• 한국식품영양학회지
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• 제33권6호
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• pp.702-709
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• 2020

The purpose of this study was to evaluate microbiological contamination of knives and cutting boards in child-care centers. Materials used in this study were swabbed of cutting boards and knives (blade, handle of knife, and joint of handle and blade) in 129 child-care centers. Mean values of total aerobic bacteria of swabs of knives and cutting boards were 1.7±0.7 log cfu/100 ㎠ and 1.7±0.9 log cfu/100 ㎠, respectively. Contamination levels of coliform bacteria from knives and cutting boards were 1.5±0.6 log cfu/100 ㎠ and 1.7±0.8 log cfu/100 ㎠, respectively. Comparing microbiological contamination levels of knives and cutting boards according to type and size of child-care centers, there was no significant difference. Bacillus cereus was detected in knife handles and cutting boards. Diarrhea-type toxin gene (entFM) was detected in B. cereus isolates. Antibiotic resistance tests showed that B. cereus was resistant to β-lactam antibiotics. To reduce microbiological contamination levels of knives and cutting boards in child-care centers and prevent food poisoning from bacteria contamination, continuous education by children's food-service management center is needed for sterilization and disinfection of knives and cutting boards.

• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.25-32
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• 2021

Inflammatory reactions activated by lipopolysaccharide (LPS) of gram-negative bacteria can lead to severe septic shock. With the recent emergence of multidrug-resistant gram-negative bacteria and a lack of efficient ways to treat resulting infections, there is a need to develop novel anti-endotoxin agents. Antimicrobial peptides have been noticed as potential therapeutic molecules for bacterial infection and as candidates for new antibiotic drugs. We previously designed the 9-meric antimicrobial peptide Pro9-3 and it showed high antimicrobial activity against gram-negative bacteria. Here, to further examine its potency as an anti-endotoxin agent, we examined the anti-endotoxin activities of Pro9-3 and elucidated its mechanism of action. We performed a dye-leakage experiment and BODIPY-TR cadaverine and limulus amebocyte lysate assays for Pro9-3 as well as its lysine-substituted analogue and their enantiomers. The results confirmed that Pro9-3 targets the bacterial membrane and the arginine residues play key roles in its antimicrobial activity. Pro9-3 showed excellent LPS-neutralizing activity and LPS-binding properties, which were superior to those of other peptides. Saturation transfer difference-nuclear magnetic resonance experiments to explore the interaction between LPS and Pro9-3 revealed that Trp3 and Tlr7 in Pro9-3 are critical for attracting Pro9-3 to the LPS in the gram-negative bacterial membrane. Moreover, the anti-septic effect of Pro9-3 in vivo was investigated using an LPS-induced endotoxemia mouse model, demonstrating its dual activities: antibacterial activity against gram-negative bacteria and immunosuppressive effect preventing LPS-induced endotoxemia. Collectively, these results confirmed the therapeutic potential of Pro9-3 against infection of gram-negative bacteria.

• 한국동물위생학회지
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• 제45권3호
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• pp.191-199
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• 2022

We investigated the virulence genes, O-serotypes, antimicrobial resistance of pathogenic E. coli isolated from carcasses (n=455) and environmental (n=372) samples of 11 cattle and 12 pig slaughterhouses from December 2020 to December 2021. E. coli were isolated from nine carcasses (2.0%), three slaughter facilities (1.4%), two utensils (2.7%) and three abattoir workers (3.5%) from four cattle and four pig slaughterhouses. Among all isolates, 13 STEC (76.5%) were identified, followed by four EPEC (23.5%). As a result of the antibiotic susceptibility test, all isolates were resistant to at least one antimicrobial, of which 70.6% isolates showed multidrug resistance patterns. The serotypes were diverse in pigs compared to cattle, with serotypes O18, O66, O109 in cattle and O9, O76, O85, O100, O153, and O159 in pigs. In a single cattle slaughterhouse, eight STEC O66 were isolated from various types of sample (4 slaughter animal surfaces, 3 gloves, and 1 knife) with two antimicrobial resistance patterns (CHL-FIS-STR and CHL-FIS). Those two types of strain were suspected cross-contamination from utensils to slaughter animal surfaces. These results showed that pathogenic E. coli were detected in carcasses and various environmental samples in cattle and pig slaughterhouses. Nationwide monitoring and hygiene management are required to prevent cross-contamination of STEC isolate slaughterhouses.

