349. Diagnostic Testing and Antibiotic Utilization in Patients with COVID-19

Background Patients with COVID-19 receive high rates of antibiotic therapy, despite viral origin of infection. Reports of bacterial coinfection range from 3.5 to 8% in the early phase of infection. This study aimed to evaluate the relationship between diagnostic tests and antibiotic utilization in patients admitted with COVID-19 at the University of Maryland Medical Center to better inform future prescribing practices. Methods Retrospective cohort study of adult patients with a positive SARS-CoV-2 PCR on admission from March 2020 through June 2020. Associations between diagnostic tests employed and antibiotic initiation and duration were explored using bivariate analysis (SPSS®). Results Baseline characteristics of 224 included patients are reported in Table 1. Excluding SARS-CoV-2 PCRs, most frequently performed diagnostic tests included blood cultures (65.6%), MRSA nasal surveillance (45.1%), respiratory cultures (36.2%), respiratory viral panel (RVP) (33.0%), and Legionella (28.6%) and pneumococcal (26.3%) urine antigens. Positivity of RVP, Legionella, pneumococcus, blood, and respiratory tests were low (1.3%, 0.4%, 0.9%, 1.8%, and 6.7%, respectively). A total of 62% of patients were initiated on antibacterial therapy with a median cumulative antibiotic duration of 77.9 hours (IQR 41.4, 111.8). History of chronic respiratory disease (76% vs. 58.6%; P=0.025), any degree of oxygen requirement on admission (72% vs. 42.6%; P=0.006), and performance of blood cultures (70.7% vs. 46.8%, P< 0.0001) were associated with antibiotic initiation. Positive bacterial diagnostic respiratory culture (median duration 72.8h [IQR 46.7, 96.6] vs. 97.3h [IQR 79.8, 194.1]; P=0.027) and positive blood culture (median duration 80.1h [IQR 42.1, 111.7] vs. 97.5h [IQR 71.8, 164.8]; P=0.046) were associated with longer antibiotic duration. Patients who did not have respiratory cultures performed had similar antibiotic durations as those with negative respiratory cultures. Table 1. Baseline Characteristics Conclusion Despite low coinfection rates, negative diagnostic tests did not result in shorter empiric antibacterial duration. These findings highlight the ongoing need for both diagnostic and antimicrobial stewardship in COVID-19. Disclosures Emily Heil, PharmD, MS, BCIDP, Nothing to disclose Kimberly C. Claeys, PharmD, GenMark (Speaker’s Bureau)

748. The Changing Epidemiology of Clostridioides difficile Infection and the NAP1/027 Strain in Two Quebec Hospitals

Background In 2003, many hospitals in Québec, Canada experienced an increase in the incidence of healthcare-associated C. difficile infection (HA-CDI) associated with increased morbidity and mortality. This increase was associated with the dissemination of the NAP1/027 strain. The objective of this study was to describe the epidemiology of HA-CDI in two tertiary care hospitals based in Montréal from 2003 to 2019. Methods Surveillance for HA-CDI was performed using standard definitions from 2003 to 2019 at the Montreal General Hospital (MGH) and Royal Victoria Hospital (RVH), in Montréal, Québec. C. difficile was isolated from stool specimens using standard methods. Pulsed field gel electrophoresis and ribotyping were performed to determine genotype. Antibiotic utilization and infection control interventions implemented over the same time period were reviewed. Results A total of 4314 cases of CDAD were identified during the study period: 2295 at the RVH and 2019 at the MGH. The incidence decreased from 29.5 to 5.9 cases per 10,000 patient-days between 2003 and 2019 at the RVH and from 23.8 to 3.9 cases per 10,000 patient-days at the MGH. Of the 124 isolates available for genotyping in 2003, 112 were NAP1 (90.3%) compared to 5 out of 53 (9.4%) in 2019. Fluoroquinolone utilization decreased from 230 to 139 DDDs per 1,000 patient-days between 2003 and 2019, whereas total antibiotic utilization increased from 1296 to 1550 DDDs per 1,000 patient-days. Infection Control interventions included empirically placing patients with diarrhea on precautions, intensified cleaning measures, formal antibiotic stewardship, introduction of a real-time PCR C. difficile test in June 2010, and a move to a facility with only single rooms at the RVH in April 2015. Incidence of HA-CDI at the RVH and MGH and antibiotic utilization between 2003 and 2019 Conclusion An important change in HA-CDI epidemiology was observed in two Canadian tertiary care hospitals based in Montréal between 2003 and 2019. There was a significant decrease in incidence of HA-CDI and a genotype shift from a predominance of NAP1 strains to non-NAP1 strains. Utilization of fluoroquinolones, to which the NAP1 strain is resistant, concurrently decreased. Infection control interventions targeting isolation, diagnosis, disinfection, and antibiotic stewardship have contributed to the major observed reduction in HA-CDI incidence. Disclosures All Authors: No reported disclosures

