Hannan, Kellie N. Arensman

Abstract Objective: Antibiotics are frequently prescribed for acute sinusitis despite national guidelines recommending antibiotics only if specific symptom criteria are met. We aimed to define the proportion of acute sinusitis encounters meeting criteria for antibiotic prescribing, characterize prescribing practices, and identify factors associated with guideline-discordant prescribing. Design: This retrospective cohort study included 1,000 randomly selected adult ambulatory encounters with a primary diagnosis of acute sinusitis between January 1, 2024 and March 31, 2024. Encounter notes were reviewed for appropriate antibiotic prescribing criteria as per national guidelines. Encounters were evaluated for drug selection and duration concordance based on local guidelines. A multivariable logistic regression analysis was performed to identify predictors of inappropriate antibiotic prescribing. Setting: Emergency departments, urgent care centers, and primary care clinics. Results: Antibiotic prescribing criteria were met for 67.6% of included encounters. Antibiotics were prescribed in 93.5% of encounters that met prescribing criteria, and 80.2% of encounters that did not. Both drug selection and duration were guideline-concordant in 49.2% of total encounters. On multivariable analysis, predictors of inappropriate antibiotic prescribing included cough (OR 2.15, 95% CI 1.08–4.29; P = 0.03) and symptom duration between 7 and 9 days (compared to <6 days; OR 7.70, 95% CI 3.24–18.31; P < 0.001). Electronic encounters were associated with lower odds of prescribing compared to in-person encounters (OR 0.03, 95% CI 0.01–0.09; P < 0.001). Conclusions: Most encounters for acute sinusitis result in an antibiotic prescription, despite prescribing criteria not being met. These findings may aid antimicrobial stewardship programs in benchmarking and optimizing antibiotic prescribing for acute sinusitis.

Abstract We describe early experience with beta-lactam therapeutic drug monitoring (TDM) in a high-volume outpatient parenteral antimicrobial therapy program. In selected patients, TDM informed dose optimization and toxicity mitigation. Illustrative cases highlight feasibility and emerging lessons supporting beta-lactam TDM in outpatient care.

Abstract Background Outpatient antibiotic stewardship programs (ASP) are recommended by the CDC and Joint Commission. We analyzed the impact of annual, focused syndrome-specific ASP interventions on trends in long-duration antibiotic prescribing (LDAP). Methods This was a retrospective, observational, multicenter cohort study from November 2020 through June 2025. All ambulatory encounters generating systemic antibiotic prescriptions within the healthcare enterprise were screened. Hospitalizations, emergency department visits, and infectious diseases encounters were excluded. Encounters generating ≥1 systemic antibiotic with &gt;7 days duration were categorized as long-duration. Targeted departments (primary and urgent care) received direct intervention (eg, education, peer-comparison reporting, data tracking). LDAP was modeled over time by month and compared by diagnosis group (ASP-priority diagnoses vs nonpriority) and provider specialty department (ASP-targeted vs nontargeted) using linear regression models. Results Of 642 579 encounters included, 42.2% were long duration. LDAP in ASP-targeted departments dropped from 46.8% to 34.8% (difference −12 percentage points [pp]), whereas nontargeted departments dropped from 45.5% to 39.1% (difference −6.4 pp). The estimated annual LDAP decrease was 3.4 pp in targeted versus 2.4 pp in nontargeted departments (difference 1.0 pp, P = .009). Within targeted departments, significant LDAP decreases were seen both in priority and nonpriority diagnoses, whereas nontargeted departments showed no change in LDAP in priority diagnoses. In a sensitivity analysis of nonpriority diagnoses, ASP-targeted departments had a larger estimated annual decrease in LDAP versus nontargeted (difference 1.4 pp, P &lt; .001). Conclusions Annual syndrome-specific ASP interventions correlated with improvements in LDAP, including outside of priority syndromes in targeted departments. LDAP is a viable metric for evaluating ambulatory ASPs.

