• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.40-50
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• 2002

Fruit fly, Drosophila melanogaster has developed efficient immune mechanisms to prevent microbial infection, which are consisted of cellular and humoral responses. During the systemic or local infection, two distinct pathways (Toll and Imd) play major roles in antimicrobial peptide synthesis. The Toll pathway is required to defend Gram-positive bacterial and fungal infections, whereas the Imd pathway is important in Gram-negative bacterial infection. We have shown that the infection of the opportunistic Gram-negative bacterium, Pseudomonas aeruginosa strain PA14 (PA14) into fly dorsal thorax can kill the flies within 48 h ($100\%$ mortality) in our optimized infection condition, suggesting that the PA14 strain can cause disease progress in fly model system. We found that flies carrying a constitutively activated mutant form of the Toll receptor $(Tl^{10b})$ showed increased resistance to P. aeruginosa infection and that flies carrying mutations in the Toll signaling pathway as well as in the Imd signaling pathway was more susceptible to PA14 infection. All these results imply that the Toll pathway might be important in the resistance to this pathogenic Gram-negative bacterial infection.

• 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.

• 대한간호학회지
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• 제9권2호
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• pp.17-26
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• 1979

This research is to prevent the infection of maternity in the hospital by examining the microbes contaminations in maternity through airbone microbes and those who are engaged in the ward of O.B. ＆ G.Y. and to furnish the basic data available to hospital management. The bacterial growth of airbone microbes contaminations in nosocomial air and who thor the nasal cavity of passers by (doctors, nurses, parturient women) who went to the ward of O.B. ＆ G.Y. contaminated or not were examined in“E”Univ. Hospital from July to August, 1979 by using thioglycollate broths and agar plates. The following results were obtained: 1. The average colony number of airborne microbes revealed as follows the pediatric ward (36 colonies), the internal ward (33 colonies), the ward of O.B. ＆ G.Y. (30 colonies), the ward of surgery (24 colonies), delivery-waiting room (11 colonies), and the delivery room (3 colonies). 2. The bacterial growth beforenoon differed from that of afternoon. Namely, the latter (24 colonies) was higher than the former (21 colonies). 3. The type of strains isolated from the air of the ward revealed staphylococci (82%), Gram negative bacilli (18%), fungi (17%), Gram positive diplococci (13%), and Bacillus subtilis (2.8%). 4. The strains isolated in the delivery-waiting room revealed staphylococci (66.7%), Gram negative bacilli (33.6%), and revealed staphylococci (75%), Gram positive diplococci (8.3%), and fungi (8.3%), in delivery room. 5. Most of strains isolated in the ward of O.B. & G.Y. revealed staphylococci (100.0%), Gram positive diplococci (8.3%), and Gram negative bacilli (6.7%). 6. The strain isolated in the surgical ward revealed staphylococci (91.7%), fungi (33.3%), Gram positive diplococci (25%), Gram negative bacilli (25%) and Bacillus subtilis (8.3%). 7. The strain isolated in the pediatric ward revealed staphylococci (75%), fungi (25%), Gram positive diplococci (8.3%), Bacillus subtilis (8.3%), and Gram negative bacilli (8.3%). 8. The strain isolated in the internal ward revealed staphylococci (91.7%), fungi (33.3%), Gram positive diplococci (25%), and negative bacilli (16.7%). The strains isolated from the nasal cavity of those doctors and nurses who and enaged in the ward of O.B. & G.Y. revealed staphylococci (80%), Bacillus subtilis (10%), and Gram negative bacilli (10%), from doctors and Gram positive diplococci (10%), instead of Gram negative bacilli (10％), from nurses. 10. The strain isolated from nasal cavity of parturient women on admission revealed staphylococci (90%), and Gram negative bacilli (10%), but after admission revealed staphylococci (70％), Gram positive diplococci (10%), and Gram negative bacilli (10%). 11. Of the total 91 staphylococci isolated from the air of the ward, the Coagulase pastive was 36 (39.6%), and the negative 55 (60.4%), As a result of the coagulase experiment of the staphylococci isolated from the nasal cavity of those who are engaged in the ward of O.B. ＆ G.Y. all were revealed as negative that belonged to non-pathogenic. 12. Consequence of the biochemic examination of the gram negative bacilli isolated from the air of the ward the aerobacter aerogens revealed was (16.7%) E-coli 5％ in the nasal cavity of those came and went to the of O.B. ＆ G.Y. and Aerobacter aerogens 7.5%.

