• 대한임상검사과학회지
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• 제48권2호
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• pp.118-123
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• 2016

지난 반세기 동안 세균 감염증 치료 또는 성장촉진을 목적으로 가금류에게 광범위하게 항균제를 사용해 왔다. 그러나 항균제 내성의 증가는 사람에게 보편적으로 사용되는 항균제들에 대한 내성을 유도하여 치료를 위한 항균제 선택에 제약을 주어 치료에 어려움을 가중시키고 있다. 본 연구에서는 경상도 지역에서 사육된 닭으로부터 분리된 장내세균을 대상으로 ${\beta}-lactam$, quinolone, 및 aminoglycoside 계열 항균제에 대한 내성유전자의 빈도를 조사하였다. 그리고 항균제 감수성 검사를 시행하여 내성유전자와의 관련성을 알아보았다. 본 연구에서 총 43균주의 장내세균이 40마리의 닭의 맹장으로부터 분리되었으며 디스크확산법을 이용하여 항균제 감수성 검사를 시행하였다. 그리고 중합효소연쇄반응과 염기서열분석을 통해 플라스미드 매개 항균제 내성 유전자를 조사하였다. 총 43균주 중 2균주가 $bla_{CTX-M-14}$ 유전자를 포함하고 있었으며 qnrS 및 aac(6')-Ib-cr 유전자도 각각 2균주와 5균주에서 확인되었다. 총 43균주를 대상으로 항균제 감수성을 조사한 결과 cefepime, ceftazidime, 및 cefaclor를 제외한 모든 항균제에 대해 0.0%부터 23.3%까지의 낮은 감수성률을 보였다. 본 연구에서는 닭으로부터 분리된 대장균에 플라스미드 매개 항균제 내성유전자가 확산되어 있음을 확인하였다. 항균제 내성 유전자의 확산을 막기 위해서는 지속적인 항균제 내성유전자의 조사와 감시가 필요할 것으로 사료된다.

• BMB Reports
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• 제31권3호
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• pp.287-295
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• 1998

Acetolactate synthase (ALS) is the first common enzyme in the biosynthesis of L-Ieucine, L-isoleucine, and L-valine. The sulfonylurea-resistant ALS gene from Nicotiana tabacum was cloned into the bacterial expression vector pGEX-2T. The resulting recombinant plasmid pGEX-ALS3 was used to transform Escherichia coli strain XL1-Blue, and the mutant tobacco ALS (mALS) was expressed in the bacteria as a protein fused with glutathione S-transferase (GST). The fusion product GST-mALS was purified in a single step on a glutathione-Sepharose column. ALS activities of 0.9-2.5 ${\mu}mol/min/mg$ protein were observed in the GST-mALS, and the Km values for pyruvate, FAD, and TPP were 10.8-24.1, $(1.9-8.9){\times}10^{-3}$, and 0.14-0.38 mM, respectively. The purified GST-mALS was resistant to both the sulfonylurea and the triazolopyrimidine herbicides, and lost its sensitivity to end products, L-valine and L-leucine. For comparision, the tobacco wild-type recombinant ALS fused with GST, GST-wALS, was also characterized with respect to its pyruvate and cofactor bindings. These results suggest that the purified mutant recombinant tobacco ALS was functionally active, that the mutations resulting in herbicide resistance has affected pyruvate and cofactor bindings," and that the two classes of herbicides interact at a common site on the plant ALS.

• 생약학회지
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• 제34권2호통권133호
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• pp.142-144
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• 2003

Acetone extracts of 301 strains of marine-derived fungus were tested for antimicrobial activity against three strains of bacteria. The bacteria consisted of three pathogens, Staphylococcus aureus, methicillin-resistant S. Aureus, and multidrug-resistant S. aureus. The acetone extracts of 10 strains (MFA117, MFA130, MFA134, MFA206, MFA217, MFA268, MFA277, MFA291, MFA292, MFA301) showed strong activity, inhibiting 100% of the bacterial growth. These antimicrobial active strains were cultlued in SWS medium on a 1 L scale and the resulting broth and mycelium were extracted to afford mycelium extract (000M) and broth extract (000B), respectively. Antimicrobial activity for all extracts has been tested as the results, the mycelium extract of one strain (217M) and the broth extracts of 9 strains (117B,130B, 134B, 206B, 268B, 277B, 291B, 292B, 301B) exhibited relatively high levels of activity at minimal inhibitory concentration (MIC) values of $500-125\;{\mu}g/mL$ range. Among them, the extracts, 277B, 291B, 292B and 301B showed the most significant antimicrobial activity with $IC_{50}$ values of $125\;{\mu}g/mL$.

