ZnO Nanoparticles-Modified Dressings to Inhibit Wound Pathogens

Zinc oxide (ZnO) nanoparticles (NPs) have been investigated for various skin therapies in recent years. These NPs can improve the healing and modulate inflammation in the wounds, but the mechanisms involved in such changes are yet to be known. In this study, we have designed a facile ZnO nano-coated dressing with improved antimicrobial efficiency against typical wound pathogens involved in biofilm and chronic infections. ZnO NPs were obtained by hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm effects were evaluated against laboratory and clinical isolates of significant Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) opportunistic pathogens, by quantitative methods. Our results have shown that the developed dressings have a high antibacterial efficiency after 6–24 h of contact when containing 0.6 and 0.9% ZnO NPs and this effect is similar against reference and clinical isolates. Moreover, biofilm development is significantly impaired for up to three days of contact, depending on the NPs load and microbial species. These results show that ZnO-coated dressings prevent biofilm development of main wound pathogens and represent efficient candidates for developing bioactive dressings to fight chronic wounds.     

A new aspect of in vitro antimicrobial leukocyte- and platelet-rich plasma activity based on flow cytometry assessment

The current literature suggests that the antibacterial effect of leukocyte- and platelet-rich plasma (L-PRP) is directly related to platelet and leukocyte concentrations. The aim of this study was twofold: first, to evaluate the antimicrobial effect of L-PRP against selected bacterial strains in vitro, and second, to correlate this effect with leukocyte and platelet content in the final concentration. Blood was collected from 20 healthy males, and L-PRP, acellular plasma (AP), and autologous thrombin were consecutively prepared. Flow cytometry analysis of the blood, L-PRP, and AP was performed. The L-PRP gel, liquid L-PRP, and thrombin samples were tested in vitro for their antibacterial properties against seven selected bacterial strains using the Kirby–Bauer disk-diffusion method. There was notable antimicrobial activity against selected bacterial strains. No statistically significant correlations between antimicrobial activities and the platelet concentration in L-PRP were observed. Statistically significant positive correlations between selected leukocyte subtypes and antimicrobial activity were noted. A negative correlation was found between elevated monocyte count and antimicrobial activity of L-PRP against one bacterial strain studied. L-PRP possesses antimicrobial activity and can be potentially useful in the fight against certain postoperative infections. The bactericidal effect of L-PRP is caused by leukocytes, and there exists a relationship among selected leukocyte subtypes and L-PRP antimicrobial activity.     

Desmopressin (DDAVP) improves recruitment of activated platelets to collagen but simultaneously increases platelet endothelial interactions in vitro

Platelet dysfunction can cause clinically relevant bleeding. Treatment with DDAVP is advocated for this condition. DDAVP increases von Willebrand factor (VWF) on endothelial cells (ECs) and in plasma. VWF could facilitate platelet deposition on subendothelial collagen. VWF also facilitates platelet/EC interactions. Therefore DDAVP could precipitate thromboembolic events. We used a flow chamber model to study in vitro and ex vivo if DDAVP alters recruitment of platelets to EC and collagen. Resting or TRAP-activated platelets and EC were treated individually or simultaneously with 0.4?ng/ml DDAVP. Fluorophor-labeled platelets (10⁶/ml) were resuspended in reconstituted blood and superfused across EC and collagen in an in vitro flow chamber model at arterial shear (320?s^?1). Adhesion of platelets to the respective surface was recorded fluorescence microscopically and platelet covered area was assessed. TRAP significantly induced adhesiveness of platelets for collagen and EC. DDAVP pretreatment of platelets did not affect adhesiveness of resting or TRAP-activated platelets for collagen or EC. Adhesiveness of resting but not TRAP-activated platelets was induced on DDAVP-treated EC. DDAVP-conditioned EC supernatant contained vWF and significantly increased platelet deposition on collagen. Platelets from patients with clinically suspected platelet dysfunction undergoing aortic valve replacement exhibited decreased platelet deposition on collagen surfaces. In summary, our data confirm that DDAVP can induce release of platelet adhesion promoting factors from EC, which is most likely vWF. DDAVP has no direct effect on platelets. Blood samples from DDAVP-treated patients do not exhibit significantly augmented platelet deposition on collagen ex vivo. This influence of released promoting factors might cause an increase of undesirable interactions of platelets with EC.     

