BACKGROUND:Long COVID (LC) manifests in 10%-30% of non-hospitalized individuals post-SARS-CoV-2 infection, leading to significant morbidity. The predictive role of gut microbiome composition during acute infection in the development of LC is not well understood, partly because of the heterogeneous nature of the disease. OBJECTIVES:To determine whether the gut microbiome composition in the acute phase of SARS-CoV-2 infection predicts subsequent LC and to investigate the role of microbiome signatures in disease subphenotypes. DESIGN:We conducted a longitudinal cohort study involving 799 outpatient participants tested for SARS-CoV-2 due to similar symptom presentation, including 380 SARS-CoV-2 positive and 419 negative individuals. Stool samples were collected at two time points for metagenomic sequencing. Logistic regression with L1 regularization was employed to predict LC based on the microbiome and clinical metadata. RESULTS:The individuals who developed LC harbored a distinct gut microbiome during acute infection compared to those who recovered fully and uninfected controls with similar symptomatology. However, the temporal changes in the gut microbiome between the acute (0-1 month) and post-acute (1-2 months) phases were similar across the three cohorts. Using machine learning, we showed that the gut microbiome carried a modest signal for subsequent LC, but model performance was insufficient for clinical prediction, likely reflecting the heterogeneous nature of LC. Finally, we identified four LC symptom clusters, with gastrointestinal and fatigue-only groups strongly linked to gut microbiome alterations. CONCLUSION:The gut microbiome can potentially offer solutions for understanding the heterogeneous nature of LC. Larger cohorts and phenotype-aware computational algorithms may help overcome current model performance limitations and support the development of targeted diagnostic and therapeutic strategies.

OBJECTIVES:To compare the efficacy and safety of antibiotic lock therapy (ALT) versus catheter removal in managing central vascular catheter-associated bloodstream infection (CVC-BSI). METHODS:We conducted a single-centre, retrospective cohort study of adult patients treated with ALT or catheter removal for management of CVC-BSI between 2018 and 2022. The primary outcome was a composite of 90 day microbiological relapse or recurrent BSI. Secondary outcomes included 30 day mortality, CVC-associated complications and Clostridioides difficile infection (CDI). Logistic regression with propensity score-adjustment was used to evaluate differences in outcomes and identify predictors of relapse. RESULTS:During the study period, 106 participants received ALT and 181 underwent catheter removal. Patients treated with ALT received shorter courses of systemic antimicrobials (11 versus 14 days; P < 0.001) and had shorter hospital stays (4 versus 10 days; P < 0.001). Median duration of catheter salvage in patients receiving ALT was 28 days (IQR 7-80). Primary composite outcome was similar between both groups, but ALT was associated with a significantly higher risk of microbiological relapse within 90 days (20% versus 7%; adjusted odds ratio 3.93, 95% CI 1.64-9.40; P = 0.002). No significant difference in 30 day mortality, CVC-related complications or CDI was observed. CoNS BSI was an independent predictor of microbiological relapse in patients treated with ALT (OR 2.28; P = 0.05). CONCLUSIONS:Although ALT offers a non-invasive catheter salvage strategy, its association with higher relapse rates, particularly in CoNS BSI, suggests catheter removal should remain the preferred approach when feasible. ALT could be considered a short-term catheter salvage strategy for pathogens with low virulence when used with close surveillance.

Long COVID (LC), manifests in 10-30% of non-hospitalized individuals post-SARS-CoV-2 infection leading to significant morbidity. The predictive role of gut microbiome composition during acute infection in the development of LC is not well understood, partly due to the heterogeneous nature of disease. We conducted a longitudinal study of 799 outpatients tested for SARS-CoV-2 (380 positive, 419 negative) and found that individuals who later developed LC harbored distinct gut microbiome compositions during acute infection, compared with both SARS-CoV-2-positive individuals who did not develop LC and negative controls with similar symptomatology. However, the temporal changes in gut microbiome composition between the infectious (0-1 month) and post-infectious (1-2 months) phases was not different between study groups. Using machine learning, we showed that microbiome composition alone more accurately predicted LC than clinical variables. Including clinical data only marginally enhanced this prediction, suggesting that microbiome profiles during acute infection may reflect underlying health status and immune responses thus, help predicting individuals at risk for LC. Finally, we identified four LC symptom clusters, with gastrointestinal and fatigue-only groups most strongly linked to gut microbiome alterations.

