15 results on '"De-mei Zhu"'
Search Results
2. Pharmacokinetics and Pharmacodynamics of Nemonoxacin against Streptococcus pneumoniae in an In Vitro Infection Model
- Author
-
Xiao-fang Liu, Qing-lan Guo, Yuran Cao, Shujing Zhang, Jiali Hu, Yingyuan Zhang, Yuancheng Chen, Wang Liang, Jing Zhang, Xiaojie Wu, Jun Huang, Miao Zhao, and De-mei Zhu
- Subjects
medicine.drug_class ,Colony Count, Microbial ,Drug resistance ,Microbial Sensitivity Tests ,Biology ,Pharmacology ,Quinolones ,medicine.disease_cause ,Pneumococcal Infections ,Microbiology ,chemistry.chemical_compound ,Pharmacokinetics ,Streptococcus pneumoniae ,Drug Resistance, Bacterial ,medicine ,Pharmacology (medical) ,Quinolone ,medicine.disease ,Anti-Bacterial Agents ,Bacterial Typing Techniques ,Penicillin ,Pneumococcal infections ,Infectious Diseases ,chemistry ,Pharmacodynamics ,Nemonoxacin ,medicine.drug - Abstract
The aim of this paper was to investigate the pharmacokinetics (PK) and pharmacodynamics (PD) of nemonoxacin, a novel nonfluorinated quinolone, against Streptococcus pneumoniae in vitro . A modified infection model was used to simulate the pharmacokinetics of nemonoxacin following scaling of single oral doses and multiple oral dosing. Four S. pneumoniae strains with different penicillin sensitivities were selected, and the drug efficacy was quantified by the change in log colony counts within 24 h. A sigmoid maximum-effect ( E max ) model was used to analyze the relationship between PK/PD parameters and drug effect. Analysis indicated that the killing pattern of nemonoxacin shows a dualism which is mainly concentration dependent when the MIC is low and that the better PK/PD index should be the area under the concentration-time curve for the free, unbound fraction of the drug divided by the MIC ( f AUC 0–24 /MIC), which means that giving the total daily amount of drug as one dose is appropriate under those conditions. When the MIC is high, the time ( T ) dependency is important and the valid PK/PD index should be the cumulative percentage of a 24-h period in which the drug concentration exceeds the MIC under steady-state pharmacokinetic conditions ( f % T >MIC), which means that to split the maximum daily dose into several separate doses will benefit the eradication of the bacteria. To obtain a 3-log 10 -unit decrease, the target values of f AUC 0–24 /MIC and f % T >MIC are 47.05 and 53.4%, respectively.
- Published
- 2013
3. Activities of colistin- and minocycline-based combinations against extensive drug resistant Acinetobacter baumannii isolates from intensive care unit patients
- Author
-
Jian Li, Jing Zhang, De-mei Zhu, Wang Liang, Xiao-fang Liu, and Jun Huang
- Subjects
Acinetobacter baumannii ,Time Factors ,Minocycline ,Drug resistance ,Microbial Sensitivity Tests ,Biology ,Pharmacology ,Meropenem ,Polymerase Chain Reaction ,Microbiology ,lcsh:Infectious and parasitic diseases ,Minimum inhibitory concentration ,Drug Resistance, Multiple, Bacterial ,medicine ,polycyclic compounds ,Humans ,lcsh:RC109-216 ,Microbial Viability ,Colistin ,Drug Synergism ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,bacterial infections and mycoses ,DNA Fingerprinting ,Anti-Bacterial Agents ,Molecular Typing ,Intensive Care Units ,Infectious Diseases ,Parasitology ,Thienamycins ,Rifampin ,Rifampicin ,medicine.drug ,Acinetobacter Infections ,Research Article - Abstract
Background Extensive drug resistance of Acinetobacter baumannii is a serious problem in the clinical setting. It is therefore important to find active antibiotic combinations that could be effective in the treatment of infections caused by this problematic 'superbug'. In this study, we analyzed the in vitro activities of three colistin-based combinations and a minocycline-based combination against clinically isolated extensive drug resistant Acinetobacter baumannii (XDR-AB) strains. Methods Fourteen XDR-AB clinical isolates were collected. The clonotypes were determined by polymerase chain reaction-based fingerprinting. Susceptibility testing was carried out according to the standards