A ncovel angiogenic factor derived from Aloe vera gel: β-sitosterol, a plant sterol

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, β-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, β-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus β-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Abciximab Pharmacodynamics Are Unaffected by Antecedent Therapy with Other GPIIb/IIIa Antagonists in Non-Human Primates

Background: Tirofiban and eptifibatide are currently approved for the medical stabilization of non-ST segment elevation acute coronary syndromes. In patients undergoing percutaneous coronary intervention (PCI) during infusion of these drugs, conversion to abciximab, which has long term proven clinical efficacy and cost-effectiveness, following PCI may be desirable. The purpose of this study was to determine if the binding or pharmacodynamics of abciximab is affected by a prior infusion of either tirofiban or eptifibatide. Methods: In vitro binding experiments were performed to determine if prior exposure to tirofiban or eptifibatide altered the affinity and extent of binding of abciximab to GPIIb/IIIa. For in vivo experiments, cynomolgus monkeys were pretreated with a bolus and 18 hour infusion of saline, tirofiban, or eptifibatide. At the end of the initial treatment, a bolus and 12 hr infusion of abciximab was started without delay. Inhibition of platelet aggregation, GPIIb/IIIa receptor blockade and abciximab pharmacokinetics were measured during and after both infusions. Results: Equilibrium binding of abciximab in vitro was unaffected by tirofiban or eptifibatide. The extent and duration of abciximab inhibition of ex vivo platelet aggregation, receptor blockade, and abciximab pharmacokinetics in monkeys during and after the abciximab infusion were not affected by prior infusion of the animals with tirofiban or eptifibatide. Conclusions: In vitro and in vivo studies revealed that the molecular interaction of abciximab with the platelet GPIIb/IIIa receptor is not altered by immediate prior exposure of platelets to small molecule GPIIb/IIIa antagonists. These preclinical studies suggest that the efficacy of abciximab should not be impaired if it is initiated following termination of therapy with small molecule GPIIb/IIIa antagonists.     

Nanomolar concentrations of adrenaline induce platelet adhesion in vitro

Adrenaline is a platelet activator having a resting plasma concentration of <1?nmol/l that increases to a few nmol/l during stress. However, most in vitro assays only detect effects of adrenaline in micromolar concentrations. This makes it difficult to estimate the relevance of in vitro data for the in vivo situation. The aim of this study was to investigate experimental conditions in vitro that could detect platelet effects of adrenaline in nanomolar concentrations. Platelet adhesion to albumin and collagen was evaluated with a static platelet adhesion assay. Our results show that 10?nmol/l adrenaline induced platelet adhesion to albumin in platelet-rich plasma (PRP) prepared at 140?×?g, while 100?nmol/l was necessary in order to increase adhesion of platelets prepared at 220?×?g. The mean platelet volume was increased after preparation at 140?×?g, suggesting that large reactive platelets contributed to the increased adrenaline sensitivity. At optimal Mg²⁺-concentration, adhesion to collagen was increased by 10?nmol/l adrenaline irrespective of centrifugal force applied during PRP preparation. More specifically, we defined two populations where adhesion to collagen was increased by 10?nmol/l adrenaline either upon centrifugation at 140?×?g but not 220?×?g or vice versa. In some experiments, platelet adhesion to collagen was induced by 3?nmol/l adrenaline, which corresponds to concentrations achieved during stress in vivo. In summary, the static adhesion assay is able to detect platelet activating effects of adrenaline very close to physiological concentrations. This is rare for in vitro assays and motivates further research about adrenergic signalling in platelets.     

Platelet-rich plasma stimulated by pulse electric fields: Platelet activation,procoagulant markers,growth factor release and cell proliferation

Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.     

