Fructooligosaccharide production with the fructosyltransferase from free cells of the native strain Aspergillus sp. N74 at laboratory level was evaluated. The biomass of the native strain Aspergillus sp. N74 was produced in a sucrose fermentation medium and was employed in the enzymatic reaction in solutions of sucrose and phosphate buffer, where pH, temperature, and initial sucrose concentration effect were evaluated. Fructooligosaccharides and reaction subproducts were identified and quantified by high-performance liquid chromatography. The enzyme produced by the strain Aspergillus sp. N74 possessed hydrolytic and transfructosylating activities that changed with process conditions. The best transfructosylating condition was obtained at 80 min reaction time at pH 5.5, 60°C, and initial sucrose concentrations higher than 550 g L −1 , with fructooligosaccharide production of about 50% w/w (based on initial sucrose concentration) and conversion selectivity higher than 90%. In addition, the transfructosylating and hydrolytic activities ratio was of 20. The high transfructosylating activity showed by the fructosyltransferase produced from the native strain Aspergillus sp. N74 suggest considering it as an alternative for the scale-up production of fructooligosaccharides by means of the whole microorganism at bench and pilot plant levels.
BackgroundThe antimicrobial resistance is a global problem, probably due to the indiscriminate and irrational use of antibiotics, prescriptions for incorrect medicines or incorrect determinations of dose, route and/or duration. Another consideration is the uncertainty of patients receiving antibiotics about whether the quality of a generic medicine is equal to, greater than or less than its equivalent brand-name drug. The antibiotics behaviors must be evaluated in vitro and in vivo in order to confirm their suitability for therapeutic use.MethodsThe antimicrobial activities of Meropenem and Piperacillin/Tazobactam were studied by microbiological assays to determine their potencies (content), minimal inhibitory concentrations (MICs), critical concentrations and capacity to produce spontaneous drug-resistant mutants.ResultsWith respect to potency (content) all the products fulfill USP requirements, so they should all be considered pharmaceutical equivalents. The MIC values of the samples evaluated (trade marks and generics) were the same for each strain tested, indicating that all products behaved similarly. The critical concentration values were very similar for all samples, and the ratios between the critical concentration of the standard and those of each sample were similar to the ratios of their specific antibiotic contents. Overall, therefore, the results showed no significant differences among samples. Finally, the production of spontaneous mutants did not differ significantly among the samples evaluated.ConclusionsAll the samples are pharmaceutical equivalents and the products can be used in antimicrobial therapy.
IntroductionPatients with febrile neutropenia (FN) exhibit changes in extracellular fluid that may alter the plasma concentrations of beta-lactams and result in therapeutic failure or toxicity. We evaluated the pharmacokinetics of piperacillin/tazobactam in patients with hematological malignancies and FN after receiving chemotherapy at a primary public cancer center.MethodsThis was an open, nonrandomized, observational, descriptive, and prospective study. Samples from 15 patients with hematological malignancies and FN were evaluated after the administration of chemotherapy. Five blood samples were taken from each patient when the antibiotic level was at steady-state 10, 60, 120, 180, and 350 min after each dose. Antibiotic concentrations were measured using gel diffusion with Bacillus subtilis. All study participants provided written informed consent.ResultsWe investigated the pharmacokinetics of piperacillin in 14 patients between the ages of 18 years and 59 years and with a mean absolute neutrophil count of 208 cells per mm3 (standard deviation (SD) ± 603.2). The following pharmacokinetic measurements were obtained: maximum concentration, 94.1–1133 mg/L; minimum concentration, 0.47–37.65 mg/L; volume of distribution, 0.08–0.65 L/kg (mean, 0.34 L/kg); drug clearance (CL), 4.42–27.25 L/h (mean, 9.93 L/h); half-life (t1/2), 0.55–2.65 h (mean, 1.38 h); and area under the curve, 115.12–827.16 mg · h/L.ConclusionPatients with FN after receiving chemotherapy exhibited significant variations in the pharmacokinetic parameters of piperacillin compared with healthy individuals; specifically, FN patients demonstrated an increase in t1/2 and decreased CL.
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