• Biomedical Science Letters
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• v.13 no.4
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• pp.293-304
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• 2007

The emergence of extended spectrum $\beta$-lactamase (ESBL) producing bacteria is worldwide concern. Until recently, the most frequently identified strains in the Republic of Korea were E. coli and Klebsiella spp. The incidence of resistance to extended spectrum $\beta$-lactam antibiotics is increasing in Wonju city, Korea. Total 57 strains of ESBL producing E. coli and Klebsiella species were isolated from Wonju Christian Hospital during a 9 month-period from April to December, 2003. To determine the prevalence and genotypes of the ESBL producing clinical isolates, antibiotic susceptibility and ESBL activity test by VITEK system and double disk synergy (DDS) test, and PCR based genotyping were performed. Fourteen (82%) isolates of 17 ESBL producing E. coli were found to have $bla_{TEM}$ gene and 5 (29%) isolates were found to have $bla_{CTX-M}$ gene by polymerase chain reaction (PCR). Thirty (75%) isolates of 40 ESBL producing Klebsiella species with $bla_{TEM}$ gene, 38 (95%) isolates with $bla_{SHV}$ gene, and 7 (20%) isolates with $bla_{CTX-M}$ type gene were also identified. Enterobacterial repetitive intergenic consensus (ERIC) PCR and similarity index by dendrogram for genetical similarity to band pattern of each clinical isolates were examined. ESBL producing E. coli were grouped into 6 clusters up to 84% of similarity index and Klebsiella species were grouped into 12 clusters up to 76% of similarity index. In conclusion, ESBL producing clinical isolates were characterized with the results from antimicrobial resistance pattern and genetical similarity using ERiC PCR.

• Journal of Microbiology and Biotechnology
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• v.2 no.1
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• pp.35-40
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• 1992

The influence of the nature of plasmids on fermentation parameters such as cell growth, cell viability, plasmid stability, and product formation has been investigated using E. coli M5248 and its recombinant derivatives M5248 [pBR322], M5248[pAS1], and M5248[pNKM21]. At a low temperature ($30^\circ{C}$), the cell growth, cell viability, and protein synthesis of the recombinants were nearly identical to those of the host cell. However, at high temperature ($42^\circ{C}$), in which transcription from the P_L$ promoter is derepressed, the recombinant cells showed decreased stability along with lower growth rates and cell viability. The ratio of total protein to cell mass was in the order of E. coli M5248>M5248[pBR322]>M5248[pAS1]>M5248[pNKM21]. It was found that transcription from the $P_L$ promoter adversely affect the plasmid maintenance and host cell metabolism even in the absence of the cloned-gene expression. Furthermore, profiles of ${\beta}$ activity were shown to vary with recombinant strains. E coli M5248[pBR322] showed highest ${\beta}-lactamase$ activity at $30^\circ{C}$, while at $42^\circ{C}\;{\beta}-lactamase$ activity was significantly reduced irrespective of the strains. The effect of the plasmid properties on plasmid-encoded gene expression has been further examined based on the relationship between $\{beta}-lactamase$ activity and plasmid-harboring cell numbers.

• 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.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.339-345
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• 2008

This study was to detect MBL (metallo-${\beta}$-lactamase) among glucose non-fermenting Gram-negative bacilli isolated from clinical specimen and to search antimicrobial combination therapy against MBL producing Pseudomonas aeruginosa. Among fifty one isolates of Gram-negative bacilli with reduced imipenem susceptibility ($MIC{\ge}8{\mu}g/ml$), nine isolates have shown positive results in MBL detection test. They were seven Achromobacter xylosoxidans subsp. xylosoxidans and two P. aeruginosa. The results from EDTA-DDST coin-cided with those of PCR and nucleotide sequence analysis which showed the presence of $bla_{VIM-2}$. The combination of aztreonam (AZT) and piperacillin-tazobactarn (TZP) or AZT and amikacin (AN) screened by one disk synergy test showed no synergistic effect. Triple antibiotic combination therapy with AZT, TZP and AN, however, was shown to be effective and the most synergistic after 8 hrs of exposure. This result strongly suggest that the triple combination therapy of AZT, TZP, and AN could be useful for the treatment of infection caused by MBL producing Gram-negative bacilli.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.162-162
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• 1996

