• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.816-823
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• 2022

The rapid spread of superbugs leads to the escalation of infectious diseases, which threatens public health. Endolysins derived from bacteriophages are spotlighted as promising alternative antibiotics against multi-drug resistant bacteria. In this study, we isolated and characterized the novel Salmonella typhimurium phage PBST08. Bioinformatics analysis of the PBST08 genome revealed putative endolysin ST01 with a lysozyme-like domain. Since the lytic activity of the purified ST01 was minor, probably owing to the outer membrane, which blocks accessibility to peptidoglycan, antimicrobial peptide cecropin A (CecA) was fused to the N-terminus of ST01 to disrupt the outer membrane. The resulting CecA::ST01 has been shown to have increased bactericidal activity against gram-negative pathogens including Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, and Enterobacter cloacae and the most affected target was A. baumannii. In the presence of 0.25 µM CecA::ST01, A. baumannii ATCC 17978 strain was completely killed and CCARM 12026 strain was wiped out by 0.5 µM CecA::ST01, which is a clinical isolate of A. baumannii and resistant to multiple drugs including carbapenem. Moreover, the larvae of Galleria mellonella could be rescued up to 58% or 49% by the administration of CecA::ST01 upon infection by A. baumannii 17978 or CCARM 12026 strain. Finally, the antibacterial activity of CecA::ST01 was verified using 31 strains of five gram-negative pathogens by evaluation of minimal inhibitory concentration. Thus, the results indicate that a fusion of antimicrobial peptide to endolysin can enhance antibacterial activity and the spectrum of endolysin where multi-drug resistant gram-negative pathogens can be efficiently controlled.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.96-115
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• 2013

본 연구는 항균성 코팅제의 개념과 동향파악으로 항균성 코팅제의 연구개발의 방향을 설정하는데 도움을 주기 위한 것이다. 항균제는 미생물을 제거하거나 성장을 저지하는데 사용되는 화합물이며 항균 코팅제에 함유되는 항균제용 재료는 무기물, 금속, 저분자 유기물, 천연유기물, 고분자가 있다. 항균코팅제는 생활용품, 병원용품, 산업용품, 전자제품, 의류, 건축 내장재 등의 표면의 항균성 부여에 쓰인다. 기존 항생제는 세균의 세포벽을 손상하지 않고 미생물을 침투하나 항균성 고분자는 세포막을 파괴하므로 항생제의 내성을 방지할 수 있다. 대부분의 고분자 항균제는 양이온 고분자에 초점을 맞추고 있다. 항균제의 분자설계와 코팅제 배합의 합리화로 항균제의 선택성, 내구성, 독성 문제가 개선될 것이다.

• 미생물학회지
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• 제45권2호
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• pp.99-104
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• 2009

본 연구에서는 2004년 1월부터 2008년 12월까지 인천지역 5개 종합 병 의원에 설사증상으로 입원 또는 내원한 환자의 대변에서 분리한 115주의 S. Enteritidis의 항생제 내성 및 다제내성 양상을 모니터링하였다. 그 결과, 가장 내성율이 높은 항생제는 nalidixic acid (54.8%)이었고, ampicillin (40.0%), ticarcillin (38.3%), chloramphenicol (20.9%), tetracycline (17.4%) 순이었다. 분리균의 91.3%는 1제 이상의 항생제에 내성이 있었다. 항생제 내성 유형을 살펴본 결과 nalidixic acid 단일 내성이 44.3%로 가장 높았으며, ampicillin-chloramphenicol-ticarcillin (11.3%) 및 ampicillin-ticarcillin (10.4%) 순이었다. 전체적으로 1제 내성이 51.9%, 2제 내성 18.2%, 3제 내성 14.5%, 4제 내성 5.8% 그리고 5제 이상 내성은 9.7%이었다.

• 한국식품과학회지
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• 제42권4호
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• pp.508-513
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• 2010