• 대한화학회지
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• 제55권6호
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• pp.960-968
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• 2011

A series of isonicotinyl hydrazones and their 4-thiazolidinones have been synthesized by condensation of isonicotinic acid hydrazide with various aromatic aldehydes to yield Schiff's bases, followed by the cyclocondensation of Schiff's bases with 2-mercaptoacetic acid to yield their 4-thiazolidinones. The synthesized compounds have been characterized by their elemental, analytical and spectral studies. All these compounds were evaluated for their invitro antimicrobial activity against a spectrum of non-resistant and resistant microbial organisms. These studies proved that compounds 5e,i against B. subtilis; 5e,f,h against B. anthracis; 5g,i against S. aureus showed good activity at lower concentrations. Compounds 5d-5i displayed significant activity against resistant strain of K. pneumonia with minimum inhibitory potency in the concentration range of 2-16 ug/ml.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.449-457
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• 2021

The aim of the present study was to survey the frequency of inducible and constitutive phenotypes and inducible cross-resistant genes by regulating the methylation of 23S rRNA (ermA, ermB, and ermC) and macrolide efflux-related msrA gene in Staphylococcus aureus and S. epidermidis strains. A total of 172 bacterial isolates (identified based on standard tests), were examined in this study. Antibiotic susceptibility was determined by the disk diffusion method, and all isolates were evaluated with respect to inducible and constitutive phenotypes. The presence of ermA, ermB, ermC, and msrA genes was investigated by a PCR assay. The constitutive resistance phenotypes showed a higher distribution among the isolates. R phenotype was detected more among S. epidermidis isolates (46.25%). ermB, ermC, and msrA genes were detected more in methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) isolates that had R and HD phenotypes (>77% strains). The ermA gene had the lowest frequency among MRSA, MRSE, MSSA, and MSSE strains (<14% isolates). Distribution of inducible resistance genes in MRSA and MRSE strains, and possibly other species, leads to increased constitutive resistance to erythromycin, clindamycin, and other similar antibiotics. Therefore, it can be challenging to treat infections caused by these resistant strains.

• 식물병연구
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• 제26권3호
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• pp.159-169
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• 2020

Pactobacterium carotovorum subsp. carotovorum (Pcc)에 의한 무름병은 전세계적으로 문제가 되고 있고 특히 온난 다습한 지역에서 문제가 심각하다. 본 연구는 Pcc에 의해 발생하는 배추 무름병에 대한 효율적인 저항성 검정법을 확립하기 위하여 실험하였다. 시판 배추 품종 65개의 Pcc KACC 10225에 대한 저항성 정도를 조사하고, 추후 실험을 위해 저항성에 차이를 보이는 3개 품종을 선발하였다. 이들 3개 품종의 접종하는 배추의 생육 시기, 접종원 농도, 접종 후 재배 온도 등의 발병 조건에 따른 무름병 발생을 조사하였다. 이들 실험의 결과로부터 배추의 무름병에 대한 저항성을 검정하기 위해서는, 배추 종자를 파종하고 온실(25±5℃)에서 21일 동안 재배한 유묘에 Pcc 균주의 세균현탁액(1×10⁷ cfu/ml)을 식물체 기부에 5 ml씩 관주하여 접종하고, 접종한 식물은 25℃ 습실상에 24시간 동안 배양한 후에 25℃, 상대습도 80%의 생육상으로 이동하여 재배하는 것을 제안하고자 한다.

• 한국작물학회지
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• 제65권4호
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• pp.314-326
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• 2020

본 연구는 유전자의 확대와 집적을 통해 벼 흰잎마름병균 K3a에 대응하는 저항성 계통을 육성하였고 육성계통에 대한 육종과정, 병 저항성반응을 분석하여 저항성 계통의 기초자료와 재배 효과를 제공하여 우수한 벼 흰잎마름병 저항성 품종 개발에 활용하고자 실험을 수행하였다. 벼 흰잎마름병 저항성 Xa3 유전자를 가지고 있는 중만생 자포니카 품종 황금누리를 반복친으로, Xa21 유전자를 가진 중만생 인디카 근동질유전자계통 IRBB21을 수여친으로 인공교배 후 3번 여교배하여 ABLs21을 얻었다. 생물검정과 분자표지검정을 활용하여 저항성 유전자 Xa3, Xa21이 집적을 확인하였다. ABLs21이 보유한 저항성 유전자는 분자표지 9643.T4 (Xa3), U1/I1 (Xa21)로 PCR 한 결과 모두 증폭되어 저항성 유전자를 가지는 것으로 확인되었다. ABLs21과 모부본의 벼 흰잎마름병 레이스에 대한 저항성 반응은 황금누리, IRBB3가 K1, K2, K3 레이스에 저항성 반응을 보였지만 K3a, K4, K5에는 감수성 반응을 나타냈다. IRBB21은 K1에 감수성 반응이었고 K2~K5에는 저항성 반응이었다. K3a 레이스 균주 접종 시 유묘단계에서 황금누리, IRBB21, ABL21-1, 분얼단계에서 황금누리, IRBB21, 성체단계에서 황금누리가 감수성 반응이었다. ABL21-1은 분얼단계에서 중도저항성을, 성체단계에서 저항성 반응을 나타냈다. K3a 레이스 18개 균주 접종 결과 ABL21-1은 각각의 수여친보다 병반길이와 표준편차가 작아 안정적인 저항성을 보여주었다. 18개 균주 각각의 반복간 병반길이의 유의차는 없어 균주의 병원성은 안정적이었으며 군집분석 결과 HB4032 균주의 병원력이 가장 큰 것으로 나타났다. ABLs21의 분자표지 다형성은 63.2%이며 평균 86.1 cM의 염색체단편이 이입되었다. ABLs21의 Xa21 유전자 부위로 추정되는 곳에 수여친의 염색체단편 이입이 일어났다.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.798-802
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• 2010

