• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1937-1945
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• 2018

Malassezia pachydermatis is a commensal yeast found on the skin of dogs. However, M. pachydermatis is also considered an opportunistic pathogen and is associated with various canine skin diseases including otitis externa and atopic dermatitis, which usually require treatment using an azole antifungal drug, such as ketoconazole. In this study, we isolated a ketoconazole-resistant strain of M. pachydermatis, designated "KCTC 27587," from the external ear canal of a dog with otitis externa and analyzed its resistance mechanism. To understand the mechanism underlying ketoconazole resistance of the clinical isolate M. pachydermatis KCTC 27587, the whole genome of the yeast was sequenced using the PacBio platform and was compared with M. pachydermatis type strain CBS 1879. We found that a ~84-kb region in chromosome 4 of M. pachydermatis KCTC 27587 was tandemly quadruplicated. The quadruplicated region contains 52 protein coding genes, including the homologs of ERG4 and ERG11, whose overexpression is known to be associated with azole resistance. Our data suggest that the quadruplication of the ~84-kb region may be the cause of the ketoconazole resistance in M. pachydermatis KCTC 27587.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.947-952
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• 2007

Mycobacterium tuberculosis is a pathogen responsible for 2-3 million deaths every year worldwide. The emergence of drug-resistant and multidrug-resistant tuberculosis has increased the need to identify new antituberculosis targets. Acetohydroxy acid synthase, (AHAS, EC 2.2.1.6), an enzyme involved in branched-chain amino acid synthesis, has recently been identified as a potential anti-tuberculosis target. To assist in the search for new inhibitors and “receptor-based” design of effective inhibitors of tubercular AHAS (TbAHAS), we constructed four different structural models of TbAHAS and used one of the models as a target for virtual screening of potential inhibitors. The quality of each model was assessed stereochemically by PROCHECK and found to be reliable. Up to 89% of the amino acid residues in the structural models were located in the most favored regions of the Ramachandran plot, which indicates that the conformation of each residue in the models is good. In the models, residues at the herbicide-binding site were highly conserved across 39 AHAS sequences. The binding mode of TbAHAS with a sulfonylurea herbicide was characterized by 32 hydrophobic interactions, the majority of which were contributed by residue Trp516. The model based on the highest resolution X-ray structure of yeast AHAS was used as the target for virtual screening of a chemical database containing 8300 molecules with a heterocyclic ring. We developed a short list of molecules that were predicted to bind with high scores to TbAHAS in a conformation similar to that of sulfonylurea derivatives. Five sulfonylurea herbicides that were calculated to efficiently bind TbAHAS were experimentally verified and found to inhibit enzyme activity at micromolar concentrations. The data suggest that this time-saving and costeffective computational approach can be used to discover new TbAHAS inhibitors. The list of chemicals studied in this work is supplied to facilitate independent experimental verification of the computational approach.

• 한국축산식품학회지
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• 제30권2호
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• pp.179-184
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• 2010

Escherichia coli O157:H7 is a food-borne pathogen that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). We compared three selective media and evaluated the performance of immunomagnetic separation (IMS) for the detection of low levels of E. coli O157:H7 in ground beef and radish sprouts with different levels of background flora. Bulk food samples (500 g for each trial) were artificially inoculated with nalidixic acid-resistant E. coli O157:H7 at the lowest dose that would generate 20 partial-positive samples of 25 g each. All samples were homogenized in mTSB (225 mL) and incubated overnight at $37^{\circ}C$. IMS was performed using the enriched mTSB samples (1 mL) along with conventional spreads plated onto three different selective media: Sorbitol MacConkey agar (SMAC), Sorbitol MacConkey agar with cefixime and tellulite (CT-SMAC), and Sorbitol MacConkey agar with nalidixic acid (NAL-SMAC) as the gold standard. Two suspicious colonies from each medium were selected and confirmed usinga serological test after transfer to tryptic soy broth with yeast extract (TSAYE). CT-SMAC was better than SMAC for detecting E. coli O157:H7 in all food types. Although there was no statistical difference in the number of positive samples when using IMS vs. non-IMS techniques, more positive samples were detected when IMS was used in both ground beef and radish sprouts. It appears that the improvement was more significant in radish sprouts, which had a higher level of background flora than ground beef. The results also suggest that the combination of CT-SMAC and IMS is sufficient to recover low levels of E. coli O157:H7 in high background flora food samples.

