bluuebunny/crossref_metadata_2025_split huggingface dataset:
292. Phosphorodiamidate Morpholino Oligomers Targeting acpP Reduce the Biofilm Burden in Burkholderia cepacia Complex
Authors: Mendez Antonio R , Pybus Christine A , Greenberg David E 
Published: November 2023

Abstract

Background
The Burkholderia cepacia complex (Bcc) is composed of highly related opportunistic species that establish pulmonary infections in immunodeficient hosts, such as those with cystic fibrosis and chronic granulomatous disease. Due to their innate antibiotic-resistant phenotypes and capacity to form biofilm, Bcc infections are difficult to eradicate with traditional antibiotics. Peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) offer an alternative therapeutic approach. These nucleotide analogues penetrate the outer membrane, bind specific mRNA, and inhibit translation. Due to high affinity base-pairing dynamics, these molecules can be rapidly modified and deployed to precisely inactivate innumerable bacterial gene targets. Previously, we found PPMOs targeting an acyl carrier protein (AcpP) are bactericidal against planktonic Bcc. It remains unknown whether PPMOs could modulate biofilm formation in these pathogens.
Proposed Mechanism of Action of PPMOs
Inside a bacterial cell, peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) targeting the acpP gene bind to mRNA near the Shine-Dalgarno sequence and AUG start site, sterically inhibiting translation. This inhibition disrupts the expression and essential functions of acyl carrier protein (ACP).

Methods
Minimum biofilm eradication concentration assays were used to test two AcpP PPMOs on 24 h biofilms formed on pegs. Viable cells were enumerated. This activity was further evaluated by microscopy and 7-day biofilm kinetic studies. Fluorescein-labeled AcpP PPMO added to B. cenocepacia K56-2 DsRed was imaged over time to evaluate colocalization. PPMO toxicity was assessed over 24 h in A549 cells by LDH release.

Results
Treatment (10-40 μM) with AcpP PPMOs demonstrated more than a 3-log reduction (p&lt; 0.0001) in biofilm burden across five clinical isolates of Bcc tested and B. thailandensis E264. PPMO bactericidal activity was visualized with confocal and scanning electron microscopy. Fluorescently labeled AcpP PPMO associated with the membrane of B. cenocepacia K56-2 DsRed in a temporal fashion. Additionally, AcpP PPMOs exhibited low toxicity in human pneumocytes.

Conclusion
PPMOs are active and bactericidal in established Bcc biofilms; thus, the biofilm setting is not a deterrent against PPMO delivery. This is further supported by the observations that AcpP PPMOs and Bcc cells colocalize in biofilm, resulting in membrane destruction and biomass reduction. Together, these data provide evidence that PPMOs are active in the biofilm setting of Bcc and could be a promising therapeutic strategy for these infections.

Disclosures
David E. Greenberg, MD, University of Texas Southwestern Medical Center: Dr. Greenberg has numerous patents on PPMOs
293. Faecal microbiota transplant to ERadicate gastrointestinal carriage of Antibiotic Resistant Organism: a prospective, randomised placebo-controlled feasibility trial - The FERARO study (IRCTN reg. no. 34467677)
Authors: Merrick Blair , Prossomariti Désirée , Kertanegara Michael , Allen Elizabeth , Sergaki Chrysi , Le Guennec Adrien D , Delord Marc , Conte Maria R , Moyes David , Shankar-Hari Manu , Douiri Abdel , Goodman Anna L , Shawcross Debbie L , Goldenberg Simon D 
Published: November 2023

Abstract

Background
The gastrointestinal tract (GIT) is a reservoir of antibiotic resistant organisms (ARO). ARO colonisation precedes infections which are more challenging to treat than if drug susceptible, with excess morbidity and mortality. Presently, no effective GI decolonisation strategy exists. Faecal microbiota transplant (FMT) has emerged as a potential therapeutic. However, there is uncertainty about feasibility, safety and effectiveness.

Methods
Population: Patients with history of invasive infection with extended spectrum beta-lactamase (ESBL) or carbapenemase producing Enterobacterales (CPE) and evidence of persistent GIT ARO carriage (assessed by culture)

Intervention
3 doses of encapsulated lyophilised FMT each manufactured from 80g raw stool given on consecutive days

Comparator
Matched placebo capsules

Outcomes
Primary outcome - participant consent rate (as proportion of those approached screened for GIT carriage of ESBL-E/CPE). Secondary outcomes – safety and efficacy metrics including adverse event (AE) rates and GIT ARO carriage rates at 1 week, 1, 3 and 6 months. Exploratory outcomes – metagenomic and metabolomic stool analyses.