Antimicrobial properties of platelet-rich preparations. A systematic review of the current pre-clinical evidence

In recent years autologous platelet concentrates (APCs) have become popular in several medicine fields, representing a valuable adjunct to regenerative surgical procedures. Beneficial effects in the control of postsurgical discomfort and infection have also been frequently reported, suggesting that APC may possess anti-inflammatory and antimicrobial properties. The aim of the present review was to summarize the current evidence regarding the antimicrobial effects of platelet concentrates, investigated by in vitro and animal studies. This review was conducted following a systematic approach. An electronic search was performed on MEDLINE, EMBASE and Scopus databases using appropriate search terms, without language or time restrictions. Preclinical studies assessing the antimicrobial activity of APC were included and divided according to the experimental design. Twenty in vitro studies and four animal studies, investigating APC effects on a broad range of microorganisms, were included. In in vitro studies APC reduced the growth of microorganisms during the first hours of incubation, while they could not completely break down the microbial load. In fact, over time a recovery of bacterial growth was always observed, suggesting that APCs display a bacteriostatic rather than a microbicidal activity. All animal studies showed that APC administered by local injections were able to reduce the infection caused by different microorganisms, although to a lesser extent compared to antibiotics. In conclusion, although the exact action mechanisms of interaction with microbial pathogens need further investigation, platelet concentrates proved to have antimicrobial properties, and therefore could represent a useful natural substance for controlling postoperative infections at surgical sites.     

The use of low dose Orgaran in heparin-induced thrombocytopenia associated with in vitro platelet aggregation at higher Orgaran concentrations

We report a case of heparin-induced thrombocytopenia with in vitro antibody cross-reactivity by platelet aggregometry to both low molecular weight heparin and the heparinoid Org 10172 (Orgaran). The in vitro reactivity with Orgaran was only present at the upper limit of concentrations that would normally be used therapeutically. Low dose Orgaran therapy was initiated, allowing successful renal replacement therapy without invoking further thrombocytopenia or thrombosis. Interestingly, in vitro platelet aggregometry following treatment did not reveal increasing sensitivity to Orgaran. This case indicates that negative in vitro platelet aggregometry at defined lower concentrations of Orgaran may predict in vivo safety at the same levels despite positive platelet aggregometry reactions at higher concentrations of Orgaran.     

In vitro assessment of platelet concentrates with multiple electrode aggregometry

Storage impairs platelet function. It was hypothesized that multiple electrode aggregometry in vitro could be used to follow aggregability in platelet concentrates over time and that the results predict the efficacy of platelet transfusion in an ex vivo transfusion model. In vitro platelet aggregability was assessed in apheresis and pooled buffy coat platelet concentrates (BCs) (n?=?13 each) using multiple electrode aggregometry with different agonists 1, 3, 5 and 7 days after preparation. In the ex vivo transfusion model, whole blood samples from nine healthy volunteers were collected every second day. The samples were supplemented with stored platelets (+146?×?10⁹?×?l^?1) from the same unit 1, 3, 5 and 7 days after preparation. Platelet aggregability was assessed in the concentrate and in the whole blood samples before and after platelet supplementation. There was a continuous reduction in in vitro platelet aggregability over time in both apheresis and pooled BCs. The same pattern was observed after ex vivo addition of apheresis and pooled BCs to whole blood samples. The best correlation between in vitro aggregability and changes in aggregation after addition was achieved with collagen as agonist (r?=?0.67, p?<?0.001). In conclusion, multiple electrode aggregometry can be used to follow aggregability in platelet concentrates in vitro, and the results predict with moderate accuracy changes in aggregation after addition of platelet concentrate to whole blood samples.     

Stimulation of PAR-1 or PAR-4 promotes similar pattern of VEGF and endostatin release and pro-angiogenic responses mediated by human platelets