149. Impact of Stewardship on Antibiotic Utilization Rates During the COVID-19 Pandemic: Successes and Challenges in a Regional Hospital

Background Antibiotic stewardship (AS) is at the core of patient safety and prevention of antimicrobial resistance. Healthcare providers prescribe antibiotics for COVID-19 despite low rates of bacterial co-infection. Our regional hospital had antibiotic utilization (AU) rates higher than other health systems even prior to the emergence of SARS-Cov2. We analyzed the effect AS on AU during the pandemic. Total Antibiotic Utilization Rates Before and During COVID-19 Pandemic Methods Total and specific AU rates were benchmarked using BD MedMined’s medication analytics system from 2nd quarter 2019 to 1st quarter 2021. The AS team released yearly antibiogram and individual prescriber’s AU rates and performed weekly, and as needed, review of antibiotic ordering and feedback. To assist in appropriate prescribing decisions, remote educational sessions or mini-lectures and local antibiotic guidelines were developed during the pandemic period. AU rates were monitored quarterly to determine the effects of the AS interventions to prescribing practices. Results Total and specific AU rates were higher (up to 34% and 80%, respectively) in our index hospital compared to other non-teaching hospitals nationally prior to the pandemic. Total antibiotic utilization increased by only 5.5% in the 2nd quarter 2020, peak of AU during the pandemic. Total, vancomycin, piperacillin-tazobactam and quinolone utilization rates decreased by 19%, 41%, 38%, and 52%, respectively, at 1st quarter 2021 compared to 4th quarter 2019. Steeper decreases were noted with implementation of educational activities. Ceftriaxone use remained high and was 50% greater than comparator hospitals at 1st quarter 2021. Conclusion Although problematic during the COVID-19 pandemic, AS can have significant impact on provider prescribing practices and decrease total and specific antibiotic utilization rates. The use of ceftriaxone, an antibiotic commonly used for empiric bacterial coverage for community acquired pneumonia, presents as a continuing challenge. Disclosures All Authors: No reported disclosures

163. MIC Shifts in Response to Increased Antibiotic Utilization During COVID-19 Pandemic

Background Multiple studies have shown that antibiotic utilization increased during the COVID-19 pandemic. However, the impact of this increased utilization has not been well established. The aim of this study is to describe the trends in minimum inhibitory concentrations for various antibiotics against common gram-negative pathogens observed since the start of the COVID-19 pandemic as compared to previous years. Methods This retrospective study was conducted at the Memphis VA. All respiratory, urine, and blood culture MicroScan results run from October 2017-March 2021 were analyzed. Only inpatient and emergency department data was included. The MIC50 and MIC90 of seven antibiotics for four of the most common pathogens were trended by quarterly intervals. Results MIC50 and MIC90 were compared using standardized breakpoints. As compared to previous years, Pseudomonas aeruginosa was noted to have the most sustained increase in MIC90 across various antibiotics. In the last 3 quarters of the study time frame, piperacillin-tazobactam mean MIC90 increased from 32 to 64, cefepime from 8 to > 16, and meropenem from 4 to > 8. Escherichia coli had a sustained increase in ceftriaxone MIC90 from < 1 to > 8 in the final quarter of 2020 and beginning of 2021. Klebsiella pneumonia was also found to have a sustained increase in cefepime mean MIC90 from < 1 to > 16 during the year of 2020, with return to previous MIC90 the following quarters. Conclusion Previous studies have clearly demonstrated a widespread increase in antibiotic utilization during the COVID era. Our study demonstrates how even short-term increases in antibiotic use can lead to shifts in MIC, if not outright resistance. This was demonstrated across multiple common gram-negative pathogens and to various broad-spectrum antibiotics which were commonly used more frequently during COVID-19. Further analysis will be needed to determine whether these trends continue or whether the decrease in antibiotic utilization in the recent months will lead to similar decrease in MIC. Disclosures All Authors: No reported disclosures