Results
Of 460 approached individuals, 124 (27%) consented. 53/124 participants (43%) fulfilled eligibility criteria. 44/53 (83%) randomised and 41/44 (93%) received investigational medicinal product (IMP): 20 FMT and 21 placebo. 39/41 (95%) completed dosing, 18/20 (90%) FMT (1 investigator and 1 participant discontinuation) and 21/21 (100%) placebo. Overall, GIT AE including reflux, bloating, change in bowel habit, were more common in FMT arm. 6 serious AE in 5 participants occurred in FMT arm, compared to 1 in placebo (all hospitalisation); none were deemed attributable to FMT. No unanticipated harms from FMT administration were realised. GIT ARO carriage rate assessed in 38/41 (93%) IMP recipients providing stool for analysis at 1-month was lower in FMT compared to placebo - FMT: 13/18 (72%) vs. placebo: 17/20 (85%), p=0.34.
FERARO trial consort diagram
ESBL/CPE detection rate
Detected by culture over time

Conclusion
Based on a priori assessment, a substantive trial would be feasible with protocol modifications. Encapsulated FMT appears safe intervention for eradication of GIT ARO carriage. Our feasibility trial informs design, and provides evidence to conduct future efficacy randomised controlled trials.

Disclosures
David Moyes, PhD, MSc, BSc, Pfizer: Grant/Research Support Simon D. Goldenberg, FRCPath, MD (Res), PGDipID, DipHIC, MSc, EnteroBiotix: Honoraria|Tillotts Pharma UK: Honoraria
294. The Impact of Mucositis on the Oral Microbiome and Clinical Outcomes in Allogenic Hematopoietic Stem Cell Transplantation
Authors: Messina Julia A , Jiang Danting , Selvan Bharathi , Hill Lauren , Bush Amy , Bokman John , Andermann Tessa , Johnson Ernya , Chao Nelson , Surana Neeraj , Sung Anthony 
Published: November 2023

Abstract

Background
Mucositis is a common complication of allogeneic hematopoietic stem cell transplantation (allo HCT) that can lead to debilitating pain, malnutrition, and bloodstream infections (BSI). We sought to characterize the oral microbiome of allo HCT recipients and correlate the oral microbiome with the development of mucositis and clinical outcomes.

Methods
We collected weekly oral swabs and clinical data from patients who underwent allo HCT from 2017-21. Swabs underwent 16S rRNA sequencing, amplifying the V4 region. Patients with paired pre-HCT (prior to conditioning) and day +30 samples were included in the microbiome analysis.

Results
91 patients were enrolled with 178 swabs sequenced. Mucositis occurred in 66/91 patients (73%) at a median 6 days post-HCT (Table 1). Patients with mucositis were significantly more likely to receive myeloablative conditioning, methotrexate/calcineurin inhibitor for graft-versus host disease (GVHD) prophylaxis, and total parenteral nutrition. There was not a significant difference in BSI rates at day +30 between patients with mucositis and those without (20% vs. 17%; p=0.69), but there was a trend toward more acute GVHD by day +30 in the mucositis group (27% vs. 12%; p=0.12). Additionally, patients with mucositis had lower rates of relapse (18% vs. 36%; p=0.07) and all-cause mortality at 1-year post-HCT (26% vs. 36%; p=0.33) although these comparisons were not statistically significant.
39 patients had paired 16S pre- and Day +30 data (28 with mucositis, 11 without). While there was no change in α-diversity in patients who did not develop mucositis, the development of mucositis was associated with a decrease in α-diversity (Figure 1). Although β-diversity of the pre-HCT samples was not different between the two groups, patients with mucositis had a lower pre-HCT abundance of Veillonella parvula.

Conclusion
Post-HCT mucositis led to a reduction in day +30 microbiota diversity, with Veillonella parvula potentially being a biomarker for the development of mucositis. Mucositis was not associated with more BSIs or higher 1-year mortality. Future study includes analysis of the gut microbiome in this same cohort to identify microbial targets that attenuate mucositis without impacting the therapeutic efficacy of HCT.

