Authors:Irena Baranowska, Piotr Markowski, Andrzej Wilczek, Magdalena Szostek, and Marlena Stadniczuk
Simple, rapid and selective NP-TLC and RP-TLC methods are described for analysis of l
-arginine, its primary metabolites (l
-arginine, agmatine, putrescine, spermidine, spermine, and creatine) and selected drugs (dexamethasone, prednisolone, furosemide, vancomycin, amikacin, fluconazole, digoxin, captopril, dipyrone, metoprolol, and sildenafil), in different therapeutic groups, in model solutions and in spiked human urine. NP-TLC and RP-TLC methods have been used to study the retention of the substances. A variety of mobile phase systems were evaluated for separation of ARG and its metabolites — methanol-50% acetic acid 3:1 (
) on silica gel and 5% acetic acid-methanol-acetonitrile 50:35:15 (
) on RP-18 — and for separation of the drugs — acetonitrile-water 2:3 (
) on silica gel. The effects on selectivity of the polar modifier of mobile phases were also studied.
Authors:Iraj Sedighi, Hoda Moez, and Mohammad Alikhani
Nasal colonization with community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is being increasingly reported, especially in places where people are in close contact and in reduced hygiene, such as day-care centers. In this study we investigated the frequency of MRSA colonization and their antibiotic susceptibility patterns in 1–6 years old children of day-care centers in Hamadan, West of Iran.Five hundred nasal swabs were collected from children of 27 day-care centers that had no risk factors for colonization by S. aureus. The specimens were cultured for isolation of S. aureus by standard methods. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. For evaluation of the frequency of erythromycin induced clindamycin resistance, disk approximation test (D-test) was applied.Totally, 148 (29.6%) children were colonized by S. aureus. Out of 260 male, 94 (36.2%) and of 240 female, 54 (22.5%) cases were nasal carriers of S. aureus (P value = 0.001). Six (4.1%) of the 148 S. aureus isolated from children were MRSA strains. None of MRSA and methicillin susceptible S. aureus (MSSA) was resistant to vancomycin and clindamycin. Three of the 6 strains of MRSA and 7 (4.9%) of the 142 MSSA strains were resistant to erythromycin, and D-test was positive in all of them.We conclude that the rate of colonization by S. aureus is high in children attending day-care centers but colonization with MRSA is not common in our areas. Clindamycin or trimethoprim-sulfamethoxazol could be used in mild to moderataly severe diseases caused by CA-MRSA. However, if the CA-MRSA isolates are erythromycin resistant, D-test should be carried out for detection of inducible clindamycin resistance.
Authors:Sofia Stokkou, Gernot Geginat, Dirk Schlüter, and Ina Tammer
, Van den Braak N, Van Belkum A, Goessens WH, Kreft D, Stroebel AB, Verbrugh HA: Comparison of eight methods to detect vancomycin resistance in enterococci. J Clin Microbiol 36, 592–594 (1998)
Authors:Péter Feiszt, György Schneider, and Levente Emődy
-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate S. aureus , mupirocin-resistant S. aureus , and vancomycin-resistant enterococci, in a concentration-dependent bactericidal manner [ 7 ]. Moreover, these favorable features are backed up with very low
Authors:F. Benaskar, A. Ben-Abdelmoumen, N. G. Patil, E. V. Rebrov, J. Meuldijk, L. A. Hulshof, V. Hessel, U. Krtschil, and J. C. Schouten
An extended cost study consisting of 14 process scenarios was carried out to envisage the cost impact of microprocessing and microwaves separately or in combination for two liquid-phase model reactions in fine-chemicals synthesis: (1) Ullmann C–O cross-coupling reaction and (2) the aspirin synthesis. The former, a Cu-catalyzed substitution reaction, was based on an experimental investigation, whereas the latter, a noncatalyzed aromatic esterification reaction, was based on literature data. The cost of 4-phenoxypyridine production, as a pharmaceutical intermediate in the synthesis of vancomycin or vancocin, was compared with that of the synthesis of aspirin, a key example of large-scale fine-chemical production plants. The operating costs in the Ullmann synthesis were found to be related to material-based process (reactant excess, pretreatment, and catalyst synthesis), whereas those in the aspirin synthesis appeared to be related to downstream-based process (workup, waste treatment). The impact of an integrated microwave heating and microprocessing system on profitability was demonstrated with respect to operational cost and chemical productivity. Different modes of microwave heating and catalyst supply were studied and compared with conventional oil-bath-heated systems in batch and continuous processes. The overall costs including profitability breakthrough for a competitive market price of product were obtained from various combinations of heating and processing. In case of the Ullmann synthesis, the CAPEX (capital expenditure) was negligible compared to the OPEX (operational expenditure), whereas in the aspirin synthesis, the CAPEX was found around 40%, both at a production scales of 1–10 kg/day using proposed upscale methods. The source of the catalyst strongly determined the profitability of a continuously operated Ullmann process due to its effect on the chemical performance. Higher energy efficiencies could be attained using single-mode microwave irradiation; however, the energy contribution to the overall cost was found to be negligible. Different scenarios provided a cost-feasible and profitable process; nevertheless, an integrated microwave heating and microflow processing led to a cost-efficient system using a micropacked-bed reactor in comparison to wall-coated microreactor, showing a profit margin of 20%.
development of different resistance mechanisms in S. epidermidis have led to the situation of emergence as limited number of antibacterial agents (e.g., vancomycin and linezolid) are available for treatment in severe hospital-acquired infections [ 12