• 한국축산식품학회지
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• 제36권4호
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• pp.547-557
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• 2016

This review discusses the status, antimicrobial mechanisms, application, and regulation of natural preservatives in livestock food systems. Conventional preservatives are synthetic chemical substances including nitrates/nitrites, sulfites, sodium benzoate, propyl gallate, and potassium sorbate. The use of artificial preservatives is being reconsidered because of concerns relating to headache, allergies, and cancer. As the demand for biopreservation in food systems has increased, new natural antimicrobial compounds of various origins are being developed, including plant-derived products (polyphenolics, essential oils, plant antimicrobial peptides (pAMPs)), animal-derived products (lysozymes, lactoperoxidase, lactoferrin, ovotransferrin, antimicrobial peptide (AMP), chitosan and others), and microbial metabolites (nisin, natamycin, pullulan, ε-polylysine, organic acid, and others). These natural preservatives act by inhibiting microbial cell walls/membranes, DNA/RNA replication and transcription, protein synthesis, and metabolism. Natural preservatives have been recognized for their safety; however, these substances can influence color, smell, and toxicity in large amounts while being effective as a food preservative. Therefore, to evaluate the safety and toxicity of natural preservatives, various trials including combinations of other substances or different food preservation systems, and capsulation have been performed. Natamycin and nisin are currently the only natural preservatives being regulated, and other natural preservatives will have to be legally regulated before their widespread use.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.858-864
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• 2007

This study investigated the antibacterial activities of sophoraflavanone G from Sophora flavescens in combination with two antimicrobial agents against oral bacteria. The combined effect of sophoraflavanone G and the antimicrobial agents was evaluated using the checkerboard method to obtain a fractional inhibitory concentration(FIC) index. The sophoraflavanone G+ampicillin(AM) combination was found to have a synergistic effect against S. mutans, S. sanguinis, S. sobrinus, S. gordonii, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis, whereas the sophoraflavanone G+gentamicin(GM) combination had a synergistic effect against S. sanguinis, S. criceti, S. anginosus, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis. Neither combination exhibited any antagonistic interactions(FIC index>4). In particular, the MICs/MBCs for all the bacteria were reduced to one-half$\sim$one-sixteenth as a result of the drug combinations. A synergistic interaction was also confirmed by time-kill studies for nine bacteria where the checkerboard suggested synergy. Thus, a strong bactericidal effect was exerted through the drug combinations, plus in vitro data suggested that sophoraflavanone G combined with other antibiotics may be microbiologically beneficial rather than antagonistic.

• 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.

• Journal of Animal Science and Technology
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• 제62권4호
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• pp.543-552
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• 2020

For efficient prevention and treatment of enteric colibacillosis, understanding about latest virulence factors and antimicrobial resistance of Escherichia coli is essentially needed. The aim of this study was to survey antimicrobial resistance and determine the prevalence of fimbriae and enterotoxin genes among 118 pathogenic E. coli isolates obtained from Korean pigs with diarrhea between 2016 and 2017. The genes for the toxins and adhesins were amplified by polymerase chain reaction (PCR). The susceptibility of the E. coli isolates to antimicrobials were tested using the standard Kirby-Bauer disk diffusion method. The most prevalent fimbrial antigen was F18 (40.7%), followed by F4 (16.9%), and the most prevalent combinations of toxin genes were Stx2e (21.2%), STb:EAST-1 (19.5%), and STa:STb (16.9%), respectively. Among the pathotypes, enterotoxigenic E. coli (ETEC) was the most predominant (67.8%), followed by Shiga-toxin producing E. coli (STEC, 23.7%). We confirmed high resistance rates to chloramphenicol (88.1%), tetracycline (86.4%), streptomycin (86.4%), and ampicillin (86.4%). And the majorities of isolates (90.7%) showed multi-drug resistance which means having resistance to 3 or more subclasses of antimicrobials. Results of this study can be a source of valuable data for investigating the epidemiology of and control measures for enteric colibacillosis in Korean piggeries.

