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BACKGROUND: Patients with cervical artery dissection (CeAD) may experience a recurrent dissection, but its frequency, risk factors, and clinical implications are not well defined. We aimed to determine the risk, associated factors, and clinical impact of recurrent CeAD. METHODS: The STOP-CAD study (Antithrombotic Treatment for Stroke Prevention in Cervical Artery Dissection) was a multicenter international retrospective observational study of patients with CeAD treated between January 2015 and June 2022. Recurrent dissection was defined as a CeAD occurring at least 7 days after the diagnosis of the index event that affects a different artery or a different segment of the same artery. Patients were followed from day 7 up to 2 years. The absolute risk of recurrent CeAD over time was calculated using Kaplan-Meier survival estimates. Multivariable logistic and Cox regression models were used to assess predictors of CeAD recurrence. RESULTS: Of the 4023 patients included in STOP-CAD, 3836 (median age 46 years, 45% women) were eligible for this analysis. During a median (interquartile range) follow-up of 295 (97–720) days, 88 (2.29%) patients had a CeAD recurrence. Median time-to-recurrent CeAD was 53 (interquartile range, 18–157) days. The estimated risk of recurrent CeAD at 2 years was 3.22% (95% CI, 2.59%–4.00%). In multivariable analyses, younger age (adjusted odds ratios, 0.98 [95% CI, 0.96–0.99]), migraine (adjusted odds ratio, 1.88 [95% CI, 1.14–3.07]), and fibromuscular dysplasia (adjusted odds ratio, 2.90 [95% CI, 1.66–5.06]) were associated with CeAD recurrence, while presenting with an ischemic stroke was associated with a lower likelihood of recurrence (adjusted odds ratio, 0.47 [95% CI, 0.29–0.75]). These associations with CeAD recurrence over time were confirmed by Cox regression analyses. Among the 88 patients with recurrent CeAD, only 5 had accompanying ischemic events (3 strokes, 2 transient ischemic attacks). CONCLUSIONS: In this retrospective study, recurrent CeAD was uncommon, approximately half of the events were diagnosed within the first 2 months of the index event, and recurrent events rarely caused new ischemic events. Younger age, migraine, absence of ischemic stroke at presentation, and signs of fibromuscular dysplasia may help identify high-risk patients.

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 Background Outpatient parenteral antimicrobial therapy (OPAT) practice has continued to increase. We sought to understand current OPAT practices in a survey of U. S. clinicians.Figure 1Respondents rated their agreement with the following statement: “The OPAT program at my hospital receives adequate support in the following areas”Figure 2Factors present in providing safe OPAT services on a scale where 1 is “extremely challenging” and 5 is “not challenging at all” Methods A survey instrument was developed by ID physicians, pharmacists and Infectious Diseases Society of America (IDSA) Emerging Infections Network (EIN) staff, utilizing prior EIN OPAT surveys. The survey focused on respondents’ role, responsibilities, time devoted to OPAT, structure of OPAT provision, location where OPAT is received, institutional support and oversight, role of complex outpatient antimicrobial therapy (COpAT) including oral antimicrobials and long-acting injectable agents, and barriers to safe OPAT care. The confidential survey was distributed to adult EIN members from Feb to March 2025. Results Overall, 622 (38%) EIN members responded to the survey, of whom 469 with a role in managing OPAT patients were eligible to complete the survey. OPAT teams varied across programs with nearly all involving ID physicians (98%), majority involving ID/OPAT pharmacists (61%), nurses (60%), and nearly half involving administrative staff (48%) and advanced practice providers (APPs, 47%). ID consultation for OPAT enrollment was required in 60% of programs. Many programs (59%) report including COpAT. Response to outpatient lab results was largely managed by ID physicians (75%); however, multidisciplinary OPAT teams (37%), pharmacists (33%), and inpatient ID physicians (30%) were also frequently involved. Lab values were most often available via fax/email (43%) or electronic health record (EHR, 41%). Nearly 25% of programs “often/always” required proactive outreach to obtain safety labs. Overall, many programs lacked data analysis, administrative, information technology, and financial support (Figure 1). Challenges faced by OPAT programs included lack of leadership awareness of the value of OPAT (51%), difficulty managing patients with substance use disorder (50%), access to timely lab values (48%), personnel to retrieve missing lab values (46%), and struggles with the EHR (43%) (Figure 2). Conclusion Compared to EIN OPAT surveys in 2013 and 2019, programs have grown in size and composition, and expanded to COpAT. Similar problems persist regarding perceived lack of support. Disclosures Monica V. Mahoney, PharmD, BCPS, BCIDP, FCCP, FIDSA, FIDP, FMSHP, gsk: Advisor/Consultant|seqirus: Advisor/Consultant Philip M. Polgreen, MD, Eli Lily: Advisor/Consultant|Pfizer: Grant/Research Support Sara C. Keller, MD, MPH, MSPH, CorMedix: Grant/Research Support