• Tuberculosis and Respiratory Diseases
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• 제60권2호
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• pp.228-234
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• 2006

연구배경 : A. baumannii는 중환자실내의 원내감염의 중요 원인균으로 인식되고 있으며, 원내 폐렴, 요로 감염증, 균혈증 등을 일으킨다. 현재 이 균의 다약제 내성이 문제되고 있으며 특히 carbapenem에 내성을 보이고 있는 것이 가장 큰 문제가 되고 있다. 이 연구의 목적은 중환자실 환자의 객담에서 배양된 A. baumannii 중 carbapenem 내성군과 감수성군 두 군으로 나누어 위험인자를 알아보고 임상적 특징을 비교 및 분석하는 것이다. 방 법 : 2003년 1월 1일부터 2003년 12월 31일까지 강원대학교 중환자실에 입원한 성인 환자들 중 객담 배양 검사상 A. baumannii가 한 번이라도 검출된 환자들을 대상으로 챠트 기록을 통한 후향적 분석을 하였다. 위험인자로 연령, 성별, APACHE II score, 동반질환, 사용한 항생제, 재원기간, 중환자실 재원기간, Clinical Pulmonary Infection Score, 인공호흡기 여부를 평가하였다. 결 과 : 총 49명으로 A. baumannii에 대한 carbapenem 감수성군은 23명 내성군은 26명이었다. 단일변량분석에서는 신장 질환, 이전의 aminoglycoside 및 carbapenem 사용력이 통계적인 의미를 보였고 다변량분석에서는 이전의 aminoglycoside 사용력은 carbapenem 내성과 음의 상관관계를(p=0.026; OR, 0.18; CI, 0.04 to 0.82), 이전의 carbapenem 사용력은 carbapenem 내성과 양의 상관관계를(p=0.024; OR, 8.17; CI 1.32 to 50.68) 보여주었다. 사망률에서는 양 군에서 유의한 차이를 보이지 않았다(30 vs 42%, P=0.39). 결 론 : Carbapenem 내성 A. baumannii의 발생의 위험인자로 이전의 aminoglycoside와 carbapenem 사용력이 있으며 carbapenem 사용 시 A. baumannii의 carbapenem 내성정도가 증가함을 볼 수 있다.

• 한국어병학회지
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• 제30권2호
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• pp.89-96
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• 2017

현재 국내에 유통되고 있는 담수관상어의 대부분은 수입에 의존하므로 외래 병원체 및 항생제 내성균의 유입 가능성이 크다. 본 연구에서는 담수에 상재하는 균으로 인수공통 감염이 가능하며 어류에 조건성병원균으로 작용하는 Aeromonas hydrophila를 다양한 수입 담수관상어로부터 분리하여 특성을 분석하고자 하였다. 수입 후 1일 이내의 관상어를 수족관으로부터 수집하여 0.5% NaCl을 포함하는 TSA 배지에 간, 신장, 비장을 도말하여 세균을 분리하였다. 세균의 형태, 생화학적 특성 및 starch- ampicillin agar (SA)에서의 clear zone 형성 유무에 근거하여 분리 균의 약 70%인 226 균주가 Aeromonas spp.로 확인되어 이들의 분리 빈도가 매우 높음을 알 수 있었다. 이들 중 9균주를 선택하여 16S rRNA gene의 sequence를 분석한 결과 모두 A. hydrophila로 동정되었으며 API 20E test에서 대부분의 분리 균주는 amygdalin, D-melibiose, D-sucrose, trisodium citrate, L-arabinose 이용에서 표준 균주와 차이를 보였다. 10종의 항균제에 대한 분리 균주의 감수성을 디스크 확산법으로 확인한 결과 amoxycillin, ampicillin에 대해서는 모든 균주가 저항성이었고 florfecicol에 대해서는 모두 감수성이었다. 그러나 7균주는 tetracycline 계통의 항균제와 erythromycin, nalidixic acid 등에 복합내성을 보였다. A. hydrophila로 동정된 9개 분리 균주를 금붕어에 인위 감염을 실시한 결과, 3 균주는 5일 이내에 60~80%의 폐사를 나타내었다. 이러한 결과는 다약제내성이면서 독력이 있는 Aeromonas가 수입관 상어를 따라 국내로 유입되어 전파될 수 있으므로 수입상에서 소비처로 판매되기 전의 방어적 조치가 필요하다는 것을 시사한다.

