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

Leadership Development for Latino Community Emancipation: An Integrative Approach in Social Work Education

A primary goal of the social work profession is social justice advocacy for disenfranchised and oppressed communities, such as the Latino community. In the context of this paper, leadership development for community emancipation relate to efforts that foster indigenous community leadership designed to procure political rights or equality for their disenfranchised or devalued populations. The paper reviews the literature on Latino/a leadership perspectives, leadership development trends, and best practices that serve as a compatible integrative Latino/a approach. The approach proposes that the process of Latino/a leadership development should be collective, culturally-attuned, transformative, and community emancipatory. The authors present a model for students, alumni, and faculty that incorporates the approach through the use of three components: (1) Sustained institutional commitment, support and resources; (2) Creation of leadership opportunities, mentoring and modeling; and (3) Leadership efforts that foster community emancipation. The approach has been successfully employed for over 30 years in a Latino Project at a New England school of social work. Discussion of the model’s components, a case scenario, considerations for replication of the approach, and future research will be offered

Host factors are associated with vaginal microbiome structure in pregnancy in the ECHO Cohort Consortium

Using pooled vaginal microbiota data from pregnancy cohorts (N = 683 participants) in the Environmental influences on Child Health Outcomes (ECHO) Program, we analyzed 16S rRNA gene amplicon sequences to identify clinical and demographic host factors that associate with vaginal microbiota structure in pregnancy both within and across diverse cohorts. Using PERMANOVA models, we assessed factors associated with vaginal community structure in pregnancy, examined whether host factors were conserved across populations, and tested the independent and combined effects of host factors on vaginal community state types (CSTs) using multinomial logistic regression models. Demographic and social factors explained a larger amount of variation in the vaginal microbiome in pregnancy than clinical factors. After adjustment, lower education, rather than self-identified race, remained a robust predictor of L. iners dominant (CST III) and diverse (CST IV) (OR = 8.44, 95% CI = 4.06–17.6 and OR = 4.18, 95% CI = 1.88–9.26, respectively). In random forest models, we identified specific taxonomic features of host factors, particularly urogenital pathogens associated with pregnancy complications (Aerococcus christensenii and Gardnerella spp.) among other facultative anaerobes and key markers of community instability (L. iners). Sociodemographic factors were robustly associated with vaginal microbiota structure in pregnancy and should be considered as sources of variation in human microbiome studies