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카테콜 치환체를 가진 세파로스포린계 항생제 LB10522의 작용기전
김무용,오정인,백경숙,김인철,곽진환,Kim, Mu-Yong,Oh, Jeong-In,Paek, Kyoung-Sook,Kim, In-Chull,Kwak, Jin-Hwan 대한약학회 1996 약학회지 Vol.40 No.1
LB10522 is a new parenteral broad spectrum cephalosporin with a catechol moiety at C-7 position of beta-lactam ring. This compound can utilize tonB-dependent iron transp ort system in addition to porin proteins to enter bacterial periplasmic space and access to penicillin-binding proteins (PBPs) which are the lethal targets of ${\beta}$-lactam antibiotics. The chelating activity of LB10522 to metal iron was measured by spectrophotometrically scanning the absorbance from 200 to 900nm. When $FeCl_3$ was added, optical density was increased between 450 and 800nm. LB10522 was more active against gram-negative strains in iron-depleted media than in iron-replete media. This is due to the increased expression of iron transport channels in iron-depleted condition. LB10522 showed a similar activity against E. coli DC2 (permeability mutant) and E. coli DCO (wild type strain) in both iron-depleted and iron-replete media, indicating a minimal permeaility barrier for LB10522 uptake. LB10522 had high affinities to PBP 3 and PBP 1A, 1B of E. coli. By blocking these proteins, LB10522 caused inhibition of cell division and the eventual death of cells. This result was correlated well with the morphological changes in E. coli exposed to LB10522. Although the in vitro MIC of LB10522 against P. aeruginosa 1912E mutant (tonB) was 8-times higher than that of the P. aeruginosa 1912E parent strain, LB10522 showed a similar in vivo protection efficacy against both strains in the mouse systemic infection model. This result suggested that tonB mutant, which requires a high level of iron for normal growth, might have a difficulty in surviving in their host with an iron-limited environment.
새로운 플루오로퀴놀론계 항생제 LB20304a가 생쥐의 맹장내 세균총에 미치는 영향
안미정(Mi Jeong Ahn),백경숙(Kyoung Sook Paek),김무용(Mu Yong Kim),김인철(In Chull Kim),곽진환(Jin Hwan Kwak) 대한약학회 1996 약학회지 Vol.40 No.3
The influence of LB20304a, a new fluoroquinolone antibiotic agent, on microflora of caecum in mice was compared with those of ciprofloxacin and piperacillin after administration of drugs for 5 days. Selective medium (CCFMA) was used for the isolation of Clostridium difficile from the specimens of mouse caecum. The emergence of C. difficile in mouse caecum induced by LB20304a was lower than that by ciprofloxacin or piperacillin at day 1 and day 7 after completing administration of drugs.
3 세대 세파계 항생제에 내성인 임상균주의 분포와 PCR 법을 이용한 TEM type beta-lactamase 생산균주의 동정
김무용(Mu Yong Kim),오정인(Jeong In Oh),송혜경(Hye Kyong Song),백경숙(Kyoung Sook Paek),곽진환(Jin Hwan Kwak) 대한약학회 1995 약학회지 Vol.39 No.3
Compared to the first-and second-generation cephalosporins, the third-generation cephalosporins are remarkably stable against hydrolysis by the beta-lactamases produced by aerobic gram-negative bacilli, such as Enterobacteriaceae. Among these bacteria, the most prevalent plasmid-encoded beta-lactamase is TEM-1 beta-lactamase belonging to class A or group 2b. This enzyme is produced constitutively and is principally active against penicillins and old cephalosporins rather than third-generation cephalosporins, carbapenems and monobactams. However, new TFM type beta-lactamases including TEM-9 and TEM-12 evolved through point mutations in a gene encoding beta-lactamase have been discovered from patients during chemotherapy. These beta-lactamases are known to be capable of hydrolyzing most of the third-generation cephalosporins. To study the prevalence of beta-lactamases from clinical isolates collected in Korea, the minimal inhibitory concentrations(MICs) of several third- generation cephalosporins against 628 clinical isolates were determined by agar dilution methods, and beta-lactamase-producing bacteria were isolated by use of cefinase disc. By polymerase chain reaction(PCR) method, clinical isolates harboring a gene for TEM type beta-lactamase were identified among the beta-lactamase producing strains. Twenty three percent of the clinical isolates was resistant to the third-generation cephalosporins, and more than 90% of resistant cells produced various beta-lactamases. TEM type beta-lactamases were dominant in gram-negative bacilli, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter species. These results suggest the necessity of the development of new cephalosporins which are stable against beta-lactamases like TEM.
생쥐의 호흡기 감염에 대한 퀴놀론계 항생제 LB20304a의 치료 효과
안미정(Mi Jeong Ahn),김무용(Mu Yong Kim),백경숙(Kyoung Sook Paek),김인철(In Chull Kim),곽진환(Jin Hwan Kwak) 대한약학회 1996 약학회지 Vol.40 No.4
The therapeutic activity of LB20304a was examined on experimental respiratory tract infection (RTI) caused by Klebsiella pneumoniae DT-S in mice. A single oral dose of LB20304a (1.2mg/mouse) showed a rapid bacteriocidal activity in lung tissue at 4,7 and 24h after administration of drug. The in vivo activity of LB20304a was comparable to that of ciprofloxacin against K. pneumoniae infection, although in vitro MIC of LB20304a was four-fold higher than that of ciprofloxacin.