• 대한치과의사협회지
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• 제52권7호
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• pp.425-431
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• 2014

Objectives : The purpose of our study was to evaluate penicillin as a still drug of choice for severe endodontic infection, by analyzing the antimicrobial susceptibilities from endodontic infections with swelling to figure out appropriate antibiotics as empirical treatment. Materials and methods : This study involved 18 patients who attended for emergency treatment because of facial or periapical swelling associated with root canal infections. Identification and antimicrobial susceptibility test of each pathogen were performed by Vitek2 Systems (bioM$\acute{e}$rieux, Marcy l'Etoile, France). Results : The most frequent bacteria was Streptococcus spp.(77%), and the resistance against penicillin was 35% in overall patients, followed by clindamycin and erythromycin (17%), which was much higher than previous studies. Conclusions : In our study, the higher resistance made penicillin alone not to be chosen as the first antibiotic drug for severe endodontic infections. Combinations with other drug, penicillin with wider spectrum of activity, or changing to other antibiotics was considered while remembering the increased risk of resistant microorganism.

• 한국자원식물학회지
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• 제31권6호
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• pp.719-724
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• 2018

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for a number of infections in humans that are difficult to treat, and as a result, is a substantial contributor to morbidity and mortality. In the present study, in search of natural products capable of inhibiting this multidrug-resistant bacterium, we investigated the antimicrobial activity of Lysimachia clethroides Duby root. The antibacterial activities of EtOH extract of Lysimachia clethroides Duby root and its n-hexane, EtOAc, n-BuOH and water fractions were evaluated against 15 strains of methicillin-resistant staphylococcus aureus (MRSA) and 1 standard methicillin-susceptible S. aureus (MSSA) strain by using the minimal inhibitory concentrations (MICs) assay, colorimetric assay using MTT test, checkerboard dilution test. Antimicrobial activity of n-hexane fraction of Lysimachia clethroides Duby root was remarkable. Against the 16 strains, the minimum inhibitory concentrations (MICs) were in the range of $31.25-62.5{\mu}g/ml$ and FICI values for n-hexane fraction of Lysimachia clethroides Duby root+AM and n-hexane fraction of Lysimachia clethroides Duby root+OX were checkerboard method performed using the MRSA, MSSA and one clinical isolate strains via MICI 0.12-1 and 0.25-0.75, showing the increase of synergistic effect. When combined together, these antibiotic effects were dramatically increased. These effective combinations could be new promising agents in the management of MRSA.

• 대한화장품학회지
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• 제33권1호
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• pp.47-52
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• 2007

[ $C_{8-12}$ ]의 medium-chain free fatty acid 및 1-monoglyceride의 다양한 미생물에 대한 항균력은 잘 알려져 있다. Lipid의 항균력에 대해 발표된 연구는 추로 사람이나 가축에 감염을 일으키는 병원성 세균 및 바이러스에 대한 항균력에 초점을 맞춰 왔으며, 실제로 화장품에 문제가 되는 미생물에 대한 체계적인 항균력 조사는 전무한 실정이다. 우선, 본 연구에서는 $C_{12}$ (glyceryl laurate)에 비해 $C_8$ (glyceryl caprylate) 사슬 길이를 가지는 1-monoglyceride의 화장품 제형 내 방부력을 조사해 보았다. 그 결과, $C_8}$ 및 $C_{12}$의 chain length를 가지는 1-monoglyceride 모두 세균에 대한 방부력은 매우 우수한 반면, 진균에 대한 방부력이 취약함을 확인하였다. 또한, $C_{12}$에 비해 $C_8$의 사슬 길이를 가지는 glyceryl caprylate는 항균력이 약간 우수하였다. 이 후 화장품 방부력 시험에 사용되는 5종의 미생물 각각에 대한 glyceryl caprylate의 항균력을 알아보기 위한 시험 결과, 그람양성균인 S. aureus와 이스트인 C. albicans에 대한 항균력이 매우 우수하게 나타났으며, 그람음성균인 E coli, P. aeruginosa 순으로 우수한 항균력을 나타내었다. 하지만, 곰팡이인 A. niger에 대해서는 다른 균에 비해 매우 취약한 항균력을 나타내었다. 따라서 본 연구에서는 glyceryl caprylate의 화장품 방부제로서의 적용을 위해 A. niger와 같은 곰팡이에 대한 항균력을 높고자 하였으며, 그 결과 glyceryl caprylate의 A. niger에 대한 항균력이 산성 조건에서 현저히 증가하는 것으로 나타났다. 또한, 7종의 다른 antimicrobial agent와의 병용을 통한 최적의 조합을 찾고자 실험한 결과, methylparaben과 조합했을 때 진균에 대한 항균력이 가장 좋아지는 것을 확인하였다.