Abstract Background Follow-up blood cultures (FUBCs) for streptococcal bacteremia are infrequently positive and may not provide sufficient clinical impact to justify the time and resources expended for their routine use. We aimed to evaluate the frequency of and risk factors for positive FUBCs in patients with streptococcal bacteremia and to compare clinical outcomes among patients with or without positive FUBCs. Methods We retrospectively reviewed hospitalized patients with streptococcal bacteremia from September 2023 to June 2024 within a multisite health system. Patients ≥18 years old with ≥1 positive blood culture for a Streptococcus species were included. Patients with polymicrobial bacteremia, those who died or were discharged to hospice within 48 hours of their index culture, and Minnesota residents who declined research authorization were excluded. Results We included 454 patients, with 48 (10.6%) having positive FUBCs. The rate of positivity ranged from 0% for Streptococcus pyogenes to 18.5% for Streptococcus anginosus. Endocarditis and osteomyelitis were more common in the positive than in the negative FUBC group (22.9% vs 12.1%, respectively, for endocarditis [P = .04] and 16.7% vs 5.4% [P = .005] for osteomyelitis). Positive FUBCs were associated with a higher incidence of infection relapse (8.5% vs 2.7%; P = .047) and longer duration of antibiotics (30 vs 16 days; P = .01), but no differences in mortality rate, length of stay, or infection-related readmission were observed. Conclusions Positive FUBCs were infrequent for S pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, and group C and G streptococci. It may be reasonable to forego FUBC for these streptococcal species if endocarditis or osteomyelitis are not clinically suspected.

Abstract Background Outpatient parenteral antimicrobial therapy (OPAT) is effective and cost-efficient, but 12%–63% of patients experience adverse events, requiring close monitoring. Therapeutic drug monitoring (TDM) is routinely used for vancomycin and aminoglycosides but is underutilized for beta-lactams (BLs) due to limited access, logistical barriers, and clinician inexperience. This study evaluated its use and clinical impact within a high-volume OPAT program. Methods This retrospective, single-center cohort included adult patients (≥18 years) enrolled in an OPAT program who received cefepime (CEF), piperacillin/tazobactam (TZP), or meropenem (MEN) and underwent BL TDM between April 2023 and April 2025. BL TDM was not protocolized within the OPAT program; however, institutional guidance supported its use in carefully selected patients. We aimed to describe TDM indications, lab trends, microbiological profiles, and the impact of TDM on treatment. Results During the study period, 25 OPAT patients underwent BL TDM. TDM was performed in patients receiving CEF (64%), TZP (20%), and MEN (16%). The most common indication for TDM was suspected beta-lactam toxicity (32%) (Figure 1). Post-TDM therapy adjustments were made in 52% (n = 13), including changes in dosing frequency (38.5%) and dosage strength (30.8%). Additional changes included infusion strategy modification or agent substitution (15.4% each). Subtherapeutic levels were the most common reason for adjustment (46.2%), followed by adverse effects, supratherapeutic levels, and changes in renal function (23.1% each). Skin, soft tissue, and musculoskeletal infections were most common (Figure 2). Positive cultures were present in 80%, with Pseudomonas spp most frequently isolated. Therapy was completed in 17 patients; 7 discontinued early, and 1 had treatment ongoing. Reasons for therapy discontinuation are detailed in Table 1. Conclusion BL TDM is contributing to a paradigm shift in OPAT practice by improving both efficacy and safety. While inpatient TDM typically targets efficacy, safety concerns more commonly motivate TDM in the OPAT setting. Although this review involved a small cohort, our experience adds to the growing body of evidence supporting BL TDM as a tool to enhance patient outcomes in the OPAT setting. Disclosures All Authors: No reported disclosures

Abstract Reducing antimicrobial exposure by limiting the duration of therapy is an effective antimicrobial stewardship strategy. In this article, we describe the impact of modification of the electronic health record to remove default durations of therapy on ambulatory antibiotic prescriptions issued from emergency departments in a large, multicenter health system.

ABSTRACT The use of ceftriaxone, a highly protein-bound drug, in the setting of hypoalbuminemia may result in suboptimal drug exposure. Patients with obesity also exhibit higher absolute drug clearance. We aimed to evaluate the impact of hypoalbuminemia on clinical success among hospitalized adults with obesity who were treated with ceftriaxone. This retrospective review included adult inpatients with weight >100 kg or body mass index >40 kg/m 2 who received ceftriaxone 2 g intravenously every 12 hours for at least 72 hours. The primary outcome was clinical success, a composite of clinical cure and microbiologic cure. Secondary outcomes included clinical cure, microbiologic cure, length of stay, ICU length of stay, mortality, 30-day readmission, and adverse events. In all, 137 patients were included, 34 of whom had a serum albumin of ≤2.5 g/dL. In a propensity-score-weighted analysis, clinical success was significantly more common among those without hypoalbuminemia (91.2%) as compared to those with hypoalbuminemia (77.8%) ( P = 0.038). Death within 30 days (13.7% vs 0%, P < 0.001) and 30-day readmission (31.6% vs 12.0%, P = 0.008) were more common in the hypoalbuminemia group. In a univariate analysis, serum albumin and indication for ceftriaxone use were found to be predictors of clinical success. Hypoalbuminemia was associated with a lower rate of clinical success among patients with obesity who were treated with ceftriaxone 2 g every 12 hours.

