• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1837-1840
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• 2006

Because there are no unified nomenclature systems for either GES-type or IBC-type extended-spectrum ${\beta}-lactamases$ (ESBLs), we propose a unified and definitive nomenclature system for GES/IBC-type ESBLs. This proposed nomenclature update is greatly helpful in two points: (i) it would not confuse microbiologists studying GES-type ESBLs, fundamentally preventing misleading nomenclature of these antibiotic resistance genes, and (ii) the definitive renaming of GES/IBC-type ESBLs can help some researchers to correctly designate new GES-type ESBLs such as novel enzymes identified trom some nationwide surveys.

• 대한임상검사과학회지
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• 제38권3호
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• pp.173-178
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• 2006

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) is the main mechanism of bacterial resistance to third-generation cephalosporins and monobactams, whose prevalence varies depending on the different geographical areas. In the last years it has increased notably to the point of being considered a health problem of great importance. The characterization of the ESBLs producing Klebsiella penumoniae strains present in clinical isolates is time-consuming. I describe here the development of a new system, which consists of a multiplex PCR. I found 51 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disc synergy test showed 47 positive K. pneumoniae, which were K. pneumoniae isolates. All ESBLs producing K. pneumoniae strains were resistant to antibiotic amikacin, gentamicin and ciprofloxacin. By multiplex PCR analysis, $bla_{TEM}$ gene in 17 strains 44 $bla_{SHV}$ genes and $bla_{CTX}$ genes in 33 strains were identified. In this study, the multiplex polymerase chain reaction (PCR) assay was a good method to detect and differentiate ESBLs producing K. penumoniae strains in clinical isolates.

• 대한임상검사과학회지
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• 제41권4호
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• pp.153-157
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• 2009

The production of extended-spectrum ${\beta}$-lactamases ($ESBL_S$) of the TEM or SHV type by bacterial pathogens is a major threat to the use of the clinically important expanded-spectrum cephalosporins. The characterization of the SHV ESBLs producing Klebsiella pneumoniae strains present in clinical isolates is time-consuming processes. We describe here in the development of a novel system, which consists of a real time PCR. We found 11 K. pneumoniae strains to be presumptive strains ESBLs producers by clinical and laboratory standards institute (CLSI) guidelines. The double disk synergy test showed 8 ESBL positive and conventional PCR showed 10 SHV ESBL positive, which were K. pneumoniae strains isolates. By real time PCR analysis, SHV gene in 11 of 11 strains were identified. When sequencing analysis was compared with real time PCR, both analysis were presented 99% similarity. In this study, we used a rapid, sensitive, and specific real-time PCR (RT-PCR) method for detection of the assay SHV ESBL producing K. pneumoniae strains in clinical isolates.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2009년도 International Meeting of the Microbiological Society of Korea
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• pp.68-69
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• 2009

• 대한임상검사과학회지
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• 제39권3호
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• pp.161-166
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• 2007

To develop a rapid and reliable single-tube-based PCR technique for detection simultaneously the quinolone resistance qnrA, qnrB and qnrS genes. After multiple alignment, primers were designed to detect known qnr variants. I was used for A total of 43 extented-spectrum ${\beta}$-lactamases (ESBLs) producing Escherichia coli and Klebsiella pneumoniae isolated from university hospital were tested for screening, as with qnr genes. In optimized conditions, all positive controls confirmed the specificity of the PCR primers. Out of 43 isolates, qnrA genes were detected 19 (44.2%), qnrB genes 5 (11.7%), qnrS genes 15 (34.9%) and 8 (18.6%) isolates were not detected. I report here a fast and reliable technique for rapid screening of qnr positive strains to be used for epidemiological surveys.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2295-2302
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• 2014

장내세균 가운데서 가장 빈번하게 나오는 대장균에서 Extended-Spectrum ${\beta}$-Lactamase(ESBL)를 생성하는 효소의 검출빈도와 이들 균주의 ESBL 효소의 유형을 구분하는 것이 이 연구의 목적이다. 균주는 충청지역 (대전, 충남, 충북)병원에서 2013년 2월부터 7월까지 6개월간 282 대장균 균주 중 ESBL을 생성하는 74균주(26.2%)를 수집하였다. 충청지역에 ESBL 균주를 포함한 대장균의 항균제 내성률은 Aztreonam 30.8%, Cefotaxim 30.9%, 그리고 Ceftazidime 32.2%로 나타났으며 ESBL을 생성하는 균주는 ${\beta}$-lactam 항균제인 Aztreonam에 58.1%, Cefotaxim 100%, 그리고 Ceftazidime 63.5%의 내성률을 보였다. 동정된 ESBL 균의 CTX-M-2은 48 균주, CTX-M-8은 20 균주, PER-1 28 균주, 그리고 VEB-1 26 균주에서 나왔다. GES-1 형은 74균주 중 2균주가 충남에서만 유일하게 나타났다. ESBL 검출빈도와 유형의 정확한 파악은 병원감염관리와 항균제 처방에 도움이 될 것이다.