Background: Platelets mediate angiogenesis through the secretion of several factors, including the pro-angiogenic vascular endothelial growth factor (VEGF) and the anti-angiogenic endostatin. Although previous findings indicated that these molecules are packed into different alpha-granules and selectively released by specific stimulation of protease-activated receptor (PAR)-1 or PAR-4, recent evidences are against this hypothesis. Objectives: To elucidate the controversies about the VEGF and endostatin release and the overall angiogenic effect of PARs-stimulated platelets. Methods: VEGF and endostatin were quantified by enzyme linked-immunosorbent assay (ELISA). Endothelial proliferation (pNPP assay), wound healing (scratch assay) and tubule formation (matrigel) of human microvascular endothelial cells (HMEC-1) and endothelial progenitor cells (EPC) were determined using supernatants from PAR-1- or PAR-4-stimulated platelets. Results: Activation of washed platelets (WPs) by PAR-1- or PAR-4-activating peptide (AP) promoted the VEGF and endostatin secretion in a concentration-dependent manner, being PAR-1-AP more potent than PAR-4-AP. The release of both molecules was abrogated by pre-incubation of platelets with PAR antagonists. Activation of platelet-rich plasma (PRP) with either PAR-1-AP or PAR-4-AP induced a significant VEGF secretion. Quantification of platelet-endostatin secretion was not possible in PRP due to the high levels of plasmatic endostatin vs. platelet content. Releasates from PAR-1- or PAR-4-activated WPs promoted similar pattern of angiogenic responses of HMEC-1 or EPC. Moreover, proliferation of HMEC-1 mediated by PAR-stimulated PRP releasates was delayed and significantly lower compared with that induced by PAR-stimulated WPs. Conclusions: Our results are in contrast with the previously described differential release of VEGF and endostatin induced by the selective PAR-1 or PAR-4 stimulation, and support the notion that while circulating endostatin accounts for the maintenance of a systemic anti-angiogenic state, locally, the release of platelet alpha-granule content promotes angiogenesis.     

Evaluation of wound healing and antimicrobial potentials of Ixora coccinea root extract

ObjectiveTo evaluate the wound healing and antimicrobial activity of root extracts of Ixora coccinea (I. coccinea).MethodsTo investigate the wound healing efficacy of root extract of I. coccinea Linn, five groups of animals were divided each containing six animals. Two wound models including incision and excision wound models were used in this study. The parameters studied were tensile strength on incision wound model and in terms of wound contraction for excision wound model were compared with standard Nitrofurazone (NFZ) ointment (0.2% w/w). Six extracts (ethanol, aqueous, petroleum ether, benzene, chloroform and ethyl acetate) of I. coccinea were screened for in vitro growth inhibiting activity against different bacterial strains viz, Staphylococcus aureus, Bacillus pumilius, Enterococcus faecalis, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa and fungi Candida albicans and Aspergillus niger were compared with the standard drugs ciprofloxacin and chloramphenicol for antibacterial and griseofulvin for antifungal screening. The serial dilution and cup (or) well plate methods were used for the antimicrobial study and MIC was determined.ResultsThe ethanolic extract showed significant (P<0.001) wound healing activity when compared to standard drug NFZ with respect to normal control group. Amongst all, ethanolic extract showed highly significant antibacterial activity against all bacterial strains used in this study when compared to standard. The aqueous extract showed moderate significant inhibition against all bacterial strains when compared to standard. All the extracts were shown negligible activity against the fungal strains used in this study.ConclusionsThe ethanolic root extract of I. coccinea showed pronounced wound healing and antibacterial activity. The probable reason to heal the wound was that the external application of the extract prevented the microbes to invade through the wound thus the protection of wound occurs against the infection of the various organisms.     

Effects of FEIBA on platelet and leucocyte activation in severe haemophilia patients with inhibitors

Factor eight inhibitory bypassing agent (FEIBA) is used as a therapeutic option in haemophilia patients who have developed inhibitors. The measurement of thrombin generation has been applied to monitor the efficacy of FEIBA. However, a major concern about the clinical use of FEIBA is whether or not an increase in thrombin activity causes subsequent platelet activation and risk of thrombosis. Our aim is to evaluate whether FEIBA causes platelet and leucocyte activation in haemophilia patients with inhibitors. We evaluated the effects of FEIBA on platelet and leucocyte activity in correlation with thrombin generation. Initially, an in vitro study was conducted to evaluate the effects of FEIBA on platelet and leucocyte activity (using flow cytometry) using peripheral blood from normal volunteers. We then performed an ex vivo study looking at the effect of FEIBA on the above parameters in two haemophiliacs with high-titre inhibitors. A parallel study was also carried out ex vivo to evaluate thrombin generation using a thrombinoscope. FEIBA did not cause platelet or leucocyte activation in either the in vitro or ex vivo studies but showed a predictable increase in thrombin generation. Our study is the first one to address the effect of FEIBA on platelet and leucocyte function. We found no evidence of ‘systemic’ platelet activation. The findings suggest that whilst FEIBA improves global haemostasis, platelet activation is likely to be contained to the site of injury and systemic platelet activation, a previously feared consequence of FEIBA infusion that that may have contributed to thrombotic risk is absent.     