of the Clinical and Laboratory Standards Institute. Activities of drug combinations were investigated against four selected strains and analyzed by mean survival time over 12 hours (MST12 h) in a time-kill study. Results The time-kill studies indicated that the minimum inhibitory concentration (MIC) of colistin (0.5 or 0.25 μg/mL) completely killed all strains at 2 to 4 hours, but 0.5×MIC colistin showed no bactericidal activity. Meropenem (8 μg/mL), minocycline (1 μg/mL) or rifampicin (0.06 μg/mL) did not show bactericidal activity. However, combinations of colistin at 0.5×MIC (0.25 or 0.125 μg/mL) with each of the above were synergistic and shown bactericidal activities against all test isolates. A combination of meropenem (16 μg/mL) with minocycline (0.5×MIC, 4 or 2 μg/mL) was synergitic to all test isolates, but neither showed bactericidal activity alone. The MST12 h values of drug combinations (either colistin- or minocycline-based combinations) were significantly shorter than those of the single drugs (p < 0.01). Conclusions This study indicates that combinations of colistin/meropenem, colistin/rifampicin, colistin/minocycline and minocycline/meropenem are synergistic in vitro against XDR-AB strains.
- Published
- 2010
4. [Pay attention to detection of drug-resistant genes in bacteria so as to improve the anti-infection ability]
- Author
-
De-Mei, Zhu and Xiao-Gang, Xu
- Subjects
Anti-Infective Agents ,Genes, Bacterial ,Drug Resistance, Bacterial - Published
- 2008
5. [Mechanisms of pandrug-resistance of Pseudomonas aeruginosa]
- Author
-
Ji-lu, Shen, De-mei, Zhu, and Ming-gui, Wang
- Subjects
DNA, Bacterial ,Sequence Homology ,Microbial Sensitivity Tests ,Sequence Analysis, DNA ,Quinolones ,Polymerase Chain Reaction ,beta-Lactam Resistance ,Aminoglycosides ,Hexosaminidases ,Anti-Infective Agents ,Bacterial Proteins ,DNA Topoisomerases, Type I ,Drug Resistance, Multiple, Bacterial ,Mutation ,Pseudomonas aeruginosa ,Humans - Abstract
To explore the mechanisms of pandrug-resistance (PDR) of Pseudomonas aeruginosa (PA).Nineteen strains of PA were collected from Huashan Hospital, Shanghai. Agar dilution method was used to detect the levels of minimum inhibitory concentration (MIC) of 14 antimicrobial drugs to the PA strains. Strain homology was investigated by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). To analyze the beta-lactam resistant mechanisms, genes of extended-spectrum beta-lactamases (ESBLs), carbapenemase, and plasmid-mediated AmpC were amplified and analyzed by PCR and DNA sequencing. To analyze the aminoglycoside resistant mechanisms, 16 aminoglycoside modifying enzyme were screened by PCR. PCR and DNA sequencing were used to amplify and analyze the genes of DNA gyrase genes gyrA and gyrB, topoisomerase IV genes parC and pare, and qnr gene for the fluoroquinolone resistance mechanisms, to amplify and analyze study the oprD2 coding genes and inhibitor MC207110 were used to detect efflux pump for the carbapenem resistance mechanisms.Five types were identified in the 19 PDR-PA by ERIC-PCR, mainly type A (n=6) and type B (n=7). 17 of the 19 PDR-PA strains produced VEB-3 type ESBL, 1 strain of which also produced OXA-10 type ESBL simultaneously. Both of the carbapenemase and plasmid-mediated AmpC were negative. All of the 19 PDR-PA strains produced aminoglycoside modifying enzyme, yielding ant (3") I and 18 strains of which produced aac (3) II simultaneously. All 19 PDR-PA strains carried gyrA mutations, 14 of which carried parC mutation simultaneously, qnr gene was negative. OprD2 coding gene sequencing analysis revealed that small fragment missing occurred to all oprD2 genes of the 19 strains. 16 strains showed efflux pump mechanism.The resistance mechanism of PDR-PA to cephalosporins, beta-lactam/beta-lactamase inhibitor, carbapenem, fluoroquinolones, and aminoglycosides are due to production of VEB-3-ESBL, aac (3) II, and ant (3") I aminoglycoside modifying enzyme, mutations of DNA gyrase gyrA and topoisomerase parC gene, OprD2 protein deficiencies, and efflux pump overexpression.