• 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 Microbiology and Biotechnology
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• 제22권1호
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• pp.25-33
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• 2012

The association of verotoxic E. coli and Acinetobacter spp. with various antibiotic-resistant, diarrhogenic, and nosocomial infections has been a cause for concern worldwide. E. coli and A. haemolyticus isolated on a number of selective media were screened for virulence factors, antibiotic resistance, and transformation of resistance genes. Out of 69 E. coli isolates obtained, 25 (35.23%), 14 (20.30%), and 28 (40.58%) were positive for Vtx1&2, Vtx1, and Vtx2, respectively, 49 (71.015%) for extendedspectrum beta-lactamases (ESBLs), 34 (49.28%) for serum resistance, 57 (82.61%) for cell surface hydrophobicity, 48 (69.57%) for gelatinase production, and 37 (53.62%) for hemolysin production. For the 14 A. haemolyticus isolates, only 2 (14.29%) in each case from all the samples investigated were positive for Vtx1, Vtx2 and Vtx1&2 respectively, 8 (57.14%) for ESBLs, 7 (50.00%) for serum resistance, 11 (78.57%) for cell surface hydrophobicity, 4 (28.57%) for gelatinase production, and 8 (57.14%) for hemolysin production. Although transformation occurred among the E. coli and Acinetobacter isolates (transformation frequency: $13.3{\times}10^{-7}-53.4^{-7}$), there was poor curing of the plasmid genes, a confirmation of the presence of stable antibiotic-resistant genes (DNA concentration between 42.7 and 123.8 ${\mu}g$) and intragenetic transfer of multidrug-resistant genes among the isolates. The isolates were potentially virulent and contained potentially transferable antibiotic resistance genes. Detection of virulence factors, antibiotic resistance genes, and transformation among these isolates is a very significant outcome that will influence approaches to proactive preventive and control measures and future investigations. However, continued surveillance for drug resistance among these bacteria and further investigation of the mechanism of action of their virulence factors are a necessity.

• 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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• 제34권4호
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• pp.342-351
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• 2006

병원내 항생제 다제 내성을 일으키는 CTX-M형 ESBL을 생성하는 E. coli와 Klebsielia pneumoniae의 생성현황을 조사하고 이들 균주로 인한 감염증치료와 역학적 조사연구에 도움이 되고자 효소의 유전형을 규명하였다. 2005년 7월-12월에 부산에 소재하고 있는 2개의 종합병원에서 분리된 E. coli와 K. pneumoniae 각각 153주, 52주를 수집하였다. 그 중에서 ESBL을 생성 하는 균주를 검출하기 위해 Double disk synergy test를 시행하여서 E. coli 23주와 K. pneumoniae 13주를 분리하였다. 균주의 동정은 Vitek system GNI card(bioMerieux Vitek Inc., Hazelwood, Mo., U.S.A.)로 확인하였고, 항생제감수성시험은 disk diffusion method 와 agar dilution method를 사용하였다. 분리된 균주들의 내성을 일으키는 ESBL유전형을 규명하기 위하여 Isoelectric focusing(IEF), polymerase chain reaction test, DNA sequencing을 시행하였다. A병원의 13주와 B병원의 10주로 총 23주의 E. coli(15.0%)와 A병원의 7주와 B병원의 6주로 K. pneumoniae 13주(25.0%)가 double disk synergy test 양성으로 ESBL 생성균주로 판정하였다. ESBL 생성 36균주를 대상으로 bla$_{TEM}$, bla$_{SHV}$, bla$_{CTX-M}$ 유전자 검출을 위한 PCR을 시행한 결과 bla$_{TEM}$ 유전자는 13주(36.1%), bla$_{SHV}$ 유전자는 13주(36.1%), bla$_{CTX-M}$ 유전자는 32주(88.9%)가 양성반응을 보여서 bla$_{CTX-M}$ 유전자를 가진 균주가 가장 많이 나타났다. 그리고, bla$_{TME}$, bla$_{SHV}$ 두 가지 유전자를 가지고 있는 균주는 1주(2.8%)만 나타났고 bla$_{TEM}$, bla$_{CTX-M}$두 가지 유전자를 가지고 있는 균주는 9주(25.0%), bla$_{SHV}$, bla$_{CTX-M}$ 두 가지 유전자를 가지고 있는 균주가 10주(27.8%)로 나타나 bla$_{CTX-M}$을 포함하는 복합유전자가 많이 증가함을 알 수 있었다. 또한 CTX-M형 ESBL을 생성하는 E. coli와 K. pneumoniae에 대한 cefutaxime의 MIC는 256 $\mu$g/m1 이상으로 ceftazidime의 16-256 $\mu$g/mL 이상보다 높은 분포를 보였다. 즉, CTX-M형 ESBL 유전자를 지닌 균주에 대한 cefotaxim의 MIC는 ceftazidime의 MIC에 비해서 상대적으로 높은 양상을 보였다. 이러한 결과는 국내의 대학병원 뿐 만 아니라 일반종합병원에서도 CTX-M형 ESBL 생성 E. coli와 K. pneumoniae가 존재하며 확산 중임을 시사한다. 앞으로 CTX-M형 ESBL의 만연과 변종 CTX-M형 ESBL의 출연을 감시하기 위한 정기적인 연구와 조사가 필요한 것으로 생각한다.