Antimicrobial performance of two preoperative skin preparation solutions containing iodine and isopropyl alcohol

BackgroundHealthcare-associated infections (HAIs) are a persistent clinical challenge caused primarily by bacteria on the skin. Proper utilization of optimized antiseptic skin preparation solutions helps reduce the prevalence and impact of HAIs by decreasing patient skin microorganisms preoperatively. The purpose of this study was to evaluate the efficacy of 2 antimicrobial solutions containing iodine and isopropyl alcohol (IPA): Povidone iodine (PVP-I) with IPA (ie, PVP-I+IPA, PurPrep) and Iodine Povacrylex+IPA (DuraPrep).MethodsThe antimicrobial activity of the test solutions was evaluated in vitro by determinations of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against 1105 diverse microbial isolates and a time-kill assay to evaluate efficacy against 120 strains of Gram-positive and Gram-negative bacteria and yeasts. Peel tests were performed between skin samples treated with test solutions and representative drape/dressing materials to determine effects of test solutions on the biomechanical adhesion properties. Finally, an Institutional Review Board (IRB)-approved, randomized, controlled, single-center, partially blinded in vivo study was performed to assess the immediate and persistent antimicrobial activity of the test solutions on the abdomen and groin.ResultsBoth PVP-I+IPA and Iodine Povacrylex+IPA solutions demonstrated broad-spectrum antimicrobial activity with MIC and MBC at less than 1% of the full-strength concentration of each product against a wide variety of microorganisms. In the time-kill tests, both solutions were able to successfully reduce all microbial populations by 99.99% (ie, 4 log₁₀) at the contact times of 30 seconds, 2 minutes and 10 minutes. The 2 solutions showed relatively similar adhesion results when tested with 3 representative operating room materials. Both PVP-I+IPA and Iodine Povacrylex+IPA met the expected Food and Drug Administration (FDA) efficacy requirements at 10 minutes and 6 hours post-treatment for both anatomic sites (ie, groin, and abdomen) in the clinical study, with no safety issues or adverse events.ConclusionsAnalysis of the in vitro antimicrobial activity, biomechanical adhesive strength, and in vivo efficacy of PVP-I+IPA demonstrated similar results compared to Iodine Povacrylex+IPA. Both products were efficacious at reducing or eliminating a wide range of clinically-relevant microorganisms in lab-based and clinical settings, supporting their use as antiseptic skin preparation solutions to reduce bacteria on the skin that can cause infection.     

Protease-activated receptor 4 activity promotes platelet granule release and platelet-leukocyte interactions

Human platelets express two protease-activated receptors (PARs), PAR1 (F2R) and PAR4 (F2RL3), which are activated by a number of serine proteases that are generated during pathological events and cause platelet activation. Recent interest has focused on PAR4 as a therapeutic target, given PAR4 seems to promote experimental thrombosis and procoagulant microparticle formation, without a broadly apparent role in hemostasis. However, it is not yet known whether PAR4 activity plays a role in platelet-leukocyte interactions, which are thought to contribute to both thrombosis and acute or chronic thrombo-inflammatory processes. We sought to determine whether PAR4 activity contributes to granule secretion from activated platelets and platelet-leukocyte interactions. We performed in vitro and ex vivo studies of platelet granule release and platelet-leukocyte interactions in the presence of PAR4 agonists including PAR4 activating peptide, thrombin, cathepsin G, and plasmin in combination with small-molecule PAR4 antagonists. Activation of human platelets with thrombin, cathepsin G, or plasmin potentiated platelet dense granule secretion that was specifically impaired by PAR4 inhibitors. Platelet-leukocyte interactions and platelet P-selectin exposure the following stimulation with PAR4 agonists were also impaired by activated PAR4 inhibition in either a purified system or in whole blood. These results indicate PAR4-specific promotion of platelet granule release and platelet-leukocyte aggregate formation and suggest that pharmacological control of PAR4 activity could potentially attenuate platelet granule release or platelet-leukocyte interaction-mediated pathological processes.     