2006년부터 2008년까지 3년간 시판 수산물 2,239건에서 분리한 V. parahaemolyticus에 대한 항생제 감수성 결과는 다음과 같았다. 어류 789건을 검사하여 42주(5.3%)의 V. parahaemolyticus가 분리 동정되었으며, 패류 735건 중 27건(3.7%), 연체류 387건 중 12건(3.1%), 기타 수산물 328건 중 12건(3.7%), 총 93건(4.2%)에서 V. parahaemolyticus가 분리 동정되었다. 내성률이 높은 항생제는 ampicillin 93.5%, cephalothin 90.3%, streptomycin 87.1%, ticarcillin 55.9%, 그리고 amikacin 40.9%이었으며, 감수성률이 높은 항생제는 nalidixic acid, chloramphenicol 및 ampicillin/sulbactam trimethoprim/sulfamethoxazole 98.9%, gentamicin 및 tetracycline 82.8%, ceftriaxone 63.4%이었다. 중등도 내성률은 kanamycin 79.6%, ciprofloxacin 64.5%, amikacin 47.3%, cefoxitin 43.0%순이었다. 항생제 내성양상은 3제 내성이 37.6%, 4제 내성 24.7%, 5제 내성 17.2%, 6제 내성 11.8%, 2제 내성6.5%, 7제 내성 2.2% 순이었으며, 가장 많은 내성 양상은 AM-CF-S의 3제 내성(22.6%), AM-CF-S-TIC 4제 내성(18.3%), AM-AN-CF-S-TIC 5제 내성(9.7%) 순이었다.

• Safety and Health at Work
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• 제3권2호
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• pp.85-91
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• 2012

The occupations involved in food animal production have long been recognized to carry significant health risks for workers, with special attention to injuries. However, risk of pathogen exposure in these occupations has been less extensively considered. Pathogens are a food safety issue and are known to be present throughout the food animal production chain. Workers employed at farms and slaughterhouses are at risk of pathogen exposure and bacterial infections. The industrialization of animal farming and the use of antimicrobials in animal feed to promote growth have increased the development of antimicrobial resistance. The changed nature of these pathogens exposes workers in this industry to new strains, thus modifying the risks and health consequences for these workers. These risks are not yet recognized by any work-related health and safety agency in the world.

• 대한수의학회지
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• 제31권3호
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• pp.279-284
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• 1991

To investigate the epidemiological aspects of listeriosis, serotypes of L monocytogenes and antimicrobial susceptibilities of Listeria spp isolated from chicken carcases and chicken slaughter house environmental specimens were determined. Of 28 L monocytogenes strains, 12 strains(42.9%) were serotype 4, and the remaining 16 strains were untypable. Peak distributions of minimum inhibitory concentration$({\mu}g/ml)$ of the isolates were $0.78{\mu}g/ml$ for ampicillin, $0.39{\mu}g/ml$ for erythromycin and penicillin G, $1.56{\mu}g/ml$ for tetracycline and $6.25{\mu}g/ml$ or $12.5{\mu}g/ml$ for chloramphenicol, and $3.13{\mu}g/ml$ to > $100{\mu}g/ml$ for kanamycin and neomycin. Most of 214 isolates were sensitive to ampicillin and erythromycin, but 20. 1~78. 0% of the strains were resistant to tetracycline, kanamycin, penicillin-G and neomycin. Single or double drug resistance were observed in 75.8% of the resistant strains. The most common resistance patterns were Nm P-G(37.4%) in double pattern and P-G(23.7%) in single pattern.

• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.1-10
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• 2019

Gram-negative pathogens, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, pose a serious threat to public health worldwide, due to high rates of antibiotic resistance and the lack of development of novel antimicrobial agents targeting Gram-negative bacteria. The outer membrane (OM) of Gram-negative bacteria is a unique architecture that acts as a potent permeability barrier against toxic molecules, such as antibiotics. The OM is composed of phospholipids, lipopolysaccharide (LPS), outer membrane ${\beta}-barrel$ proteins (OMP), and lipoproteins. These components are synthesized in the cytoplasm or in the inner membrane, and are then selectively transported to the OM by the specific transport machines, including the Lol, BAM, and Lpt pathways. In this review, we summarize recent studies on the assembly systems of OM components and analyze studies for the development of inhibitors that target these systems. These analyses show that OM assembly machines have the potential to be a novel attractive drug target of Gram-negative bacteria.

• 대한수의학회지
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• 제58권1호
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• pp.17-25
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• 2018

This study aimed at determining the current knowledge, attitude, and practices (KAP) of layer and pig farmers to antimicrobial usage and its consequences. Description of such KAP could provide insights useful for promoting the rational use of antimicrobials in livestock. From May 2014 to February 2016, a survey involving 251 respondents in Chiang Mai, Lamphun, and Chonburi provinces, Thailand, was conducted by using a validated questionnaire. More than half (51.0%) of the respondents incorrectly believed that antimicrobial drug efficacy could not be reduced by using sub-recommended dosages, 61.2% had misconceptions about non-therapeutic antimicrobial use, and 66.9% inaccurately felt that antimicrobials were also effective for virus and fungi. Over half (50.6-55.2%) did not see the need to follow instructions or advice of veterinarians. Moreover, only 10.4% regularly relied on responses to drugs sensitivity tests when evaluating the effectiveness of antimicrobials. Overall, assessment of KAP regarding antimicrobial usage indicated that the majority of respondents had low levels of knowledge of antimicrobials, neutral rather than positive attitudes, and employed poor practices in the use of antimicrobials. The results indicate improvements in KAP could be helpful in developing more effective interventions by farmers, reduce antibiotic usage, and slow the growth of antimicrobial resistance.

