bluuebunny/crossref_metadata_2025_split huggingface dataset:
192. Characteristics of Staphylococcus aureus Bacteremia in Patients With Substance Use at a Large Academic Safety-Net Hospital 2020-2021
Authors: Gomez Christian , Sopirala Madhuri , Kambhampati Aparna 
Published: November 2023

Abstract

Background
Staphylococcus aureus bacteremia is a serious infection with a high mortality rate. Substance use disorder has been identified as a risk factor and poses unique challenges for treatment and outpatient parenteral antibiotic therapy (OPAT) eligibility. Outcomes of in this patient population have not been well studied. To address this gap, we conducted a retrospective study to evaluate the outcomes of patients with substance use disorder admitted with S.aureus bacteremia.

Methods
We conducted a retrospective epidemiological study of adults with substance use within 1 year and admitted to Parkland Hospital from April 2020 to March 2021 with diagnosis of S. aureus bacteremia during admission. Clinical and epidemiological data was collected using the electronic medical records system.

Results
68 patients met inclusion criteria. 35 patients (52.4 %) reported active Intravenous drug use (IV). Cocaine use was reported by 40 %, Opioid use by 65.7 %, and amphetamine use by 26.9% of patients. 46% of patients were homeless and 52% were uninsured. Initial sources of bacteremia included skin and soft tissue infections (34%), bone and joint infections (31%), and infective endocarditis (22%). Most patients (40%) were discharged to a facility, while 24% were discharged home and 24% left against medical advice.
Readmission within 30 days was observed in 21% of patients. Mortality at 30 days was 4.5%, while mortality at 1 year was 12%, with 17 patients (25%) lost to follow-up. Infectious complications related to S. aureus bacteremia within 1 year were seen in 31% of patients, with SSTI being the most common complication (16.4%). Six patients (9%) were diagnosed with endocarditis in a subsequent encounter. Leaving against medical advice was associated with an increased risk of S. aureus related complications after discharge (OR 6.6, 1.69-25 P=0.006)

Conclusion
There is significant burden of S. aureus bacteremia in patients with substance use disorder. Findings also suggest that infectious complications related to S. aureus bacteremia after discharge are common and require close monitoring and timely intervention. There is need for continued research to better understand the outcomes of patients with substance use disorder and to identify strategies for improving care

Disclosures
All Authors: No reported disclosures
225. Dalbavancin Usage in Patients Who Inject Drugs (PWID)
Authors: Patel Kaya , Nakagami Peter , Morita Kazumi , Gallagher Jason , Schultz Sara K 
Published: November 2023

Abstract

Background
Dalbavancin is a lipoglycopeptide antibiotic approved for the treatment of acute bacterial skin and skin structure infections (ABSSSI) secondary to gram-positive organisms. Given its long half-life, there has been increasing off-label use for other indications: osteomyelitis, joint infections, and bacteremia. One application where it can be effective is in PWID due to high rates of incomplete IV therapy. Herein we describe characteristics of PWID patients that receive dalbavancin and outcomes including recurrence of infection.

Methods
We conducted a retrospective chart review of all patients receiving dalbavancin at our large academic medical center in Philadelphia between Nov 1, 2019, to October 31, 2022. Charts were reviewed in Epic with data collection in REDCap.

Results
Fifty-two patients with substance use disorder with injection behavior that received dalbavancin were reviewed. Forty-seven (90%) of these patients had unstable housing. Patients were recommended dalbavancin due to concerns for adherence to prolonged oral regimen (31, 60%) or to avoid lengthy hospitalization which did not align with patient’s goals of care (43, 83%). Patient directed discharges occurred in 20 (38%) patients. Indications included bone/joint infections (25, 48%), bone/joint infections involving prosthesis (3, 6%), bacteremia (9, 17%), endocarditis (3, 6%) and ABSSSI (24, 46%). Twenty-one (40%) patients who received dalbavancin avoided a full IV antibiotic course. Forty-eight (92%) patients received effective antibiotics prior to dalbavancin (average of 6.2 days). Forty-three (83%) patients received a full dalbavancin course, of which 2 (5%) patients were readmitted for relapsed infection in 90 days. Nine (17%) patients received partial dalbavancin treatment courses, of which 6 (66%) had 90-day readmissions for relapsed infection. (Table 1).

