bluuebunny/crossref_metadata_2025_split huggingface dataset:
P-1811. Impact of Hemo-Alert Program on Appropriate Antimicrobial Therapy in Hospitalized Patients with Bacteremia: Results from a Quasi-experimental Study
Authors: Phuetphaichit Siwakan , Kamolvit Witchuda , Samanloh Surangkana , Rattanaumpawan Pinyo 
Published: January 2025

Abstract

Background
Hemo-Alert program is an antimicrobial stewardship strategy, designed to shorten the time to appropriate antimicrobial therapy in bacteremic patients.

Methods
Eligible subjects were all hospitalized patients with at least one positive hemoculture. The standard of care included a prompt notification of positive hemoculture via a phone call. However, the final identification and susceptibility results need to be individually retrieved. The Hemo-alert program included a prompt notification of final identification and susceptibility results via a direct SMS to physician and by placing results on patient’s medical chart. Appropriateness of antimicrobial therapy was determined by two independent infectious disease specialists. Antimicrobial therapy for colonization, too-broad or too-narrow regimen were considered inappropriate.

Results
There were 150 subjects in the pre-implementation group and 150 subjects in the post-implementation group. Approximately half of both groups (pre vs. post; p-value) were male (50.7% vs. 48.7%; p=0.73) with a comparable mean age (66.14±17.13 vs. 68.57±14.41; p=0.18). The three leading causative pathogens were Escherichia coli (24.0% vs. 26.7%; p=0.60), followed by Klebsiella pneumoniae (14.0% vs. 16.7%; p=0.52), and Staphylococcus aureus (9.3% vs. 10.7%; p=0.70). The proportion of appropriate antimicrobial therapy within the first 72 hours was significantly higher in the post-implementation group (22.7% vs. 34.0%; p=0.03). Good clinical response was significantly higher in the post-implementation group (74.0% vs. 85.3%; p=0.02). Furthermore, the 28-day mortality was comparable between the two groups (24.0% vs. 18.0%; p=0.20).

Conclusion
Our study confirmed the positive impact of the Hemo-Alert program on the appropriateness of antimicrobial therapy and treatment response among bacteremic patients.

Disclosures
All Authors: No reported disclosures
P-1817. Reducing The Use of Piperacillin/Tazobactam for Common Infections – A Danish Quality Improvement Study
Authors: Hagen Trine L 
Published: January 2025

Abstract

Background
During a 4-year period we noticed a doubling of Piperacillin/Tazobactam (PIT) consumption in our hospital, which was not supported by the local antibiotic guideline. This quality improvement study aimed to study prescription behavior. We hypothesized that an intervention might increase guideline adherence, thus decreasing the use of PIT as first line treatment for common infections.

Methods
Baseline data on PIT consumption were collected from April 2022 to March 2023 as defined daily doses (DDD)/100 bed-days. We collected baseline data on guideline adherence from January to March 2023 and performed an audit by reviewing patient charts. A multifaceted intervention was carried out from April 1st to December 31st, 2023, consisting of teaching sessions, feedback to prescribers, discouraging use of urinary dipsticks, creating pocket guidelines, and revision of the antibiotic guideline.
Inclusion criteria: Immuno-competent patients ≥ 18 years being prescribed PIT for community-acquired infections. Patients with immunosuppression or at risk of hospital-acquired infection were excluded.
We compared the number of PIT prescriptions between baseline and intervention by using unpaired t-tests. Change in adherence to guidelines was tested using the Chi-squared test.
The primary outcome was reduction in PIT use and secondary outcome was increased guideline adherence.

Results
Three-hundred and sixty-nine patients were included. During the intervention, we observed a 26% decrease in PIT use (DDD/100 bed days) and 41% reduction in the number prescribed PIT doses/week. Correctly prescribed PIT doses increased from 49.6% to 53.8% after the intervention. The correct prescriptions were differentiated between senior (75%), junior (57.7%) and locum doctors (43.5%).

Conclusion
By using a multifaceted intervention strategy to encourage prescribers to follow local guidelines, we observed a substantial reduction in the use of PIT for community-acquired infections in immuno-competent patients. Forming a formal antimicrobial stewardship team may play an important role in maintaining vigilance towards antibiotic prescribing behavior.

