• 치위생과학회지
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• 제15권4호
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• pp.383-392
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• 2015

치과치료를 위해 다양한 용도로 DCU에서 배출되는 물이 사용된다. 이 DCU 물의 질에 관한 계속되는 논란으로 인한 환자들의 불안감을 줄이고 양질의 치과 치료를 제공하기 위해서는 DCU 물이 음용수만큼 깨끗하게 유지되어야 한다. 따라서 본 논문은 DCU 물의 세균 오염 수준과 오염된 DCU 물의 임상적 위험성에 대하여 설명하고, 세균 오염을 방지하기 위한 여러 가지 관리 방법들을 검토하였다. 여러 국가에서 DCU 물을 대상으로 오염도를 확인하는 연구가 많이 진행되어 DCU 물이 높은 수준으로 오염되어있다는 것이 입증되었다. 오염된 DCU 물로 인해 감염된 일부 사례도 보고되었고 이는 DCU 물이 감염의 잠재적인 원인일 수 있음을 보여주었다. DCU 물로 인한 잠재적 감염의 위험성을 줄이기 위해서는 효율적인 소독방법을 사용하고 자체적인 모니터링 또한 시행되어야 한다. 하지만 제안되고 있는 여러 가지 수관관리 소독방법으로 인해 치과종사자들의 혼란이 야기되고 있으며, 효율적인 소독방법을 보편화하기 위해서는 관련 연구가 더 진행되어야 할 것으로 생각된다. 치과치료를 받는 환자들을 안심시킬 수 있는 좋은 치과서비스를 제공하기 위해서는 정책적인 개선과 국내 치과 상황에 맞는 수관 관리 지침이 빠른 시일 내에 시행되어야 할 것으로 생각된다.

• 한국동물위생학회지
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• 제21권4호
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• pp.413-429
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• 1998

Escherichia coli is recovered from a wide variety of infections in many animals species. It may be a primary or secondary agent. Nursing and young animals are particularly susceptible, and urinary tract infections are frequent. The various serotypes of E coli are intestinal inhabitants of animals including humans and probably infect most mammals and birds : therefore, they have a cosmopolitan distribution. Colibacillosis refers to any totalized or systemic infection caused entirely or partly by E coli. Collibacillosis in mammals is most often a primary enteric disease, whereas collibacillosis in poultry is typically a secondary located or systemic disease occurring when host defenses have been impaired or overwhelmed. Other opportunistic bacteria, which can be identified by culture, may play a similar role to that of I coli in secondary infections. Collectively, infections caused by E coli are responsible for significant economic losses to the animal performance. From the standpoint of pathogenic mechanisms and diseases, four major categories of E coli are recognized : enterotoxigenic(ETEC), enteropathogenic (EPEC), enteroinvasive(EIEC), and enterohemorrhagic(EHEC). In addition, two less-well-defined E coli categories are recognized in animals and humans : enteroaggregative and cytotoxin necrotizing factor-positive. The aforementioned categories are represented by different serotypes. Certain serotypes show a host preference and are encountered more frequently in some disease syndromes. Of the four major categories, ETEC is the most common cause of diarrhea in calves, lambs, and pigs. Strains in the other categories cause the less-common diarrhea and other disease syndromes. Enterotoxins and pilus antigens are the two most prominent virulence factors thus far identified for ETEC. Two enterotoxins, one heat-stable(ST) and one heat-labile(LT), are produced by enterotoxigenic strains of E coli : not all culture produce both of these plasmid-based enterotoxins.

• Mycobiology
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• 제41권3호
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• pp.145-148
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• 2013