• 대한수의학회지
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• 제29권4호
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• pp.493-501
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• 1989

A total of 108 strains of C jejuni isolated from pigs and chickens were examined for the susceptibility to 10 antimicrobial agents and normal sera of cattle, sheep, guinea pigs and chickens. Minimal inhibitory concentration(MIC) ranges of antimicrobial agents to C jejuni isolates were $${\leq_-}1.56$$ to $${\geq_-}100{\mu}g/ml$$ for erythromycin, rifampin, streptomycin and tetracycline, 50 to $${\geq_-}100{\mu}g$$ for cephalothin, $${\leq_-}1.56$$ to $50{\mu}g$ for ampicillin, $${\leq_-}1.56$$ to $25{\mu}g$ for kanamycin and nalidixic acid, $${\leq_-}1.56$$ to $12.5{\mu}g$ for chloramphenicol and gentamicin. Resistance rates of C jejuni were showed to in order of rifampin(84.7%), tetracycline(56.2 %), erythromycin(17.1%) and ampicillin(3.8%), all of the strains were sensitive to chloramphenicol, gentamicin and kanamycin, and the incidence rates of resistant C jejuni were highly frequent in pig isolates than chicken isolates. The drug resistance patterns of 87 chicken isolates C jejuni to 9 antimicrobial drugs were showed 12 patterns, and Sm Ra Tc(24.1%), Sm Ra(21.8%) and Ra Tc(14.9%) were relatively common, and also 21 pig isolates were showed 6 patterns and Em Sm Ra Tc(57.1%) were most frequent. The majority of the isolates showed multiple drug resistance. Bactericidal activity of 10% normal sera from healthy animals were examined for 60min at $37^{\circ}C$. C jejuni were decreased from 0.4 to 1.0 ${\log}_{10}$(p<0.01), and serum susceptibility were high in order of guinea pig, sheep, chicken and cattle sera. Serum sensitivity of C jejuni Ch-39 strain in increased serum concentation up to 10, 20, 40 and 80% were highly significant. In the normal animal serum, the number of Ch-39 strain were decreased from $1.8{\times}10^4/ml$ to $2.7{\times}10^3/ml$ after 60 min incubation(p<0.01), but the numbers were decreased to $6.6{\times}10^3/ml$ in the heat inactivated normal serum for 30 min at $56^{\circ}C$. Bactericidal activity was restored in the heat inactivated normal serum after the serum of complement source was added.

• 약학회지
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• 제52권6호
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• pp.434-440
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• 2008

The purpose of this research was to investigate the microbiological quality and antimicrobial susceptibilities of the ready-to-eat side dishes, which are were collected from the grocery stores, big markets, and department stores in Seoul throughout November, 2007. Of total 124 samples, presence of staphylococci and enteric bacilli was observed in 38 samples (31%) and 53 samples (43%), respectively. And 30 samples (24%) were shown to be of unsatisfactory quality for total bacterial count (>$10^5$). Antimicrobial susceptibilities of the staphylococci isolated from the side dishes were tested for six different antimicrobial agents, which are in widespread clinical use in Korea, as well as four new antimicrobials, daptomycin, linezolid, quinupristin/dalfopristin and tigecycline. As a result, the staphylococcal isolates were found to be resistant to oxacillin (${MIC}_{90}$, >128 ${\mu}g$/ml), teicoplanin (${MIC}_{90}$, >128 ${\mu}g$/ml), mupirocin (${MIC}_{90}$, >128 ${\mu}g$/ml), linezolid (${MIC}_{90}$, 128 ${\mu}g$/ ml) and quinupristin/dalfopristin (${MIC}_{90}$, 32 ${\mu}g$/ml). Especially, some of the staphylococcal isolates exhibited high level and multi-drug resistance. Moreover, these bacteria were also resistant to new antimicrobials, except tigecycline.