Discussion

Overall, we found adding GN-BSI bundle recommendations in the EMR was successful without negatively impacting patient outcomes. There was a statistically significant increase in the primary team’s ownership of vancomycin discontinuation (37.9% vs 66.7%; P < 0.001) and a numerical increase in antimicrobial de-escalation (27.3% vs 36.1%; P = 0.310). Also, significantly more patients were narrowed to aminopenicillins in postBG (3.8% vs 14.9%; P = 0.043). Our study results are similar to previous experience. Musgrove et al reported using a simple microbiology comment nudge improved pneumonia prescribing practices. In their study, respiratory cultures with no dominant organism growth were reported by the clinical microbiology laboratory as “commensal respiratory flora only: No S. aureus/MRSA [methicillin-resistant Staphylococcus aureus] or P. [Pseudomonas] aeruginosa.” They found de-escalation/discontinuation of unnecessary broad-spectrum antibiotics was more commonly performed in the intervention group without causing harm (39% vs 73%, P < .001). ^{Reference Musgrove, Kenney and Kendall16}

Erickson et al showed a decrease in DOT (14 vs 10 days; P < 0.01) and a decrease in time to IV to PO switch (5 days vs. 4 days; P = 0.46), while Walsh et al showed a decrease in time to definitive therapy (32.6 hours vs 10.5 hours; P < 0.001). ^{Reference Erickson, Tritle, Spivak and Timbrook11,Reference Walsh, Bremmer and Moffa12} There were no differences in these outcomes in our study. In Erickson and Walsh, ASP PAF and rapid diagnostic testing were part of the bundles under evaluation, while these interventions were constant across our study’s groups: ASP PAF occurred in both time periods and rapid diagnostics in neither. In addition, the main goal of our GN-BSI bundle was to utilize the bundle as a passive nudge-based strategy to empower the primary team to discontinue unnecessary empiric vancomycin and perform antimicrobial de-escalation on their own without ASP intervention.

The nudge-based recommendation to discontinue unnecessary vancomycin led to a shift where the primary team stopped vancomycin without prompting from either ASP or ID consultation. PAF can often be labor intensive and nudge-based bundle recommendations provided to the clinician at the point of care can facilitate optimal therapy by stopping unnecessary empiric broad-spectrum antimicrobials. ^{Reference Langford, Leung and Haj13,Reference Barlam, Cosgrove and Abbo14} There also was a numerical increase in de-escalation done by the primary team and an increase in the use of narrow spectrum agents with aminopenicillin therapy based on the bundle recommendations.

The order and passive nature of the bundle recommendations may have affected the impact of each individual guidance, with later recommendations receiving less consideration. Discontinuation of vancomycin was the 2^nd recommendation in the bundle and the intervention primary teams followed most often on their own, while there was no change seen in the last recommendation to consider a 7-day DOT. In addition, we hypothesize that the lack of change between the groups in de-escalation done by the primary team may result from the need for a higher level of ID training and comfortability in interpreting susceptibility data when selecting targeted narrow-spectrum therapy.

In postBG, we found a slightly longer time to ID consultation resulting in a median of 7.2 hours later. There was also a trend towards decreased ID consultation (P = 0.096) which reached statistical significance for patients growing ESBL-producing organisms (90% preBG vs 64.3% postBG; P = 0.043). These finding may be attributed to the primary team’s increased comfort with the initial treatment of GN-BSI facilitated by the bundle, which included a reference link to our institutional treatment guidelines. The decrease in ID consultation for ESBL-producing organisms may also have been a result of the bundle recommending ID consultation specifically for CRE. This delay and decreased ID consultation for ESBLs without findings of any impact on clinical outcomes, suggests the bundle may allow for improved use of ID consultation resources, by decreasing unnecessary consults.

The last recommendation in the bundle is to consider a 7-day DOT for uncomplicated GN-BSI in patients with no immunocompromising conditions. Our study showed the bundle did not influence antimicrobial DOT. When we compare the DOT seen in the included population to the population excluded due to rounding CPS on the primary team, 7-day DOT still remained low (in excluded patients: 6% preBG vs 15% postBG, P = 0.112). A possible contributing factor to this finding includes the placement of the 7-day DOT as the last recommendation of the bundle. In addition, considering urine was the most common source of bacteremia, our institutional guidelines for urinary tract infections at the time may have influenced this result, as these guidelines recommend 7–14 days for complicated cystitis and 10–14 days for pyelonephritis. Primary teams may have used those guidelines defaulting to the longer durations over recommendations in the GN-BSI guidelines.

Our study had several limitations. First, this was a before-and-after, quasi-experimental study design and cannot account for confounding factors or changes in practice over time compared to a randomized study. Although the bundle populates and remains visible in the EMR, we cannot confirm the primary team fully utilized or read the entirety of the GN-BSI bundled recommendations. It is possible that the changes in postBG could be caused by other variables other than the bundle. Second, we excluded patients in the ICU or who are immunocompromised, which limits the generalizability in these specific populations. Third, the primary composite outcome only evaluated readmission or infection recurrences within our institution and did not account for admissions or recurrences from outside hospitals. Fourth, by including 2^nd and 3^rd generation cephalosporins in our definition of narrow spectrum therapy, this may not be consistent with other antibiotic use classifications. However, this is a common de-escalation practice at our institution since our automated susceptibility testing platform, at the study time, did not measure cefazolin MICs to below the breakpoint for bacteremia.

Overall, the use of a nudge-based GN-BSI bundle in the EMR showed an increase in vancomycin discontinuation by the primary team and a trend towards an increase in antimicrobial de-escalation without negatively affecting patient specific outcomes. This nudge-based bundle may be a useful strategy as it empowers the primary team to have more ownership in their antimicrobial decision-making and can allow ASP and ID consultants to focus their time on higher-level interventions. Additional research should evaluate the use of different and/or a combination nudging strategies to identify the most effective approach to this stewardship practice as well as the impact of this concept to less resourced programs.