Abstract Background Catheter-related bloodstream infection (CRBSI) is an important complication of long-term central venous catheters (CVCs) and is associated with high morbidity and cost. While line removal is optimal, it is not always feasible and is not without complications. Antibiotic lock therapy (ALT) may be an alternative strategy for line salvage, but the efficacy of this approach particularly among immunocompromised hosts is unknown. Methods We retrospectively reviewed adult patients with CRBSI managed with ALT between 2018 and 2022 at our tertiary medical center. We reviewed patient comorbidities, type and indications for CVC use, microbiology of CRBSI, ALT, and use of systemic antibiotics. Outcomes included 30-day mortality, 90-day microbiologic relapse (with same bacteria as index case), 90-day recurrent BSI (with different bacteria from index case), and adverse events. Results 86 patients were reviewed, a majority of whom were immunocompromised (91%) due to hematopoietic stem cell transplantation (85%) and thrombocytopenic (platelet count 36; IQR 17-112). 78% had tunneled CVC for indications including peri-transplant therapy (72%), chemotherapy (15%), and TPN (6%) (Table 1). The median time to CRBSI following CVC insertion was 45 days (IQR 19-86). Infections were frequently monomicrobial (80%) due to Gram-positive organisms (n=75) including coagulase-negative staphylococci and Enterococcus spp. The minority of Gram-negative (n=17) infections were due to E coli and Enterobacter spp. 94% of patients received systemic antibiotics and all patients received ALT for a median of 11 days [IQR 6-15] and 11.5 days [IQR 6-14], respectively (Table 2). The 30-day attributable mortality rate was low at 1%. Rates of 90-day microbiologic relapse (20%) and recurrent BSI (16%) were high, occurring at a median of 42 days (IQR 12-55) and 35 days (IQR 25-50) following completion of ALT, respectively (Table 3). Conclusion Despite high rates of microbiologic relapse and recurrent BSI, ALT may be an effective line salvage strategy extending the use of CVC by up to 30 days with minimal impact on mortality even among immunocompromised patients. Disclosures John C. O'Horo, Sr., MD, MPH, Janssen Pharmaceuticals.: Grant/Research Support|nference: Grant/Research Support

In this report, we describe a case of septic arthritis caused by the newly described Mycobacterium persicum (formerly Mycobacterium kansasii complex). The patient's only significant exposure was home gardening. To our knowledge, this represents the first documented case of M. persicum infection in the United States and first septic arthritis.

A 36-year-old man from Minnesota presented to the emergency department with a constellation of symptoms that included progressive nausea, difficulty swallowing, shortness of breath, and productive cough with brown sputum. He had a history of alcohol use disorder complicated by malnutrition and protein S deficiency leading to recurrent deep vein thromboses and was on lifelong anticoagulation. Since stopping alcohol 2 months earlier, he developed intermittent episodes of productive cough and malaise.