• 한국미생물·생명공학회지
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• 제35권2호
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• pp.158-162
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• 2007

의료환경에서 MRSA의 분포정도를 알아보고자 전국적으로 400병동 이상의 규모 13개 병원에 대해서 간호사, 의사, 보호자 및 환자의 손과 비강에서 MRSA를 모니터링 하였다. 검체 채취 대상인 의사, 간호사, 보호자, 환자 그리고 일반인으로부터 S. aureus 625균주를 분리하였다. 검출률을 보면 비강에서는 의사 40%, 간호사 23.8%, 보호자 32.3%, 환자 21.5%,일반인 27.5%의 검출률을 보였고, 손에서는 의사 54.6%, 간호사 18.5%, 보호자 46.2%, 환자 37.7%, 일반인에서 33.1%의 검출률을 나타내었다. 항생제 내성률을 살펴본 결과 분리된 S. aureus 625 균주 중 1가지 이상의 항생제에 내성을 가지고 있는 균주는 585균주로 93.6%의 내성률을 나타내었다. 대체적으로 의료 환경에서 분리한 균이 일반인에게서 분리한 균보다 많은 종류의 항생제에 내성을 보이는 것으로 나타났다. 4가지 계열의 서로 다른 항생제에 내성이 있는 균주인 다제 내성균은 112주(17.9%)가 검출되었다. 대체적으로 간호사와 환자의 비강과 손에서 분리된 균의 다제 내성률이 높게 나왔다. 의료인, 환자, 보호자 및 일반인의 비강에서 분리한 S. aureus 252 균주 중 penicillin과 oxacillin에 동시에 내성을 보인 MRSA로 49균주(19.4%)가 분리되었다. 구체적으로 보면 의사 11균주(16.7%), 간호사 13균주(32.5%), 보호자 6균주(11.1%), 환자에서 19균주 (48.7%)가 분리되었고 일반인의 비강에서는 분리되지 않았다. 의료인, 비 의료인 및 일반인의 손에서 분리한 S. aureus 373주 중 MRSA로 103균주(27.6%)가 분리되었다. 구체적으로 보면 의사 22균주(22.4%), 간호사 13균주(43.3%), 보호자 24균주(24.2%), 환자 31균주(41.9%), 일반인에서 13균주(18.1%)가 분리되었다. 따라서 의료 환경 내 의료인(의사, 간호사)에서는 비강보다 손에서 MRSA가 높은 비율로 검출되었으며 의사보다 간호사에서 MRSA가 많이 분리되었다. 비 의료인(보호자, 환자, 일반인)의 경우 일반인 보다 의료 환경 내에 있는 보호자와 환자에게서, 보호자보다는 환자에게서 MRSA가 많이 분리되었다. 이번에 실시한 의료 환경 중에서는 MRSA 152균주(24.3%)가 분리되어 축산이나 수산환경에서 보다 높은 분리율을 보였는데 이는 축산과 수산 환경에서보다 직접적으로 항생제를 많이 사용하고 또 항생제에 많이 노출되어 있기 때문이라고 사료되었다. 전체적으로 의료인보다 비의료인 환자에서 보다 많은 MRSA가 분리되고 MIC는 대체적으로 비슷하거나 조금 더 높은 것으로 나타나 병실의 환경개선이 필요할 것으로 사료되었다.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.803-811
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• 2014