Abstract Background Beta-lactam pharmacokinetics can be significantly altered in patients with malignancy. Therapeutic drug monitoring (TDM; i.e., drug level testing) may facilitate pharmacokinetic/pharmacodynamic (PK/PD) target attainment, but the data are limited. This study aimed to characterize PK/PD target attainment of anti-pseudomonal beta-lactams in hematology/oncology patients.Table 1:Case DescriptionGraph 1:Distribution of Beta-Lactam TDM Indications Methods We conducted a retrospective review of beta-lactam TDM performed between June 2022 and June 2024 in hospitalized adults with hematologic or solid organ malignancies. We included patients who underwent beta-lactam TDM during clinical care, typically for extracorporeal membrane oxygenation (ECMO), extremes of body weight, suspected augmented renal clearance, multidrug-resistant infection, or suspected dose-dependent beta-lactam toxicity. Primary outcomes were (1) the proportion achieving target beta-lactam concentrations and (2) the proportion undergoing antibiotic dose adjustment based on TDM results.Table 2:Institutional Dosing Guidelines Results There were 47 TDM episodes in 20 unique patients. Considering only the first TDM per patient, 10 (50%) patients achieved target concentrations, 2 (10%) were below target, and 6 (30%) were above target. Antibiotic dose adjustments were made in 8 (40%) patients in response to TDM results. The most common indication for beta-lactam TDM was concerns regarding accurate renal clearance, followed by extremes of weight. Conclusion Retrospective findings suggest that beta-lactam TDM facilitated individualization of therapy in 40% of patients with either hematological or solid organ malignancy, with dose adjustments often intended to improve antibiotic safety. Future studies should refine the criteria for beta-lactam TDM use in this population and determine the need for tailored PK/PD targets in patients with impaired host response to infection. Disclosures All Authors: No reported disclosures

Abstract Background Antimicrobial stewardship programs (ASP) commonly employ formulary restriction and prospective audit with feedback; however, frontline prescribers and other unit-based clinicians may enhance core ASP tactics as ASP extenders. We hypothesized that unit-based pharmacists act as ASP extenders and sought to characterize ASP interventions in their routine work.Top individual antimicrobial classes intervened on by unit-based pharmacistsUnit-based pharmacist antimicrobial intervention types Methods Retrospective, observational study of ASP interventions by unit-based pharmacists from July 2017 - April 2025 across the Mayo Clinic Enterprise. ASP interventions recorded using a standardized pharmacist documentation tool (Epic iVents [Software]) were collected retrospectively. Interventions on hospitalized, adult patients categorized as ‘ASP’ or linked with an antimicrobial were included; interventions by ASP dedicated staff were excluded. Secondary outcomes included: intervention subtypes and outcomes, location, and associated antimicrobial(s). Frequencies and percentages were used to summarize categorical data. Results A total of 104,055 interventions were included from 59,106 unique patients at 26 hospitals with the majority performed at the three destination sites. On average, 1,107 interventions were completed monthly by unit-based pharmacists. Frequently targeted antimicrobial classes were vancomycin and derivatives, penicillins, and 3rd/4th-generation cephalosporins (e.g., ceftriaxone and cefepime) (Figure 1); 20,111 (19.3%) interventions were on ≥ 1 antimicrobial. Of the 66,827 interventions with a documented subtype, ASP was the most common (77.8%), with the remainder classified as dose (17.3%), medication (3%), or duration changes (1%) (Figure 2). A minority (2.2%) were documented as conducted under pharmacist collaborative practice agreements. Documented prescriber intervention rejections were uncommon (6.6%). Reported outcomes, when available, included therapy optimization, cost savings and avoidance of adverse drug events. Conclusion Unit-based pharmacists acted frequently as ASP extenders. These findings support unit-based pharmacist and ASP collaborative efforts. Disclosures All Authors: No reported disclosures

