To evaluate the comparative activity of seven oral antimicrobial agents against 100 strains of Streptococcus pneumoniae (S pneumoniae) Methods Total 100 strains of S pneumoniae were collected from gener...To evaluate the comparative activity of seven oral antimicrobial agents against 100 strains of Streptococcus pneumoniae (S pneumoniae) Methods Total 100 strains of S pneumoniae were collected from general hospitals in Beijing from June 1996 to June 1997 E test method was used to detect the minimum inhibitory concentration (MIC) values of the following seven drugs against S pneumoniae : penicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, ceftriaxone, azithromycin and ofloxacin The breakpoint of susceptibility categories was defined according to NCCLS Results 74% of isolates were susceptible (S, MIC 0 06?mg/L) to penicillin, and 5% were penicillin resistant (R, MIC 2?mg/L). The intermediately resistant (I, MIC 0 1-1?mg/L) rate to penicillin was 21% The total rates of R or I were 26% for penicillin, 6% for both amoxicillin/clavulanate and ceftriaxone, 9% for cefuroxime, 66% and 68% for azithromycin and ofloxacin respectively Overall 94%, 94% and 91% of the pneumococcal isolates were susceptible to amoxicillin/clavulanate, ceftriaxone and cefuroxime respectively S pneumoniae was highly resistant to azithromycin tested as a representative of macrolides (MIC 50 and MIC 90 both >256?mg/L, R rate 66%), and had a highly intermediately resistant rate to ofloxacin (I rate 62%) Conclusions Our data suggest that in vitro activity of oral amoxicillin/clavulanate was as good as ceftriaxone and cefuroxime It can be considered as an alternative compound in the treatment of community acquired pneumoniae and other respiratory tract infections caused by multiresistant S pneumoniae展开更多
本文对青霉素扩环酶(Penicillin expandase,也称Deacetoxycephalosporin C synthase,DAOCS)在高浓度青霉素G下的底物抑制现象进行初步评价与表征,筛选适合工业应用条件的高活力突变体。我们通过HPLC对已报道的几个DAOCS高活力突变体在...本文对青霉素扩环酶(Penicillin expandase,也称Deacetoxycephalosporin C synthase,DAOCS)在高浓度青霉素G下的底物抑制现象进行初步评价与表征,筛选适合工业应用条件的高活力突变体。我们通过HPLC对已报道的几个DAOCS高活力突变体在青霉素G浓度5.6至500 mmol/L间的比活力进行定量测定,并与不同催化反应动力学模型的理论推测变化趋势比较,发现DAOCS野生型酶及高活力突变体H4、H5、H6与H7在高浓度青霉素G条件下均表现出明显的底物抑制现象,但是变化趋势不同。野生型酶与突变体H4的比活力先上升后下降,与竞争性抑制模型预测不符。突变体H5、H6与H7的比活力变化呈现更复杂的变化趋势。在所有测试的突变体中,H6的活性显著高于其他突变体酶。青霉素G对野生型DAOCS的底物抑制现象符合非竞争性抑制模型的预测。而部分突变体表现出复杂的底物抑制行为,表明其具有更复杂的作用机制。在高底物浓度下筛选具有较强催化活性的青霉素扩环酶突变体对于推动其在工业生产中的应用具有重要指导作用。展开更多
The effects of penicillin potassium salt （PenK） on the solubility, Krafft temperature TK, critical micelle concentration CMC of SDS micelle and the phase behavior of SDS/n-C5H11OH/H2O system were studied. The partia...The effects of penicillin potassium salt （PenK） on the solubility, Krafft temperature TK, critical micelle concentration CMC of SDS micelle and the phase behavior of SDS/n-C5H11OH/H2O system were studied. The partial phase diagrams of SDS/PenK/H2O system at different temperatures were determined. The release amounts of PenK in SDS/n-C5H11OH/H2O system and the distribution coefficient of PenK between micelle and water were measured by UV-Vis spectroscopy. The results show that in the presence of PenK, the CMC of SDS was decreased while the TK of SDS was increased and the solubility of SDS in both water and SDS/n-C5H11OH/H2O oil in water （O/W） microemulsion was decreased, but increased in water in oil （W/O） microemulsion. SDS micelles and SDS/n- C5H11OH/H20 O/W microemulsion could accelerate the release rate of PenK. The addition of SDS and water could both increase the release rate of PenK, whereas the presence of n-C5H11OH reduced the release rate of PenK. The above results were related to the electrostatic repulsion between PenK and SDS.展开更多
