Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

From user insights to evidence-based strategy selection: designing for behaviour change with the behavioural lenses approach

This workshop provides participants with the opportunity to familiarise themselves with the Behavioural Lenses Toolkit. This toolkit supports designers in using theory from the behavioural sciences to inform their work. The workshop consists of an introduction to the toolkit and a couple of hands-on exercises in which we will demonstrate and try out the toolkit in establishing use (r) contexts in behavioural design projects. Furthermore, we will try out a new prototype tool that supports making an evidence-based transition from user insights to behavioural change strategies

Outcomes after appendectomy in children with acute appendicitis treated at a tertiary paediatric centre: results from a retrospective cohort study

Purpose: In general, an appendectomy is presumed to have a limited burden of disease. However, in current literature, reported complication rates vary. This study aims to provide additional insights in the incidence of post-appendectomy complications in children with acute appendicitis. Methods: This retrospective cohort study included children (0–17 years old) that underwent appendectomy at our tertiary referral centre for suspected acute appendicitis (January 2011–December 2018). Children referred to our centre, and those that underwent non-operative treatment were excluded. Post-appendectomy complications were recorded from electronic medical charts using predefined definitions and classified as severe (Clavien-Dindo III–IV) or less severe (Clavien-Dindo I–II). Results: A total of 131 children were included. Simple and complex appendicitis was diagnosed in 66 (50%) and 60 (46%) children, respectively. A non-inflamed appendix was seen in five (4%) children. One or more complications were identified in 33 (25%) patients. Eight (12%) children with simple appendicitis developed a complication, three of these were severe. In children with complex appendicitis, 23 (38%) children developed a complication, 14 of these were severe. Conclusion: This study shows a high rate of complications compared with current literature, both in children with simple and complex appendicitis. This is probably the result of our definition of complications and being a tertiary referral centre receiving more severe appendicitis cases. However, these results still show that appendectomy is not always a routine procedure with only few complications. Substantiating the need to keep optimizing treatment for children with appendicitis

Management of appendiceal mass and abscess in children; early appendectomy or initial non-operative treatment? A systematic review and meta-analysis

Background: Appendiceal mass and abscess and its treatment are associated with significant morbidity and high costs. Still, the optimal treatment strategy is the point of debate. Therefore, this systematic review and meta-analysis aimed to compare overall complications between initial non-operative treatment (NOT) and early appendectomy (EA) in children with appendiceal mass and/or abscess. Methods: Pubmed and Embase were searched. Only randomized controlled trials and prospective or historical cohort studies that compared NOT with EA in children with appendiceal mass or abscess in terms of complications were eligible for inclusion. Risk of bias was assessed. Primary outcome was the overall complication rate. Secondary, length of stay and readmission rate were investigated. A meta-analysis of overall complications associated with both treatment strategies was performed. Results: 14 of 7083 screened studies were selected, including 1022 children in the NOT group and 333 in the EA group. Duration of follow-up ranged between four weeks and 12 years. Risk of bias was moderate in four and serious in 10 studies. NOT was associated with a lower overall complication rate (risk ratio (RR) 0.37 [95% confidence interval (CI) 0.21–0.65]). However, NOT led to increased length of stay (mean difference varied between 0.2 and 8.4 days) and higher readmission rate (RR 1.75 [95%CI 0.79–3.89]), although not significantly. Interval appendectomy after NOT was performed as a routine procedure in all but one study. This study found a recurrence rate of 34% in a group of 38 patients during a follow-up period of 3.4 ± 1.7 years. Conclusion: NOT may reduce the overall complication rate compared to EA, but the evidence is very uncertain. As evidence is scarce, and of low level, and heterogeneity between studies is substantial, the results should be interpreted with caution. Large prospective studies are needed to determine the optimal treatment strategy for children with appendiceal mass and/or abscess

Outcome after vaginal delivery of women with a previous medical history of surgically corrected anorectal malformations: a systematic review

Objective: Discussion remains on how to advise women with a past medical history of surgically corrected anorectal malformations (ARMs) regarding vaginal delivery. The aim of this review is to evaluate and review the reported obstetrical complications and outcomes after vaginal delivery for these women. Data sources: A systematic search was performed from inception up to 25 July 2022 in PubMed, Embase.com and Clarivate Analytics/Web of Science Core Collection, with backward citation tracking. Study eligibility criteria/appraisal: All articles reported on the outcomes of interest in women with a past medical history of surgically corrected anorectal malformation and had a vaginal delivery were included with the exception of editorial comments or invitational commentaries. Screening, data extraction and risk of bias assessment was done by two authors independently with a third and fourth reviewer in case of disagreement. Tool for Quality assessment depended on the type of article. As low quality evidence was expected no meta-analysis was performed. Results: Only five of the 2377 articles screened were eligible for inclusion with a total of 13 attempted vaginal deliveries in eight women. In three patients complications were reported: failed vaginal delivery requiring urgent cesarean section in two patients, and vaginal tearing in one patient. Conclusion: High quality evidence regarding outcomes and complications after vaginal delivery in women with a history of surgically corrected anorectal malformation is lacking. Therefore, based upon this systematic review no formal recommendation can be formulated regarding its safety. Future studies are essential to address this problem. Trial registration: CRD42020201390. Date: 28–07-2020s