Abstract Background Optimizing antimicrobial regimens for outpatients with community-acquired pneumonia (CAP) represents an area of opportunity for ambulatory antimicrobial stewardship programs. A pre-populated, antibiotic order panel for outpatient respiratory syndromes was implemented in the Mayo Clinic Enterprise on 1/4/2021. For CAP, it provides national guideline adherent regimens (i.e., selection, dosing, and durations) by patient comorbidity and beta-lactam allergy status. We aimed to assess impacts of panel use on antibiotic prescribing in outpatients with CAP. Methods This retrospective review included Mayo Clinic outpatient encounters from Minnesota in 2021 and 2022. Eligible encounters used a CAP-related primary ICD-10 code, conveyed intention to treat CAP in encounter notes, and were performed by primary care, emergency department, or urgent care clinicians who managed ≥1 CAP patient with the panel and ≥1 without the panel during the study period. Encounters were excluded if patients were already receiving antibiotics at the time of encounter. The primary outcome was adherence (drug and duration) to guideline recommendations. Secondary outcomes included utilization rate by agent and therapy duration. Outcomes were analyzed with Kruskal-Wallis rank sum and Pearson’s chi-squared tests (α level = 0.05). Results 352 encounters (134 panel vs. 218 non-panel) were included. Prescribing was guideline adherent in 61.9% and 29.4% (p&lt; 0.01) of panel and non-panel encounters, respectively. The most common reason for guideline non-adherence during panel use was inappropriate drug selection (n = 45/51, 88.2%). This was predominantly driven by use of the incorrect section of the treatment panel based on patient comorbidity status (n = 30/45, 66.7%). Individual antibiotic utilization rates differed between panel and non-panel cohorts (Table 1), with higher rates of amoxicillin and amoxicillin/clavulanate use and lower rates of azithromycin and doxycycline use in the panel cohort. Durations &gt;5 days were more common in the non-panel as compared to the panel cohort (34.4% vs. 7.5%, p &lt; 0.01). Conclusion Use of a pre-populated antimicrobial order panel in outpatients with CAP resulted in greater adherence to national guideline recommendations. Disclosures Paschalis Vergidis, MD, MSc, AbbVie: Advisor/Consultant|Ansun: Grant/Research Support|Cidara: Grant/Research Support|Scynexis: Grant/Research Support

Abstract Background Due to extensive protein binding, use of ceftriaxone in the setting of hypoalbuminemia may result in suboptimal drug exposure via higher concentrations of unbound drug resulting in increased volume of distribution and increased drug clearance. We aimed to evaluate the impact of hypoalbuminemia on clinical success among hospitalized adults with obesity who were treated with ceftriaxone for a bacterial infection. Methods This retrospective review included adult inpatients with weight &gt; 100 kg or body mass index (BMI) &gt; 40 who received ceftriaxone 2 grams intravenously every 12 hours for at least 72 hours for one of the following indications: bloodstream infection, pneumonia, urinary tract infection, non-enterococcal endocarditis, skin and soft tissue infection, or bone and joint infection. The primary outcome was clinical success, a composite of clinical cure and microbiologic cure. Clinical cure was defined as resolution of signs and symptoms compatible with active infection without need to change or extend antibiotic therapy due to inadequate effect of ceftriaxone. Microbiologic cure was defined as negative repeat sterile site cultures, if applicable. Secondary outcomes included length of stay, mortality, and 30-day readmission. Outcomes were analyzed with Mann-Whitney U tests, Pearson’s chi-squared tests, and Fisher’s exact tests (α level = 0.05). Results 137 patients were included, 34 of whom had a serum albumin ≤ 2.5 g/dL. Patients were predominantly white (94.2%) and male (69.3%) with a median BMI of 48.6 (Table 1). Clinical success, a composite of clinical and microbiologic cure, was achieved in 76.5% and 92.2% (p = 0.013) of those with and without hypoalbuminemia, respectively. Clinical cure was significantly more common among those without hypoalbuminemia (93.2%) as compared to those with hypoalbuminemia (76.5%) (p = 0.007). Death during hospitalization was more common (14.7% vs. 0%, p &lt; 0.001) and median length of stay was longer (14 vs. 9 days, p = 0.009) in the hypoalbuminemia group. No difference was seen in 30-day readmission (23.5% vs. 11.7%, p = 0.089). Conclusion Hypoalbuminemia was associated with a lower rate of clinical success among patients with obesity who were treated with ceftriaxone 2 grams every 12 hours. Disclosures Christina G. Rivera (O'Connor), Pharm.D, Gilead Sciences: Advisor/Consultant|Gilead Sciences: Board Member|Gilead Sciences: Grant/Research Support|Gilead Sciences: Honoraria