• Journal of Digital Convergence
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• v.13 no.12
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• pp.313-318
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• 2015

We investigated the prevalence of extended spectrum ${\beta}$-lactamase (ESBL) genes and 16S rRNA methyltransferase genes to study antimicrobial resistance mechanisms of Enterobacter cloacae strains isolated from a university hospital in the Chungcheong province of Korea. Eight of the bacteria strains involved in this study contained CTX-M-15 type ESBL. Among 8 strains harboring the ESBL gene, 3 strains also harbored armA gene. The three isolates showed resistance to antimicrobial agents belonged to third cephalosporin, aminoglycoside, and fluoroquinolones. Furthermore, interspecies plasmid transfer of the antimicrobial resistant genes may induced horizontal spreading of the genes and emergence of multidrug resistant bacteria. Therefore, surveillance for existence of antimicrobial resistance determinants is important to prevent distribution of antimicrobial resistant strains.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2295-2302
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• 2014

The study aims primarily to evaluate the resistance of antibiotics and the prevalence of these enzymes among Escherichia coli the most frequent isolate of Enterobacteriaceae producing Extended-Spectrum ${\beta}$-Lactamase(ESBLs), to differentiate the types of enzymes in these isolates. Total 74(26.2%) Strains of producing ESBLs among the 282 E. coli isolates were isolated from hospitals of Chungcheong area (Daejeon, Chungnam, and Chungbuk) during a 6 month-period from February to July, 2013. 282 E. coli isolates including ESBL shown resistance rates of aztreonam 30.8%, Cefotaxim 30.9%, and Ceftazidime 32.2%, 74 isolates producing ESBLs in E. coli were resistant rates to Aztreonam 58.1%, Cefotaxim 100%, and Ceftazidime 63.5% of ${\beta}$-lactam antibiotics. CTX-M-2 (48 isolates) was the most prevalent type of ESBLs identified. Followed the order of frequency by PER-1 (28 isolates), VEB-1 (26 isolates) and CTX-M-8 (20 isolates), of the 74 isolates, 2 isolates only showed GES-1 in Chungnam province. Accurate identification type of ESBLs would aid in hospital infection control. This would give aid to the physician to prescribe more appropriate antibiotics.

• Pediatric Infection and Vaccine
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• v.22 no.1
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• pp.29-35
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• 2015

Purpose: The purpose of this study was to investigate the clinical characteristics and outcome of febrile urinary tract infections (UTIs) caused by community-acquired extended-spectrum ${\beta}$-lactamase (CA-ESBL)-producing and -nonproducing bacteria. Methods: We analyzed febrile UTIs in children hospitalized at Gachon University Gil Medical Center from January 2011 to December 2013 through retrospective data collection from their medical records. Results: Among pathogens causing 374 episodes of UTIs, the proportion of ESBL-producing bacteria was 13.1% (49/374). The proportion of ESBL-producing Escherichia coli and Klebsiella spp. was 13.6% (48/354) and 5.0% (1/20), respectively. There was no significant difference between the CA-ESBL and CA non-ESBL groups in duration of fever ($4.2{\pm}2.7$ vs. $3.7{\pm}2.1$ days, P=0.10) and bacterial eradication rate with empirical antibiotics (100% vs. 100%). The risk of cortical defects on renal scan significantly depended on existence of vesicoureteral reflux rather than ESBL production of pathogen. Conclusions: There was no significant difference between the CA-ESBL and CA non-ESBL groups in renal cortical defects and clinical outcome. Careful choice of antibiotics is important for treatment of community-acquired UTI in children.

• Journal of Life Science
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• v.23 no.5
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• pp.703-709
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• 2013

The aim of this study was to investigate the prevalence of Extended-spectrum ${\beta}$-lactamase (ESBL) gene and quinolone resistance determinant (qnr) and the pattern of antibiotic resistance in the ESBL-producing Escherichia coli clinical isolates. The 42 ESBL-producing strains from total 274 isolates were detected using a double disk synergy test. They were isolated from various specimens, such as urine (28 strains), sputum (6 strains), pus (3 strains), wound (2 strains), blood (2 strains), and tissue (1 strain). Using the PCR with the specific primers ESBL, ESBL and qnr gene types were determined. Thirty-five strains possessed one or two ESBL genes. CTX-M-1 type was the most abundant followed by CTX-M-9 type and TEM, but SHV, CTX-M-2, and CTX-M-8 gene types were not detected. qnr gene types were detected from ten isolates in the order of qnrB4, qnrB1, and qnrS. Coexistence of ESBL and qnr genes was found. ESBL-producing isolates showed high resistance against some antibiotics, such as cefotaxmie (80.0%), levofloxacin (82.9%), and ampicillin (100%). Neither a synergy effect from the coexistence of ESBL and qnr genes on antibiotic resistance nor a correlation between the production of qnr gene and quinolone resistance were found.