Disclosures
Neeraj Surana, MD, PhD, Pfizer: Stocks/Bonds Anthony Sung, MD, clasado: Grant/Research Support|dsm: Grant/Research Support|merck: Grant/Research Support
298. A Novel Murine Model of Neonatal Staphylococcus aureus Colonization Induces Changes in the CD4 T cell Compartment and Protects from Lethal Bacteremia
Authors: Olson Patrick D , Bubeck-Wardenburg Juliane 
Published: November 2023

Abstract

Background
Staphylococcus aureus is a leading infectious cause of invasive bacterial infection in the United States. The pathogen’s capacity to cause disease is due, in part, to its ability to asymptomatically colonize the human host. Classically, the nose has been presumed to be the primary colonization site, but there is increasing evidence that the gastrointestinal tract may be a fundamental niche occupied during S. aureus colonization. There remain significant deficits in preclinical modeling of invasive S. aureus infection; Laboratory mice are commonly employed for modeling of S. aureus infection, but are rarely colonized by or pre-exposed to S. aureus. This contrasts with the human interaction with the pathogen, where a vast majority of humans demonstrate a specific adaptive response to S. aureus and a plurality of patients have lifelong colonization. To overcome this deficit, we designed a novel neonatal mouse model of asymptomatic intestinal S. aureus colonization.

Methods
Neonatal mice were subjected to oral gavage with S. aureus at day 10 of life; colonization was followed by fecal S. aureus titer. Infection outcomes were compared between mock- and S. aureus colonized mice.

Results
Mice from internal breeding and external vendors had no detectable S. aureus in the nasopharynx or feces at all time points tested. We found that adult mice are unable to be durably colonized by S. aureus despite multiple methods of inoculation. We identified that neonatal mice have a narrow, early window of susceptibility when they can be durably colonized, demonstrating robust fecal titers of S. aureus sustained through adulthood. Intestinal exposure to S. aureus shifted the nature of the colonic T cell compartment to encompass a greater proportion of CD4 T regulatory cells and a decreased frequency of GATA3+ CD4 cells. Finally, colonized mice demonstrated protection from severe infection, mimicking what is seen in humans.

Conclusion
Our findings support the hypothesis that gastrointestinal colonization influences the development of systemic immunity against S. aureus. This model will allow exploration into the mechanism of protective immunity against S. aureus and may inform the development of novel therapeutic and vaccination approaches to mitigate staphylococcal disease.

Disclosures
All Authors: No reported disclosures
299. Distinct TGF-β1 Patterns in Patients with Sepsis and Non-alcoholic Fatty Liver Disease
Authors: Papic Neven , Vrsaljko Nina , Radmanic Leona , Simicic Petra , Krznaric Juraj , Gjurasin Branimir , Zidovec Lepej Snjezana , Vince Adriana 
Published: November 2023

Abstract

Background
There is growing evidence that non-alcoholic fatty liver disease (NAFLD) might impact infection course and outcomes. However, the immune responses in patients with NAFLD and sepsis have not been described. TGF-β1 is a key biological regulator that exhibits broad immunosuppressive and healing effects in sepsis. Although TGF-β pathway dysregulation is described in patients with NAFLD, TGF-β responses in patients with sepsis and NAFLD are still unknown. The aim was to determine whether patients with NAFLD and sepsis have distinct circulating TGF-β1 patterns.

Methods
A prospective cohort study included 80 patients with community-acquired sepsis (SOFA &gt; 2); 40 patients with NAFLD and 40 without NAFLD. TGF-β1 serum concentrations were analyzed at admission and on day 5 of hospitalization. Routine demographic, laboratory, microbiological, and clinical data were collected. Data are presented as frequencies and medians with interquartile ranges.

Results
The main sources of sepsis were respiratory (25, 31.2%), urinary (18, 22.5%), and skin and soft tissue infection (16, 20%). Groups were matched regarding age (65 [53-74] years), sex (39 males), and comorbidities, except for obesity which was more frequent in the NAFLD group (BMI of 35 [28-40] vs 26 [22-28] kg/m2). There were no differences in routine laboratory findings including CRP, procalcitonin, lactate, and WBC, except for GGT which was higher in the NAFLD group (60 [31-115] vs 33 [21-69] IU/L). Upon admission, patients with NAFLD had higher TGF-β1 concentrations than patients without NAFLD (207 [87-350] vs 65 [13-172] pg/mL). However, distinct temporal changes were observed on day 5; while TGF-β1 decreased in most patients with NAFLD (in 24, 60%, median of 140 [43-305] pg/mL), in the non-NAFLD group TGF-β1 concentrations increased in 34 (85%) patients to 151 [82-367] pg/mL), as shown in Figure 1.

