• 미생물학회지
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• 제46권1호
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• pp.38-45
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• 2010

본 연구는 부산 환경관리공단 수영사업소 산하 수영공공하수종말처리장 하수로부터 광범위 베타락탐 분해효소(ESBL, extended-spectrum ${\beta}$-lactamase)의 유형을 파악하기 위하여 이루어졌다. 수영공공하수처리시설은 부산광역시의 동북부 생활하수와 수세식변기의 오수가 표준활성슬러지공법으로 처리되며 일 생활하수 처리량은 총 550,000톤이다. 이중디스크 확산 검사, 제 3세대 세파계열 항균제에 대한 최소억제농도 시험을 통하여 14균주를 선별하였다. Indole, methyl-red, Voges-Proskauer, Simmon's citrate, decarboxylase-dihydrolase 시험과 당 발효 시험 등 생화학 검사를 통하여 동정한 결과 Escherichia coli (10균주), Klebsiella pneumoniae (4균주)가 동정되었다. 이를 전달균주로, sodium azide에 내성을 가진 피전달 균주인 E. coli J53에 교차접합을 시켜 11균주 (E. coli 9균주, K.pneumoniae 2균주)가 접합이 이루어졌다. 접합자중 2균주는 ESBL 유전자를 전달받지 못하였고 9균주는 부모로부터 ESBL 유전자를 전달받았다. 등전점, 유전자서열과 단백질서열 분석 등을 통하여 피전달균주인 E. coli J53에 전달된 유전자유형은 TEM형의 모형인 TEM-1과 SHV-12형으로 규명되었다.

• Journal of Microbiology and Biotechnology
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• 제24권3호
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• pp.421-426
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• 2014

To characterize the extended-spectrum beta-lactamases (ESBLs) in diarrheagenic Escherichia coli from Korea in 2008-2011, we screened seven enterotoxigenic E. coli (ETEC) and one enteroaggregative E. coli (EAEC) that produce ESBLs from a nationwide survey. All eight isolates produced CTX-M-type ESBLs, including CTX-M-12 (n = 4), CTX-M-14 (n = 2), and CTX-M-15 (n = 2). PCR-based replicon typing indicated that the $bla_{CTX-M-12}$ genes of four ETEC isolates were carried on a conjugative IncF plasmid, whereas the $bla_{CTX-M-14}$ of one EAEC was located on an IncK plasmid. This is the first report of the occurrence of $bla_{CTX-M}$ genes in clinical isolates of EAEC in Korea. The ESBL-producing isolates were shown to be different based on pulsed-field gel electrophoresis and multilocus sequence typing, whereas the four isolates with CTX-M-12 were clonally related. These observations raise an alarm for the spread of plasmid-mediated resistance to ESBL among diarrheagenic E. coli.

• Journal of Yeungnam Medical Science
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• 제6권1호
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• pp.59-68
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• 1989

반합성 ${\beta}$-lactam 항생제로서 여러 세균에 ${\beta}$-lactamase에 대해 높은 안정성을 나타내는 ceftizoxime의 임상 분리 장내 세균 18주에 대한 시험관대 및 생체내 항균효과와 내성균의 출현여부를 조사하고 ampicillin, tetracycline, gentamicin 및 cefadroxyl와의 항균력을 시험관내 설험으로 비교하였으며 또한 마우스 장내 정상균총에 미치는 영향을 관찰하여 다음과 같은 결론을 얻었다. 1. Ceftizoxime은 그람음성 장내 세균에 대하여 시험관내에서 높은 항균력을 나타내었으며 이러한 항균력은 ampicillin, tetracycline, gentamicin보다 높았으며 ${\beta}$-lactamase 산생 내성균주의 치료제로 알려진 cefadroxyl 보다도 높았다. 2. 시험관내 다체 내성균주는 ampicillin, cefadroxyl, gentamicin 및 tetracycline에 대한 내성주는 E. coli 1주, ampicillin, cefadroxyl 및 tetracycline에 대한 내성주는 E. coli 2주, ampicillin, gentamicin 및 tetracycline에 대한 내성주는 Shigella dysenteriae 이였으며, ampicillin 및 tetracycline에 대한 내성주는 Enterobacter cloacae였고 ampicillin 및 tetracycline에 대한 내성주는 E. coli 5주이었다. 3. Ceftizoxime에 대한 내성균주의 출현율은 매우 낮았다. 4. 서로 다른 내성을 보인 9균주 E. coli (6 strains, Shigella dysenteriae, Enterobacter cloacae, and Samonella typi)중 plasmid 분리는 6균주에서 관찰되었으며 이는 E. coli 5주와 Shigella dysenteriae 1주 있었다. 그러나 항생제에 대한 저항의 marker로서는 결정할 수 없으므로 이를 위해서는 curing experiment를 사용하여야 한다. 5. Ceftizoxime은 마우스 장내 정상균총에는 현저한 영향을 미치지 않았다. 이상의 결과에서 ceftizoxime은 그람음성 장내 세균에 대하여 높은 항균력을 나타내며 장내세균 감염치료에 선택적 항생제로 이용될 수 있을 것으로 사료된다.