Vegetative growth signaling of the opportunistic human pathogenic fungus Aspergillus fumigatus is mediated by GpaA ($G{\alpha}$). FlbA is a regulator of G protein signaling, which attenuates GpaA-mediated growth signaling in this fungus. The flbA deletion (${\Delta}flbA$) and the constitutively active GpaA ($GpaA^{Q204L}$) mutants exhibit enhanced proliferation, precocious autolysis, and reduced asexual sporulation. In this study, we demonstrate that both mutants also show enhanced tolerance against $H_2O_2$ and their radial growth was approximately 1.6 fold higher than that of wild type (WT) in medium with 10 mM $H_2O_2$. We performed quantitative PCR (qRT-PCR) for examination of mRNA levels of three catalase encoding genes (catA, cat1, and cat2) in WT and the two mutants. According to the results, while levels of spore-specific catA mRNA were comparable among the three strains, cat1 and cat2 mRNA levels were significantly higher in the two mutants than in WT. In particular, the ${\Delta}flbA$ mutant showed significantly enhanced and prolonged expression of cat1 and precocious expression of cat2. In accordance with this result, activity of the Cat1 protein in the ${\Delta}flbA$ mutant was higher than that of $gpaA^{Q204L}$ and WT strains. For activity of the Cat2 protein, both mutants began to show enhanced activity at 48 and 72 hr of growth compared to WT. These results lead to the conclusion that GpaA activates expression and activity of cat1 and cat2, whereas FlbA plays an antagonistic role in control of catalases, leading to balanced responses to neutralizing the toxicity of reactive oxygen species.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.579-585
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• 2013

Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus, SEZ) is an important pathogen associated with opportunistic infections of a wide range of species, including pigs and humans. The absence of a suitable vaccine makes it difficult to control SEZ infection. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been previously identified as an immunogenic protein using immunoproteomic techniques. In the present study, we confirmed that the sequence of GAPDH was highly conserved with other Streptococcus spp. The purified recombinant GAPDH could elicit a significant humoral antibody response in mice and confer significant protection against challenge with a lethal dose of SEZ. GAPDH could adhere to the Hep-2 cells, confirmed by flow cytometry, and inhibit adherence of SEZ to Hep-2 cells in an adherence inhibition assay. In addition, real-time PCR demonstrated that GAPDH was induced in vivo following infection of mice with SEZ. These suggest that GAPDH could play an important role in the pathogenesis of SEZ infection and could be a target for vaccination against SEZ.

• Tuberculosis and Respiratory Diseases
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• 제45권1호
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• pp.213-221
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• 1998

Pulmonary mucormycosis is an uncommon, but important opportunistic fungal infection associated with diabetes mellitus, leukemia, lymphoma and other immunocompromised states. Mucor species grow best in acidic-high glucose medium. which explaining the particular susceptibility of diabetic patient who are ketoacidic. Early consideration of this diagnosis, along with aggressive diagnostic evaluation, is critical to effective therapy and patient survival. We have experienced a case of pulmonary murcomycosis mimicking bilateral pulmonary edema on chest Xray that associated with diabetic ketoacidosis. A brief review of the literature was given.

• Tuberculosis and Respiratory Diseases
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• 제64권5호
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• pp.387-391
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• 2008

폐트리코모나스증은 인체에 기생하는 3가지 종류의 편모충류(구강편모충, 질편모충, 장세포편모충)에 의해 유발되는 매우 드문 기회 감염성 질환으로 대부분 만성 폐질환이나 화농성 또는 괴사성 폐질환을 앓고 있는 환자 및 면역저하를 동반하는 전신질환을 앓고 있는 사람에서 흡입 또는 직접 전파에 의해 발생된다. 일반적으로 질편모충을 제외한 구강 및 장세포편모충은 병원성이 없는 것으로 고려되어 치료가 필요하지 않지만, 정상적으로 분포하지 않는 장기에서 기회감염을 일으키는 경우 적극적인 치료가 고려되어야 한다. 저자들은 폐 및 전신적인 기저 질환이 없는 무증상의 건강한 남성에서 우연히 발견된 흉부 방사선 검사상 이상 소견에 대해 폐트리코모나스증을 진단하여 항균제 치료로 호전된 드문 예를 경험하여 보고하는 바이다.