• The Korean Journal of Physiology and Pharmacology
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• 제25권4호
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• pp.321-331
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• 2021

Vancomycin, an antibiotic used occasionally as a last line of treatment for methicillin-resistant Staphylococcus aureus, is reportedly associated with nephrotoxicity. This study aimed at evaluating the protective effects of lutein against vancomycin-induced acute renal injury. Peroxisome proliferator-activated receptor gamma (PPARγ) and its associated role in renoprotection by lutein was also examined. Male BALB/c mice were divided into six treatment groups: control with normal saline, lutein (200 mg/kg), vancomycin (250 mg/kg), vancomycin (500 mg/kg), vancomycin (250 mg/kg) with lutein, and vancomycin (500 mg/kg) with lutein groups; they were euthanized after 7 days of treatment. Thereafter, samples of blood, urine, and kidney tissue of the mice were analyzed, followed by the determination of levels of N-acetyl-β-D-glucosaminidase (NAG) in the urine, renal creatine kinase; protein carbonyl, malondialdehyde, and caspase-3 in the kidney; and the expression of PPARγ, nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor-kappaB (NF-κB) in renal tissue. Results showed that the levels of protein carbonyl and malondialdehyde, and the activity of NAG, creatine kinase and caspase-3, were significantly increased in the vancomycin-treatment groups. Moreover, the levels of Nrf2 significantly decreased, while NF-κB expression increased. Lutein ameliorated these effects, and significantly increased PPARγ expression. Furthermore, it attenuated vancomycin-induced histological alterations such as, tissue necrosis and hypertrophy. Therefore, we conclude that lutein protects against vancomycin-induced renal injury by potentially upregulating PPARγ/Nrf2 expression in the renal tissues, and consequently downregulating the pathways: inflammation by NF-κB and apoptosis by caspase-3.

• Journal of Microbiology and Biotechnology
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• 제32권11호
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• pp.1416-1426
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• 2022

The need to discover new types of antimicrobial agents has grown since the emergence of antibiotic-resistant pathogens that threaten human health. The world's oceans, comprising complex niches of biodiversity, are a promising environment from which to extract new antibiotics-like compounds. In this study, we newly isolated Pseudomonas sp. NIBR-H-19 from the gut of the sea roach Ligia exotica and present both phenotypes and genomic information consisting of 6,184,379 bp in a single chromosome possessing a total of 5,644 protein-coding genes. Genomic analysis of the isolated species revealed that numerous genes involved in antimicrobial secondary metabolites are predicted throughout the whole genome. Moreover, our analysis showed that among twenty-five pathogenic bacteria, the growth of three pathogens, including Staphylococcus aureus, Streptococcus hominis and Rhodococcus equi, was significantly inhibited by the culture of Pseudomonas sp. NIBR-H-19. The characterization of marine microorganisms with biochemical assays and genomics tools will help uncover the biosynthesis and action mechanism of antimicrobial metabolites for development as antagonistic probiotics against fish pathogens in an aquatic culture system.

• 대한약침학회지
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• 제26권4호
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• pp.307-318
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• 2023

