A Type I Restriction-Modification System Associated with Enterococcus faecium Subspecies Separation.

The gastrointestinal colonizer Enterococcus faecium is a leading cause of hospital-acquired infections. Multidrug-resistant (MDR) E. faecium isolates are particularly concerning for infection treatment. Previous comparative genomic studies revealed that subspecies referred to as clade A and clade B exist within E. faecium MDR E. faecium isolates belong to clade A, while clade B consists of drug-susceptible fecal commensal E. faecium isolates. Isolates from clade A are further grouped into two subclades, clades A1 and A2. In general, clade A1 isolates are hospital-epidemic isolates, whereas clade A2 isolates are isolates from animals and sporadic human infections. Such phylogenetic separation indicates that reduced gene exchange occurs between the clades. We hypothesize that endogenous barriers to gene exchange exist between E. faecium clades. Restriction-modification (R-M) systems are such barriers in other microbes. We utilized a bioinformatics analysis coupled with second-generation and third-generation deep-sequencing platforms to characterize the methylomes of two representative E. faecium strains, one from clade A1 and one from clade B. We identified a type I R-M system that is clade A1 specific, is active for DNA methylation, and significantly reduces the transformability of clade A1 E. faecium Based on our results, we conclude that R-M systems act as barriers to horizontal gene exchange in E. faecium and propose that R-M systems contribute to E. faecium subspecies separation.IMPORTANCEEnterococcus faecium is a leading cause of hospital-acquired infections around the world. Rising antibiotic resistance in certain E. faecium lineages leaves fewer treatment options. The overarching aim of this work was to determine whether restriction-modification (R-M) systems contribute to the structure of the E. faecium species, wherein hospital-epidemic and non-hospital-epidemic isolates have distinct evolutionary histories and highly resolved clade structures. R-M provides bacteria with a type of innate immunity to horizontal gene transfer (HGT). We identified a type I R-M system that is enriched in the hospital-epidemic clade and determined that it is active for DNA modification activity and significantly impacts HGT. Overall, this work is important because it provides a mechanism for the observed clade structure of E. faecium as well as a mechanism for facilitated gene exchange among hospital-epidemic E. faecium isolates.

Analysis of central venous catheter utilization at a quaternary care hospital.

Central line-associated bloodstream infections (CLABSIs) are one of the most dangerous and costly types of hospital-acquired infections. Incidence of CLABSI can be significantly reduced through proper aseptic techniques, surveillance, and active management strategies, including elimination of idle central line days. This quality improvement project examined two central venous catheter (CVC) cohorts. The institutional electronic health record (EHR) was utilized to generate a daily report indicating CVC utilization by patient care unit. The EHR was further scrutinized for documentation of appropriate indications for CVC use employing an appropriateness tool developed by the institutional vascular access team. Cohort 1 included 12 National Healthcare Safety Network-reportable units audited on a daily basis over a 4-week time period; cohort 2 included selected National Healthcare Safety Network-nonreportable units audited on a daily basis over a 2-week time period. Central venous catheters that did not meet defined indications as outlined by the institutional vascular access team's data collection checklist were escalated the same day to the unit clinical nurse manager for review and possible removal. The percentage of clinically nonindicated CVCs in cohort 1 fell by 65% over the 4-week period of daily audit and real-time feedback, with similar results noted for cohort 2. In conclusion, real-time audit and feedback regarding appropriate clinical indications for CVC use can result in decreased idle or nonindicated central line days, potentially contributing to decreased CLABSI rates.