Abstract Background Colonization with extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) is increasingly recognized in critically ill patients and impacts infection prevention practices and empiric antibiotic selection. However, contemporary United States estimates of ESBL-E prevalence at the time of ICU admission are limited.Table 1.ICU-Specific Prevalence of ESBL Colonization at Admission Confirmed by Whole Genome SequencingFigure 1.Distribution of ESBL Gene Variants Among ESBL-Producing Enterobacterales Isolates by Bacterial Species (n = 173) Methods We conducted a prospective molecular epidemiology study of ESBL-E colonization among adult and pediatric patients admitted to nine ICUs at The Johns Hopkins Hospital between March and August 2023. Routine rectal surveillance swabs (Copan Eswab) collected at ICU admission were plated on selective chromogenic media (HardyCHROM™ ESBL) to identify third-generation cephalosporin-resistant Enterobacterales (3GCRE). Species identification was performed using MALDI-TOF MS, and ceftriaxone resistance was confirmed by broth microdilution. Whole-genome sequencing (WGS) was performed on the first isolate of each species per patient to confirm ESBL gene carriage and assess molecular features. Results Among 3,278 ICU admissions, 328 (10%) had 3GCRE isolated on admission swabs. Of these isolates, 173 (5% of all admissions) were confirmed by WGS to harbor at least one ESBL gene—representing approximately 53% of all 3GCRE isolates. ESBL-E colonization was most prevalent in the medical (10%) and cardiac (8%) ICUs. The most common ESBL-E species were Escherichia coli (72%) and Klebsiella pneumoniae (19%). Dominant E. coli sequence types were ST131 (36%), ST1193 (7%), and ST38 (6%). Nearly all ESBL genes belonged to the blaCTX-M family (95%), with blaCTX-M-15 as the predominant allele (63%). Other ESBL genes included blaCTX-M-27 (17%), blaCTX-M-14 (5%), blaCTX-M-55 (5%), and blaSHV-12 (3%). Conclusion In this large, prospective cohort, 5% of ICU patients were colonized with ESBL-E at admission, most commonly E. coli and K. pneumoniae harboring blaCTX-M genes. Phenotypic detection of 3GCRE overestimated ESBL-E prevalence by nearly 90%, highlighting the need for molecular confirmation to accurately characterize resistance. These findings suggest ESBL-E colonization remains uncommon in the U.S., even at a major referral center, supporting non-carbapenem empiric therapy in low-risk patients and reinforcing the need for targeted surveillance. Disclosures All Authors: No reported disclosures

Objective Cervical artery dissection (CeAD) may be limited to the extracranial extradural space or extend to the intradural space. Intradural extension can potentially increase the risk of stroke and subarachnoid hemorrhage. However, the factors associated with intradural extension and its impact on clinical outcome remain unclear. Methods This was a secondary analysis of the STOP‐CAD observational, multi‐center study. Patients with CeAD and intradural extension (CeADid) were compared with those with pure CeAD extradural dissections (CeADed) using multiple regression analyses. Results Of 4,023 patients with CeAD, 534 (13.3%) had CeADid. In comparison to patients with CeADed, those with CeADid more often had clinical overt stroke or transient ischemic attack (TIA) at presentation, acute infarcts on imaging, a vertebral artery affected, and severe stenosis of the involved vessel ( p < 0.001 for all). In contrast, carotid involvement and complete occlusions were more frequent in patients with CeADed ( p < 0.001 for both). CeADid was associated with a shift in the distribution of scores on the modified Rankin Scale (mRS) toward worse functional outcome (odds ratio [OR] = 0.76, 95% confidence interval [CI] = 0.62–0.92) but the odds for favorable outcomes (mRS = 0–2) did not differ between the groups after appropriate adjustments on multivariate analysis. CeADid was independently associated with higher mortality at 180 days on multivariate analysis (adjusted OR = 2.84, 95% CI = 1.50–5.38). Interpretation CeADid is associated with more severe clinical presentation, a shift toward less favorable outcomes, and higher mortality rates. These findings suggest that CeADid may represent a high‐risk type of CeAD. ANN NEUROL 2026;99:1189–1197