• 한국식품과학회지
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• 제54권3호
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• pp.343-350
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• 2022

밀누룩과 탁주의 미생물 군집을 NGS로 분석하여 탁주의 이상 발효 원인을 규명하였다. 우점도가 높은 미생물은 알코올 발효 이후 변화하여, 누룩에서는 Aspergillus 속 곰팡이와 Staphylococcus 속 세균이 우세하였고, 탁주에서는 Saccharomyces 속 효모와 Pediococcus, Bacillus, Lactobacillus, Enterobacter 속 세균이 우세하였다. 특이적으로 본 연구에서 분석된 누룩과 탁주 시료는 유산균의 함량이 상대적으로 낮았다. 이러한 미생물학적 환경에서 Bacillus 속과 Enterobacter 속이 기회 감염균인 Bacillus wiedmannii와 Enterobacter cloacae로 확인되었고, B. wiedmannii와 E. cloacae는 각각 유기산의 농도가 급격히 감소한 밑술 발효 3일과 원료가 첨가된 덧술 발효 1일에서부터 점차적으로 증가하였다. 이를 통해 탁주의 미생물은 누룩을 포함한 원료 및 발효 조건에 영향을 받으며, 유산균의 부재가 탁주에서 E. cloacae와 B. wiedmannii의 이상 증식에 영향을 주었다고 보여진다. 결론적으로 NGS를 통한 미생물 군집 분석은 누룩과 탁주의 미생물 구성과 발효 특성을 포괄적으로 이해하는데 도움을 주며, 더 나아가 전통누룩의 발효 조건 개선 및 고품질 전통주 생산에 활용할 수 있을 것으로 기대한다.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1234-1244
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• 2022

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1609-1616
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• 2024

The Burkholderia cepacia complex (Bcc) consists of opportunistic pathogens known to cause pneumonia in immunocompromised individuals, especially those with cystic fibrosis. Treating Bcc pneumonia is challenging due to the pathogens' high multidrug resistance. Therefore, inhalation therapy with tobramycin powder, which can achieve high antibiotic concentrations in the lungs, is a promising treatment option. In this study, we investigated potential mechanisms that could compromise the effectiveness of tobramycin therapy. By selecting for B. cenocepacia survivors against tobramycin, we identified three spontaneous mutations that disrupt a gene encoding a key enzyme in the biosynthesis of cobalamin (Vitamin B₁₂). This disruption may affect the production of succinyl-CoA by methylmalonyl-CoA mutase, which requires adenosylcobalamin as a cofactor. The depletion of cellular succinyl-CoA may impact the tricarboxylic acid (TCA) cycle, which becomes metabolically overloaded upon exposure to tobramycin. Consequently, the mutants exhibited significantly reduced reactive oxygen species (ROS) production. Both the wild-type and mutants showed tolerance to tobramycin and various other bactericidal antibiotics under microaerobic conditions. This suggests that compromised ROS-mediated killing, due to the impacted TCA cycle, underlies the mutants' tolerance to bactericidal antibiotics. The importance of ROS-mediated killing and the potential emergence of mutants that evade it through the depletion of cobalamin (Vitamin B₁₂) provide valuable insights for developing strategies to enhance antibiotic treatments of Bcc pneumonia.

• Parasites, Hosts and Diseases
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• 제28권1호
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• pp.31-38
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• 1990

실험용 마우스(ICR)에 프레드니솔론을 주어 인공적으로 면역억제시키면서 Cryptosporidium 발현 여부를 7주 동안 관찰한 바 다음과 같은 결과를 얻었다. 면역 억제 1주 후부터 마우스 대변에서 Cryptosporidium의 Oocyst (크기 440 ㎛)가 검출되었고 2주 후부터 마우스가 사망하기 시작하였다. 대변에서 oocyst가 검출된 마우스의 소장 절편을 H&E 염색하여 광학현미경으로 관찰한 결과 Cryptosporisium은 공장 하부에서 호발하였으며 장 융모의 점막 상피세포 표면에 점같이 붙은 모습으로 무수히 발견되었고 호염기성이었으며 크기는 직경 2∼4 ㎛정도 되었다. 이들의 여러 발육 단계에 대해 주사 전자현미경 및 투과 전자현미경으로 입체구조를 관찰하였으며 그 결과 충체의 종은 C. Parvum으로 동정하였다. 항균제(tetracycline, trimethoprim-sulfamethoxazole)를 면역억제제와 함께 투여한 실험군에서도 Cryptosporidium이 발현되었으나 면역 억제제만을 투여한 실험군의 마우스보다 수명을 다소 연장시킬 수 있었다. 이 실험 결과 우리 나라에도 Cryptosporidium(C. Parvum)이 존재하고 있음을 확인하였으며 인체 감염례가 있을 가능성을 짐작할 수 있었다.