• YAKHAK HOEJI
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• v.39 no.2
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• pp.131-136
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• 1995

Clinically isolated bacterial strains resistant to almost of all the clinically superior .betha.-lactam antibiotics can be used to screen the promising ones among the newly synthesized $\beta$-lactam antibiotics. To select the resistant strains, the susceptibility of 389 strains of S. aureus, 144 strains of coagulase negative staphylococci, 509 strains of E. coli, 115 strains of E. cloacae and 187 strains of P. aeruginosa to methicillin, ampicillin, piperacillin and gentamicin was determined. The susceptibility of 19 bacterial strains selected through the first screening to cefixime, cefotiam, cefotaxime, flomoxef, cepfirome, cefdnir, SCE-2787, panipenem and imipenem was determined. Four strains of S. aureus finally selected have high degree of resistance to almost of all $\beta$-lactam antibiotics used and also produce $\beta$-lactamases. These 4 strains of S. aurues can be used to screen effectively the promising $\beta$-lactam antibiotics among the numerous numbers of the newly synthesized $\beta$-lactam antibiotics.

• YAKHAK HOEJI
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• v.28 no.1
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• pp.25-27
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• 1984

Some $\betha$-lactam antibiotics-penicillins and cephalosporins-were determined by gas chromatography (GC) with flame photometric detector (FPD) which was selective and sensitive to sulfur-containing compounds. Methyl ester derivatives of carboxyl group in $\betha$-lactam antibiotics were prepared using 0.5Mmethyl iodide in methylene chloride and were taken for gas chromatography with 0.9% or 0.6% QF-1 on Chromosorb WAW-DMCS. We have found that it is possible to determine methyl esters of $\betha$-lactam antibiotics by GC/FPD.

• Biomolecules & Therapeutics
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• v.31 no.2
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.

• Korean Journal of Veterinary Research
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• v.43 no.1
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• pp.113-120
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• 2003

The antimicrobial effect of ${\beta}$-lactam antibiotics, which had ${\beta}$-lactamase inhibitor activity, on Staphylococcus aureus isolated from mastitis was investigated in this study. Out of 166 isolates, 99 isolates (59.6%) produced ${\beta}$-lactamase, and 98 isolates of 99 were ${\beta}$-lactamase positive in above $12.5{\mu}g/m{\ell}$ MIC of penicillin. In the providence distribution, ${\beta}$-lactamase production rate of 4 providence, Gangwon, Gyeonggi, Chungcheong, and Jeolla was 100%, 65.7%, 58.8%, and 50.0%, respectively. Antibiotic activities of ${\beta}$-lactam antibiotics against lactamase positive isolates also were investigated. Antimicrobial effects of ampicillin/sulbactam or amoxicillin/clavulanic acid treated group were better than ampicillin or amoxicillin treated group. In antimicrobial effects on intracellular S aureus, there was no difference 1 hour and 4 hour treatment in control, ampicillin, and amoxicillin group, but in 18 hours treatment, ampicillin/sulbactam or amoxicillin/clavulanic acid had a better effect than ampicillin or amoxicillin (p<0.05).

• Fisheries and Aquatic Sciences
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• v.19 no.10
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• pp.45.1-45.5
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• 2016

As a novel strategy to remove ${\beta}$-lactam antibiotic residues from fish tissues, utilization of ${\beta}$-lactamase, enzyme that normally degrades ${\beta}$-lactam structure-containing drugs, was explored. The enzyme (TEM-52) selectively degraded ${\beta}$-lactam antibiotics but was completely inactive against tetracycline-, quinolone-, macrolide-, or aminoglycoside-structured antibacterials. After simultaneous administration of the enzyme with cefazolin (a ${\beta}$-lactam antibiotic) to the carp, significantly lowered tissue cefazolin levels were observed. It was confirmed that the enzyme successfully reached the general circulation after intraperitoneal administration, as the carp serum obtained after enzyme injection could also degrade cefazolin ex vivo. These results suggest that antibiotics-degrading enzymes can be good candidates for antibiotic residue depuration.