• Journal of Microbiology
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• 제45권6호
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• pp.590-592
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• 2007

We report the isolation of Salmonella enterica serotype Typhimurium phage type DT104 (CCARM 8104) from swine in Korea. The CCARM 8104 isolate was resistant to nalidixic acid and showed reduced susceptibility to quinolones. The CCARM 8104 isolate had a missense mutation, Asp87Asn, in the quinolone resistance-determining region in gyrA and produced PSE-1. The CCARM 8104 isolate carried two different class 1 integrons, and the PSE-1 ${\beta}$-lactamase gene was inserted into a 1,200 bp class 1 integron. The presence of DT104 with pse-1 in an integron located in a plasmid and reduced susceptibility to quinolone in swine pose a significant threat of possible horizontal spread between swine and humans.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.394-401
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• 2016

Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR/Cas9) system, a genome editing technology, was shown to be versatile in treating several antibiotic-resistant bacteria. In the present study, we applied the CRISPR/Cas9 technology to kill extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. ESBL bacteria are mostly multidrug resistant (MDR), and have plasmid-mediated antibiotic resistance genes that can be easily transferred to other members of the bacterial community by horizontal gene transfer. To restore sensitivity to antibiotics in these bacteria, we searched for a CRISPR/Cas9 target sequence that was conserved among >1,000 ESBL mutants. There was only one target sequence for each TEM- and SHV-type ESBL, with each of these sequences found in ~200 ESBL strains of each type. Furthermore, we showed that these target sequences can be exploited to re-sensitize MDR cells in which resistance is mediated by genes that are not the target of the CRISPR/Cas9 system, but by genes that are present on the same plasmid as target genes. We believe our Re-Sensitization to Antibiotics from Resistance (ReSAFR) technology, which enhances the practical value of the CRISPR/Cas9 system, will be an effective method of treatment against plasmid-carrying MDR bacteria.

• 한국미생물·생명공학회지
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• 제48권2호
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• pp.230-235
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• 2020

The global evolution of antibiotic resistance has threatened the efficacy of available treatment options with ravaging impacts observed in developing countries. As a result, investigations into the prevalence of antibiotic resistance and the role of plasmids are crucial. In this study, we investigated the presence and distribution of bla_TEM and gyrA genes, plasmid profiles, and the antimicrobial susceptibility pattern of Salmonella strains isolated from raw meat and stool sources across Niger State, Nigeria. Ninety-eight samples, comprising 72 raw meat and 26 stool samples, were screened for Salmonella spp. The antimicrobial susceptibility of Salmonella isolates to 10 commonly used antimicrobial agents was determined using the KirbyBauer disc diffusion method. Isolates were further analyzed for plasmids, in addition to PCR amplification of beta-lactamase (bla_TEM) and gyrA genes. A total of 31 Salmonella spp. were isolated, with 22 from raw meat (70.97%) and 9 from stool (29.03%). Salmonella spp. with multiple resistance patterns to ceftazidime, cefuroxime, ceftriaxone, erythromycin, ampicillin, cloxacillin, and gentamicin were detected. Ofloxacin and ciprofloxacin were found to be the most effective among the antibiotics tested, with 67.7% and 93.5% susceptible isolates, respectively. Nine (29.03%) isolates harbored plasmids with molecular sizes ranging between 6557 bp and 23137 bp. PCR amplification of gyrA was detected in 1 (3.23%) of the 31 isolates while 28 isolates (90.32%) were positive for bla_TEM. This study shows the incidence of antibiotic resistance in Salmonella isolates and the possible role of plasmids; it also highlights the prevalence of ampicillin resistance in this local population.

• 한국동물위생학회지
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• 제42권1호
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• pp.17-24
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• 2019