Objectives: Bacterial biofilm is regarded as a significant threat to the production of safe food and the arise of antibiotic-resistant bacteria. The objective of this investigation is to evaluate the quorum sensing inhibitory effect of Nepeta curviflora methanolic extract. Methods: The effectiveness of the leaves at sub-inhibitory concentrations of 2.5, 1.25, and 0.6 mg/mL on the virulence factors and biofilm formation of P. aeruginosa was evaluated. The effect of N. curviflora methanolic extract on the virulence factors of P. aeruginosa, including pyocyanin, rhamnolipid, protease, and chitinase, was evaluated. Other tests including the crystal violet assay, scanning electron microscopy (SEM), swarming motility, aggregation ability, hydrophobicity and exopolysaccharide production were conducted to assess the effect of the extract on the formation of biofilm. Insight into the mode of antiquorum sensing action was evaluated by examining the effect of the extract on the activity of N-Acyl homoserine lactone (AHL) and the expression of pslA and pelA genes. Results: The results showed a significant attenuation in the production of pyocyanin and rhamnolipid and in the activities of protease and chitinase enzymes at 2.5 and 1.25 mg/mL. In addition, N. curviflora methanolic extract significantly inhibited the formation of P. aeruginosa biofilm by decreasing aggregation, hydrophobicity, and swarming motility as well as the production of exopolysaccharide (EPS). A significant reduction in AHL secretion and pslA gene expression was observed, indicating that the extract inhibited quorum sensing by disrupting the quorum-sensing systems. The quorum-sensing inhibitory effect of N. curviflora extract appears to be attributed to the presence of kaempferol, quercetin, salicylic acid, rutin, and rosmarinic acid, as indicated by LCMS analysis. Conclusion: The results of the present study provide insight into the potential of developing anti-quorum sensing agents using the extract and the identified compounds to treat infections resulting from quorum sensing-mediated bacterial pathogenesis.

• 한국어병학회지
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• 제37권1호
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• pp.79-88
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• 2024

Aeromonas spp. 감염은 관상어 산업뿐만 아니라 양식업에서도 상당한 경제적 손실을 초래하는 것으로 보고되고 있다. 한편 2022년 12월부터 2023년 1월 사이에 국내에서 사육중인 금붕어(Crassius auratus)에서 Aeromonas병증을 보이는 어체에 대해서 발병 원인균을 규명하기 위해서 조사 하였다. 병증을 보이는 금붕어의 피부와 내부 장기에서 그람 음성균이 분리되었다. Biochemical test와 16S rRNA gene으로는 Aeromonas 속까지 동정할 수 있었으나 종레벨까지는 구분하기 어려웠다. 이에 가장 상동성이 높았던 A.veronii를 대상으로 species-specific PCR을 수행했고 명확히 종 수준으로 동정할 수 있었다. 아울러서 장독소 유전자, 감염 실험 및 항생제 내성 분석을 수행하였다. 금붕어에 대한 균주의 생체 내 병원성 시험 결과, 실험 주사 후 일주일 이내에 감염된 숙주에서 100%의 치사율을 나타냈다. 장독소 유전자인 act 독력 유전자가 검출되었다. 균주의 항균제 감수성 분석 결과 대부분의 항균제에 감수성을 보였으나, Ampicillin, Imipenem, Meropenem 및 Clindamycin 약제에는 내성을 보였다.

• Pediatric Infection and Vaccine
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• 제14권2호
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• pp.162-170
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• 2007

목 적 : Vancomycin 내성 장구균(이하 VRE)은 1980년대 후반 처음으로 보고된 이후 전세계적으로 그 빈도가 증가하고 있으나 소아 환자에 대한 체계적인 연구는 미흡한 실정이다. 이에 저자 등은 소아 환자의 VRE 감염 빈도 및 임상 검체에서 분리된 VRE 균주의 임상 양상과 VRE 감염의 위험인자 및 경과에 대해 조사하여 VRE 감염에 대한 적절한 대처 방안을 모색하고자 본 연구를 시행하였다. 방 법 : 2001년 1월부터 2006년 12월까지 연세의료원 세브란스병원에 입원한 15세 이하의 소아 환자에서 분리된 VRE 230주를 대상으로 후향적으로 자료를 분석하였다. 대상 환아는 ICU 환자군과 Non-ICU 환자군으로 분류하여 두 군간에 있어 VRE가 분리되기 전 처치형태 및 분리된 균주의 항균제 감수성을 조사하였다. 결 과 : ICU 환자군 및 수술이나 중재적 시술을 받았던 경우, 3세대 cephalosporin이나 glycopeptide등의 광범위 항생제를 투여했던 경우에서 VRE 분리 빈도가 높았으며 대부분의 경우 E. faecium이 분리되었다. 항균제 감수성 검사에서는 tetracycline을 제외한 항생제에 높은 내성을 지니고 있었으며 분리 전 3세대 cephalosporin의 투여 비율이 가장 높았다. 3세대 cephalosporin의 투여 비율은 계속 증가하는 추세이나 2006년에 들어서는 glycopeptide의 사용이 감소하였으며, 2006년에는 VRE가 분리된 환아 수가 감소하였으나 1998년부터 보았을 때 전체적으로는 증가 추세를 보였다. 결 론 : 소아의 경우에서도 VRE는 증가하고 있는 추세로 VRE 감염의 전파를 방지하기 위해서는 위험인자를 가진 환자군에 대한 적극적인 감시와 항균제 사용 제한이 필요하며 이미 분리된 환자에 있어서도 신중한 항생제 선택과 함께 지속적이고 적극적인 감염 관리가 중요할 것으로 사료된다.

