The interferon-gamma inducible protein 16 (IFI16) is a nuclear DNA sensor that mediates antiviral responses by activating the inflammasome, triggering an interferon response, and silencing lytic genes of herpesviruses. The last, which helps maintain latency of the oncoherpesvirus Epstein-Barr virus (EBV), is accomplished via H3K9me3 heterochromatinization through unknown mechanisms.

Background: Members of the genus Corynebacterium are increasingly recognized as pathobionts and can be very resistant to antimicrobial agents. Previous studies have demonstrated that Corynebacterium striatum can rapidly develop high-level daptomycin resistance (HLDR) (minimum inhibitory concentration [MIC] ≥256 μg/mL). Here we conducted a multi-center study to assay for this in vitro phenotype in diverse Corynebacterium species. Methods: Corynebacterium clinical isolates (n=157) from four medical centers were evaluated. MIC values to daptomycin, vancomycin, and telavancin were determined before and after overnight exposure to daptomycin to identify isolates able to rapidly develop daptomycin non-susceptibility. To investigate assay reproducibility, 18 isolates were evaluated at three study sites. In addition, stability of daptomycin non-susceptibility was tested using repeated subculture without selective pressure. The impact of different media brands was also investigated. Results: Daptomycin non-susceptibility emerged in 12 of 23 species evaluated in this study (C. afermentans, amycolatum, aurimucosum, bovis, jeikeium, macginleyi, pseudodiphtheriticum, resistens, simulans, striatum, tuberculostearicum, and ulcerans) and was detected in 50 of 157 (31.8%) isolates tested. All isolates displayed low (susceptible) MIC values to vancomycin and telavancin before and after daptomycin exposure. Repeated subculture demonstrated 2 of 9 isolates (22.2%) exhibiting HLDR reverted to a susceptible phenotype. Of 30 isolates tested on three media brands, 13 (43.3%) had differences in daptomycin MIC values between brands. Conclusions: Multiple Corynebacterium species can rapidly develop daptomycin non-susceptibility, including HLDR, after a short daptomycin exposure period.

BackgroundUrine is the most frequently cultured specimen type for the majority of clinical microbiology laboratories. Typically, around 30% of cultures are positive for uropathogens with 70% yielding insignificant or mixed growth. BD is developing a software Urine Culture Application (UCA) for the BD Kiestra Total Laboratory Automation (TLA) system to screen images of urine culture plates, sort them based on growth vs. insignificant growth and also allow for presumptive pathogen identification.MethodsDe-identified urine specimens were inoculated onto BD BBL™ CHROMagar™ Orientation Media (CHROM; BD, Sparks, MD), CHROM/Trypticase™ Soy Agar II with 5% Sheep Blood (TSA) biplate, BD BBL MacConkey II agar, and TSA using the BD Kiestra TLA system. Plates were imaged at 24 hours using the BD Kiestra™ ReadA Compact imaging acquisition software and an algorithm was applied to the images using the UCA (Version 2.0). Semi-quantitative measurements of <100, 100–1,000, 1,000–10,000, 10,000–100,000, and >100,000 cfu/mL growth were determined by UCA for all media types and presumptive ID was determined using CHROM. Manual reading of the images by two technologists was the gold standard for comparison. For discrepant results, a third manual reader was used as an arbitrator.ResultsTesting between 877 and 934 urine specimens on each of five media types using UCA resulted in an exact semi-quantitative agreement with manual reading for 85.5–95.0% of specimens (Table 1). If semi-quantitative values ± one category of agreement are included, the number rises to 98.2–99.4% agreement. Using CHROM for presumptive identification of pure or predominant organisms, UCA was in agreement with manual identification in 251 of 272 cultures (92.3%). Of the 21 discrepant organisms, 19 were classified as “other” by manual reading but were identified as specific organisms by UCA. Definitive organism identification was not performed.ConclusionUCA was able to accurately categorize bacterial growth into five semi-quantitative categories using five media types. Pure and predominant uropathogens were accurately identified from CHROM using UCA. The use of UCA software application may enable laboratories to save time screening urine cultures by allowing more efficient use of technologist time. Disclosures All authors: No reported disclosures.

During the course of infection, human immunodeficiency virus (HIV) maintains a stably integrated reservoir of replication-competent proviruses within the host genome that are unaffected by antiretroviral therapy. Curative advancements rely heavily on targeting the reservoir, though determinants of its evolutionary origins remain ill-supported through current strategies and are often limited by sample variety. Here, we describe a single-cell deoxyribonucleic acid sequencing (scDNA-seq) method, optimized for sequencing of proviral and host DNA from a treatment-interrupted HIV animal model. We report its benefits for improving viral reservoir resolution to support critical evolutionary events otherwise considered unreliable using traditional viral envelope gene signal alone, as well as comparative advantages to existing near-full-length genome sequencing methods. Given the variety of proviral characteristics that may influence viral rebound, scDNA-seq holds immense value in its ability to streamline many of the present-day applications available in viral reservoir studies, such as integration status and putative replication competency.

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