Alginate oligosaccharides enhance the antifungal activity of nystatin against candidal biofilms

Background: The increasing prevalence of invasive fungal infections in immuno-compromised patients is a considerable cause of morbidity and mortality. With the rapid emergence of antifungal resistance and an inadequate pipeline of new therapies, novel treatment strategies are now urgently required. Methods: The antifungal activity of the alginate oligosaccharide OligoG in conjunction with nystatin was tested against a range of Candida spp. (C. albicans, C. glabrata, C. parapsilosis, C. auris, C. tropicalis and C. dubliniensis), in both planktonic and biofilm assays, to determine its potential clinical utility to enhance the treatment of candidal infections. The effect of OligoG (0-6%) ± nystatin on Candida spp. was examined in minimum inhibitory concentration (MIC) and growth curve assays. Antifungal effects of OligoG and nystatin treatment on biofilm formation and disruption were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and ATP cellular viability assays. Effects on the cell membrane were determined using permeability assays and transmission electron microscopy (TEM). Results: MIC and growth curve assays demonstrated the synergistic effects of OligoG (0-6%) with nystatin, resulting in an up to 32-fold reduction in MIC, and a significant reduction in the growth of C. parapsilosis and C. auris (minimum significant difference = 0.2 and 0.12 respectively). CLSM and SEM imaging demonstrated that the combination treatment of OligoG (4%) with nystatin (1 µg/ml) resulted in significant inhibition of candidal biofilm formation on glass and clinical grade silicone surfaces (p < 0.001), with increased cell death (p < 0.0001). The ATP biofilm disruption assay demonstrated a significant reduction in cell viability with OligoG (4%) alone and the combined OligoG/nystatin (MIC value) treatment (p < 0.04) for all Candida strains tested. TEM studies revealed the combined OligoG/nystatin treatment induced structural reorganization of the Candida cell membrane, with increased permeability when compared to the untreated control (p < 0.001). Conclusions: Antimicrobial synergy between OligoG and nystatin against Candida spp. highlights the potential utility of this combination therapy in the prevention and topical treatment of candidal biofilm infections, to overcome the inherent tolerance of biofilm structures to antifungal agents

Impact on Clinical and Cost Outcomes of a Centralized Approach to Acute Stroke Care in London:A Comparative Effectiveness Before and After Model

Background In July 2010 a new multiple hub-and-spoke model for acute stroke care was implemented across the whole of London, UK, with continuous specialist care during the first 72 hours provided at 8 hyper-acute stroke units (HASUs) compared to the previous model of 30 local hospitals receiving acute stroke patients. We investigated differences in clinical outcomes and costs between the new and old models. Methods We compared outcomes and costs ‘before’ (July 2007–July 2008) vs. ‘after’ (July 2010–June 2011) the introduction of the new model, adjusted for patient characteristics and national time trends in mortality and length of stay. We constructed 90-day and 10-year decision analytic models using data from population based stroke registers, audits and published sources. Mortality and length of stay were modelled using survival analysis. Findings In a pooled sample of 307 patients ‘before’ and 3156 patients ‘after’, survival improved in the ‘after’ period (age adjusted hazard ratio 0.54; 95% CI 0.41–0.72). The predicted survival rates at 90 days in the deterministic model adjusted for national trends were 87.2% ‘before’ % (95% CI 86.7%–87.7%) and 88.7% ‘after’ (95% CI 88.6%–88.8%); a relative reduction in deaths of 12% (95% CI 8%–16%). Based on a cohort of 6,438 stroke patients, the model produces a total cost saving of £5.2 million per year at 90 days (95% CI £4.9-£5.5 million; £811 per patient). Conclusion A centralized model for acute stroke care across an entire metropolitan city appears to have reduced mortality for a reduced cost per patient, predominately as a result of reduced hospital length of stay

Comparison of ‘before’ and ‘after’ sample and resource use.

*<p>Patients may receive more than 1.</p><p><b>Abbreviations: SLSR –</b> South London Stroke Register; <b>SINAP –</b> Stroke Improvement National Audit Programme; <b>LMDS –</b> London Minimum Dataset; <b>SD –</b> Standard Deviation<b>; LOS</b><b>–</b> Length of Stay; <b>HASU –</b> Hyper Acute Stroke Unit; <b>ASU –</b> Acute Stroke Unit; <b>SU –</b> Stroke Unit; <b>ICU –</b> Intensive Care Unit; <b>CT –</b> Computerised Tomography; <b>MRI –</b> Magnetic Resonance Imaging.</p

Results of cost-effectiveness analysis and sensitivity analysis time horizon 10 years: After minus before.

<p>Total cost, deaths and QALYs calculated over 6438 patients. All costs in 2010/11 UK£ (key figures in US$ in text). In the 10 year model costs and benefits are discounted at an annual rate of 3.5%. In the difference (“Diff.”) columns negative (positive) costs, deaths and QALYs mean that costs, deaths and QALYs are lower (higher) in the After period compared with the Before period. “Dominant” means that costs are lower and either deaths are lower or QALYs are higher in the After period compared with the Before period.</p

Cost-effectiveness acceptability curves.

<p><b>- - - - -</b> 10 years. <b>———</b> 90 days. The curves in the figure graph the probability that the new London Stroke Service is cost-effective against the cost-effectiveness threshold measured in terms of the incremental cost per QALY gained. This accounts simultaneously for uncertainty in the cost-effectiveness estimates and in the value of the cost-effectiveness threshold (the level of cost-effectiveness that the new London Stroke Service needs to be more cost-effective than, i.e., have a lower incremental cost per QALY gained than to be considered good value for money). In England the cost-effectiveness threshold used by NICE is in the range £20,000–£30,000 per QALY gained (US$31,000–£46,500 using an exchange rate of UK£1 = US$1.55). Curves are shown for each time horizon.</p

Results of cost-effectiveness analysis and sensitivity analysis time horizon 90 days: After minus before.

<p>Total cost, deaths and QALYs calculated over 6438 patients. All costs in 2010/11 UK£ (key figures in US$ in text). In the difference (“Diff.”) columns negative (positive) costs, deaths and QALYs mean that costs, deaths and QALYs are lower (higher) in the After period compared with the Before period. “Dominant” means that costs are lower and either deaths are lower or QALYs are higher in the After period compared with the Before period.</p

Neisseria meningitidis recruits factor H using protein mimicry of host carbohydrates

The complement system is an essential component of the innate and acquired immune system, and consists of a series of proteolytic cascades that are initiated by the presence of microorganisms. In health, activation of complement is precisely controlled through membrane-bound and soluble plasma-regulatory proteins including complement factor H (fH; ref. 2), a 155 kDa protein composed of 20 domains (termed complement control protein repeats). Many pathogens have evolved the ability to avoid immune-killing by recruiting host complement regulators and several pathogens have adapted to avoid complement-mediated killing by sequestering fH to their surface. Here we present the structure of a complement regulator in complex with its pathogen surface-protein ligand. This reveals how the important human pathogen Neisseria meningitidis subverts immune responses by mimicking the host, using protein instead of charged-carbohydrate chemistry to recruit the host complement regulator, fH. The structure also indicates the molecular basis of the host-specificity of the interaction between fH and the meningococcus, and informs attempts to develop novel therapeutics and vaccines