Concerns over drug-resistant bacteria have stimulated interest in developing alternative methods to control bacterial infections. Endolysin, a phage-encoded enzyme that breaks down bacterial peptidoglycan at the terminal stage of the phage reproduction cycle, is reported to be effective for the control of bacterial pathogenic bacteria. Bioinformatic analysis of the SPN9CC bacteriophage genome revealed a gene that encodes an endolysin with a domain structure similar to those of the endolysins produced by the P1 and P22 coliphages. The SPN9CC endolysin was purified with a C-terminal oligo-histidine tag. The endolysin was relatively stable and active over a broad temperature range (from $24^{\circ}C$ to $65^{\circ}C$). It showed maximal activity at $50^{\circ}C$, and its optimum pH range was from pH 7.5 to 8.5. The SPN9CC endolysin showed antimicrobial activity against only gram-negative bacteria and functioned by cutting the glycosidic bond of peptidoglycan. Interestingly, the SPN9CC endolysin could lyse intact gram-negative bacteria in the absence of EDTA as an outer membrane permeabilizer. The exogenous lytic activity of the SPN9CC endolysin makes it a potential therapeutic agent against gram-negative bacteria.

• 한국가금학회지
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• 제31권1호
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• pp.37-44
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• 2004

It has been recognized that the hen, like its mammalian counterparts, provides young chicks with antibodies as protection against hostile invaders. This system facilitates the transfer of specific antibodies from serum to egg yolk, and provides a supply of antibodies called immunoglobulin Y(IgY) to the developing embryo and the hatched chick. The protection against pathogens that the relatively immune-incompetent newly hatched chick has, is through transmission of antibodies from the mother via the egg. Egg yolk, therefore, can be loaded with a large amount of IgY against pathogens which can immobilize the existing or invading pathogens during the embryo development or in day-old chicks. Thus, the immunization of laying hens to various pathogens results in production of different antigen-specific IgY in eggs. Egg yolk contains 8∼20 mg of jmmunoglobulins (IgY) per ml or 136∼340 mg per yolk suggesting that more than 30 g of IgY can be obtained from one immunized hen in a year. By immunizing laying hens with antigens and collecting IgY from egg yolk, low cost antibodies at less than $10 per g compared to more than $20,000 per g of mammalian IgG can be obtained. This IgY technology opens new potential market applications in medicine, public health, veterinary medicine and food safety. A broader use of IgY technology could be applied as biological or diagnostic tool, nutraceutical or functional food development, oral-supplementation for prophylaxis, and as pathogen-specific antimicrobial agents for infectious disease control. This paper has emphasized that when IgY-loaded chicken eggs are produced and consumed, the specific antibody binds, immobilizes and consequently reduces or inhibits the growth or colony forming abilities of microbial pathogens. This concept could serve as an alternative agent to replace the use of antibiotics, since today, more and more antibiotics are less effective in the treatment of infections, due to the emergence of drug-resistant bacteria.

• 한국약용작물학회지
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• 제21권6호
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• pp.493-497
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• 2013

This study was designed to analyze the chemical composition of essential oil in 'Shiranuhi' immature fruit and to test their biological activities. 'Shiranuhi' immature essential oils (SIEO) were obtained by steam distillation from fruits collected from Jeju Island and were analyzed using gas chromatograph (GC)-flame ionization detectors (FID) and GC-MS. Fourteen components were identified in the essential oil. Limonene (75.21%) and terpineol (8.68%) were the major components in SIEO. Since acne vulgaris is the combined result of a bacterial infection and the inflammatory response to that infection, we examined whether SIEO possessed antibacterial against skin pathogens. As a result, SIEO showed excellent antibacterial activities against drug-susceptible and -resistant Propionibacterium acnes and Staphylococcus epidermidis, which are acne-causing bacteria. In this study, SIEO was examined on DPPH radical scavenging activities, which showed moderate antioxidant activity ($SC_{50}$, $15.36{\mu}L/mL$). In order to determined whether SIEO can be safely applied to human skin, the cytotoxicity effects of SIEO were determined by colorimetric MTT assays in normal human fibroblasts and keratinocyte HaCaT cells. They exhibited low cytotoxicity at $0.5{\mu}L/mL$ in both celllines. Based on these results, we suggest the possibility that essential oil of 'Shiranuhi' maybe considered as an antibacterial and antioxidant agent.