Disclosures
All Authors: No reported disclosures
P-1823. Development of a Nocardia Reporter Strain to Study Cell-type Specific Phagocytosis and Killing in vivo
Authors: Abers Michael S , Finin Peter M , Ma Li , Zelazny Adrian , Boshoff Helena , Barry Clifton E , Holland Steven M , Lionakis Michail S 
Published: January 2025

Abstract

Background
Nocardia infections are associated with substantial morbidity and mortality. Little is known about how the immune system defends against Nocardia.

Methods
Nocardia was transformed to contain a genomic copy of mScarlet. The cell wall was then labelled with AlexaFluor633 (AF633) to generate dually labelled (mScarlet+ AF633+) Nocardia. Cybb knockout (KO) mice (chronic granulomatous disease or CGD) and wildtype (WT) controls were inoculated with 5-10 million colony forming units (CFU) via oropharyngeal aspiration. High-dimensional flow cytometry (HDFC) and bacterial burden were determined in lung and bronchoalveolar lavage (BAL) fluid obtained 24 hours post-infection. Phagocytic index (PI) was defined as % of cells that are AF633+ cells. Killing capacity (KI) was defined as % of AF633+ cells that are mScarlet–.

Results
Live cultures of dually labelled Nocardia were positive for both mScarlet and AF633. mScarlet but not AF633 fluorescence decreased to undetectable levels upon killing of Nocardia. HDFC demonstrated that alveolar macrophages (AM), interstitial macrophages (IM), neutrophils, monocytes, and type 2 dendritic cells (cDC2) are the primary cell types that interact with Nocardia in vivo. PI was highest in AM and IM. PI was greater in cells from BAL versus lung (P&lt; 0.01) while the opposite was true for other cell types. KI was lower in neutrophils versus other cell types (P&lt; 0.05). Mortality and bacterial burden in lung were higher in CGD mice compared to WT controls (P&lt; 0.01 for both comparisons). CGD mice demonstrated reduced PI in neutrophils, AM, IM (P&lt; 0.05 for both). KI was impaired in AM and neutrophils.

Conclusion
Use of a dually labelled Nocardia reporter strain demonstrated cell-type specific defects in both phagocytosis and killing of Nocardia in CGD mice. This might explain the underlying predisposition to nocardiosis seen in humans with CGD. Ongoing studies aim to elucidate the molecular basis for the susceptibility to nocardiosis in humans and mice with CGD.

Disclosures
All Authors: No reported disclosures
P-1827. Novel Evaluation System for Aspergillus fumigatus Interactions with Human Cells via Combination of Imaging and Electrical Impedance
Authors: Kakuno Shigeki , Shibata Wataru , Umeyama Takashi , Miyazaki Yoshitsugu , Kakeya Hiroshi 
Published: January 2025

Abstract

Background
Aspergillus fumigatus is a major fungal pathogen causing pulmonary aspergillosis, an important disease associated with transplantation and immunosuppression. However, the interactions between A. fumigatus and human cells are not well understood. This study evaluated the interaction of A. fumigatus with THP-1 macrophages and A549 lung epithelial cells using fluorescence imaging and electrical impedance measurements to monitor fungal growth and cellular damage continuously.Figure 1.Schematic diagram of the relationship between electrical impedance and cell damage

Methods
The experimental setup used xCELLigence eSight (Agilent) and a specialized 96-well plate with electrodes at the bottom to measure impedance changes as cells adhered or detached (Figure 1). THP-1 and A549 cells were cultured, then infected with fluorescent A. fumigatus conidia. In addition, antifungal drugs (micafungin, caspofungin, voriconazole, isavuconazole, amphotericin B) were added to this experimental system at broth microdilution method and tested.Figure 2.Macrophage and A. fumigatus (MOI 4.0) in relation to each antifungal agentA:Voriconazole(VRCZ), B : Amphotericin B (AMPH-B)

Results
Results showed A. fumigatus filament growth leading to decreased impedance indicative of cell damage in both cell types, with faster damage at higher conidial loads. Fluorescence showed echinocandins inhibited hyphal growth but did not prevent impedance drops. Voriconazole and isavuconazole prevented impedance drops at clinically relevant concentrations (Figure 2A). Amphotericin B caused rapid impedance drops at high doses, suggesting direct cytotoxicity (Figure 2B).