- Published
- 2008
6. [Changes of antimicrobial resistance among clinical isolates of Escherichia coil in Shanghai 1990-2004]
- Author
-
Ying-yuan, Zhang, De-mei, Zhu, Fu-pin, Hu, Shi, Wu, and Fu, Wang
- Subjects
China ,Drug Resistance, Bacterial ,Escherichia coli ,Humans ,Bacterial Infections ,Microbial Sensitivity Tests ,Anti-Bacterial Agents - Abstract
To investigate the trend of resistance to antimicrobial agents among clinical isolates of Escherichia coli 1990-2004.Agar diffusion test was used to analyze the changes of drug susceptibility of 33,495 strains of E. coli isolated from 11 hospitals in Shanghai to 21 antimicrobial agents 1990-2004.The resistance rates of 33,495 E.coli isolates to 21 antimicrobial agents mostly increased 1990-2004. The resistance rates to ampicillin and piperacillin increased from 69% and 30% to 85% and 71.4% respectively. The resistance rates to cephalosporins, except ceftazidime and cefepime, all increased, e. g., the resistance rates to cefazolin (24.0%--48.3%), cefuroxime (18.0%--45.7%), and cefaclor (33.3%--46.8%), especially that to cefotaxime (6.0%--35.2%). The resistance rate to fluoroquinolones increased from 11.0% to 55.4%. The resistance rate to gentamicin increased from 44.0% to 54.0%. The resistance rates to tetracycline, chloramphenicol, SMZ/TMP remained at high levels. However, ceftazidime, cefepime, imipenem, amikacin, beta-lactams/beta-lactamase inhibitors, and nitrofurantoin remained active against the E.coli isolates. The detectable rate of extended-spectrum beta-lactamase-producing strains in E. coli increased from 14.7% to 36.5%.The trend of resistance of E. coli to commonly used antimicrobials was upward 1990-2004.
- Published
- 2006
7. CTX-M-14, CTX-M-24 and resistance in Escherichia coli and Klebsiella pneumoniae clinical isolates
- Author
-
Zi-zhong, Xiong, De-mei, Zhu, Fu, Wang, and Ying-yuan, Zhang
- Subjects
Klebsiella pneumoniae ,Base Sequence ,Conjugation, Genetic ,Drug Resistance, Bacterial ,Molecular Sequence Data ,Escherichia coli ,Humans ,Microbial Sensitivity Tests ,Transformation, Bacterial ,Polymerase Chain Reaction ,beta-Lactamases ,Electrophoresis, Gel, Pulsed-Field - Published
- 2006
8. [Study of pharmacokinetics/pharmacodynamics of levofloxacin]
- Author
-
Jing, Zhang, Ji-cheng, Yu, Yao-guo, Shi, Le, Zhou, Xin-yu, Ye, De-mei, Zhu, and Ying-yuan, Zhang
- Subjects
Adult ,Male ,Humans ,Bacterial Infections ,Levofloxacin ,Microbial Sensitivity Tests ,Anti-Bacterial Agents - Abstract
To evaluate the dosing regimens of levofloxacin.The drug concentrations in serum and urine were assayed by HPLC method and the pharmacokinetic parameters were calculated after intravenous infusion of a single dose of 200 mg, 300 mg and 500 mg levofloxacin to healthy volunteers. The in vitro activity MIC of levofloxacin against 823 clinical isolates were determined and compared with other antimicrobial agents. Based on the above results, the PK/PD parameters C(max)/MIC and AUC/MIC were calculated and the dosing regimens of levofloxacin were proposed for infections caused by different pathogens.The results of clinical pharmacokinetic study