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Objective: To evaluate various types of samples from the different marine environments as sources of actinomycetes from the Yalujiang coastal wetland, North China, and to screen their antimicrobial properties. Further, the identified actinomycetes were characterized based on morphological, biochemical, and physiological characteristics. Methods: Eight different production media were used to isolate actinomycetes from different stations of marine soil sediments in Yalujiang coastal wetland and the genotypic positions were established by 16S rDNA. Results: A total of 172 actinomycetal isolates were obtained from 13 samples using five media. The most effective culture media in the isolation of actinobacteria were Gause's Synthetic agar and Starch-casein agar. Among 172 isolates, 46 isolates (26.74%) showed antibacterial activity, 70.93% belonged to the genus Streptomyces, others were Micromonospora spp. and Rhodococcus spp. Out of the 46 isolates, two cultures were further supported by morphological characterization analysis. Conclusions: This is the first report about actinomycetes isolated from Yalujiang coastal wetland and it seems that the promising isolates from the unusual/unexplored wetland may prove to be an important step in the development of microbial natural product research.
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Objective To evaluate the efficacy and safety of therapeutic drug monitoring (TDM ) based vancomycin dose adjustment in patients with gram‐positive infections .Methods A cohort study was designed with 128 inpatients undergoing TDM in Huashan Hospital from January 2005 to September 2014 .The clinical data of these patients were used to analyze the efficacy and safety of vancomycin therapy by Cox model and survival analysis .Results The patients undergoing TDM‐based dose adjustment had a higher daily dose and blood trough concentration ,which may lead to better bacteriological efficacy and overall efficacy .Cox proportional hazards model analysis showed that TDM‐based dose adjustment is a protective factor .No safety‐related risk factor was found .Conclusions TDM‐based vancomycin dose adjustment is important for patients to achieve better outcomes in fighting gram‐positive infections .
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Objective:To evaluate various types of samples from the different marine environments as sources of actinomycetes from the Yalujiang coastal wetland, North China, and to screen their antimicrobial properties. Further, the identified actinomycetes were characterized based on morphological, biochemical, and physiological characteristics. Methods:Eight different production media were used to isolate actinomycets from different stations of marine soil sediments in Yalujiang coastal wetland and the genotypic positions were established by 16S rDNA. Results:A total of 172 actinomycetal isolates were obtained from 13 samples using five media. The most effective culture media in the isolation of actinobacteria were Gause’s Synthetic agar and Starch-casein agar. Among 172 isolates, 46 isolates (26.74%) showed antibacterial activity, 70.93%belonged to the genus Streptomyces, others were Micromonospora spp. and Rhodococcus spp. Out of the 46 isolates, two cultures were further supported by morphological characterization analysis. Conclusions: This is the first report about actinomycetes isolated from Yalujiang coastal wetland and it seems that the promising isolates from the unusual/unexplored wetland may prove to be an important step in the development of microbial natural product research.
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Objective To establish and validate an ultra performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS)method for quantification of MRX-I,a new oxazolidinone antibacterial agent,in human plasma and urine.Methods Chromatographic separation was performed on a Waters ACQUITY UPLC BEH C8 column using an isocratic elution.The mo-bile phase consisted of acetonitrile and water (40∶60,v/v).Quantitative analysis was conducted in the multiple reaction moni-toring mode.Linezolid was used as an internal standard.Liquid-liquid extraction with ethyl acetate was used to remove impuri-ties in the plasma and urine samples.The method was validated in terms of matrix effect,recovery,precision,accuracy and stability.Results The calibration curves were linear within the range of 0.005 00-1 .00 mg/L.The lower limit of quantification was 0.005 00 mg/L for both plasma and urine samples.Retention time was less than 1 .5 min for both MRX-I and internal standard in plasma and urine.The ma-trix effect factors of plasma and urine for MRX-I was 90.4%±8.2% and 82.7%±7.9%,respectively.The recovery of MRX-I was 112.8% ± 13.4% from plasma and 105.6% ± 13.4% from urine samples,respectively.The inter- and intra-day accuracy of MRX-I was 98.9%-105.0% and 96.5%-102.6% in plasma samples,and 92.7%-98.6% and 95.1 %-105.7% in urine samples.MRX-I was stable for 24 h at room tem-perature,48 h in automatic sampler after pretreatment,and stable after 3 freeze-thaw cycles in plasma and urine.MRX-I was also stable at-40℃for eight months in plasma and six months in urine,respectively.Conclusions The UPLC-MS/MS method established in this study shows high sensitivity and specificity for determination of MRX-I in human plasma and urine.The re-sults of validation are consistent with the requirement of bioanalytical method validation.
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ObjectiveTo investigate the clinical pharmacokinetics (PK) and pharmacodynamics (PD) of gemifloxacin tablet in healthy Chinese volunteers and to provide evidences for optimal clinical dosing.MethodsTwenty volunteers were enrolled in the randomized (1∶1) double-blind study,and divided into administration group and control group.Each group received multiple oral doses of 320 mg of gemifloxacin tablet or placebo.The plasma and urine samples for gemifloxacin were analyzed by igh-performance liquid chromatogram(HPLC)-fluorometricmethod. Theminimuminhibition concentrations (MIC)of gemifloxacin against190clinical isolateswere determinedby broth microdilution method.The fAUC0～24 h/MIC and fCmax/MIC,with target value of 25 and 5,were used as the indices to evaluate PK and PD characteristics of gemifloxacin. The cumulative fraction of response (CFR) of gemifloxacin against each bacterium and the probability of target attainment (PTA) under various MIC level were evaluated using Monte Carlo simulation following multiple administration at steady state.ResultsThe Cmax of gemifloxacin after once-daily oral doses for 7 days were (1.55 ±0.32) μg/mL and (1.57±0.31) μg/mL for the first and last dose,while the AUC0～24 h were (7.91±1.52) and (8.91±1.15) h · μg · mL-1,respectively.The accumulation factor was 1.13±0.05.The time-profile of gemifloxacin could be described using two-compartment model and the half-life of distribution and elimination phase were (0.64 ± 0.17) and (7.10 ± 2.10) h,respectively. The cumulative urinary excretion rates within 24 h of gemifloxacin were 34.83 ％ and 38.95 ％ for the first and the last dose,respectively.PD study showed that the MIC90 of gemifloxacin were 0.25 mg/L and 0.125 mg/L against Streptococcus pneumoniae and Moraxelle catarrhalis,respectively,while the MIC90 was 2 mg/L against Hemophilus influenza. However,most of Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA) were resistant to gemifloxacin ( MIC90 ＞ 32mg/L).The PTA values of fAUC0～24 h/MIC and fCmax/MIC of gemifloxacin 320 mg daily for 7 days were close to 100％ when MIC was ≤0.06 mg/L.ConclusionsGemifloxacin is rapidly absorbed after oral administration of single doses in healthy Chinese volunteers,and the plasma concentration could reach steady state at the third day,while a minimal accumulation is shown after consecutive 7 days dosing.The PK/PD analysis suggests that the favorable clinical and bacteriological efficacy could be obtained when using thisregimen in treatment of sensitive patients with community-acquired pneumonia and acute exacerbation of chronic obstructive pulmonary disease.