Conclusion
A549 epithelial cells survived longer than macrophages, suggesting they play a defensive role against A. fumigatus. Impedance changes correlated with visual antifungal effects for azoles and amphotericin B but not echinocandins. This system enables evaluating fungal-host interactions using different cell types and fungi. Combining impedance with fluorescence imaging provides a comprehensive and objective assessment of antifungal activity and cellular responses.

Disclosures
Hiroshi Kakeya, MD, PhD, Asahikasei Phrma: Honoraria|GSK: Honoraria|MSD: Honoraria|Pfizer: Honoraria|Shionogi: Honoraria|Sumitomo Parma: Honoraria
P-1833. Acute Virulence Expression and Evolution of Artificial Airway Adapted Pseudomonas aeruginosa
Authors: Rapsinski Glenn J , Cooper Vaughn , Kozemchok Anna 
Published: January 2025

Abstract

Background
Mechanical ventilation is life-saving and may be lifelong in medically complex children with tracheostomy tubes (TT). Ventilator-associated infections (VAI), a common complication of mechanical ventilation, result in an estimated $1.25 billion per year of healthcare costs. Pseudomonas aeruginosa (Pa) frequently colonizes TT and endotracheal tubes and is a leading cause of VAI. Despite the importance of VAI, little is known about how Pa establishes colonization, limiting our ability to improve management. We hypothesize that Pa adaptively evolves to reduce its potential for acute virulence to facilitate colonization.

Methods
Convenience samples of Pa isolates from patients requiring endotracheal tubes or TT were collected from the UPMC Children’s Hospital of Pittsburgh microbiology lab. Isolates were screened for virulence factors including proteases, rhamnolipids, twitching motility, lysis and sheen, amino acid auxotrophy, and mucoid colony morphology. Isolate infectivity was tested on a in vitro primary human cell epithelial model. DNA was extracted from longitudinal isolates for whole genome sequencing.

Results
One hundred thirty-five isolates from 124 unique patients were screened for acute and chronic virulence phenotypes in a cross-sectional study. Low protease production, rhamnolipid production, and reduced twitching motility were more frequently present in respiratory isolates compared to skin and soft tissue infection (SSTI) isolates. Lysis and sheen were present in approximately one-third of respiratory isolates, similar to SSTI isolates. In longitudinal specimens from 23 patients, 95% of patients maintained their Pa genotype over time and representation from all three clades (PAO1, PA14, and PA7) of Pa were detected, with the PAO1 clade containing most isolates. Whole genome sequencing revealed mutations in global virulence regulators. Respiratory isolates had reduced infectious capabilities in an epithelial cell infection model.

Conclusion
These data suggest that isolates from mechanically ventilated patients are diverse between patients, maintained within a given patient over time, and have lower virulence expression than Pa isolates from other sites.

Disclosures
All Authors: No reported disclosures
P-1834. An Enteric Bacterial Infection Disrupts Brain Homeostasis and Induces Chronic Neuroinflammation by Breaching the Gut-Brain Axis in 3xTg-AD Transgenic Mice
Authors: Park Gwoncheol , Kadyan Saurabh , Hochuli Nathaniel , Nagpal Ravinder 
Published: January 2025

Abstract

Background
In previous studies, we found that an enteric infection caused by Klebsiella pneumoniae (Kpn) not only disturbs the balance of gut microbiome but also translocates to the brain, leading to inflammation and impairments in neurobehavior.

Methods
Triple-transgenic (3xTg-AD) mice were split into three categories: those infected with Kpn (Kpn group), a subset of Kpn mice treated with antibiotics to induce dysbiosis (Kpn+Ab group), and a control group receiving no treatment (TgCt group). Metabolomic and inflammation profiles of gut, serum, and brain samples collected six weeks after infection were evaluated using NMR-based metabolomic analysis and transcriptomics analysis conducted with the NanoString nCounter system.