Rational parameters for antibiotic therapy in patients with cystic fibrosis

Summary Data from the literature and the authors' experiences were used to review aspects of antibiotic therapy of patients with cystic fibrosis; attention was paid toin vitro antimicrobial susceptibility tests and assessment of therapy directed against mucoidPseudomonas aeruginosa. The heterogeneity ofP. aeruginosa within single sputa with respect to antibiotic susceptibility is stressed. Quantitative viable counts of bacteria based on an analysis of homogenised sputum is recommended. The mode ofin vivo growth of mucoidP. aeruginosa is discussed to explain the survival of hypersusceptibleP. aeruginosa in vivo, and the clinical benefit observed in the absence of a significant reduction of the pathogen. The value of ceftazidime in the treatment of exacerbations due toHaemophilus influenzae is emphasised. The social benefits from oral administration of ciprofloxacin also emphasises that the patient's quality of life must also be considered.

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Parameter für eine rationelle Antibiotikatherapie bei Patienten mit zystischer Fibrose

Zusammenfassung In einer Übersicht werden Daten aus der Literatur und eigene Erfahrungen in der Antibiotikatherapie bei Patienten mit zystischer Fibrose dargestellt. DieIn vitro-Testung und klinische Beurteilung der Therapie von Infektionen durch mukoide Stämme vonPseudomonas aeruginosa finden besondere Beachtung.P. aeruginosa-Isolate aus einer einzigen Sputumprobe weisen im Hinblick auf ihre Antibiotikaempfindlichkeit eine bemerkenswerte Heterogenität auf. Keimzahlenbestimmungen sollten an homogenisierten Sputumproben vorgenommen werden. DasIn vivo-Wachstumsverhalten mukoiderP. aeruginosa-Stämme gibt Aufschluß über die Beobachtung, daß hochempfindliche Stämme vonP. aeruginosa in vivo überleben. Auf das Phänomen der klinischen Besserung ohne signifikante Erregerreduktion wird eingegangen. Hervorgehoben wird der Wert von Ceftazidim in der Therapie akuter Exazerbationen durchHaemophilus influenzae. Der soziale Gewinn einer oralen Therapie mit Ciprofloxacin weist auf die Bedeutung der Lebensqualität für den Patienten hin.

     

Resistance among Gram-negative ESKAPE pathogens isolated from hospitalized patients with intra-abdominal and urinary tract infections in Latin American countries: SMART 2013–2015

Gram-negative ESKAPE pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are important etiologic agents of nosocomial infection that are frequently resistant to broad-spectrum antimicrobial agents. Gram-negative ESKAPE pathogens were collected from hospitalized patients in 11 Latin American countries from 2013 to 2015 as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) global surveillance program. In total, 2113 isolates from intra-abdominal infections (IAI) and 970 isolates from urinary tract infections (UTI) were tested against antimicrobial agents using standardized CLSI broth microdilution methodology. Of the agents tested, amikacin demonstrated the highest rates of susceptibility (%) for K. pneumoniae (92.2, 92.3), Enterobacter spp. (97.5, 92.1), and P. aeruginosa (85.3, 75.2) isolates from both IAI and UTI, respectively. Ertapenem (68.5, 62.6) and imipenem (79.2, 75.9) showed substantially higher rates of susceptibility (%) than other β-lactams, including piperacillin-tazobactam (35.9, 37.4) against ESBL-positive isolates of K. pneumoniae from IAI and UTI, respectively. Rates of susceptibility to all agents tested against A. baumannii were ≤30.9%. Gram-negative ESKAPE pathogens isolated from Latin America demonstrated compromised in vitro susceptibility to commonly prescribed broad-spectrum, parenteral antimicrobial agents. Continued surveillance is warranted. New antimicrobial agents with potent activity against Gram-negative ESKAPE pathogens are urgently needed.     