• Tuberculosis and Respiratory Diseases
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• 제47권2호
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• pp.184-194
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• 1999

연구배경: 페니실린의 출현으로 폐렴구균 감염증의 사망률이 현저히 감소하기는 했으나 폐렴구균 균혈증의 사망률은 여전히 높다. 최근 페니실린 내성 폐렴구균이 증가하고 있는 추세이며 이는 치료 항생제 선태에 어려움을 주고 있다. 한국은 페니실린 내성 폐렴 구균의 빈도가 세계에서 가장 높은 나라로 알려져 있으며 이에 대한 연구가 더 필요한 상황이다. 저자 등은 서울대학병원에서 폐렴 구균 균혈증의 임상상과 페니실린 내성 여부가 사망에 미치는 영향을 알아보기 위해 본 연구를 시행하였다. 방법: 서울대학교 병원에서 1990년 1월에서 1997년 7월까지 혈액배양에서 폐렴 구균이 증명되었던 66예 중에서 병록 검토가 가능했던 50예를 대상으로 후향적 연구를 시행하였다. 결과: 연령의 중앙값은 56세였고, 50세 이상이 62%를 차지했다. 폐렴구균 예방접종을 시행한 기왕력이 있었던 예는 없었다. 기저 질환은 48예(96%)에서 있었다. 동반된 국소 병변으로는 폐렴이 21예(42%)로 가장 많았고, 자발성 세균성 복막염이 7예(14%), 담도염 5예(10%), 뇌막염 4예(8%), 간농양 2예(4%), 인두편도염 2예(4%), 부비동염 1예(2%), 봉와직염이 1예(2%)에서 관찰되었고, 원발성 균혈증이 7예(14%)가 있었다. 총 사망 예는 12예(24%)였다. 이 중 폐렴은 9예로 총 폐렴 예의 42%가 사망하였고, 뇌막염 2예, 원발성 균혈증 1예가 사망하였다. 페니실린 내성군은 내성 여부를 확인할 수 있었던 63예 중 25예(40%)를 차지하였다. 페니실린 내성률은 1991년 이후 급격한 증가를 보였다. 페니실린 내성군에서 최근 3개월 내 항생제 사용 예가 많았고 (p=0.022) 최근 입원 예가 많아(p=0.030) 페니실린 내성 감염의 위험 인자로 작용함을 알 수 있었다. 감수성 군과 내성군 간의 연령, 기저 질환의 중증도, 병원 감염 여부, 면역 억제 여부, 속이나 급성신부전의 빈도 등은 양 군에서 통계적으로 유의한 차이가 없었다. 사망률은 페니실린 감수성군에서 23%, 내성군에서 29%로 통계적으로 유의한 차이가 없었다. 결론: 페니실린 내성 여부는 사망률에 영향을 미치지 못했으나 폐렴구균 균혈증의 사망률은 전반적으로 높았다. 따라서 폐렴구균 예방 접종의 적응증이 되는 경우에는 적극적인 예방 접종이 필요하리라 사료된다.