• Journal of Microbiology and Biotechnology
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• 제31권11호
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• pp.1481-1489
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• 2021

Early and accurate detection of pathogens is important to improve clinical outcomes of bloodstream infections (BSI), especially in the case of drug-resistant pathogens. In this study, we aimed to develop a culture-independent digital PCR (dPCR) system for multiplex detection of major sepsis-causing gram-negative pathogens and antimicrobial resistance genes using plasma DNA from BSI patients. Our duplex dPCR system successfully detected nine targets (five bacteria-specific targets and four antimicrobial resistance genes) through five reactions within 3 hours. The minimum detection limit was 50 ag of bacterial DNA, suggesting that 1 CFU/ml of bacteria in the blood can be detected. To validate the clinical applicability, cell-free DNA samples from febrile patients were tested with our system and confirmed high consistency with conventional blood culture. This system can support early identification of some drug-resistant gram-negative pathogens, which can help improving treatment outcomes of BSI.

• Archives of Plastic Surgery
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• 제33권3호
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• pp.330-334
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• 2006

Polymicrobial nature of diabetic foot infection has been well documented in the literature. Initial antibiotic therapy of diabetic foot infection is usually empiric until reliable culture data is shown. This study was carried out to determine the common bacteriological flora of diabetic foot infection and antimicrobial sensitivity pattern in order to enhance possible empiric treatment. The specimens were obtained from wounds of 207 cases of diabetic foot ulcer, and the bacteriological isolation, and antimicrobial susceptibility tests of the isolates were carried out by standard microbiological methods. Staphylococcus aureus was the most common isolate, with 46.2% of recover rate among total bacterial isolated cases. Among gram-negative organisms, Pseudomonas aeruginosa was most common. Gram-positive organisms showed significant susceptibility to clindamycin, trimethoprim/sulfamethoxazole, and levofloxacin, besides vancomycin. Cefoperazone, piperacillin/tazobactam, and amikacin in addition to imipenem were most effective agents compared to gram-negative organisms. Diabetic foot infection requires use of combined antimicrobial therapy for initial management. Our results indicate that the most effective antibiotic combination for diabetic foot infection of Korean patients is clindamycin plus cefoperazone.

• Archives of Plastic Surgery
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• 제34권3호
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• pp.314-318
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• 2007

Purpose: Pressure sore wound develops inevitably in long-term, immobilized and hospitalized patients. Sore wound infection is common problem and makes healing process difficult. We aimed to identify the pathogens of the purulent discharge in sore wound and to obtain information for appropriate antibiotics through a sensitivity test Methods: The bacteriologic study was made on 120 cases of patients who admitted or visited our hospital from 2004 January to 2005 December for sore wound treatment. Culture material was collected in BBL transport media with cotton swab and cultured by MacConkey agar plate. The method of MIC by VITEK and Microscan was used for sensitivity test. Results: Among 120 specimens, organisms were isolated from 77(64.2%) cases. Gram positive organisms were cultured in 73 specimens, Gram negative organisms in 46 specemens, and fungi in 2 specimens. Mixed infection by Gram (+) and Gram (-) bacteria were observed in 34 specimens. Among them, S. aureus was the most common isolate in 24(31.2%) patients and 10 (13.0%) S. Aureus isolates were MRSA. The most prevalent Gram-negative organism was Escherichia coli in 20 patients(25.9%). Vancomycin and teicoplanin showed highest sensitivity to Gram-positive organisms and imipenem and amikacin to Gram-negative organisms. Conclusion: Pressure sore wound demands consideration of multimodal therapeutic aspects and these findings would be useful informations to physicians, nurses and clinical assistants in understanding the nature of sore wound and selecting appropriate antibiotics.

• Clinical and Experimental Pediatrics
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• 제62권1호
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• pp.36-41
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• 2019

Purpose: In this study, we investigated the clinical features and prognostic factors of early-onset sepsis (EOS) in neonatal intensive care unit (NICU) patients. Methods: A retrospective analysis was conducted on medical records from January 2010 to June 2017 (7.5 years) of a university hospital NICU. Results: There were 45 cases of EOS (1.2%) in 3,862 infants. The most common pathogen responsible for EOS was group B Streptococcus (GBS), implicated in 10 cases (22.2%), followed by Escherichia coli, implicated in 9 cases (20%). The frequency of gram-positive sepsis was higher in term than in preterm infants, whereas the rate of gram-negative infection was higher in preterm than in term infants (P<0.05). The overall mortality was 37.8% (17 of 45), and 47% of deaths occurred within the first 3 days of infection. There were significant differences in terms of gestational age (26.8 weeks vs. 35.1 weeks) and birth weight (957 g vs. 2,520 g) between the death and survival groups. After adjustments based on the difference in gestational age and birth weight between the 2 groups, gram-negative pathogens (odds ratio [OR], 42; 95% confidence interval [CI], 1.4-1,281.8) and some clinical findings, such as neutropenia (OR, 46; 95% CI, 1.3-1,628.7) and decreased activity (OR, 34; 95% CI, 1.8-633.4), were found to be associated with fatality. Conclusion: The common pathogens found to be responsible for EOS in NICU patients are GBS and E. coli. Gram-negative bacterial infections, decreased activity in the early phase of infection, and neutropenia were associated with poor outcomes.