Abstract Background Achromobacter spp. are important pathogens that are most frequently implicated in opportunistic infections, especially in patients with chronic lung disease, malignancy, and solid organ or hematopoietic stem cell transplantations. They commonly cause pneumonia, bacteremia, and device-associated infections. Intrinsic and acquired resistance mechanisms usually complicate treatment. Further characterization of the changing antibiotic susceptibilities and clinical manifestations of Achromobacter spp. are needed to improve clinical practice. Methods We performed a retrospective review of Achromobacter isolates from 2013 to 2023 in the Mayo Clinic Enterprise with available antimicrobial susceptibility testing (AST) data. Variables included sample source, collection date, and AST by agar dilution with susceptibility defined according to Clinical and Laboratory Standards Institute (CLSI) breakpoints. Samples were categorized into quartiles based on collection date and grouped into source types (respiratory, genitourinary, etc.) and AST. Results A total of 1,506 patients were identified with a total of 1,546 unique Achromobacter spp. isolates from 2013 - 2023. The most common species was A. xylosoxidans, encompassing 40.1% of all isolates (Table 1). Respiratory samples (sputum, bronchoalveolar lavage) were the most common source (57.5%), followed by musculoskeletal and soft tissue (16.4%), genitourinary (12.2%), and oropharyngeal sources (10.3%). AST from 2013 to 2023 showed persistent high levels of resistance to aztreonam and tetracycline, with stable susceptibility to piperacillin-tazobactam, trimethoprim-sulfamethoxazole, and carbapenems (Table 2). Over our 10-year analysis, there was increased resistance to aminoglycosides, fluoroquinolones, ceftazidime, and cefepime.Table 1.Achromobacter Species Identification and Isolate Percentage (%) Stratified by Year Table 1 lists the Achromobacter species identified stratified by the year each sample was collected. Each value represents the number of isolates that were identified as the listed Achromobacter species, with "Achromobacter sp." indicating an isolate without species identification. Percentages of species are listed in parentheses (%). Sample totals are listed in the right column.Table 2.Antibiotic Susceptibility of All Tested Achromobacter Isolates (Percentage of Susceptible Isolates) Table 2 lists antibiotics by class, stratified by year that Achromobacter isolates were tested. Each value is the total number of isolates tested for antimicrobial susceptibility, followed by the percentage of susceptible isolates in parentheses (%). Total isolates tested and overall susceptibility percentage is also listed over the 10-year period. Conclusion Achomobacter continues to be a clinically significant organism with a complex resistance profile. Our dataset shows a significant prevalence of non-respiratory and non-genitourinary samples, in addition to increasing resistance over many antibiotic classes. Our data suggests that piperacillin-tazobactam, imipenem, and minocycline are appropriate empiric regiments for Achromobacter. Disclosures All Authors: No reported disclosures

Abstract Background As the acute phase of the COVID-19 pandemic subsides, an increasing number of individuals are recognized as having long COVID, affecting over 65 million people worldwide. Recent studies have suggested a potential link between long COVID and alterations in the gut microbiome. In this study, we examined the gut microbiome of a large outpatient cohort during acute phase of infection, with the ultimate goal of determining predictors of long-term COVID-19 health outcomes. Methods We conducted a study of 394 COVID-19 patients with positive SARS-CoV-2 testing from November 2020 to September 2021 at a multi-site healthcare system. Long COVID was defined as the persistence of symptoms for four weeks or more after illness onset. DNA extraction was performed using the MoBio PowerSoil Pro DNA isolation kit. Samples were sequenced using shotgun metagenomics. Stool SARS-CoV-2 RNA was tested using qRT-PCR of the E gene, and stool ELISA was performed for calprotectin levels. Standard biostatistical tools in R (v 4.2.3) were used for statistical analysis. Results Of the 394 COVID-19 patients, 84 (21%) had long COVID, with fatigue being the most common persistent symptom (Table 1). No significant differences were seen in age, BMI, and antibiotic use. Those with long COVID were more likely to be female, had higher Charlson's comorbidity scores, more severe index illnesses. However, the two groups had no difference in SARS-CoV-2 stool PCR positivity or stool calprotectin levels (Table 2). Principal coordinate analysis of Bray Curtis dissimilarities revealed that patients with long COVID had a distinct microbial composition compared with those without long COVID during the acute phase of infection (ANOSIM R2= 0.005, P= 0.01). Categorizing patients by number of long COVID symptoms showed significant differences among groups (ANOSIM R2=0.1, P=0.007), mainly between patients with >3 symptoms and those with 0-1 symptoms (Bonferroni, P= 0.018). Alpha diversity was lower in patients with > 3 symptoms, although this was not statistically significant (Shannon diversity, two-way-ANOVA, P=0.051). Figure 1 Conclusion Long COVID patients show distinct gut microbial composition during the acute phase of infection, suggesting a potential role in predicting long-term COVID health outcomes. Disclosures John C. O'Horo, Sr., MD, MPH, Janssen Pharmaceuticals.: Grant/Research Support|nference: Grant/Research Support Purna C. Kashyap, MD, Intrinsic Medicine: Advisor/Consultant|Novome Biotechnologies: Advisor/Consultant|Pendulum Therapeutics: Advisor/Consultant