• Bulletin of the Korean Chemical Society
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• v.10 no.2
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• pp.185-190
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• 1989

Geometries for a number of representative ${\beta}$ -lactam antibiotics (penams, cephems and monobactams) have been calculated by computer graphics/molecular mechanics energy minimization procedures using both MM2 and AMBER force fields. The calculated geometries have been found in reasonable agreement with the geometries reported in the X-ray crystal structures, especially in terms of the pyramidal character of the amide nitrogen in the ${\beta}$-lactam ring and the Cohen distance. Based on these calculations, it is suggested that the nitrogen atom in the monobactams may also have pyramidal geometries in the biologically active conformations.

• Journal of Life Science
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• v.8 no.6
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• pp.723-728
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• 1998

Bacillus subtilis J105, high resistant bacteria against $\beta$-lactam antibiotics, become higher resistant through induction of $\beta$--lactamase in the presence of $\beta$--lactam antibiotics. When there is no antibiotics in medium, the production of resistance-inductive $\beta$--lactamase reached its plateau 15 hours later. But when there is ampicillin (500$\mu\textrm{g}$/$m\ell$) in medium, the production of enzyme reached its plateau 25 hours later since cultivating bacteria, whereas it is found that enzyme 2,900 units/$m\ell$ about 20 times as much as compared with not-presence of antibiotics was actived. In addition, as the result of MIC comparing applying ampicillin-treated and non-treated strain MIC of ampicillin-treated strain is about 2~27 times higher. It is considered that this strain induce $\beta$--lactamase production by ampicil-lin-treatment, then increasing it resistance. It is found that this resistant strain induce $\beta$--lactamase production against cephalosporin antibiotics as well as peni-cillin. As the result of examining the time of adding antibiotics for each phase of growth, it is concluded that logarith-mic phase is the most effective. As the aboves, it is suggested that this strain is a peculia strain that its resistance is induced high by various $\beta$--lactam antibiotics.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.698-706
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• 2004

$\beta$-Lactam antibiotics such as penicillin G, amoxicillin, and ampicillin were determined by a potentiometric biosensor system which exploited penicillinase immobilized on Immobilon cellulose nitrate membrane and a flat-bottomed pH electrode-as the biological component and transducer. The optimum reaction buffer for maximum sensitivity was found as 2 mM of sodium phosphate buffer (pH 7.2). The detection limit of the biosensor could be extended to 1 $\mu{M}$ of the analytes by increasing the enzyme loading for immobilization to 100 units/$m\ell$. The model samples spiked with each of the standard penicillins were measured for their biosensor responses and HPLC peak area, resulting in the relative responses of 82.1-103.5% and 79.5-106.1% for the biosensor method along with HPLC analysis, respectively. This result showed a good precision of the current biosensor method for screening the penicillin compounds.

• Journal of Yeungnam Medical Science
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• v.27 no.1
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• pp.8-17
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• 2010

It is important to select appropriate antimicrobials for the treatment of infection according to the results of antimicrobial susceptibility tests (ASTs), yet the clinical isolates are sometimes susceptible to antibiotics that are clinically ineffective or this is due to technical error of the ASTs. So, interpretive reading of ASTs is needed and especially for the ${\beta}$-lactams for treating $Enterobacteriacae$. This review describes the interpretive reading of ASTs according to natural antimicrobial resistance and the mechanisms of mechanisms, with giving special attention to the antibiotics phenotypes for $Enterobacteriacae$. Further, as all the diffent tissues have a different antimicrobial concentration for identical antimicrobials, more information is needed on the antimicrobial tissue distribution for the appropriate treatment of infection. (ED note: I hope you send me the paper.)

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.75-79
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• 1991

A series of compounds, N-(2-substituted-1-carboxy)vinylazetidinones were successfully synthesized in order to test the hypothesis that biological activities of ${\beta}$-lactam antibiotics could be attributed to the smooth flow of electrons after a nucleophilic attack at the carbonyl carbon in the ${\beta}$-lactam ring. After introduction of aminothiazolylacetamido group at 3-position of the azetidinones, their biological activities were evaluated. Their low activities led to the conclusion that the smooth electron flow in ${\beta}$-lactams in not the sufficient source for the biological activities.