文摘To evaluate the comparative activity of seven oral antimicrobial agents against 100 strains of Streptococcus pneumoniae (S pneumoniae) Methods Total 100 strains of S pneumoniae were collected from general hospitals in Beijing from June 1996 to June 1997 E test method was used to detect the minimum inhibitory concentration (MIC) values of the following seven drugs against S pneumoniae : penicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, ceftriaxone, azithromycin and ofloxacin The breakpoint of susceptibility categories was defined according to NCCLS Results 74% of isolates were susceptible (S, MIC 0 06?mg/L) to penicillin, and 5% were penicillin resistant (R, MIC 2?mg/L). The intermediately resistant (I, MIC 0 1-1?mg/L) rate to penicillin was 21% The total rates of R or I were 26% for penicillin, 6% for both amoxicillin/clavulanate and ceftriaxone, 9% for cefuroxime, 66% and 68% for azithromycin and ofloxacin respectively Overall 94%, 94% and 91% of the pneumococcal isolates were susceptible to amoxicillin/clavulanate, ceftriaxone and cefuroxime respectively S pneumoniae was highly resistant to azithromycin tested as a representative of macrolides (MIC 50 and MIC 90 both >256?mg/L, R rate 66%), and had a highly intermediately resistant rate to ofloxacin (I rate 62%) Conclusions Our data suggest that in vitro activity of oral amoxicillin/clavulanate was as good as ceftriaxone and cefuroxime It can be considered as an alternative compound in the treatment of community acquired pneumoniae and other respiratory tract infections caused by multiresistant S pneumoniae
文摘本文对青霉素扩环酶(Penicillin expandase,也称Deacetoxycephalosporin C synthase,DAOCS)在高浓度青霉素G下的底物抑制现象进行初步评价与表征,筛选适合工业应用条件的高活力突变体。我们通过HPLC对已报道的几个DAOCS高活力突变体在青霉素G浓度5.6至500 mmol/L间的比活力进行定量测定,并与不同催化反应动力学模型的理论推测变化趋势比较,发现DAOCS野生型酶及高活力突变体H4、H5、H6与H7在高浓度青霉素G条件下均表现出明显的底物抑制现象,但是变化趋势不同。野生型酶与突变体H4的比活力先上升后下降,与竞争性抑制模型预测不符。突变体H5、H6与H7的比活力变化呈现更复杂的变化趋势。在所有测试的突变体中,H6的活性显著高于其他突变体酶。青霉素G对野生型DAOCS的底物抑制现象符合非竞争性抑制模型的预测。而部分突变体表现出复杂的底物抑制行为,表明其具有更复杂的作用机制。在高底物浓度下筛选具有较强催化活性的青霉素扩环酶突变体对于推动其在工业生产中的应用具有重要指导作用。
基金ProJect supported by the National Natural Science Foundation of China （No. 20233010）.
文摘The effects of penicillin potassium salt （PenK） on the solubility, Krafft temperature TK, critical micelle concentration CMC of SDS micelle and the phase behavior of SDS/n-C5H11OH/H2O system were studied. The partial phase diagrams of SDS/PenK/H2O system at different temperatures were determined. The release amounts of PenK in SDS/n-C5H11OH/H2O system and the distribution coefficient of PenK between micelle and water were measured by UV-Vis spectroscopy. The results show that in the presence of PenK, the CMC of SDS was decreased while the TK of SDS was increased and the solubility of SDS in both water and SDS/n-C5H11OH/H2O oil in water （O/W） microemulsion was decreased, but increased in water in oil （W/O） microemulsion. SDS micelles and SDS/n- C5H11OH/H20 O/W microemulsion could accelerate the release rate of PenK. The addition of SDS and water could both increase the release rate of PenK, whereas the presence of n-C5H11OH reduced the release rate of PenK. The above results were related to the electrostatic repulsion between PenK and SDS.