showed that the C(max) of levofloxacin was 3.4 mg/L +/- 0.8 mg/L, 4.8 mg/L +/- 1.4 mg/L and 7.6 mg/L +/- 1.1 mg/L respectively, AUC(0-infinity) was 14.4 mg.h/L +/- 2.5 mg.h/L, 21.9 mg.h/L +/- 4.5 mg.h/L and 38.3 mg.h/L +/- 4.9 mg.h/L respectively, T(1)/2 beta was 6.2 h +/- 0.4 h, 6.4 h +/- 0.9 h and 6.5 h +/- 0.6 h respectively, and 69% +/- 5%, 69% +/- 6%, and 65% +/- 4% of the doses were excreted in urine within 24 h after intravenous infusion of a single dose of levofloxacin 200 mg, 300 mg and 500 mg. The in vitro pharmacodynamic study showed that levofloxacin was highly active against Hemolytic streptococcus and Moraxella catarrhalis. It was active against Streptococcus pneumoniae (including penicillin nonsusceptible strains), Hemophilus influenzae, methicillin-sensitive Staphylococcus aureus (MSSA), Klebsiella pneumoniae and Stenotrophomonas maltophilia. Levofloxacin also had good activity against Pseudomonas aeruginosa and K.pneumoniae. However, most of isolates of enterococcal spp. were resistant to levofloxacin. Above 50% of Escherichia coli isolates were resistant to levofloxacin. Based on the results of PK/PD parameters, the adequate dosing regimens of levofloxacin should be once daily 200 mg once daily of levofloxacin was expected to be effective for the treatment of infections caused by M. catarrhalis. The regimen of 300 mg once daily could be effective for the treatment of infections caused by Hemolytic streptococcus. 500 mg once daily of levofloxacin was expected to be effective for the treatment of respiratory tract infections caused by S. pneumoniae or H. influenzae. For treatment of respiratory tract infections and urinary tract infections caused by levofloxacin-susceptible organisms including K. pneumoniae, E. coli, P. aeruginosa, and S.maltophilia, 500 mg once daily of levofloxacin was needed to obtain good clinical efficacy. But PK/PD parameters predicted that 500 mg daily of levofloxacin was not effective for infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and Enterococci.The proposed dosing regimens of levofloxacin based on PK/PD concepts are expected to provide good efficacy in clinical practice.
- Published
- 2005
9. [Identification and expression of blaCTX-M-14 and blaCTX-M-24]
- Author
-
Zi-Zhong, Xiong, De-Mei, Zhu, Fu, Wang, and Ying-Yuan, Zhang
- Subjects
DNA, Bacterial ,Klebsiella pneumoniae ,Genes, Bacterial ,Drug Resistance, Bacterial ,Escherichia coli ,Humans ,Cefotaxime ,Escherichia coli Infections ,beta-Lactam Resistance ,beta-Lactamases ,Anti-Bacterial Agents ,Klebsiella Infections - Abstract
To identify the ESBL gene and the prevalence in Escherichia coli and Klebsiella pneumoniae strain isolated from Huashan Hospital, Shanghai.Isolates were confirmed as an ESBL producing strain by double-disk synergy test and NCCLS Confirmatory Test. Antibiotic susceptibilities were determined by standard agar dilution procedure on Mueller-Hinton agar. To determine whether the resistance was transferable, the conjugation experiment was performed; plasmids were isolated from clinical isolates and transcojugants. The partial bla(gene) of ESBL producing isolates