Conclusion
At our institution, dalbavancin was used to treat infections beyond ABSSSI, in a population of predominantly PWID. We show low rates of 90-day readmission for recurrent infection, including patients with bacteremia and endocarditis, following full courses of dalbavancin. Dalbavancin is a viable alternative to lengthy oral or IV antibiotic regimens in patients that would otherwise not receive full treatment courses.

Disclosures
Jason Gallagher, PharmD, Entasis: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Qpex: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant Sara K. Schultz, MD FACP FIDSA, AbbVie: Advisor/Consultant
226. Low incidence of Pseudomonas species in Gram negative blood stream infections in nine hospitals across Ecuador: an unexpected find
Authors: Zurita Jeannete , Sevillano Gabriela , Belen Solis Maria , Paz y Miño Ariane , Rizkallah Alves Beatriz , Zurita-Salinas Camilo , Bacteremia Ecuadorian 
Published: November 2023

Abstract

Background
Over the last years, several studies on bloodstream infections (BSI) have ranked P. aeruginosa in the top 5 list of Gram-negative causal agents. However, there is very limited data regarding the incidence of Pseudomonas bacteremia in Latin America. The aim of this study was to establish the incidence of bacteremia caused by Pseudomonas species

Methods
During the period from November 2021 to May 2022 in 9 hospitals in Ecuador, blood culture samples were taken according to the clinical requirements of each patient. The bacteria identification was carried out using automated system (Vitek2 and Phoenix1000) and was confirmed by proteomic (MALDITOF) and molecular sequencing. Antimicrobial susceptibility was performed according to CLSI 2021.

Results
A total of 297 gram-negative bacilli BSI were identified across the 9 hospitals where the study took place. Blood cultures positive for Pseudomonas spp. represented just 0.043% (13/297) of all bacteremia (Table 1). Four of the thirteen Pseudomonas presented a MDR profile. Resistance to carbapenems was higher than that observed in antipseudomonal cephalosporins (Table 2). P. aeruginosa species was the most prevalent variant (9/13) 69.2%, however other species such as P. stutzeri, P. libanensis, P. mosselii, and P. otitidis were also identified. It is important to emphasize that automated system failed to recognize these species. These four Pseudomonas species have not been reported before in Ecuadorian hospitals, most likely because in many hospitals MALDITOF and genomics are not routinely performed. The population demographic profile is shown in Table 3. Among the 13 patients with confirmed Pseudomonas spp. BSI, presumed bacteremia source varied among the samples.

Conclusion
This study provided relevant information on BSI caused by Pseudomonas in Ecuador.There are only few population-based studies evaluating bacteremia epidemiology in Latin America. SENTRY in 1997 estimated that P. aeruginosa contributed to 10.6% of gram-negative nosocomial and community-acquired bloodstream infections. Lower incidence levels, as seen in this study (0.043%), could help better understand population trends and help guide treatment.

Disclosures
Jeannete Zurita, n/a, Pfizer: Grant/Research Support
233. All Clostridium butyricum strains isolated from blood cultures were derived from probiotics: a single-centre retrospective study
Authors: Sada Ryuichi M , Motooka Daisuke , Kutsuna Satoshi , Hamaguchi Shigeto , Yamamoto Go , Ueda Akiko 
Published: November 2023

Abstract

Background
Clostridium butyricum
(C. butyricum) is a strictly anaerobic, Gram-positive, spore-forming bacillus named for its capacity to produce high amounts of butyric acid. Some strains of C. butyricum involved in infectious diseases are known to be currently used as probiotics in Asia. Especially in Japan, MIYA-BM® is one of the probiotics commonly used as prescription drugs and it contains C. butyricum MIYAIRI 588 strain (CBM588). On the other hand, other strains involved in infectious diseases are known to be pathogenic. Bacteremia due to C. butyricum is a rare condition, and the prevalence, clinical features, and bacteriological and genetic origins of the condition are unknown.

Methods
We conducted a retrospective cohort study of medical records of patients to detect cases of C. butyricum bacteremia in Osaka University Hospital from September 19, 2011, to February 5, 2023. We analyzed the whole-genome sequencing of C. butyricum strains from positive blood culture samples, as well as strains from the probiotic MIYA-BM®. We also analyzed to determine the homology between these strains.