753. Impact of COVID-19 on Healthcare Facility-Onset Clostridiodes difficile Infection

Background It is estimated that the majority of hospitalized COVID-19 patients around the world received antibiotics despite the fact that bacterial co-infections are rare. This can lead to increased antimicrobial resistance and Clostridioides difficile infections (CDI). Gastrointestinal symptoms of COVID-19 may also contribute to increased testing. The objective of this study was to assess the impact of the COVID-19 pandemic on our healthcare facility-onset (HO) CDI rates. Methods This was a retrospective cross-sectional study comparing CDI rate per 1,000 patient days, C. diff order rate per 1,000 patient days, Standardized Antimicrobial Administration Ratio (SAAR), and Standardized Infection Ratio (SIR) in the pre-COVID-19 period from January 1, 2019 to December 31, 2019 to the COVID-19 period from April 1, 2020 to March 31, 2021 at a 877-bed tertiary care hospital in Detroit, Michigan. CDI and order rates were extracted from the electronic medical record (Epic™ Bugsy). SAAR and SIR data were extracted from National Healthcare Safety Network (NHSN). Results The average CDI rate per 1,000 patient days was 4.29 pre-COVID-19 compared to 1.98 during COVID-19 with a 54% reduction, and the C. diff order rate per 1,000 patient days also decreased from 130.89 to 93.03, resulting in a 29% reduction (Figure 1). The SIR was 0.383 compared to 0.308 during COVID-19 (P-value 0.404). SAAR decreased from 1.095 to 0.945 (P-value < 0.001). However, our institution experienced three COVID-19 waves, with peaks in April 2020, November 2020 and March 2021, that correlated with high risk CDI antibiotic utilization in intensive care unit (ICU) (Figure 2). The average hand hygiene rate increased from 82% to 92%. Figure 1. Clostridioides difficile order and infection rates pre-and during COVID-19 pandemic. Figure 2. Standardized Antimicrobial Administration Ratio (SAAR) pre-and during COVID-19 pandemic. Conclusion Despite the COVID-19 pandemic, the HO-CDI and C. diff order rates and overall SAAR decreased; however, antibiotic utilization increased in the ICU during the COVID-19 waves. The overall decrease may be multifactorial and related to increased hand hygiene compliance, isolation and personal protective equipment use and overall decreased antibiotic use and C. diff orders. Disclosures Rachel Kenney, PharmD, Medtronic, Inc. (Other Financial or Material Support, spouse is an employee and shareholder)

A Culture Change: Impact of a Pediatric Antimicrobial Stewardship Program Based on Guideline Implementation and Prospective Audit with Feedback

Reports analyzing the impact of pediatric antimicrobial stewardship programs (ASP) over long periods of time are lacking. We thus report our ASP experience in a pediatric tertiary referral center over a long-term period from 2011 to 2018. Our ASP was implemented in 2011. The program was based primarily on guideline development with key stakeholders, engaging and educating providers, followed by prospective audit with feedback (PAF). Monitored antibiotics included meropenem, piperacillin–tazobactam, and cefepime, followed by the addition of ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, levofloxacin, linezolid, and vancomycin at various time points. Specifically, the program did not implemented the core strategy of formulary restriction with prior authorization. Process- and outcome-related ASP measures were analyzed. We saw a 32% decrease in overall antibiotic utilization, a 51% decrease in the utilization of antibiotics undergoing PAF, and a 72% reduction in the use of broad-spectrum antibiotics such as meropenem. There was a concomitant increase in organism susceptibility and a reduction in yearly drug purchasing costs of over USD 560,000 from baseline without changes in sepsis-related mortality. Our study highlights that a pediatric ASP based primarily on the principles of guideline development and PAF can improve antibiotic utilization and institutional bacterial susceptibilities without a detrimental impact on patient outcomes by changing the culture of antimicrobial utilization within the institution.