• 한국임상수의학회지
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• 제21권2호
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• pp.129-132
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• 2004

Causative agents of mastitis were isolated from glandular tissues of 101 culled Holstein cow udders and tested with antimicrobials by standardized disc diffusion method. Pathogens most commonly isolated were coagulase-negative staphylococci (43.9%) and streptococci (21.4%). Most of the udders (88.5%) showed mixed infections with more than two species of bacteria. Antimicrobial sensitivity tests revealed that 90.0% and 84.5% of the isolated organisms were susceptible to amoxicillin and gentamicin, while most organisms were resistant to erythromycin. Coliforms were resistant to ampicillin, cephalothin, cefazolin, erythromycin, kanamycin, neomycin, penicillin and tetracycline and streptococci to erythromycin, kanamycin, neomycin, trimethoprim/sulfamethoxazole and tetracycline.

• Pediatric Infection and Vaccine
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• 제18권1호
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• pp.15-22
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• 2011

Invasive Candida infections (ICI) have become the third most common cause of late-onset infection among premature infants in the neonatal intensive care unit (NICU). Risk factors include birth weight less than 1,000 g, exposure to more than two antimicrobials, third generation cephalosporin exposure, parenteral nutrition including lipid emulsion, central venous catheter, and abdominal surgery. Candida colonization of the skin and gastrointestinal tract is an important first step in the pathogenesis of invasive disease. Strict infection control measures against the infection should be done in the NICU. The following practices are likely to contribute to reducing the rate of ICI: (1) restriction of broad-spectrum antibiotics, antacids and steroid; (2) introduction of early feeding and promoting breast milk. Fluconazole prophylaxis may be an effective control measure to prevent Candida colonization and infections in individual units with high incidence of fungal infection. In addition, there is a need of further data including the development of resistant strains and the effect on long-term neurodevelopmental outcomes of infants exposed to drugs before the initiation of routine application of antifungal prophylaxis in the NICU.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.429-438
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• 2017

For centuries, plants have been used for a wide variety of purposes, from treating infectious diseases to food preservation and perfume production. Presently, the increasing resistance of microorganisms to currently used antimicrobials in combination with the appearance of emerging diseases requires the urgent development of new, more effective drugs. Plants, due to the large biological and structural diversity of their components, constitute a unique and renewable source for the discovery of new antibacterial, antifungal, and antiparasitic compounds. In the present paper, the history, composition, and antimicrobial activities of the basil, oregano, and thyme essential oils are reviewed.

• International Journal of Oral Biology
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• 제40권4호
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• pp.217-221
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• 2015

Cariogenic Streptococcus mutans encounters a variety of host defense factors produced in oral cavity. Nitric oxide (NO) and NO-mediated reactive nitrogen species are potential antimicrobials of innate immunity that can threaten the fitness of S. mutans in their ecological niches. Streptococcal strategies to detoxify cytotoxic NO, which allow S. mutans to persist in caries or other environments of the oral cavity, remain unknown. In this study, we directly measured NO consumption rates of S. mutans isolated in Korea. Surprisingly, all S. mutans strains were unable to consume exogenous NO efficiently, while an intracellular parasite Salmonella enterica serovar Typhimurium expressing the NO-metabolizing enzyme flavohemoglobin consumed most of the NO. This result suggested that S. mutans has alternative detoxification systems for tolerating NO-induced nitrosative stresses.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.118-123
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• 2008

A new method for antimicrobial susceptibility testing of vitro-cultured bacteria on an ordinary fluorescence spectrometer was developed. The viable bacteria reduced 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to produce insoluble particles that displayed intense resonance scattering light. The assay showed a linear relationship between the number of viable bacteria and the intensity of resonance scattering light. Dead bacteria were unable to reduce MTT. Methicillin-resistant Staphylococcus aureus exposed to flavonoids from Marchantia convoluta showed a flavonoids concentration-dependent inhibition of the ability to reduce MTT. In the assay, less than 12 h was required to attain susceptibility results and fewer bacteria were utilized than in traditional methods. The RLS technique could, in combination with the MTT assay, be a rapid and sensitive measuring method to determine the in vitro activity of new antimicrobials.

• Animal Bioscience
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• 제36권4호
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• pp.540-554
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• 2023

Heat stress is a major challenge to animal production in tropical and subtropical climates. Rabbits suffer from heat stress more than farm animals because they have few sweat glands, and their bodies are covered with thick fur. Intensive farming relies on antibiotics as antimicrobials or growth promoters to increase animals' productivity and health. However, the European Union and many countries have banned or restricted the use of antibiotics in animal feed for human health concerns. Several studies have found that replacing antibiotics in rabbit feed with natural plants or feed additives increases productivity and improves immune capacity, especially under heat stress conditions. Growth performance, immune response, gut microflora, and carcass yield may be increased in rabbits fed a diet supplemented with some natural plants and/or propolis. In this review article, we discuss and summarize the effects of some herbs and plant extracts as alternative feed additives on rabbit productivity, especially for those raised under hot ambient temperatures.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.345-352
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• 2023

Antibacterial activity against foodborne bacteria (Bacillus cereus, Staphylococcus aureus, Salmonella Enteritidis) and inhibitory activity against murine norovirus, a human norovirus surrogate, of 28 extracts from plants endemic to Korea were investigated in this study. All plant extracts showed antibacterial activity only against gram-positive bacteria, B. cereus and S. aureus. Extracts from Callistemon speciosus and Nymphaea tetragona showed inhibition zones of 16.54 and 24.35 mm against B. cereus and S. aureus, respectively, presenting the highest antibacterial activities recorded in this study. Among all samples, Ardisia japonica extract at concentrations of 100 and 200 ㎍/mL showed the highest virucidal activities of 96.6 and 100.0%, respectively. Ardisia japonica, Duchesnea indica, Polygonum aviculare, and Geum japonicum extracts showed high antibacterial and virucidal activity simultaneously without Raw 264.7 cell cytotoxicity. These plant extracts may serve as potential antimicrobials to control foodborne infections.