Results
Out of a total of 6576 positive blood culture samples, we detected five cases (0.08%) of bacteremia due to C. butyricum. Whole-genome analysis showed that the genes of each strain had only 1-33 mutations compared to the genes of the CBM588 strain, identifying them as the same clone derived from MIYA-BM®. The detail of case characteristics is shown in Table 1. All patients had bacteremia during hospitalization, with two male and three female patients. Four patients had concurrent use of MIYA-BM®. Four patients had immunocompromised conditions, and two patients had end-stage kidney disease on dialysis. All patients had a fever and abdominal symptoms such as diarrhea and pain. A patient with non-occlusive mesenteric ischemia died within 90 days.Table.Detailed clinical and microbiological information on five cases.

Conclusion
All C. butyricum strains detected from blood cultures in our hospital were derived from probiotics. Although C. butyricum bacteremia is rare condition, the use of MIYA-BM® use in hospitalized patients with multiple medical interventions is considered to cause C. butyricum bacteremia.

Disclosures
All Authors: No reported disclosures
238. Comparison of Outcomes of Patients with Gram-Negative Bacterial Left Ventricular Assist Device-Related Infections on Chronic Suppressive Antibiotic Therapy versus Patients Monitored on No Antibiotic Therapy
Authors: Svoronos Petros , Marschalk Nicholas , Sarwar Sajed , Lampert Brent , Nichols Courtney 
Published: November 2023

Abstract

Background
Left ventricular assist devices (LVAD) are used for short- and long-term support in heart failure. LVAD-related infections may manifest as infections of the driveline or bacteremia and may result in morbidity and mortality. Treatment may involve surgical debridement and prolonged antimicrobial therapy. Given concern for recurrent infection due to retained hardware, suppressive antibiotics are commonly utilized after the index infection. However, minimal data is available to guide these decisions.

Methods
This was a single-center, retrospective cohort study at our institution from November 1, 2011 to September 1, 2021 comparing outcomes after index LVAD-related gram negative driveline infections or bacteremia who received suppressive antibiotic therapy versus those who did not. Patients on suppressive antibiotics for previous gram-positive infections were excluded. Fischer’s exact test was used to evaluate for statistically significant differences between the two groups.

Results
Of 460 patients who underwent LVAD placement, 32 patients met inclusion criteria. Demographic data and infection related outcomes are summarized in Tables 1 and 2. Number of infection recurrence (61.5% vs 57.9%) and LVAD-related infection re-admissions (69.2% vs 73.7%) were similar between the two groups. A higher proportion of patients started on chronic suppressive therapy during the index infection had surgical management (53.8% vs 36.8%) and bacteremia as their index infection (30.8% vs 18.8%). Subsequent cultures positive for multidrug resistant (MDR) organisms (15.4% vs 10.5%) and infection-related mortality (15.4% vs 0%) were also both observed to be higher in the group on chronic suppressive antibiotics. No statistically significant difference was observed in outcomes between the two groups (Table 2).

Conclusion
Following index gram-negative LVAD-related infections, patients transitioned to suppressive antibiotic therapy were observed to have similar outcomes compared to those monitored off chronic antibiotic therapy at our institution. Future studies with a larger sample size are necessary to determine if there is a statistically significant benefit to suppressive antibiotic therapy after gram-negative LVAD-related infections.

Disclosures
All Authors: No reported disclosures
275. Genotype-to-Phenotype Agreement of Antimicrobial Resistance in Escherichia coli
Authors: Hwang Munok , Choi Hosoon , Navarathna Thanuri , Boykin Katherine , Corona Brandon , Dhar Sorabh , Donskey Curtis , Cadnum Jennifer , Chatterjee Piyali , Kaye Keith S , Jinadatha Chetan 
Published: November 2023

Abstract

Background
Most Escherichia coli reside as commensal intestinal microflora without harming human health. But some E. coli strains are pathogenic and can cause deadly infections. Antimicrobial resistant E. coli is associated with more than 1.5 million deaths globally. Here, we studied the prevalence of antimicrobial resistance in E. coli isolates from two cities based on the antimicrobial(AMR) genes and MIC values. By correlating genotypic and phenotypic antimicrobial resistance, we also examined the performance of whole genome sequencing (WGS) based prediction of phenotypic resistance.

Methods
A total 109 E. coli isolates from Detroit, MI and Cleveland, OH hospitals underwent WGS. Antibiotic susceptibility testing (AST) was performed using the gram-negative AST cards on the VITEK 2 system. WGS was performed with Nextseq 550 using Nextera flex kits. After de novo assembly, AMR genes were identified using AMR gene database, ResFinder.