• Journal of Life Science
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• v.19 no.12
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• pp.1718-1723
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• 2009

In this study, we characterized extended-spectrum $\beta$-lactamase (ESBL)-producing Enterobacteriaceae isolated from clinical specimens in Korea and found two strains harboring plasmid-mediated $bla_{SHV-11}$, Klebsiella pneumoniae. First, the isolates were detected using the Vitek system and confirmed by the double-disk synergy test. The classification of gene coding for ESBL was also performed by polymerase chain reactions and followed by DNA sequencing. The transmission of genes was confirmed by transconjugation and transformation. Resistant expression of transformants was determined by broth microdilution minimal inhibitory concentration test. Genotypic analysis revealed that one strain harbored the $bla_{TEM-1}$, $bla_{SHV-11}$ and $bla_{CTX-M-15}$ and the other strain harbored the $bla_{SHV-11}$ and $bla_{CTX-M-15}$. They showed high resistance to oxyiminocephalosphorins (3rd-generation cephalosporins), while the transformant containing only $bla_{SHV-11}$ did not show any resistance to the antibiotics.

• Biomolecules & Therapeutics
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• v.7 no.1
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• pp.44-53
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• 1999

The resistant strains due to the extended-spectrum $\beta$-lactamase (ESBL) were susceptible to cefatrizine combined with clavulanic acid. The purpose of this study was to evaluate the in vitro and in vivo antibacterial activities of cefatrizine/clavulanic acid (CTRZ/CV) combination at a ratio of 2 : 1 in comparison with cefaclor (CCLO), cefuroxime (CRXM), cefuroxime axetil (CRXMA) and amoxicillin/clavulanic acid (AMXCCV). CTRZ/CV showed good activity against laboratory strains of gram-positive and gram-negative bacteria and exhibited excellent antibacterial activity against $\beta$-lactamase-producing strains. The bactericidal activity of CTRZ/CV was superior to that of CCLO and CRXM, and almost equal to that of AMXCCV against the $\beta$-lactamase-producing strains. The in vitro results were substantiated. by in vivo mouse experimental infection studies with $\beta$-lactamase-producing and non-producing strains. In mixed experimental infection due to $\beta$-lactamase-producing and non-producing strains, the therapeutic efficacy of CTRZ/CV was superior to that of CTRZ, CCLO, CRXMA and AMXCCV. In respiratory tract infection in mice due to Klebsiella pneumoniae EB4O, CTRZ/CV was more erective than CCLO, CRXMA and AMXCCV and also more efficacious than CCLO, CRXMA and AMXCCV in urinary tract infection in mice due to Escherichia coli EB13. These results indicate that CTRZ/CV is a useful drug for the treatment of infection caused by $\beta$-1actamase-producing strains including ESBL-producing strains.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.237-237
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• 1996

DA-1131, imipenem(IPM) 및 meropenem(MEPM)은 각종 $\beta$-lactamase를 산생하는 세균에 대하여 우수한 항균력을 나타내었으나 cefpirome(CPR), ceftazidime(CAZ) 및 azthreonam(AZT)의 경우에는 extended broad spectrum cephalosporinase 산생 균주를 포함하여 일부 균주의 내성획득이 확인되었다. DA-ll3l의 $\beta$-lactamase Inducible activity는 DA-1131, IPM 및 MEPM이 거의 동일하였으며, imipenemase 산생균주로 동점된 Serratia marcescens 11001이 산생하는 $\beta$-lactamase이외의 효소에는 대부분 가수분해되지 않는 결과를 나타내었다. S. marcescens 11001이 산생하는 $\beta$-lactamase에 대한 효소역학상수는 DA-1131, IPM 및 MEPM에서 모두 유사하였고, $\beta$-lactamase에 대한 affinity도 큰 차이를 나타내지 않았다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1191-1196
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• 2013

Among Gram-negative pathogens in Korea, the incidence of resistance to third generation cephalosporins is becoming an ever-increasing problem. The production of extended-spectrum ${\beta}$-lactamase (ESBL) is the main mechanism of bacterial resistance to a third-generation cephalosporins and monobactams. Accurate identification of the ESBL genes are necessary for surveillance and epidemiological studies of the mode of transmission in the hospital. This study was conducted to detect the genes encoding ESBL of 46 K. penumoniae isolated from Daejeon, Chungnam and Chungbuk regional university hospitals from February to August in 2012. The phenotypes of the isolated specimens were examined according to the combination disc test (CDT) by the Clinical and Laboratory Standards Institute (CLSI). Forty two ESBL producing K. penumoniae isolates could be detected using ceftazidime (CAZ) discs with and without clavulanate (CLA). By CDT, 42 K. pneumoniae strains were confirmed to be ESBL strains. Genotyping was performed by multiplex PCR with type-specific primers. By PCR analysis, TEM gene in 46 strains, SHV gene in 37 strains and CTX-M genes in 14 strains were identified. Ten isolates did carry genes encoding ESBLs of all types TEM, SHV and CTX-M. The multiplex polymerase chain reaction (PCR) analysis was better to detect and differentiate ESBL producing K. penumoniae strains in clinical isolates.

• Journal of Microbiology and Biotechnology
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• v.16 no.11
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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.