katsumadaii Semen, Magnoliae Cortex of medicinals resolving dampness with aroma are available to antimicrobial agent of pathogenic vaginal microorganisms in vitro.

• 한국축산식품학회지
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• 제38권5호
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• pp.1064-1079
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• 2018

In this study, the antimicrobial activity of a bacteriocin produced by Enterococcus faecalis KT11, isolated from traditional Kargı Tulum cheese, was determined, and bacteriocin KT11 was partially characterized. The results showed that bacteriocin KT11 was antagonistically effective against various Gram-positive and Gram-negative test bacteria, including vancomycin- and/or methicillin-resistant bacteria. The activity of bacteriocin KT11 was completely abolished after treatment with proteolytic enzymes (proteinase K, ${\alpha}$-chymotrypsin, protease and trypsin), which demonstrates the proteinaceous nature of this bacteriocin. Additionally, bacteriocin KT11 remained stable at pH values ranging from 2 to 11 and after autoclaving at $121^{\circ}C$ for 30 min. In addition, the activity of bacteriocin KT11 was stable after treatment with several surfactants (EDTA, SDS, Triton X-100, Tween 80 and urea) and organic solvents (chloroform, propanol, methanol, ethyl alcohol, acetone, hexane and ethyl ether). Cell-free supernatant of E. faecalis KT11 was subjected to ammonium sulfate precipitation and then desalted by using a 3.5-kDa cut-off dialysis membrane. The bacteriocin activity was determined to be 711 AU/mL in the dialysate. After tricine-SDS-PAGE analysis, one peptide band, which had a molecular weight of ~3.5 kDa, exhibited antimicrobial activity. Because the bacteriocin KT11, isolated from E. faecalis KT11, exhibits a broad antimicrobial spectrum, heat stability and stability over a wide pH range, this bacteriocin can be used as a potential bio-preservative in foods. Additionally, bacteriocin KT11 alone or in combination with conventional antibiotics may provide a therapeutic option for the treatment of multidrug-resistant clinical pathogens after further in vivo studies.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.798-802
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• 2010

Recently, a total of 74 Staphylococcus pseudintermedius isolates were collected from clinical cases of canine pyoderma and otitis externa in Korea. In this study, we examined in vitro fluoroquinolone resistance among those isolates using a standard disc diffusion technique. The results demonstrated that, except for one isolate, approximately 18.9% to 27.0% of the isolates possessed bacterial resistance to both veterinary- and human-licensed fluoroquinolones including moxifloxacin (18.9% resistance), levofloxacin (20.3% resistance), ofloxacin (24.3% resistance), ciprofloxacin (25.7% resistance), and enrofloxacin (27.0% resistance). Most surprisingly, 14 out of 74 (18.9%) isolates were resistant to all the five fluoroquinolones evaluated. Moreover, a PCR detection of the methicillin resistance gene (mecA) among the 74 isolates revealed that 13 out of 25 (52.0%) mecApositive isolates, but only 7 out of 49 (14.3%) mecA-negative isolates, were resistant to one or more fluoroquinones. Taken together, our results imply that bacterial resistance to both veterinary- and human-use fluoroquinolones becomes prevalent among the S. pseudintermedius isolates from canine pyoderma and otitis externa in Korea, as well as that the high prevalence of the mecA-positive S. pseudintermedius isolates carrying multiple fluoroquinolones resistance could be a potential public health problem.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.226-236
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• 2020

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21^st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 ㎍/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 ㎍/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 ㎍ of AgNPs/ml, the pigment production was reduced by about 15-100%, respectively.

• 한국식품위생안전성학회지
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• 제22권4호
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• pp.294-299
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• 2007