새로 합성된 6-exomethylene penamsulfone derivatives 7종에 대해 In Vitro antibacterial activities를 Broth Microdilution법으로 Sulbactam-Na(SAM), Clavulanic acid-K(CLA)와 Cefotaxime-Na(CFT), Ampicillin Trihydrates(AMP), Amoxicillin-Na(AMX), Cefoperazone(CFZ)을 병용투여하여 $\beta$-lactamase 생성 균주(30 여종)에 실시, MIC를 구하였다. 균주에 따라 SAM, CLA에 비해 CH1145, CH1155 등이 우수한 효과를, CH1140, CH2150등이 유사한 효과를 보였다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.159-159
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• 1996

6-Substituted exomethylene 기를 갖는 penam계 화합물이 $\beta$-lactamase 억제제로서 강력한 활성을 보여주고 있어서, 6-exomethylene기 도입에 필요한 1-substituted thioalkyl-1,2,3-triazole-4-carboxaldehyde를 합성하였다. Haloalkanol에 NaN$_3$를 반응시켜서 합성한 azidoalkanol과 propargyl alcohol을 산화시킨 propargyl aldehyde를 반응시켜서 1-(2-hydroxyalkyl-1,2,3-triazole-4-carboxaldehyde을 얻었다. 이것을 trifluoromethanesulfonic anhydride와 triethylamine 존재 하에 mercapto 화합물과 반응시켜서 목적물을 합성하였다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.236-236
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• 1996

DA-1131은 IPM이 D2 channel 특이적인 세포외막투과성을 나타내는 것과는 달리 D2 channel 이외에 azthreonam 투과경로도 이용하는 것으로 확인되었다. IPM 감수성 및 내성인 P aeruginosa 균주들에 대하여 $\beta$-lactamase의 inducible activity, hydrolytic susceptibility, affinity를 측정한 결과, Inducible activity는 DA-1131, PPM 및 MEPM이 거의 동일하였으며, 3가지 약물 모두 가수분해에 대한 안정성을 나타내었다. 그러나 $\beta$-lactamase에 대한 affinity는 IPM이 가장 컸고, MEPM, DA-1131의 순으로 감소하였다. DA-1131은 P8P2와 PBP3를 동시에 저해하며, IPM은 PBP2의 저해 후 순차적으로 PBP3를 저해하였고 이러한 시험결과는 PBPs blinding pattern과 밀접한 관계가 있는 것으로 알려진 균형태변화로도 확인되었다.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.3
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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.

• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.129-134
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• 1992

Segregational instability of a recombinant plasmid, pDML6, encoding extracellular $\beta$-lactamase in Streptomyces lividans PD6 was characterized by growth kinetic analysis. The quantitative determination of the plasmid harbored in the mycelia was evaluated with mycelia fragmented mechanically, and also with colonies regenerated from protoplasts. Conditions for the formation of protoplasts and regeneration of protoplasts were established. The maximal specific growth rates of the host strain and the plasmid-harboring strain in a chemically defined medium without selection pressure were the same. The probability of plasmid loss from the harbouring cells was higher at higher growth rates. Mathematical models for the prediction of cell growth, substrate uptake, and accumulation of the cloned gene product were developed.

• YAKHAK HOEJI
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• v.45 no.2
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• pp.140-146
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• 2001

The synthesis of new 6-exomethylene penams with triazole ring for $\beta$-lactamase inhibitor was described. The 6,6-dibromopenam 6 was treated with $CH_3$MgBr and carbaldehyde 5 to afford the 6-bromo-6-(1-hydroxy-1-methyl)penicillanate 7, which was reacted with acetic anhydride to give acetoxy compound 8. The deacetoxybromination of 8 with zinc and acetic acid gave 6-exomethylenepenams, Z-isomer 9 and E-isomer 10, which were oxidized to sulfones 11 and 12 by m-CPBA. The p-methoxybenzyl compounds 9~12 were deprotected by AIC1$_3$and neutralized to give the sodium salts 13~16.