The aim of this study was to investigate the prevalence and characterization of plasmid-mediated quinolone resistance (PMQR) gene in 79 Enterobacteriaceae isolated from dogs and cats. Of 79 isolates, PMQR genes were found in 10 (12.7%) isolates, including aac(6')-lb-cr, qnrB, qnrS and qnrA detected alone or in combination in 8 (10.1%), 4 (5.1%), 2 (2.5%) and 1 (1.3%) isolates, respectively. Interestingly, two qnrS genes were detected in nalidixic acid and ciprofloxacin susceptible isolates. Extended-spectrum ${\beta}$-lactamase (ESBL) was detected in 90% (9 isolates) of PMQR positives isolates. Among ESBL genes, CTX-M, TEM and SHV were detected in 9, 8 and 3 isolates, respectively. Almost all PMQR genes were detected in co-existence with ESBL genes. All PMQR positives isolates were multidrug resistance (i.e. resistant to five or more antibiotics). qepA, OXA and CMY-2 genes were not found. The six transconjugants were obtained by conjugation experiment. The aac(6')-lb-cr, qnrB and qnrS were co-transferred with CTX-M, TEM and/or SHV, whereas qnrA was not observed among transconugants. This is the first report of the presence of aac(6')-lb-cr and qnrA gene among Enterobacteriaceae isolates from dogs in Korea. The prudent use of antimicrobials and continuous monitoring for companion animals are required.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.765-770
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• 2014

This study aimed to characterize CTX-M producers of urinary E. coli and K. pneumoniae isolates and to determine the prevalence of plasmid-mediated antimicrobial resistance genes among them. Minimum inhibitory concentrations (MICs) were determined, and PCR and sequencing were performed. Among the 42 (82.3%) E. coli and 24 (77.4%) K. pneumoniae isolates containing $bla_{CTX-M}$, $bla_{CTX-M-14}$ and $bla_{CTX-M-15}$ were detected in 23 and 19 E. coli isolates, respectively, and in 7 and 17 K. pneumoniae isolates, respectively. CTX-M producers of urinary E. coli and K. pneumoniae were resistant to multiple antibiotics and contained other antimicrobial resistance genes. CTX-M-15 producers contained more antimicrobial resistance genes than did CTX-M-14 producers.

• 대한수의학회지
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• 제57권1호
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• pp.9-15
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• 2017

To construct a novel vaccine candidate against bovine enterotoxigenic Escherichia coli (ETEC), FanC, the major subunit of K99 fimbriae adhesion, was inserted into secretion plasmid pYA3560 containing a ${\beta}-lactamase$ secretion system. This was then transformed into ${\Delta}asd$ ${\Delta}crp$ Salmonella (S.) Typhimurium and designated as JOL950. Secretion of recombinant fanC fimbrial antigens was confirmed by immunoblot analysis. Groups of mice were inoculated with single or double doses of JOL950. Another group was used as a negative control. Compared to control mice, all immunized mice had significantly higher levels (p < 0.05) of serum immunoglobulin (Ig)G, and secretory IgA against FanC. The IgG2a and IgG1 titer assays revealed that immunization highly induced IgG2a compared to that of IgG1, indicating that T helper-1- related cell-mediated immune responses may be elicited by JOL950. The results show that both systemic and mucosal immunities against selected fimbrial antigens of bovine ETEC expressed by a live attenuated S. Typhimurium strain are prominently produced in mice immunized with JOL950 via an oral route.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.517-525
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• 2023

다제내성 P. aeruginosa (MRPA)의 출현과 확산은 전 세계적으로 심각한 문제가 되었다. 특히 metallo-β-lactamases (MBLs)의 carbapenem 고도내성 관여 정도는 심각한 수준이며, 특히 P. aeruginosa는 장내세균 속 균종과는 달리 새로운 클론들이 지속적으로 나타나고 기존에 확산되었던 우세 클론을 대체하는 과정이 매우 빠르게 진행되고 있다. 이에 본 연구에서는 2017년 9월부터 2019년 9월까지 부산의 한 종합병원에서 다양한 의료용 시료로부터 분리된 18균주의 P. aeruginosa 균주에 대한 항균제 내성 유전자 분석과 DNA 염기서열 분석을 통한 Integron의 유전자 카세트 분석 및 접합에 의한 Plasmid 전달 분석을 수행하며 이에 대한 역학관계를 조사하고자 하였다. 18균주 모두 XDR 표현형을 보이는 균주였으며, Colistin(100%)을 제외한 대부분의 항생제에 내성을 나타냈으나, aztreonam(22.2%), ceftazidime(16.6%)에 일부 감수성을 보였다. 균주의 66.7%는 다양한 항균제 내성을 나타내는 Class1 integron을 가지고 있었으며, 접합에 의한 Plasmid전달도 성공적으로 이루어졌다(83.3%). 이는 이전의 장내세균에 대한 연구결과보다 25.8% 상향한 결과를 보여 공중보건에 대한 심각한 역학관점의 고찰을 필요로 한다. 특히, IMP-6 ST235 (66.7%)가 주를 이루며, VIM-2 ST357 (16.7), IMP-1 ST446 (16.7)이 확인되었다. 흥미롭게도, 국내에서는 아직까지 보고된 바가 없는 IMP-1 생성 ST446의 확인은 또 다른 MRPA 고위험 클론의 생성과 유행이라는 관점에서 주목할 만하다.