To describe our experience with men admitted to a tertiary care hospital with genital injury. Adult men with injuries of the genitals, admitted to our institution between January 2013 and June 2018, were identified from our institutional trauma registry. Patient charts were queried to extract mechanism, management, follow-up, and complications. 118 men met inclusion criteria. 39% and 61% sustained penetrating and blunt injuries, respectively. The most common mechanisms of penetrating trauma were external violence (48%) and self-inflicted injury (40%). The most common mechanisms of blunt trauma were motorcycle crash (33%) and sexual injury/intercourse (22%). 38% presented with penile and 71% with scrotal injuries. 48% of men with scrotal injuries had concomitant testis injury. 9.3% presented with both a penile and a scrotal injury. Concomitant urethral injuries were found in 17% of all genital injuries. Genital trauma was more common in the summer months. 74% of all genital injuries were managed operatively, with surgery more common after penetrating injury (89% vs 64%, p value < 0.01). 73% of 84 men with scrotal trauma were managed operatively. 27 men received surgical intervention for testis rupture, with a testicular salvage rate of 44%. 60 (51%) patients presented for follow-up. The median length of follow-up from initial injury was 29 (± 250) days. Of these, 9 (15%) patients developed one or more complications Genital injuries can occur via numerous mechanisms and frequently require operative intervention. Concomitant urethral injury is common. More work is needed to evaluate the long-term sequelae of these injuries.

Nucleoside diphosphate kinases (NDKs) are implicated in a wide variety of cellular functions owing to their enzymatic conversion of NDP to NTP. NDK from Borrelia burgdorferi ( Bb NDK) was selected for functional and structural analysis to determine whether its activity is required for infection and to assess its potential for therapeutic inhibition. The Seattle Structural Genomics Center for Infectious Diseases (SSGCID) expressed recombinant Bb NDK protein. The protein was crystallized and structures were solved of both the apoenzyme and a liganded form with ADP and vanadate ligands. This provided two structures and allowed the elucidation of changes between the apo and ligand-bound enzymes. Infectivity studies with ndk transposon mutants demonstrated that NDK function was important for establishing a robust infection in mice, and provided a rationale for therapeutic targeting of Bb NDK. The protein structure was compared with other NDK structures found in the Protein Data Bank and was found to have similar primary, secondary, tertiary and quaternary structures, with conserved residues acting as the catalytic pocket, primarily using His132 as the phosphohistidine-transfer residue. Vanadate and ADP complexes model the transition state of this phosphoryl-transfer reaction, demonstrating that the pocket closes when bound to ADP, while allowing the addition or removal of a γ-phosphate. This analysis provides a framework for the design of potential therapeutics targeting Bb NDK inhibition.

