Layering vaccination with antibiotic therapy results in protection and clearance of Burkholderia pseudomallei in Balb/c mice.

Melioidosis is a disease that is difficult to treat due to the causative organism, Burkholderia pseudomallei being inherently antibiotic resistant and it having the ability to invade, survive, and replicate in an intracellular environment. Combination therapy approaches are routinely being evaluated in animal models with the aim of improving the level of protection and clearance of colonizing bacteria detected. In this study, a subunit vaccine layered with the antibiotic finafloxacin was evaluated in vivo against an inhalational infection with B. pseudomallei in Balb/c mice. Groups of mice vaccinated, infected, and euthanized at antibiotic initiation had a reduced bacterial load compared to those that had not been immunized. In addition, the subunit vaccine provided a synergistic effect when it was delivered with a CpG ODN and finafloxacin was initiated at 48 h post-challenge. Vaccination was also shown to improve the outcome, in a composite measure of survival and clearance. In summary, layering a subunit vaccine with the antibiotic finafloxacin is a promising therapeutic alternative for use in the treatment of B. pseudomallei infections.

Modeling the effect of temperature and relative humidity on exposure to SARS-CoV-2 in a mechanically ventilated room.

Computational fluid dynamics models have been developed to predict airborne exposure to the SARS-CoV-2 virus from a coughing person in a mechanically ventilated room. The models were run with three typical indoor air temperatures and relative humidities (RH). Quantile regression was used to indicate whether these have a statistically significant effect on the airborne exposure. Results suggest that evaporation is an important effect. Evaporation leads to respiratory particles, particularly those with initial diameters between 20 and 100 µm, remaining airborne for longer, traveling extended distances and carrying more viruses than expected from their final diameter. In a mechanically ventilated room, with all of the associated complex air movement and turbulence, increasing the RH may result in reduced airborne exposure. However, this effect may be so small that other factors, such as a small change in proximity to the infected person, could rapidly counter the effect. The effect of temperature on the exposure was more complex, with both positive and negative correlations. Therefore, within the range of conditions studied here, there is no clear guidance on how the temperature should be controlled to reduce exposure. The results highlight the importance of ventilation, face coverings and maintaining social distancing for reducing exposure.

Considerations in the design of animal infection pilot studies.

Ethical research with experimental systems (animals or humans) requires a rationale for the number of subjects to be included in a study. Standard methods for estimating sample size are not fit-for-purpose when the experimenter cannot predict the effect size/outcome with any certainty. These types of studies are often designated "pilot study"; however, there are few guidelines for sample size needed for a pilot study. Here we seek to address this issue. Concerning survival analysis it is noted that the experimenter can adjust the parameters of the experiment to improve the power. We propose that the experimenter needs to consider the "limit of interest" needed to represent an effect that the experimenter would be prepared to defend in terms of scientific or medical interest. Conventional power analysis is then used to estimate the n to deliver an alpha (false positive rate) of p < 0.2. This approach provides a balance that can inform a future study, demonstrate a strong effect or dismiss if no effect was observed. Where weight change or infection burden is considered, parametric analysis can be used. Here the main requirement for the pilot study is to establish a meaningful estimate of variability for subsequent power analysis. When considering the confidence intervals for standard deviations, it can be noted that a turning point is reached for n of four to six, beyond which we observe diminishing returns, suggesting that sample sizes should be greater than four. Finally, we discuss both the importance in statistical blocking and repeated measures in maximising the usefulness of the pilot study; and the importance of considering and outlining analysis techniques prior to performing the experiment. These findings are intended to be useful in the design of experiments in further prospective research.

Statistical methods used to combine the effective reproduction number, [Formula: see text], and other related measures of COVID-19 in the UK.

In the recent COVID-19 pandemic, a wide range of epidemiological modelling approaches were used to predict the effective reproduction number, R(t), and other COVID-19-related measures such as the daily rate of exponential growth, r(t). These candidate models use different modelling approaches or differing assumptions about spatial or age-mixing, and some capture genuine uncertainty in scientific understanding of disease dynamics. Combining estimates using appropriate statistical methodology from multiple candidate models is important to better understand the variation of these outcome measures to help inform decision-making. In this paper, we combine estimates for specific UK nations/regions using random-effects meta-analyses techniques, utilising the restricted maximum-likelihood (REML) method to estimate the heterogeneity variance parameter, and two approaches to calculate the confidence interval for the combined estimate: the standard Wald-type and the Knapp and Hartung (KNHA) method. As estimates in this setting are derived using model predictions, each with varying degrees of uncertainty, equal-weighting is favoured over the standard inverse-variance weighting to avoid potential up-weighting of models providing estimates with lower levels of uncertainty that are not fully accounting for inherent uncertainties. Both equally-weighted models using REML alone and REML+KNHA approaches were found to provide similar variation for R(t) and r(t), with both approaches providing wider, and therefore more conservative, confidence intervals around the combined estimate compared to the standard inverse-variance weighting approach. Utilising these meta-analysis techniques has allowed for statistically robust combined estimates to be calculated for key COVID-19 outcome measures. This in turn allows timely and informed decision-making based on all available information.