and their transcojugants were detected by PCR using universal primers for TEM, SHV, CTX-M-1group, Toho-1group, CTX-M-13group respectively. The entire bla(CTX-M-13) group were amplified by PCR using the primers outside the Open Reading Frame (ORF) of CTX-M-13group beta-lactamases; the PCR products of entire bla(CTX-M-13)group were cloned into vector and the recombinant plasmids were transformed into the recipient strain for expression; the PCR products were also directly sequenced and analyzed; the clinical isolates of ESBL producers were detected by PFGE.ESBL producers were resistant to most beta-lactams and non-beta-lactams. Most transconjugants were obtained at frequency of 10(-4) approximately 10(-5) and resistance to non-beta-lactams was cotransferred with the ESBL activity to the transconjugant. A plasmid of about23.1 kb was obtained from each tansconjugant by plasmid extraction. Partial gene amplification products of CTX-M-13 group gene were obtained from isolates and their transconjugants. The bla(CTX-M-13)group from 4 transconjugants were identified as bla(CTX-M-14), and other six were bla(CTX-M-24); those ESBLs were mediated by plasmids (23.1 kb); the transformants producing CTX-M-14 or CTX-M-24 were resistant to most beta-lactams, which were much more resistant to cefotaxime than to ceftazidine; PFGE patterns of those isolates were different.clinical isolate of Escherichia coli and Klebsiella pneumoniae isolated from Huashan Hospital, Shanhai produced CTX-M-14 or CTX-M-24, which caused the isolate resistant to most beta-lactams; no clone spread in those isolates was found.
- Published
- 2004
10. Uptake of ciprofloxacin in methicillin-resistant Staphylococcus aureus
- Author
-
Yong-le Wu, Yu-qing Wang, Yong-xin Zhang, and De-mei Zhu
- Subjects
Staphylococcus aureus ,business.industry ,Pharmacology toxicology ,MEDLINE ,Drug Resistance, Microbial ,Drug resistance ,Microbial Sensitivity Tests ,medicine.disease_cause ,Methicillin-resistant Staphylococcus aureus ,Methicillin resistance ,Microbiology ,Anti-Bacterial Agents ,Ciprofloxacin ,Pharmacotherapy ,DNA Topoisomerases, Type II ,Anti-Infective Agents ,medicine ,Pharmacology (medical) ,Methicillin Resistance ,business ,medicine.drug - Published
- 1995
11. In Vitro Antibacterial Activity of Levofloxacin
- Author
-
Yingyuan Zhang, Fu Wang, Jing-de Zhang, De-mei Zhu, and Le Zhou
- Subjects
Ofloxacin ,Bacteria ,business.industry ,Pharmacology toxicology ,Levofloxacin ,Microbial Sensitivity Tests ,Pharmacology ,In vitro ,Pharmacotherapy ,Anti-Infective Agents ,Medicine ,Pharmacology (medical) ,business ,Antibacterial activity ,medicine.drug - Published
- 1995
12. Surveillance of Bacterial Resistance to Quinolones
- Author
-
De-mei Zhu, Fu Wang, and Yu-qing Wang
- Subjects
medicine.medical_specialty ,Pharmacotherapy ,Antibiotic resistance ,business.industry ,Pharmacology toxicology ,Medicine ,Pharmacology (medical) ,business ,Intensive care medicine - Published
- 1993
13. Activities of colistin- and minocycline-based combinations against extensive drug resistant Acinetobacter baumannii isolates from intensive care unit patients.