Introduction: Tumor necrosis factor (TNF) antagonists are effective treatments for moderate-severe Crohn's disease (CD). Up to one third of patients have primary-nonresponse to TNF therapy, which has been reported to predict low rates of response to subsequent TNF agents. No study to date has specifically assessed the effectiveness of intravenously (IV) administered TNF therapy following primary-nonresponse to subcutaneously (SC) administered TNF. We hypothesize that IV administration and weight-based dosing of TNF therapy offers advantages over SC fixed dose TNFs and may be effective despite primary-nonresponse to previous SC TNF. This retrospective case series assesses clinical and endoscopic improvement to IV TNF therapy following primary nonresponse to prior SC TNF therapy. Methods: From administrative data at a single site, we identified 19 patients with primary nonresponse to one or more SC TNF therapies (adalimumab (ADA), certolizumab pegol (CZP) and/or golimumab (GLB)) who subsequently received IV infliximab (IFX) for ≥12 weeks. We described baseline characteristics, disease activity by Harvey Bradshaw Index (HBI) and Simple Endoscopic Activity Score in Crohn's Disease (SESCD), and biochemical assessments. Results: Key characteristics of 19 patients described in Table 1. After ≥12 weeks of IFX, 12 (63.2%) patients reported clinical response, defined as ≥3 point decrease in HBI compared to baseline. 15 (78.9%) patients reported clinical remission, defined as HBI ≤4. Mean CRP decreased from 13.7 mg/L pre-IFX to 9.8 mg/L post-IFX (RR 0.0-10.0). Of 11 patients with available endoscopic data, restaging colonoscopy 6-18 months after starting IFX revealed endoscopic improvement in 7 patients, defined as ≥50% decrease in SESCD. Four patients were in endoscopic remission, defined as SESCD ≤2.Table: Table. Patient demographics and disease characteristicsConclusion: Patients with moderate-severe CD with prior primary-nonresponse to one or more SC TNF agent who are subsequently treated with IV TNF therapy have high rates of clinical and endoscopic response and remission. Therefore, despite primary-nonresponse to SC TNF, patients may benefit from IV TNF therapy and may not require a change to a different class of biologic therapy. As these medications all have the same mechanism of action (MOA), this suggests that the different response rates may be due to using an IV, weight-based therapy rather than fixed dose SC therapy and is not due to lack of response to the MOA.

BACKGROUND:A large gap for the support of point-of-care testing is the availability of reagents to support quality control (QC) of diagnostic assays along the supply chain from the manufacturer to the end user. While reagents and systems exist to support QC of laboratory screening tests for glucose-6-phosphate dehydrogenase (G6PD) deficiency, they are not configured appropriately to support point-of-care testing. The feasibility of using lyophilized recombinant human G6PD as a QC reagent in novel point-of-care tests for G6PD deficiency is demonstrated.METHODS:Human recombinant G6PD (r-G6PD) was expressed in Escherichia coli and purified. Aliquots were stored at -80°C. Prior to lyophilization, aliquots were thawed, and three concentrations of r-G6PD (representing normal, intermediate, and deficient clinical G6PD levels) were prepared and mixed with a protective formulation, which protects the enzyme activity against degradation from denaturation during the lyophilization process. Following lyophilization, individual single-use tubes of lyophilized r-G6PD were placed in individual packs with desiccants and stored at five temperatures for one year. An enzyme assay for G6PD activity was used to ascertain the stability of r-G6PD activity while stored at different temperatures.RESULTS:Lyophilized r-G6PD is stable and can be used as a control indicator. Results presented here show that G6PD activity is stable for at least 365 days when stored at -80°C, 4°C, 30°C, and 45°C. When stored at 55°C, enzyme activity was found to be stable only through day 28.CONCLUSIONS:Lyophilized r-G6PD enzyme is stable and can be used as a control for point-of-care tests for G6PD deficiency.

Plasmodium falciparum (Pf) prolyl-tRNA synthetase (ProRS) is one of the few chemical-genetically validated drug targets for malaria, yet highly selective inhibitors have not been described. In this paper, approximately 40,000 compounds were screened to identify compounds that selectively inhibit PfProRS enzyme activity versus Homo sapiens (Hs) ProRS. X-ray crystallography structures were solved for apo, as well as substrate- and inhibitor-bound forms of PfProRS. We identified two new inhibitors of PfProRS that bind outside the active site. These two allosteric inhibitors showed >100 times specificity for PfProRS compared to HsProRS, demonstrating this class of compounds could overcome the toxicity related to HsProRS inhibition by halofuginone and its analogues. Initial medicinal chemistry was performed on one of the two compounds, guided by the cocrystallography of the compound with PfProRS, and the results can instruct future medicinal chemistry work to optimize these promising new leads for drug development against malaria.