• 한국식품위생안전성학회지
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• 제24권3호
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• pp.189-193
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• 2009

본 연구는 $\varepsilon$-polylysine, 키토을리고당, 복합황금추출(BMB-FS)을 조합한 10가지 혼합조성물의 효모에 대한 항균력을 평가하여 식품산업에 적용하고자 하였다. 천연항균제 10종의 formula에 따라 각 효모의 성장 속도가 차이가 났으나, 14일까지는 균수가 증가하였고 $14{\sim}28$ 일 사이에 항균효과가 나타나 28일 이후에는 S. cerevisiae, Z. bailii, P. anolmala는 검출한계 (ND < 10 CFU/mL)이하까지 감소하여 천연항균제에 민감한 반응을 보였다. P. membranaefaciens는 가장 저항성이 강한 균으로 14일까지 $0.12{\sim}1.48\;\log_{10}\;CFU$/mL가 증가하였으나, 28일이 지난 후 $1.61{\sim}3.55\;\log_{10}\;CFU$/mL가 감소하였고, F10에서는 2 개월이 지난 후 검출한계 이하로 감소하여 가장 항균효과가 크게 나타났다. 대부분 6개월이 지난 후 $2.68{\sim}s.62\;\log_{10}\;CFU$/mL가 감소한 것으로 나타났다. C. albicans는 두 번째로 저항성이 강한 균으로 14일까지 $0.13{\sim}28\;\log_{10}\;CFU$/mL가 증가하였으나 $14{\sim}28$일 사이에 감소하기 시작하여 28일 째에는 $1.51{\sim}5.30\;\log_{10}\;CFU$/mL가 감소하였고, F2, F4, F5, F6, F10은 검출한계 이하로 감소시켰다. 6개월이 지난 후에는 F1, F3, F8, F9도 검출한계 이하로 감소한 것으로 나타났다. 이에 따라 본 연구는 기능성 음료의 효모에 의한 변질을 막을 수 있는 천연 항균제 조성물을 개발하여 실용화 하고자 하였다.

• 한국식품위생안전성학회지
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• 제33권4호
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• pp.255-258
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• 2018

본 연구에서는 도축장에서 분리된 Listeria monocytogenes를 저해할 수 있는 식물성 항균 물질을 탐색하고, 각 항균 물질의 최소살균농도(MBC)를 확인하였다. 잠재적인 항균 물질로 자몽종자 추출물, 감귤류 추출물, 생강 추출물, 배 추출물, 매실 농축액, 도라지 추출물, 대추 추출물, 오미자 추출물을 선정하였고, 대상 균주로는 국내 도축장에서 분리한 15 개의 L. monocytogenes 균주를 혼합하여 사용하였다. MBC 확인 결과, 최대 $4.0{\mu}g/mL$ 농도의 생강 추출물, 배 추출물, 매실 농축액, 도라지 추출물, 대추 추출물, 오미자 추출물은 고농도의 L. monocytogenes (7 Log CFU/mL)에 대해 균 저해 효과가 전혀 나타나지 않았다. 반면, 7 Log CFU/mL의 L. monocytogenes에 대한 자몽종자 추출물과 감귤류 추출물의 MBC는 $0.002{\mu}g/mL$인 것으로 확인되었다. 3 Log CFU/mL의 L. monocytogenes에 대한 MBC를 시험해 본 결과, 자몽종자 추출물과 감귤류 추출물의 MBC는 $0.001{\mu}g/mL$로 나타났다. 이상의 결과로 볼 때 자몽종자 추출물과 감귤류 추출물은 L. monocytogenes를 제어하기 위해 적용될 수 있을 것으로 판단된다.

• 농업과학연구
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• 제42권1호
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• pp.29-35
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• 2015

This study was performed to analyze the distribution and antimicrobial resistance of pathogenic microorganisms isolated from the carcass and environments of chicken processing plant located in Gyeonggi province from October to November in 2010. Chicken slaughterhouse was visited 3 times and totally 40 samples were collected from chicken carcass before and after washing (n=14), chicken cuts (n=7), cooling water (n=8), brine (n=2), cutting knives (n=7) and working plate (n=2). Whole-chicken rinsing technique (for chicken carcasses) and swab technique (for working plate and knives) were used to analyze the distribution of pathogenic microorganisms. In addition, brine and chilling water from storage tanks were gathered using sterilized tubes and used as samples. The matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for whole cell fingerprinting in combination with a dedicated bioinformatic software tool was used to identify the isolated microorganisms. The pathogenic microorganisms, such as Bacillus cereus (n=8) and Staphylococcus aureus (n=9), were isolated form the chicken processing process (chicken carcasses of before and after chilling, chicken cuts, and working plate). The antimicrobial susceptibility of those isolated microorganisms was analyzed using 21 antimicrobial agents. In the case of B. cereus, it showed 100% of resistance to subclasses of penicillins and peptides, and it also resistant to cephalothin, a member of critically important antimicrobials (CIA), however there was no resistance (100% susceptible) to vancomycin and chloramphenicol. S. aureus showed 100% resistance to subclasses of peptides and some of penicillins (penicillin and oxacillin), however, it showed 100% susceptibility to cephalosporins (cefazolin and cephalothin). All of the tested pathogens showed multi drug resistance (MDR) more than 4 subclasses and one of B. cereus and S. aureus showed resistance to 9 subclasses. After the ban on using the antimicrobials in animal feed in July 2011, there would be some change in microbial distribution and antimicrobial resistance, and it still has a need to be analyzed.