서울시 가락동 수산물 도매시장에서 시판되는 건포류 164건에 대해 API strep kit를 사용하여 87주의 균주들을 분리하였고 이 가운데 28주에서 E. faecalis, and E. faecium가, 11주에서 Lactococcus lactis ssp. lactis가 분리되었다. 28주의 E. faecalis와 E. faecium에서는 내성을 나타내는 항생제들이 streptomycin(95.6%), kanamycin(84.5%), gentamycin(66.7%), cephaloxin(97.8%), ampicillin/sulbactam(88.9%), ticarcillin(66.7%), amikacin(97.8%), sulfonamides(97.8%), ceftriaxone(75.6%), nalidixic acid(100.0%), 그리고 cefoxitin(100.0%) 등이었고, 감수성을 나타내는 항생제들은 amoxicillin/clavulanic acid(97.8%), chloramphenicol(95.6%), solfamethoxazole/trimethoprim(97.8%), 그리고 tetracycline(71.1%)등으로 나타났다. 또한, 이 가운데 가장 많은 다제내성 형태로는 10 균주의 E. faecalis에서 나타난 $S-K-GM-CF-SAM-TIC-An-S_3-CRO-NA-FOX$에 대한 것이었다. 결국, 건포류에서 분리한 E. faecalis 균주에서 항생제 다제내성이 분포함으로 나타나 probiotics로 사용되고 있는 이러한 균에 대한 항생제 내성의 결과가 의의가 있다고 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권9호
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• pp.1336-1342
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• 2005

The present research work was conducted to evaluate the beneficial effects as well as the safety aspects of lactobacilli as probiotic. Lactobacilli were isolated from poultry faecal samples, feed samples and from some known preparations procured from poultry feed manufacturers. L. acidophilus and L. sporogenes were tested for the antibacterial activity against four poultry pathogens viz. Escherichia coli, Salmonella spp., Proteus spp. and Pseudomonas aeruginosa. Cell free supernatant (CFS) of L. acidophilus exhibited significantly higher antibacterial activity against Salmonella spp. at original pH (4.50${\pm}$0.02). At the adjusted pH (6.50${\pm}$0.02) significantly higher antibacterial activity was recorded against indicator organism except for P. aeruginosa. Likewise, L. sporogenes exhibited similar antibacterial activity at original as well as adjusted pH except for E. coli. Antibacterial activity against E. coli was significantly higher at adjusted pH than at original pH of CFS. The competitive exclusion of E. coli by lactobacilli over the intestinal epithelial cells (IEC) was checked. L. acidophilus strain I, which was of poultry origin, exhibited maximum attachment over IEC as compared to other three strains of non-poultry origin viz. L. acidophilus strain II, L. sporogenes strain I and II. Overall, L. acidophilus exhibited higher competitive exclusion as compared to L. sporogenes. All the lactobacilli of poultry origin were most sensitive to penicillin G, amoxycillin, ampicillin and chloramphenicol, least sensitive to sulphamethizole, ciprofloxacin, neomycin, norfloxacin and pefloxacin and resistant to metronidazole and nalidixic acid. The isolates from probiotic preparations were most sensitive to ampicillin, amoxycillin and tetracycline, least sensitive to sulphamethizole, norfloxacin, neomycin and ceftriazone and resistant to nalidixic acid and metronidazole. Eight of the multiple drug resistant lactobacilli isolates were studied for the presence of plasmids. Plasmids could be extracted from six isolates of lactobacilli. These plasmids could be responsible for bacteriocin production or for antibiotic resistance of the strains. The lactobacilli need further studies regarding their safety for use in the probiotic preparations.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2100-2105
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• 2015

Probiotic bacteria must have not only tolerance against bile salt but also no genes for antibiotic resistance. Leuconostoc citreum is a dominant lactic acid bacterium in various fermented foods, but it is not regarded as a probiotic because it lacks bile salt resistance. Therefore, we aimed to construct a bile salt-resistant L. citreum strain by transforming it with a bile salt hydrolase gene (bsh). We obtained the 1,001 bp bsh gene from the chromosomal DNA of Lactobacillus plantarum and subcloned it into the pCB4170 vector under a constitutive P710 promoter. The resulting vector, pCB4170BSH was transformed into L. citreum CB2567 by electroporation, and bile salt-resistant transformants were selected. Upon incubation with glycodeoxycholic acid sodium salt (GDCA), the L. citreum transformants grew and formed colonies, successfully transcribed the bsh gene, and expressed the BSH enzyme. The recombinant strain grew in up to 0.3% (w/v) GDCA, conditions unsuitable for the host strain. In in vitro digestion conditions of 10 mM bile salt, the transformant was over 67.6% viable, whereas only 0.8% of the host strain survived.