- Author
-
Wang Liang, Xiao-fang Liu, Jun Huang, De-mei Zhu, Jian Li, and Jing Zhang
- Subjects
DRUG resistance ,ACINETOBACTER infections ,POLYMERASE chain reaction ,INTENSIVE care units ,RIFAMPIN - Abstract
Background: Extensive drug resistance of Acinetobacter baumannii is a serious problem in the clinical setting. It is therefore important to find active antibiotic combinations that could be effective in the treatment of infections caused by this problematic 'superbug'. In this study, we analyzed the in vitro activities of three colistin-based combinations and a minocycline-based combination against clinically isolated extensive drug resistant Acinetobacter baumannii (XDR-AB) strains. Methods: Fourteen XDR-AB clinical isolates were collected. The clonotypes were determined by polymerase chain reaction-based fingerprinting. Susceptibility testing was carried out according to the standards of the Clinical and Laboratory Standards Institute. Activities of drug combinations were investigated against four selected strains and analyzed by mean survival time over 12 hours (MST
12 h ) in a time-kill study. Results: The time-kill studies indicated that the minimum inhibitory concentration (MIC) of colistin (0.5 or 0.25 μg/ mL) completely killed all strains at 2 to 4 hours, but 0.5xMIC colistin showed no bactericidal activity. Meropenem (8 μg/mL), minocycline (1 μg/mL) or rifampicin (0.06 μg/mL) did not show bactericidal activity. However, combinations of colistin at 0.5xMIC (0.25 or 0.125 μg/mL) with each of the above were synergistic and shown bactericidal activities against all test isolates. A combination of meropenem (16 μg/mL) with minocycline (0.5xMIC, 4 or 2 μg/mL) was synergitic to all test isolates, but neither showed bactericidal activity alone. The MST12 h values of drug combinations (either colistin- or minocycline-based combinations) were significantly shorter than those of the single drugs (p < 0.01). Conclusions: This study indicates that combinations of colistin/meropenem, colistin/rifampicin, colistin/minocycline and minocycline/meropenem are synergistic in vitro against XDR-AB strains. [ABSTRACT FROM AUTHOR]- Published
- 2011
- Full Text
- View/download PDF
14. Coexistence of qnrB4 and qnrS1 in a clinical strain of Klebsiella pneumoniae.
- Author
-
Fu-pin Hu, Xiao-gang Xu, De-mei Zhu, and Ming-gui Wang
- Subjects
KLEBSIELLA pneumoniae ,QUINOLONE antibacterial agents ,PLASMIDS ,METABOLIC conjugation ,GENES ,DNA - Abstract
Aim: To identify the location and the relationship, and to analyze the genetic background of 2 plasmid-mediated quinolone resistance genes, qnrB4 and qnrS1, carried by a clinical strain of Klebsiella pneumoniae ( K pneumoniae). Methods: The plasmids carrying qnrB4 or qnrS1 were identified by Southern blotting. A HindIII fragment containing qnrB4 or qnrS1 was cloned into plasmid puc18 and sequenced. Results: qnrB4 and qnrS1 were located on 2 different plasmids, pHS7 and pHS8, and were 180 and 45 kb in size, respectively. A transconjugant carrying plasmid pHS7 bearing qnrB4 and another transconjugant carrying pHS9 bearing qnrB4 and qnrS1 were obtained by conjugation. Plasmid pHS8 bearing qnrS1 was also transferred to J53 by transformation. The ciprofoxacin minimal inhibitory concentrations (MIC) for J53 transconjugants or the transformant carrying qnrB4 only, qnrS1 only, and both qnrB4 and qnrS1 were 0.19, 0.25, and 0.25 mg/L, respectively, while the parent clinical strain of K pneumoniae had a MIC of 0.75 mg/L. qnrB4 was located in a sul1-type integron with blaDHA-1, ampR and psp genes in upstream and insertion sequence IS26, and sap genes in downstream of qnrB4. qnrS1 was not located in an integron, but IS26 was found both upstream and downstream, and IS2 was found directly upstream of qnrS1. Conclusion: qnrB and qnrS can be harbored simultaneously by a single clinical strain of K pneumoniae. These 2 genes are carried by 2 different plasmids and have different genetic environments in plasmid DNA structure. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
15. Resistance Mechanism of MRSA to Quinolones
- Author
-
Yong-xin Zhang, De-mei Zhu, Fu Wang, Mayumi Tanaka, Yasuaki Osada, and Kenichi Sato
- Subjects
Pharmacotherapy ,Mechanism (biology) ,business.industry ,Pharmacology toxicology ,Medicine ,Pharmacology (medical) ,Pharmacology ,business - Published
- 1993
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.