Conclusion
Patients with NAFLD have higher baseline TGF-β1 serum concentrations that fail to further increase, but rather decrease in a compensatory anti-inflammatory phase of sepsis. A better understanding of these TGF-β1 changes could potentially help elucidate the complex and aberrant immune responses in NAFLD patients during sepsis.

Disclosures
All Authors: No reported disclosures
300. Disturbance of Gut Microbial Diversity in ICU Patients from Colombia is Driven by Multi-Drug Resistant Organisms (MDRO) Colonization
Authors: Parada Torres Alexandra , Castro Betsy , Malavet Thomas , Forero Nicolas , Matiz Juan , Rodriguez Yordy , Zambrano Luis , Melissa Ordoñez Karen , Santamaria Alejandra , Ospina Fidel , Beltran Jaime , Guevara Fredy , Martinez Juliana , Porras Alexandra , Sarmiento Paola , Aroca Luisa , Mora Alejandra , Arias Cesar A , Paola Carvajal Lina , Rincon Sandra , Reyes Jinnethe 
Published: November 2023

Abstract

Background
Gut microbiota plays a critical role in health, with essential functions in physiology, metabolism, immunity, regulation, and protection against pathogens. Critically-ill patients admitted on the ICU experience perturbation in the microbiota, with reduction in the phylogenetic diversity and composition. Here, we aimed to investigate the rectal microbiota in patients admitted on the ICU from Colombia, focused on MDRO colonization.

Methods
Microbiome analysis and microbiological screening for MDRO and WGS were performed in rectal swabs taken on admission day from 180 patients from 5 ICUs. Microbiome analysis was determined by 16S rRNA sequencing using Illumina Miseq platform. alpha-diversity metrics were calculated by Richness, Simpson, and Shannon indexes, and beta-diversity was determined using Similarity Percentages (SIMPER) analysis. Patients were grouped into 2 cohorts: MDRO-colonized and non-colonized. Clinical data was collected using REDCap.

Results
MDRO colonization was detected in 13 patients (7%), and Enterobacter cloacae complex was the most prevalent microorganism (38%), followed by K. pneumoniae (23%), and P. aeruginosa (15%). Of these MDRO, 23% and 15% harbored KPC-2 and KPC-3/OXA-9 combination, respectively. Prevotella and Bacteroides were the most abundant genus in the microbiota of all patients. Interestingly, microbiota of MDRO-colonized patients showed lower diversity (Shannon p:0.0025, Simpson p: 0.0031 and richness 0.012) and had less bacterial taxa than the observed in the non-colonized group (n=167), in which Bacteroides, Porphyromonas, Campylobacter, and Oscillospiraceae genus were exclusively detected. Moreover, Parabacteroides was a genus exclusively identified in the MDRO colonized group. Further, 14 genus including Oscillospiraceae, Lactobacillus, and Faecalibacterium related to beneficial functions were lower in abundance from MDRO-colonized patients, whereas some pathobionts were present in high abundance in this group. Most of patients were men (58%); median age was 59 y/o. Charlson comorbidity index 4 (IQR=1-6).

Conclusion
Loss in microbial diversity, with low abundance of beneficial microorganisms were associated with MDRO gut colonization in ICU patients from Colombia.

Disclosures
Karen Melissa Ordoñez, n/a, Pfizer: Advisor/Consultant|Pfizer: Honoraria
302. Investigating NAI Titer as a Neutralizing IAV Correlate of Protection
Authors: Rumfelt Kalee E , Lauring Adam S , Martin Emily T , Monto Arnold , Petrie Joshua 
Published: November 2023

Abstract

Background
Influenza vaccines are updated each year to maximize protection against circulating strains. This process relies on Correlates of Protection (CoPs) that compare an assay’s measure of an immune response with the level of protection. Three common CoPs for Influenza A Virus (IAV) are Hemagglutinin (HA) Inhibition (HAI), Neuraminidase (NA) Inhibition (NAI), and microneutralization (MN) titers. These capture different aspects of the immune response, and the degree to which NA antibodies provide protection is not well understood. Determining how these assays are related has implications for understanding the contribution of multiple antibody-based mechanisms of protection against infection.