Background Deep brain stimulation (DBS) has been investigated for patients with drug-resistant epilepsy who are not candidates for resective surgery. Because different types of epilepsy involve distinct brain networks, numerous DBS targets have been explored, yet a comprehensive synthesis is lacking. Methods To provide a comprehensive overview of this expanding literature, we conducted a systematic review of studies for DBS in epilepsy, including case series, prospective and retrospective studies. We collected data on surgical targets, individual disease characteristics, outcomes and precise electrode placements. DBS electrode coordinates were gathered into a common template space and related to clinical outcomes. Results We included 124 studies, corresponding to 1210 patients and 20 distinct surgical targets. While the anterior (ANT) and centromedian (CM) nuclei of the thalamus remain the most studied, we also review less commonly used targets that show promise for specific forms of epilepsy and may warrant further investigation. Substantial variability in targeting strategies and electrode placement was observed within each of the target regions. Importantly, significant relationships between stimulation location and outcomes were identified for ANT-DBS and CM-DBS. For ANT-DBS, shorter distance to the mammillothalamic tract junction was associated with greater seizure reduction on both study-level and patient-level analyses (r=−0.55, p<0.001 and r=−0.51, p<0.001, respectively). For CM-DBS, localisation effects may be dependent on the form of epilepsy, with stimulation of the parvocellular CM being associated with better outcomes in generalised epilepsy. Conclusions Our results emphasise the importance of accurate targeting in DBS for epilepsy. Our database and atlas of DBS targets are made publicly available, potentially serving further meta-analytical work. PROSPERO registration number CRD420250649304.

ABSTARCT BACKGROUND: IRRAflow is a novel active cerebrospinal fluid (CSF) exchange system for the treatment of hemorrhagic strokes and intracranial infections. It is a closed system that irrigates various medications dissolved in irrigation solutions at a speed of up to 180 mL/h, expediting resolution. Disrupting this closed system to withdraw CSF samples or infuse medications is necessary in certain circumstances. We report our novel approach for maintaining the sterility of the closed IRRAflow system using a needleless extension and assess the compatibility and safety of this technology throughout treatment. METHODS: We used a needleless extension to withdraw CSF samples and deliver medications to 5 patients treated with the IRRAflow system. We used 1 stopcock with a 3-way valve, 2 neutral needleless connectors, and 2 antiseptic caps. The stopcock was connected between the irrigation and drainage ports of the catheter. The needleless connectors were mounted at the 12 o’clock position of the attached stopcock and the irrigation port with antiseptic caps covering the distal ends. To initiate fluid exchange, the 2 needleless connectors were separated. The extra stopcock valve was connected between the drainage arm, the cassette, and the irrigation arm. The needleless connectors remained mounted at the 12 o’clock position of the stopcock and irrigation port throughout treatment. RESULTS: The needleless connectors mounted on the 12 o’clock position of the stopcock and irrigation port on the drainage and irrigation arms, respectively, provided efficient management of fluid exchange, CSF fluid sampling, and medication delivery. Our needleless extension was compatible with the IRRAflow device and prevented secondary infections despite repeated CSF sampling and medication delivery. CONCLUSION: The needleless extension facilitated a simple and safe interaction with the closed IRRAflow system without compromising the sterile environment during CSF sampling and medication delivery.