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

Disparities in Diagnosis and Treatment of Autism in Latino and Non-Latino White Families

Objectives: To compare barriers to autism spectrum disorder (ASD) diagnosis and current ASD-related service use among non-Latino white (NLW) families and Latino families with English proficiency (L-EP) or limited English proficiency (L-LEP). Methods: We conducted a mixed-mode survey of families of children with confirmed ASD seen at specialty clinics in 3 United States cities. Bivariate and multivariate analyses compared barriers to ASD diagnosis, current service use, and unmet therapy need among NLW, L-EP, and L-LEP families. Results: Overall, barriers to ASD diagnosis were prevalent: families (n = 352) experienced a mean of 8 of 15 barriers to ASD diagnosis. The most prevalent barriers overall were stress of diagnostic process, parent knowledge about ASD, and understanding medical system. Compared with NLW families, L-LEP families were more likely to experience barriers related to knowledge about ASD and trust in providers. Children in L-LEP families also had fewer current therapy hours and more unmet therapy needs than children in NLW families. L-EP families\u27 barriers and treatment services use profile was more similar to NLW than to L-LEP families. Conclusions: English proficiency was an important marker for barriers to ASD diagnosis and treatment in Latinos. Increasing ASD-related knowledge and provider trust may decrease disparities in the diagnosis and treatment of ASD among US Latinos