• Food Science and Biotechnology
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• 제14권6호
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• pp.847-853
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• 2005

A total of 60 growth curves were generated with combinations of temperature, pH, and potassium lactate (PL) (60% (v/v) commercial solution) to determine the lag time (LT) and specific growth rate (SGR) of L. monocytogenes in broth. LT and SGR were significantly (P<0.05) affected by temperature, pH, concentration of PL, or the combined interaction of these factors. LT was extended and SGR was reduced significantly (P<0.05) by increased concentration of PL at lower temperature and pH. Listericidal effect was observed in the broth containing 2, 3, and 4% PL at pH 5.0 and $4^{\circ}C$. The antimicrobial activity of PL against L. monocytogenes increased when the pH of the medium was decreased at all temperatures tested. The results suggest that PL has antimicrobial properties to suppress the growth of L. monocytogenes. Potassium lactate has many potential applications as an antimicrobial additive in variety of refrigerated ready-to-eat foods.

• 한국어병학회지
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• 제13권1호
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• pp.45-51
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• 2000

최근 육상의 넙치 양식장에서는 두 가지의 서로 다른 특성을 가지는 세균성질병이 같이 감염되는 혼합감염증이 빈번하게 발생하고 있는데, 혼합감염증은 서로 다른 원인균의 특성 때문에 단일 종류의 약제만으로는 치료효과를 거두기가 어려운 실정이다. 그러므로 본 연구는 약제의 병용 투여에 의해 이들의 상승작용을 이용함으로써 합병증에 대한 치료효과를 높이기 위한 기초자료를 얻고자 실시하였다. 어류 세균성질병의 원인세균인 Vibrio anguillarum, Edwardsiella tarda, Streptococcus sp., Staphylococcus epidermidis을 선정하여 병용 항균제의 시험관내 활성을 평가하는 대표적 방법인 Checkerboard법을 적용하여 fractional inhibitory concentration (FIC)지수를 구하여 상승효과를 나타내는 병용 항균제를 찾아내었다. (OTC+LM), (TC+FF), (OTC+FF)의 병용 항균제는 V. anguillarum에 대하여, (SNF+FF), (TC+FF), (SNF+OXA), (OTC+FF)의 병용 항균제는 E. tarda에 대하여, (CFX+OL), (OTC+OL), (TC+OL), (OTC+LM), (OTC+SPM), (OTC+EM), (DOXY+OL), (TC+SPM)의 병용 항균제는 Streptococcus sp.에 대하여, (CFX+EM), (FF+EM), (DOXY+OL), (CFX+OL)의 병용 항균제는 S. epidermidis에 대하여 시험관내 상승적 상호작용을 나타내었다.

• Natural Product Sciences
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• 제17권2호
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• pp.160-164
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• 2011

The purpose of this investigation was to extract the bioactive agents from Alpinia officinarum Hance. The methanol with ethylacetate extracts alone and combined were examined for their activities against VRE (vancomycin-resistant enterococci) and pathogenic yeast in vitro. The incidence of infections caused by VRE and other pathogenic microorganisms and the importance of using novel synergistic drug combinations has become important. Previously, we reported the antimicrobial effects of the butanol extract from Lonicera japonica and have evaluated combinations of solvent extracts, with a focus on the MeOH and EtOAc extracts from A. officinarum. In the present study, enhanced inhibitory effects were achieved by employing a combination of the two solvent extracts. The MeOH and EtOAc combination was especially effective against four VRE strains: E. faecalis (K-10-22), E. faecaium (K-11-212), E. faecalis (K-10-57) and E. faecalis (K-10-361) with MIC values of 12.5, 12.5, 6.25 and 25 ${\mu}g/ml$, respectively. Thus, the combination was more effective than other antibiotics such as kanamycin, gentamicin or tetracycline against bacteria including E. coli, Staphylococcus aureus, and Micrococcus luteus. In addition, the combination was effective against yeasts such as Candida albicans, Candida tropicalis and Cryptococcus neoformans.