Recently, a total of 74 Staphylococcus pseudintermedius isolates were collected from clinical cases of canine pyoderma and otitis externa in Korea. In this study, we examined in vitro fluoroquinolone resistance among those isolates using a standard disc diffusion technique. The results demonstrated that, except for one isolate, approximately 18.9% to 27.0% of the isolates possessed bacterial resistance to both veterinary- and human-licensed fluoroquinolones including moxifloxacin (18.9% resistance), levofloxacin (20.3% resistance), ofloxacin (24.3% resistance), ciprofloxacin (25.7% resistance), and enrofloxacin (27.0% resistance). Most surprisingly, 14 out of 74 (18.9%) isolates were resistant to all the five fluoroquinolones evaluated. Moreover, a PCR detection of the methicillin resistance gene (mecA) among the 74 isolates revealed that 13 out of 25 (52.0%) mecApositive isolates, but only 7 out of 49 (14.3%) mecA-negative isolates, were resistant to one or more fluoroquinones. Taken together, our results imply that bacterial resistance to both veterinary- and human-use fluoroquinolones becomes prevalent among the S. pseudintermedius isolates from canine pyoderma and otitis externa in Korea, as well as that the high prevalence of the mecA-positive S. pseudintermedius isolates carrying multiple fluoroquinolones resistance could be a potential public health problem.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1178-1184
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• 2018

The spread of antibiotic-resistant Enterobacteriaceae in the community is one of the main challenges for antibiotic treatment of community-onset infections. We evaluated the microbiological and molecular characteristics of stool samples from adults with comprehensive health examinations. Of 109 fecal samples, bacterial growth was observed in 86 samples and 61 gram-negative bacterial isolates were identified, of which 45 were Escherichia coli isolates (73.8%). Two isolates of Raoultella showed imipenem resistance, and both E. coli and Citrobacter freundii showed intermediate resistance to imipenem. Colistin resistance was identified in isolates of Klebsiella variicola and Salmonella subterranean, but no isolates carried mcr-1. As for E. coli genotypes, 35 sequence types were identified. $bla_{TEM-1}$, $bla_{TEM-30}$, and $bla_{CTX-M}$ were identified in 15, 1, and 4 E. coli isolates, respectively. In addition, all four Klebsiella pneumoniae isolates carried $bla_{SHV}$. Many genotypes that have been identified in isolates causing human infections were found in isolates in this study. There is a need to control the rise and spread of antibiotic-resistant pathogens by fecal carriage.

• Clinical and Experimental Pediatrics
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• 제60권6호
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• pp.167-174
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• 2017

Mycoplasma pneumoniae pneumonia (MPP) is one of the most common forms of community-acquired pneumonia in children and adolescents. Outbreaks of MPP occur in 3- to 7-year cycles worldwide; recent epidemics in Korea occurred in 2006-2007, 2011, and 2015-2016. Although MPP is known to be a mild, self-limiting disease with a good response to macrolides, it can also progress into a severe and fulminant disease. Notably, since 2000, the prevalence of macrolide-resistant MPP has rapidly increased, especially in Asian countries, recently reaching up to 80%-90%. Macrolide-resistant Mycoplasma pneumoniae (MRMP) harbors a point mutation in domain V of 23S rRNA with substitutions mainly detected at positions 2063 and 2064 of the sequence. The excessive use of macrolides may contribute to these mutations. MRMP can lead to clinically refractory pneumonia, showing no clinical or radiological response to macrolides, and can progress to severe and complicated pneumonia. Refractory MPP is characterized by an excessive immune response against the pathogen as well as direct injury caused by an increasing bacterial load. A change of antibiotics is recommended to reduce the bacterial load. Tetracyclines or quinolones can be alternatives for treating MRMP. Otherwise, corticosteroid or intravenous immunoglobulin can be added to the treatment regimen as immunomodulators to downregulate an excessive host immune reaction and alleviate immune-mediated pulmonary injury. However, the exact starting time point, dose, or duration of immunomodulators has not been established. This review focuses on the mechanism of resistance acquisition and treatment options for MRMP pneumonia.