Antimicrobial PAA/PAH Electrospun Fiber Containing Green Synthesized Zinc Oxide Nanoparticles for Wound Healing

Wound infections are the main complication when treating skin wounds. This work reports a novel antimicrobial material using green synthesized zinc oxide nanoparticles (ZnONPs) incorporated in polymeric fibers for wound healing purposes. ZnONPs are a promising antimicrobial nanomaterial with high activity against a range of microorganisms, including drug-resistant bacteria. The electrospun fibers were obtained using polyacrylic acid (PAA) and polyallylamine hydrochloride (PAH) and were loaded with ZnONPs green synthesized from Ilex paraguariensis leaves with a spherical shape and ~18 nm diameter size. The fibers were produced using the electrospinning technique and SEM images showed a uniform morphology with a diameter of ~230 nm. EDS analysis proved a consistent dispersion of Zn in the fiber mat, however, particle agglomerates with varying sizes were observed. FTIR spectra confirmed the interaction of PAA carboxylic groups with the amine of PAH molecules. Although ZnONPs presented higher antimicrobial activity against S. aureus than E. coli, resazurin viability assay revealed that the PAA/PAH/ZnONPs composite successfully inhibited both bacteria strains growth. Photomicrographs support these results where bacteria clusters were observed only in the control samples. The PAA/PAH/ZnONPs composite developed presents antimicrobial activity and mimics the extracellular matrix morphology of skin tissue, showing potential for wound healing treatments.     

Effects of interleukin-2 administration on platelet function in cancer patients

Platelet function in 16 patients with metastatlc renal cell carcinoma and melanoma was studied sequentially over the first 96 hr of treatment with moderate and highdose inter-leukin-2 (IL-2). During the first 96 hr of therapy, an increased ex vivo platelet maximal aggregation (MA) response to ADP, epinephrine, and arachidonlc acld was paralleled by a decrease In the peripheral platelet count. Plasma speclmens from patients receiving the moderate dose schedule showed a significant IL-2 induced secretory response of the platelet α-granule components β-thromboglobulin (BTG) and platelet factor 4 (PF4) and the eicosanoid thromboxane B₂ (TBX₂) as measured by RIA. The increase in TXB₂ was highly correlated with MA when analyzed by bivariate regression analysls, whereas the addition of PF4 to TXB₂ in a multiple regression analysls further Increased their correlation to MA. The observed decrease In peripheral platelet count correlated significantly with MA and PF4 secretion. High-dose IL-2-treated patlents showed a statistically significant increase in the percentage of large platelets exceeding 12 fl in diameter and platelet responsiveness to hypotonic shock. These observations suggest that IL-2 therapy results in a reduced peripheral platelet pool, with an increased proportion of the remaining pool of platelets larger, more viable, and actlvated. © 1994 Wiley-Liss, Inc.     

A shear-induced in vitro platelet function test can assess clinically relevant anti-thrombotic effects

Morphological features of haemostatic plugs formed in vitro under high shear forces were investigated. Electron microscopy confirmed the relevance of such haemostatic plug to a platelet-rich arterial thrombus, which is formed in vivo. In rat blood samples, the effects of anticoagulants and various antiplatelet agents on platelet reactivity (rate of haemostatic plug formation) and subsequent coagulation of the flowing blood were investigated. Haemostasis did not occur in citrated blood, and heparin greatly inhibited the shear-induced platelet reaction. Aspirin (1 mM), a thromboxane A₂ receptor antagonist (5 μM), a stable prostacyclin (0.55 nM), a stable prostaglandin E₁ (141 nM) and a phosphodiesterase inhibitor (100 μM) were tested. All these agents exerted significant inhibitory effect on shear-induced platelet reaction, including the inhibition of the very first phase of platelet plug formation, due to aggregation of shear-activated platelets. Except for the phosphodiesterase inhibitor, which prolonged clotting time, none of the above agents affected dynamic coagulation. These results suggest that the employed in vitro shear-induced thrombosis/haemostasis test can reveal in vivo the antithrombotic effect of various agents independently of their mechanism of action.