Results
Significant shifts were observed in gut metabolites, while serum metabolites showed minor changes, particularly with an upward trend in branched-chain amino acids in Kpn-treated mice. In the gut, an inflammatory response was evident, characterized by the increased expression of inflammatory genes such as Cd14, Ptgs2, and Il6st. Transcriptomic analysis of the brain revealed disrupted homeostasis, with heightened neuropathological processes, including oxidative stress and cytokines, and reduced structural and anti-pathological functions, particularly notable in the Kpn+Ab group. Specifically, genes associated with inflammation and neurodegeneration, such as Il1r1 and Ptgs2, were upregulated in the Kpn+Ab group, suggesting a chronic inflammatory state potentially worsening neuropathology. Indeed, elevated levels of total tau were observed in the brains of Kpn+Ab mice. Furthermore, dysregulation in redox signaling linked to the malate-aspartate shuttle was evident, as indicated by increased levels of aspartate and N-acetylaspartate alongside decreased serine concentrations.

Conclusion
The results indicate that Kpn enteric infection leads to persistent inflammation in both the gut and the brain, disrupting essential pathways for brain homeostasis. This disruption may contribute to the buildup of AD pathologies and impairments in neurobehavioral function.

Disclosures
All Authors: No reported disclosures
P-1852. Investigating the infant gut microbiome in relation to R21/Matrix-M™ vaccine immunogenicity and efficacy
Authors: Datoo Mehreen S , Yen Sandi , Edwards Nick , Traore Ousmane , Some Athanase , Natama Hamtandi M , Johnson Jethro , Hill Adrian V S , Tinto Halidou 
Published: January 2025

Abstract

Background
R21/Matrix-M™ malaria vaccine was recently licensed in young children following good vaccine efficacy and induction of high titre antibody responses to the central repeat (NANP) of the P. falciparum circumsporozoite protein. Variability in NANP responses and efficacy was noted in the populations assessed and according to age.
Links between the gut microbiome and the immune system mean early life gut microbiome is an important consideration when understanding vaccine responses. We investigated the relationship of these and participant factors with the gut microbiome in Burkinabe infants in the R21/Matrix-M™ phase IIb trial.

Methods
A phase IIb double-blind, randomised controlled trial assessing safety, immunogenicity and efficacy of R21/Matrix-M™ in 5-17 month olds took place in Nanoro, Burkina Faso from 2019 to 2023. Rectal swabs were collected at baseline and a year later, for both malaria vaccine (n=223) and control participants (n=77). Participant factors (i.e. age, gender, feeding, number of siblings, and Z-score), malaria episodes, and anti-NANP antibody responses were measured. Microbiome was assessed using 16S rRNA gene sequencing. Microbiome alpha- and beta- diversity were characterized, and microbial abundances were analysed using univariate and multivariate models.

Results
Participant microbiomes showed two discernible compositional phenotypes at baseline and follow-up timepoints. The microbiome of majority of participants (93%) were predominantly Firmicutes (39%) and Bacteroidetes (37%) and low in Proteobacteria (13%). However, a subset of participants (7%) had microbiomes that were mainly Proteobacteria (63%). Within-individual alpha-diversity significantly varied with age, but not other participant factors. Relative abundances of certain bacteria were associated with age. Microbial abundances will be analysed and presented against antibody responses, as well as the number of clinical malaria episodes in the first two years.

Conclusion
We describe the microbiome of Burkinabe infants within the context of R21/Matrix-M™ malaria vaccination. This dataset provides insight into a previously underrepresented population during early life, which is a key window for immunological and microbiome development.

Disclosures
Adrian V S Hill, PhD, Serum Institute of India: Grant/Research Support|Serum Institute of India: I am named as a co-inventor on patent applications related to R21
P-1854. Children with Congenital Heart Disease and PICS (Persistent Inflammation, Immunosuppression, and Catabolism Syndrome) Demonstrate Both Pro- and Anti-Inflammatory Cytokine Profiles
Authors: Beneschott Natalya M , Yoder Sandy M , Brady Eric , Williams Amanda K , Buddy Creech C 
Published: January 2025

Abstract

Background
Patients with chronic critical illness have variable recovery from acute events, such as surgery or sepsis, and experience dysregulated inflammation, blunted immune responses, and recurrent infections. The development of persistent inflammation, immunosuppression, and catabolism syndrome (PICS) increases the risk of healthcare associated infections, poor wound healing, and indolent organ failure. The pathophysiology of PICS has not been characterized in critically ill pediatric populations, particularly those with congenital heart disease (CHD).

