Short and long term impact of combining restrictive and enabling interventions to reduce aztreonam consumption in a community hospital.

Background Antimicrobial stewardship initiatives combining restrictive and enabling components may be an effective strategy to achieve short- and long-term objectives. Aztreonam, a relatively high-cost antipseudomonal antibiotic, is an appropriate target for stewardship initiatives based on propensity for overuse in penicillin allergy, an activity profile often warranting additional empiric gram-negative and gram-positive coverage, and a unique durability to Ambler class B metallo-beta-lactamases. Objective Analyze the immediate and long-term impact on aztreonam prescribing of combining restrictive and enabling interventions. Setting Single 233-bed community hospital with 45 adult intensive care unit beds in Nashville, Tennessee. Method Retrospective, interrupted time series analysis comparing all patients receiving aztreonam prior to intervention between January 1, 2010 and September 30, 2011 and following intervention between October 1, 2011 and September 30, 2019. Quarterly defined daily doses/1000 adjusted patient days and microbiology laboratory annual surveillance data were utilized for analysis. Main outcome measure Post-intervention change in trend of aztreonam consumption. Results Following intervention, a significant decline in aztreonam consumption was observed (- 1.97 defined daily doses/1000 adjusted patient days; p = 0.003) resulting in a sustained decrease in aztreonam consumption from 2011 (3rd quarter) to 2019 (3rd quarter) from 15.2 to 0.26 defined daily doses/1000 adjusted patient days. Short-term group 2 carbapenem consumption increased (p = 0.044). Pseudomonas aeruginosa susceptibility to aztreonam improved from 2011 to 2018 (72% vs. 84%; p = 0.0004) without deleterious effects to alternative antipseudomonal beta-lactams. Conclusion Combining restrictive and enabling interventions had immediate and sustained impact on aztreonam consumption with P. aeruginosa susceptibility improvement.

Disentangling Complex Inheritance Patterns of Plant Organellar Genomes: An Example From Carrot.

Plant mitochondria and plastids display an array of inheritance patterns and varying levels of heteroplasmy, where individuals harbor more than 1 version of a mitochondrial or plastid genome. Organelle inheritance in plants has the potential to be quite complex and can vary with plant growth, development, and reproduction. Few studies have sought to investigate these complicated patterns of within-individual variation and inheritance using experimental crosses in plants. We carried out crosses in carrot, Daucus carota L. (Apiaceae), which has previously been shown to exhibit organellar heteroplasmy. We used mitochondrial and plastid markers to begin to disentangle the patterns of organellar inheritance and the fate of heteroplasmic variation, with special focus on cases where the mother displayed heteroplasmy. We also investigated heteroplasmy across the plant, assaying leaf samples at different development stages and ages. Mitochondrial and plastid paternal leakage was rare and offspring received remarkably similar heteroplasmic mixtures to their heteroplasmic mothers, indicating that heteroplasmy is maintained over the course of maternal inheritance. When offspring did differ from their mother, they were likely to exhibit a loss of the genetic variation that was present in their mother. Finally, we found that mitochondrial variation did not vary significantly over plant development, indicating that substantial vegetative sorting did not occur. Our study is one of the first to quantitatively investigate inheritance patterns and heteroplasmy in plants using controlled crosses, and we look forward to future studies making use of whole genome information to study the complex evolutionary dynamics of plant organellar genomes.

SV40 utilizes ATM kinase activity to prevent non-homologous end joining of broken viral DNA replication products.

Simian virus 40 (SV40) and cellular DNA replication rely on host ATM and ATR DNA damage signaling kinases to facilitate DNA repair and elicit cell cycle arrest following DNA damage. During SV40 DNA replication, ATM kinase activity prevents concatemerization of the viral genome whereas ATR activity prevents accumulation of aberrant genomes resulting from breakage of a moving replication fork as it converges with a stalled fork. However, the repair pathways that ATM and ATR orchestrate to prevent these aberrant SV40 DNA replication products are unclear. Using two-dimensional gel electrophoresis and Southern blotting, we show that ATR kinase activity, but not DNA-PK(cs) kinase activity, facilitates some aspects of double strand break (DSB) repair when ATM is inhibited during SV40 infection. To clarify which repair factors associate with viral DNA replication centers, we examined the localization of DSB repair proteins in response to SV40 infection. Under normal conditions, viral replication centers exclusively associate with homology-directed repair (HDR) and do not colocalize with non-homologous end joining (NHEJ) factors. Following ATM inhibition, but not ATR inhibition, activated DNA-PK(cs) and KU70/80 accumulate at the viral replication centers while CtIP and BLM, proteins that initiate 5' to 3' end resection during HDR, become undetectable. Similar to what has been observed during cellular DSB repair in S phase, these data suggest that ATM kinase influences DSB repair pathway choice by preventing the recruitment of NHEJ factors to replicating viral DNA. These data may explain how ATM prevents concatemerization of the viral genome and promotes viral propagation. We suggest that inhibitors of DNA damage signaling and DNA repair could be used during infection to disrupt productive viral DNA replication.