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All (β-lactam sensitive bacteria contain enzymatic penicillin binding proteins (PBPs), which are membrane-bound enzymes and targets of β-lactam antibiotics. In this work evaluation of the significance of PBPs in immune response to benzylpenicillin was presented. 35 patients with allergic reactions to penicillin and 17 subjects without penicillin allergy, but exposed, were studied. Proliferative T-cell responses to benzylpenicillin, penicillin and PBPs conjugates (Pc-PBPs) from E. coli, K. oxytoca, S. aureus, S. epidermidis or serum protein (Pc-S) were measured. Although each allergic individual responds to Pc-PBPs in several different ways, specific proliferation of T lymphocytes with Pc-PBPs from bacterial membranes was significant higher than with Pc or Pc-S. This observation gives us a real insight into the causes of the drug allergy: individual allergic reaction and susceptibility to the drug is in strict correlation with bacterial infection. It seems likely that acylation of PBPs could be the trigger for primary immune response to the hapten benzylpenicillin.
L-forms of S. epidermidis were induced at 35°C with the use of an L-form medium with penicillin. The aim of this study was to evaluate the frequency of L-form induction and demonstrate whether the origin of the clinical strains affects the frequency of L-forms induction, as well as to study whether the time of action of the antibiotic has an influence on frequency of L-form induction.
There are increasing studies indicating neuroprotective effects for vitamin B12. In the present study, the effect of intracortical microinjection of vitamin B12 was investigated on penicillin-induced epileptiform activity. We also examined the effects of intracortical microinjection of diazepam (a GABA-benzodiazepine receptor agonist) and flumazenil (a GABA- benzodiazepine receptor antagonist) to clarify the possible mechanism of vitamin B12. In urethane-anesthetized rats, epileptiform activity was induced by intracortical microinjection of penicillin (300 IU, 1.5 ^l), and the number and amplitude of spike waves were analyzed using electroencephalographs (EEG) recordings. Intracortical microinjections of vitamin B12 at doses of 100 and 200 ng/site, diazepam at a dose of 200 ng/site and their ineffective doses (50 ng/site of vitamin B12 with 50 ng/site of diazepam) co-microinjection treatment significantly (P<0.05) reduced both the number and amplitude of spike waves. In addition, combined microinjection of effective doses of vitamin B12 (100 ng/site) and diazepam (200 ng/site) produced more antiepileptiform effect in comparison with their alone used doses. The antiepileptic effects induced by microinjection of vitamin B12 and diazepam at a same dose of 200 ng/site were prevented by the same site microinjection of 50 ng/site of flumazenil. The results showed antiepileptiform activities for vitamin B12 and diazepam at the cerebral cortex level. A central GABA-benzodiazepine receptor complex-mediated mechanism might be involved in the antiepileptiform activity of vitamin B12.
Enterococcus faecalis plays a significant role in hospital-acquired infections (HAIs), and combination of penicillin with aminoglycoside is important in therapy of invasive HAIs. Penicillin resistance in this organism is due to modification of the drug target, penicillin-binding protein (PBP5), its overproduction and expression of β-lactamase. Although rare, this phenotype is often associated with multi-resistant high-risk enterococcal clonal complexes (HiRECCs), such as CC2 and CC9 which may promote its spread in the near future.
Methicillin-resistant Staphylococcus aureus (MRSA) has two mechanisms of resistance to P-lactam antibiotics; one is mediated by mecA gene expression, and the other by penicillinase production. It has been generally accepted in the clinical field that β-lactam antibiotics are not the drugs of choice for MRSA infection. In this report, however, ampicillin and penicillin G were shown to have relatively good activity against MRSA if combined with a β-lactamase inhibitor, sulbactam. These β-lactam antibiotics were found to have relatively high binding affinities to PBP2', the mecA-encoded MRSA-specific penicillin-binding protein. The possible therapeutic application of sulbactam/ampicillin against MRSA infection in combination with arbekacin, an aminoglycoside antibiotic newly developed and introduced into clinical use in Japan, is discussed.
This paper presents the influence of penicillin, erythromycin, Oxytetracycline and streptomycin on aquatic microorganisms isolated from three reservoirs with varied extent of environmental pollution (Sulejów Reservoir, Zegrze Reservoir and Vistula River). The experiments were conducted in especially prepared microcosms (aerated 15 l aquariums). From among the examined antibiotics streptomycin showed the longest activity in the water environment (27 days), followed by Oxytetracycline (22 days). Erythromycin had 13 days activity while the penicillin only 4 days. The highest number of bacteria was observed in the Vistula, fewer in Zegrze Reservoir. Sulejów Reservoir was characterized by the lowest number of bacteria. The strains isolated from Sulejów Reservoir were characterized by higher degree of biodiversity than those from Zegrze Reservoir or Vistula River. The dominant genera were Pseudomonas (49%), followed by Acinetohacter (21 %), Flavomonas (9%), Alcaligenes (9%), Vibrio, Moraxella and Oligella. The Vistula River was dominated by Aeromonas (88%) and Pseudomonas (12%) genera. The strains isolated from Sulejów Reservoir were more sensitive to antibiotics than those from the much more polluted Vistula, this being evidenced by lower MIC and MBC values.
In vitro effect of sub-inhibitory concentrations of penicillin and erythromycin on the number, growth rate, and cultural and biochemical characteristics of Staphylococcus aureus was examined. A decreased number and a slow growth of Staph.aureus in broth and minced meat comprising selected concentrations of antibiotics, and alterations in enzymatic and biochemical activities were found.
Antibiotic resistance of bacteria was observed in various aquatic environments including seas, rivers, lakes, coastal areas, surface water and sediments. The increased implementation of antibiotics into these environments through medical therapy, agriculture and animal husbandry has resulted in new selective pressures on natural bacterial aquatic populations. Antibiotic resistance of heterotrophic bacteria isolated from the surface microlayer and subsurface water of freshwater coastal polymictic and low-productive lake was studied. Antibiotic resistance was determined by the single disc diffusion method. The resistance level of bacteria to various antibiotics differed considerably. Bacteria were most resistant to ampicillin, ciprofloxacin, clindamycin, erythromycin and penicillin. Majority of bacterial strains showed resistance to 4–6 out of 18 antibiotics tested. As a rule, neustonic bacteria (antibiotic resistance index, ARI 0.44) were more resistant to the studied antibiotics than planktonic bacteria (ARI 0.32). 70–90% of neustonic bacteria were resistant to ampicillin, clindamycin and erythromycin, 60– 70% of planktonic bacteria were resistant to ampicillin, ciprofloxacin and penicillin. Differences between pigmented and non-pigmented bacteria in their resistance to the tested antibiotics were observed. Above 40% of achromogenic bacterial strains were resistant to ampicillin, clindamycin and penicillin. Among bacterial strains characterised by their ability to synthesize carotenoids, more than 30% was resistant to ampicillin and ciprofloxacin. Bacterial resistance level to antibiotics depended on their chemical structure. Bacteria isolated from study lake were most resistant to quinolones and lincosamides while they were most susceptible to tetracyclines and aminoglycosides. Results presented in this paper indicate that antibiotics are a significant selection factor and probably play an important role in regulating the composition of bacterial communities in aquatic ecosystems. Adaptive responses of bacterial communities to several antibiotics observed in the present study may have possible implications for the public health.
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