Methods
The PICASSO study is an ongoing, observational cohort study of immunologic dysregulation in children with CHD who undergo cardiopulmonary bypass for surgical repair. Three groups were defined in this preliminary analysis. Children with uncomplicated post-operative courses served as control participants. Group 1 includes children who underwent CHD repair and were anticipated to have prolonged recovery (n=6), and Group 2 includes children with culture-confirmed, post-operative infection (n=2). PICS was defined as having at least 2 of the following criteria: lymphocyte count &lt; 1500 cells/mL, CRP &gt; 10 mg/dL, and albumin &lt; 3 mg/dL. Blood samples were collected weekly for up to one month in Groups 1 and 2; controls had one sample collected at discharge. Plasma cytokines were measured using a 25-plex panel (Human Immunotherapy Fixed Panel, Luminex®).

Results
Thirty-four samples from 15 patients were analyzed. Plasma cytokines analysis across groups is shown in Figure 1. While come cytokines were more abundant in Group 1 compared to Group 2 and controls (e.g., IL-9 and IP-10), no significant differences were observed. Next, we compared cytokine levels in participants with (n=4) and without PICS (n=11). Both IL-1Ra and IP-10 were increased among children with PICS (p=0.007 and p=0.012, respectively).

Conclusion
In a preliminary analysis of the first 15 patients in the cohort, children with CHD and PICS demonstrate increased plasma levels of both pro-inflammatory (IP-10) and anti-inflammatory (IL-1Ra) cytokines that mirror the clinical phenotype of PICS. Ongoing analysis includes immunophenotyping and immunometabolic profiling of peripheral blood mononuclear cells.

Disclosures
C. Buddy Creech, MD, MPH, CommenseBio: Advisor/Consultant|GSK: Advisor/Consultant|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant
P-1856. Difference in T-cell responses to influenza internal proteins according to HLA type
Authors: Cho Yoon Kyung , Kang Hyun Mi , Kang Kyu Ri , Kang Jin Han 
Published: January 2025

Abstract

Background
Gene variants in HLA are known to influence the degree of immune responses to influenza vaccines leading to varying immunogenicity among different populations. Universal influenza vaccines that contain internal proteins which elicit immunogenicity to various influenza strains are under development, and in order to provide the best protection for vaccine recipients, this study aimed to investigate difference in T-cell responses to influenza internal proteins according to HLA type.

Methods
In the murine challenge model, HLA-A*02:01 and HLA-A*11:01 transgenic mice were immunized with a seasonal influenza vaccine and then injected intramuscularly with two doses of one the following internal proteins: nucleoprotein (NP), nonstructural protein 1 (NS1), nonstructural protein 2 (NS2), matrix protein 1 (M1), matrix protein 2 (M2), and polymerase acidic protein (PA)). The mice were then challenged with A/Cambodia/e0826360/2020 (H3N2) virus.

Results
The NS1NS2 protein showed 0% survival in the A*11:01 type but a high immune response in the HLA-A*02:01 type. In the chemokine/cytokine analyses, the PA_A2.1 group followed by NS1NS2_A2.1, M1M2_A2.1, and M1M2_A11.1 showed the highest positive scores for cytokines MIP-1a, RANTES, IFN-γ, KC, and MCP-1. Furthermore, the PA_A11.1 group showed statistically valid IFN-γ and CD8+ T cell percentages in the lungs, whereas in the spleen, the PA_A2.1 group showed high percentages.

Conclusion
Internal proteins that showed adequate immune responses in HLA-A*02:01 type was NS1NS2, and M1M2 showed adequate responses in both HLA-A*02:01 and HLA-A*11:01 type.

Disclosures
All Authors: No reported disclosures