• Clinical and Experimental Pediatrics
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• 제56권8호
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• pp.332-337
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• 2013

Purpose: To identify the frequency of bacterial isolates in early-onset neonatal sepsis (EONS) and their antimicrobial resistance pattern. Methods: A retrospective study of EONS was conducted at the Beni Suef University Hospital from September 2008 to September 2012. A case of EONS was defined as an infant who had clinical signs of infection or who was born to a mother with risk factors for infection, and in whom blood culture obtained within 72 hours of life grew a bacterial pathogen. Results: Of 673 neonates screened, there were 138 positive blood cultures (20.5%) (confirmed EONS). Of the recovered isolates, 86.2% were gram-negative pathogens. Klebsiella pneumoniae (42.8%), Enterobacter cloacae (22.5%), and Escherichia coli (13.8%) were the commonest isolated organisms. The most common gram-positive microorganism was Staphylococcus aureus accounting for only 12 isolates (8.7%). All Klebsiella isolates and 93% of Enterobacter isolates were resistant to ampicillin. Gram-negative pathogens had the maximum overall sensitivity to imipenem, cefepime, and ciprofloxacin; whereas, gram-positive isolates were most susceptible to vancomycin, imipenem, and piperacillin. Conclusion: K. pneumoniae was the predominant causative bacteria of EONS followed by E. cloacae and E. coli. There was a high resistance to ampicillin. Imipenem had the maximum overall activity against the causative bacteria. Continuous surveillance is needed to monitor the changing epidemiology of pathogens and antibiotic sensitivity.

• 약학회지
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• 제40권1호
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• pp.95-101
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• 1996

The in vitro antibacterial activities of LB10522, a new catechol-substituted cephalosporin, were compared with those of cefpirome, ceftazidime, ceftriaxone, and cefoperaz one against clinical isolates and laboratory standard anaerobes. LB10522 had broad spectrum antibacterial activities against both gram-positive and gram-negative microorganisms. It was most active against gram-positve bacteria among the reference cephalosporins tested. Against gram-negative strains such as the family Enterobacteriaceae, LB10522 showed an activity comparable to that of cefpirome. But LB10522 was more potent than ceftazidime, ceftriaxone and cefoperazone. In particular, Pseudomonas aeruginosa was highly susceptible to LB10522, which was 32-fold and 64-fold more active than ceftazidime and cefpirome, respectively. Against anaerobic strains, the activity of LB10522 was similar to those of reference compounds. LB10522 exhibited potent therapeutic activities against experimental local infections in mice. The therapeutic effect of LB10522 against urinary tract infection (UTI) caused by P. aeruginosa 1912E in mice was superior to that of cefpirome. Against experimental respiratory tract infection (RTI) caused by K. pneumoniae DT-S in mice, LB10522 was as effective as cefpirome. The in vivo efficacy of LB10522 was correlated well with its in vitro activity.

• Pediatric Infection and Vaccine
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• 제31권1호
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• pp.46-54
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• 2024

목적: 본 연구는 2013년부터 2023년까지 최근 10년간 분당서울대학교병원 소아 혈액종양 환자들에게 발생한 균혈증 발생 숫자를 확인하고, 원인균 발생 빈도 및 분포와 이들의 항생제 감수성을 분석하면서 경험적 항생제를 선택하는 데에 필요한 치료 지침의 기초 자료로 활용하고자 수행되었다. 방법: 2013년 1월부터 2023년 7월까지 분당서울대학교병원에 입원한 환자 중 기저혈액종양질환이 있으면서 혈류감염이 발생한 환자들을 대상으로 후향적 의무기록 분석을 하였다. 결과: 10년의 연구 기간동안 총 74명의 환자에게서 98례의 혈류감염이 확인되었고, 이 중 그람 양성균, 그람 음성균, 진균이 각각 57.1% (n=56), 38.8% (n=38), 4.1% (n=4)이었다. 가장 흔한 그람 양성균은 coagulase-negative staphylococci (n=21, 21.4%) 와 Staphylococcus aureus (n=14, 14.3%) 였고, 가장 흔한 그람 음성균은 Klebsiella species (n=16, 16.3%) 와 Escherichia coli (n=10, 10.2%) 였다. 전체 사망한 환자들 중 균혈증 발생으로부터 30일 이내로 사망한 사례는 총 6건 (6.1%) 이었다. 결론: 본 연구는 혈액종양질환을 진단받은 소아 환아들에게서 발생한 균혈증의 원인균 분포 및 각 원인균의 항생제 분포를 분석하였다. 연구결과를 토대로, 연구자들은 현재 사용하는 경험적 항생제 가이드라인을 유지할 수 있다는 점을 알 수 있었다. 소아 혈액종양질환 환아들에게서 발생한 균혈증에서 사용해야 할 적절한 경험적 항생제는 각 기관별로 조사한 항생제 감수성 양상에 기초하여 결정되어야 하며, 지속적인 모니터링은 반드시 이루어져야 한다.