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Calcareous rocks are commonly found in subduction zones, but few studies have investigated the consolidation and compactive deformation of these rocks prior to subduction, and their potential effects on subduction and accretionary processes are thus poorly understood. Using drilling data obtained during International Ocean Discovery Program (IODP) Expeditions 372 and 375 combined with 2D and 3D seismic reflection data, the structure, growth history, and slip rates of normal faults identified in the incoming pelagic sedimentary sequences of the Hikurangi Margin were investigated. A seismic coherence depth slice and vertical profiles show that these faults exhibit polygonal structure that has rarely been documented at subduction margins. The polygonal faults are closely spaced and layer-bound within sequences dominated by pelagic carbonate and calcareous mudstone of Paleocene-Pliocene age. Kinematic modeling and 2D displacement analysis reveal that fault throws decrease toward the upper and lower tipline. In detail, two groups of throw profiles are defined by locations of displacement maxima, possibly reflecting lateral variations in physical properties. The polygonal fault system (PFS) likely formed by syneresis processes that involve diagenetically induced shear failure and volumetric contraction of the pelagic unit associated with fluid escape. Fault growth sequences reveal multiple, weakly correlated intervals of contemporaneous seafloor deformation and sedimentation and allow estimates of fault slip rates. We find evidence for a significant increase in typical slip rates from 0.5-3 m/Ma during pelagic sedimentation to >20 m/Ma following the onset of terrigenous sedimentation. These observations suggest that rapid loading of the pelagic sediments by the trench-wedge facies was associated with renewed and faster growth of the PFS. The PFS will eventually be transported into the base of the accretionary wedge, enhancing geometric roughness and heterogeneity of materials along the megathrust, and providing inherited zones of weakness. Selective fault reactivation may facilitate deformation and episodic vertical fluid migration in the lower wedge associated with microearthquakes, tremor, and slow slip events.

Background Bloodstream infections are associated with considerable morbidity and mortality in the United States. Most patients initially receive parenteral antibiotics for gram-negative bacteremia, and more data is emerging supporting de-escalation to oral (PO) antibiotics to complete treatment. Previous studies evaluating PO antibiotics for gram-negative bacteremia often exclude or have underrepresented immunocompromised patients. This study evaluated clinical failure in immunocompromised patients receiving intravenous (IV) antibiotics compared to patients transitioned to PO antibiotics for gram-negative bacteremia. Methods A single center, retrospective cohort study was conducted at 446-bed academic medical center. Patients were included if they were immunocompromised and admitted with a positive blood culture for E. coli, Klebsiella spp., Citrobacter spp., Serratia spp., Enterobacter spp., Proteus spp., P. aeruginosa. between November 4, 2017 to November 4, 2020. Patients were excluded from this study if they had polymicrobial bacteremia, no source control within the first 5 days, or an indication for prolonged duration of treatment. The primary endpoint of this study was clinical failure defined as an escalation from PO to IV antibiotics, worsening clinical status, or readmission for the same infection within 30 days of discharge. The secondary endpoints included 30-day mortality, 90-day mortality, 30-day readmission, and time to microbiologic clearance. Results A total of 31 immunocompromised patients were included in the study with 26 patients receiving PO step-down therapy and 5 patients being continued on IV treatment for gram-negative bacteremia. There was no difference in the primary outcome of clinical failure between the PO step-down group versus the IV therapy group (15.4% vs 20%; p = 0.613). The most common immunocompromised state in both groups was being HIV positive. Patients in the PO step-down group had a significantly shorter hospital length of stay (7.4 days vs. 13.6 days; p = 0.016). Conclusion Oral step-down therapy for gram-negative bacteremia showed similar clinical failure rates to continuous IV therapy in the immunocompromised patient population and may be an option to shorten hospital length of stay. Disclosures All Authors: No reported disclosures

Background Treatment strategies surrounding bacteremia are constantly changing as new data emerges. Transition from intravenous (IV) to oral (PO) antibiotics in patients with Gram-negative rod bloodstream infections (GNR BSI) remains controversial. The objective of this study was to characterize clinical outcomes in patients who received early (≤72 hours) vs. late (>72 hours) stepdown therapy (ES vs. LS, respectively) for GNR BSIs. Methods A single-center, retrospective cohort study was conducted including adults with GNR BSIs admitted to a 610-bed tertiary care academic medical center between January 1, 2016 and December 31, 2017 who were transitioned from IV to PO antibiotics. Patients with severe renal impairment, inadequate source control, prolonged antibiotic course, HIV/AIDS, and pregnancy were excluded. The primary endpoint was clinical failure and secondary endpoints were 30- and 90-day all-cause mortality, duration of bacteremia, and adverse events. Results 164 patients (ES = 61; NS = 103) were included. Population median age was 63 years, 56% were male, and 19% were immunocompromised. Genitourinary source was most common (48.7%), while the most common organism isolated was Escherichia coli (52.4%). Most infections were community-acquired (70.1%) and the most common step-down therapy choice was ciprofloxacin in 75% of patients. There were no major differences in baseline demographic and clinical characteristics between groups except for the greater presence of central venous catheters (16.4% vs. 35.9%; P = 0.006) in the LS group. Overall clinical failure was 9.8% vs. 13.6% between the ES and LS groups, respectively. The LS group had a higher rate of clinical failure defined by escalation from PO to IV antibiotics (1.6% vs. 10.7%; P = 0.03). Patients who failed therapy tended to be immunocompromised and/or have an intra-abdominal source of infection. Secondary endpoints did not differ between groups. Conclusion Higher clinical failure rates in the LS group indicate that these patients may have underlying clinical characteristics not amenable to stepdown therapy. Choice of step-down therapy was not driven by the source of infection or patient acuity. Further analysis and studies are needed to determine optimal time and population for stepdown. Disclosures All authors: No reported disclosures.

Background: Delayed intensification of blood pressure (BP) management is associated with an increased risk of cardiovascular disease. Pharmacist-physician collaborative care models (PPCMs) improve BP control rates and reduce mean BP, but it is unknown if PPCMs affect time to BP goal when compared to