Investigation of a combination therapy approach for the treatment of melioidosis.

The efficacy of finafloxacin as a component of a layered defense treatment regimen was determined in vitro and in vivo against an infection with Burkholderia pseudomallei. Doxycycline was down-selected from a panel of antibiotics evaluated in vitro and used in combination with finafloxacin in a Balb/c mouse model of inhalational melioidosis. When treatment was initiated at 24 h post-infection with B. pseudomallei, there were no differences in the level of protection offered by finafloxacin or doxycycline (as monotherapies) when compared to the combination therapy. There was evidence for improved bacterial control in the groups treated with finafloxacin (as monotherapies or in combination with doxycycline) when compared to mice treated with doxycycline. Survival comparisons of finafloxacin and doxycycline (as monotherapies) or in combination initiated at 36 h post-infection indicated that finafloxacin was superior to doxycycline. Doxycycline was also unable to control the levels of bacteria within tissues to the extent that doxycycline and finafloxacin used in combination or finafloxacin (as a sole therapy) could. In summary, finafloxacin is a promising therapy for use in the event of exposure to B. pseudomallei.

Do surgical margins matter after mastectomy? A systematic review.

BACKGROUND: No consensus exists regarding adequacy of margins after mastectomy. To determine if pathological margin proximity is associated with local (LR) or distant recurrence after mastectomy for early invasive breast cancer or ductal carcinoma in situ. METHODS: A systematic review of literature published from 1980 to 2019 and meta-analysis was conducted. Unpublished data were sought from authors (PROSPERO (CRD42019127541)). Thirty-four studies comprising 34,833 breast cancer patients were included in the quantitative synthesis. Eligible studies reported on patients undergoing curative mastectomy for cancer allowing estimation of outcomes in relation to margin status/width. The association between pathological margin status and local (LR) and distant recurrence was considered using random effects modelling. PRISMA guidelines were followed. RESULTS: Positive margins were associated with increased LR on multivariable analyses (HR, 2·64, (95%CI 2·01-3·46)) and LR was higher regardless of the distance of tumour from the margin defined as positive. After skin-sparing mastectomy, positive margins were associated with increased LR (HR 3·40, (95%CI 1·9-6·2)). In the 4 studies reporting distant recurrence, patients with involved margins had a higher risk (HR 1·53, (95%CI 1·03-2·25)). CONCLUSIONS: Failure to achieve clear margins after mastectomy may increase the risks of local and distant recurrence. Adequate margin clearance should be recommended to minimize recurrence after mastectomy in National and International Guidelines.

Immune reconstitution in children following chemotherapy for acute leukemia.

Although survival rates for pediatric acute lymphoblastic leukemia are now excellent, this is at the expense of prolonged chemotherapy regimens. We report the long-term immune effects in children treated according to the UK Medical Research Council UKALL 2003 protocol. Peripheral blood lymphocyte subsets and immunoglobulin levels were studied in 116 participants, at six time points, during and for 18-month following treatment, with 30-39 patients analyzed at each time point. Total lymphocytes were reduced during maintenance chemotherapy and remained low 18 months following treatment completion. CD4 T cells remained significantly reduced 18 months after treatment, but CD8 cells and natural killer cells recovered to normal values. The fall in naïve B-cell numbers during maintenance was most marked, but numbers recovered rapidly after cessation of treatment. Memory B cells, particularly nonclass-switched memory B cells, remained below normal levels 18 months following treatment. All immunoglobulin subclasses were reduced during treatment compared to normal values, with IgM levels most affected. This study demonstrates that immune reconstitution differs between lymphocyte compartments. Although total B-cell numbers recover rapidly, disruption of memory/naïve balance persists and T-cell compartment persist at 18 months. This highlights the impact of modern chemotherapy regimens on immunity, and thus, infectious susceptibility and response to immunization.