Methods
Pre-/ post-season sera were collected from individuals enrolled in the HIVE study for the 2016-17 and 2017-18 seasons. HAI and NAI assays were performed on 216 samples from 139 individuals for A/Hong Kong/4801/2014 and A/Singapore/INFIM-16-0019/2016. MN assays were performed on 179 samples from 81 individuals using A/Hong Kong. Linear regression was used to assess the association between the NAI and MN titers, controlling for HAI titers. Descriptive statistics were used to determine the level of antibody cross-reactivity of the subsequently-circulating A/Singapore NA, with a 4-fold difference in titer indicating discordance.

Results
After adjusting for age, the regression model produced beta estimates of 0.16 for HAI and 0.54 for NAI titers, but neither were significant (HAI p= 0.09 NAI p= 0.08). The percentage of individuals with NAI titers that were discordant for A/Hong Kong was 14.8% in 2016-17 and 20.8% in 2017-18. No individuals had A/Singapore titers that were discordant compared to A/Hong Kong titers.

Conclusion
Although not significant, we found NAI assay titers were more strongly associated with LMN titers, suggesting that NA antibodies provide some degree of neutralizing activity. A small proportion of individuals had discordant NAI results, which indicate limited cross-reactivity across strains. This raises questions regarding differences in antibody production toward differing NAs. The findings of this study suggest that NA antibodies are capable of neutralizing IAV and this activity differs across strains and individuals.

Disclosures
Adam S. Lauring, MD, PhD, Roche: Advisor/Consultant|Sanofi: Advisor/Consultant Emily T. Martin, PhD, MPH, Merck: Grant/Research Support Arnold Monto, MD, Roche: Advisor/Consultant|Roche: Honoraria Joshua Petrie, PhD, CSL Seqirus: Grant/Research Support
303. Tissue-compartment specific differences in T-cell response found in 44 fatal COVID-19 cases
Authors: Stantliff Trevor M , Platt Andrew , Stein Syndey R , Oguz Cihan , Vannella Kevin M , Ramelli Sabrina , Hewitt Stephen , Chertow Daniel S 
Published: November 2023

Abstract

Background
T-cells play an essential role in recognizing and clearing viruses from infected tissues. While the peripheral blood T-cell responses among patients with coronavirus disease 2019 (COVID-19) has been well characterized in the recent literature, little is known about the overall repertoire diversity of T-cell responses and SARS-CoV-2-specific T-cell breadth and depth across tissues in patients with severe COVID-19. To fill this knowledge gap, we evaluated the T-cell immune repertoires using bulk sequencing of multiple tissue samples from a cohort of fatal COVID-19 cases.

Methods
Lungs, thoracic lymph nodes and spleens were collected at autopsy from a cohort of 44 patients who died with or from COVID-19. DNA was isolated from paraffin embedded tissues fixed with an ethanol buffer and from peripheral blood mononuclear cells (PBMCs) collected perimortem. T-cell receptor beta (TCRb) sequencing was performed using the Adaptive ImmunoSeq platform and the SARS-CoV-2-specific T-cell response was quantified by exact matching of the TCRb sequences with those reported in the ImmuneCODE and VDJdb databases.

Results
Significantly lower T-cell clonality and higher numbers of unique T-cell rearrangements were observed in lymph nodes compared to the lung tissues and PBMCs across all patients, indicating higher T-cell diversity in the lymph nodes. Clonal expansion was greatest in the PBMCs and least in the lymph node tissues. Pearson correlations between age and SARS-CoV-2 specific T-cell depth, which were controlled for gender and the number of days between onset and death, varied significantly across tissue compartments in both magnitude and directionality. We observed a strong positive correlation (0.35, p&lt; 0.05) between the SARS-CoV-2 specific T-cell depth and older age in the lymph node samples, that was in contrast with an opposite trend in the PBMCs (-0.52, p&lt; 0.001).Figure 1:Lymph node tissues had increased T-cell counts (clone_count: color scale) and increased unique T-cells (clonotype_count: circle size) when compared to PBMCs and lung tissues.Figure 2.PBMC and lung samples have increased clonality (sample_clonality: circle size) and max frequency for the immunodominant clonotype (max_frequency: color scale) when compared to lymph node tissues.

Conclusion
The higher depth of SARS-CoV-2 specific T-cells within lymph nodes of older patients that was not observed within circulating PBMCs suggest a deficit of translocation of virus-specific T cells from the site of antigen presentation to circulation and the site of infection, with implications for the increased severity of disease observed in older patients with COVID-19.

Disclosures
All Authors: No reported disclosures