Results
The resistance to beta-lactam antibiotics including 1st and 3rd generation cephalosporins were very high among the E. coli isolates. They were susceptible to penicillin combinations and 2nd generation cephalosporins. While resistance to quinolone antibiotics was high, resistance to aminoglycoside, tetracycline, and sulfonamide/trimethoprim were relatively low (Figure 1). As shown in Table 1, WGS-based method accurately predicted the majority of antimicrobial resistance phenotypes with accuracy of 0.89 ∼ 1.0. However, for cephalothin (0.36), piperacillin/tazobactam (0.69), and amikacin (0.63), the prediction accuracy was low which could potentially lead to false predictions of antimicrobial resistance. Extended Spectrum Beta-Lactamase (ESBL) genes such as blaCTX-M, blaOXA, and blaTEM were abundant, though subtle difference in the prevalence of AMR genes between two cities was observed (Figure 2).Figure 1.The prevalence of antimicrobial resistance to various antibiotics in E. coli isolates from Detroit, MI and Cleveland, OH.Figure 2.Prevalence of WGS identified AMR genes associated with antibiotics drugs.

Conclusion
Most of the E. coli isolates contained various ESBL genes and their gyrA genes were mutated to quinolone resistant forms. Therefore, most of the isolates were resistant to many beta-lactam and quinolone drugs. WGS based prediction of phenotypic resistance showed good predictive values but needs more studies to increase sensitivity and specificity.

Disclosures
Keith S. Kaye, MD, MPH, Abbvie: Advisor/Consultant|Abbvie: Honoraria|Entasis: Advisor/Consultant|Entasis: Honoraria|GSK: Advisor/Consultant|GSK: Honoraria|Merck: Advisor/Consultant|Merck: Honoraria|Shionogi: Advisor/Consultant|Shionogi: Honoraria|VenatoRx: Advisor/Consultant|VenatoRx: Honoraria
297. Prevalence and Genomic Analysis of Hypermucoviscous Klebsiella pneumoniae in a Single Center in Japan: Insights into Virulence and Potential Clinical Implications
Authors: Nishiyama Naoya , Arakaki Wakako , Uechi Kohei , Utsumi Daisuke , Sato Yukuto , Nakamatsu Masashi , Kinjo Takeshi , Yamamoto Kazuko 
Published: November 2023

Abstract

Background
Hypervirulent Klebsiella pneumoniae (hvKp) is associated with severe clinical outcomes, including liver abscesses and disseminated infections (Fig 1). The hypermucoviscosity phenotype (HMV), confirmed by the String test, has been linked to hvKP. This study aimed to investigate the prevalence and genomic characteristics of HMV-Kp isolates in patients with K. pneumoniae bacteremia in a single medical center in Japan.Figure 1.The case of endophthalmitis and multiple abscesses by hypermucovisucosity phenotype K. pneumoniae

Methods
We conducted a retrospective study at University of the Ryukyus Hospital between January 2021 and November 2022, extracting patients with HMV-Kp bacteremia. K. pneumoniae isolates were subjected to String test (Fig 2), antimicrobial susceptibility testing, and genomic analysis. Whole-genome sequencing and genomic analysis were conducted to identify multilocus sequence type (MLST), K capsule serotype, virulence genes, and antimicrobial resistance genes.Figure 2.String test

Results
During the study period, 29 cases of K. pneumoniae bacteremia were identified, with six cases of HMV-Kp bacteremia. Five of these cases were male patients and had organ abscess formation (Table 1). The results of the genomic analysis are shown in Table 2. All six HMV-Kp strains were positive for rmpA/rmpA2. MLST and K serotyping revealed that two isolates belong to ST23-K1 and ST86-K2, a known hypervirulent clone. All strains contained virulence genes, with the two ST23-K1 strains carrying all the typical hvKp virulence genes. No strains harbored ESBL or carbapenemase genes.Table 1.Clinical backgrounds of the cases.Table 2.Sequence typing and Virulence genes of the isolates.

Conclusion
All HMV-Kp strains isolated in this study carried virulent genes, including the hvKP clones ST23-K1 and ST86-K2. The String test for HMV phenotype confirmation appears useful to estimate the presence of hvKp. Our findings provide insights into the virulence and potential clinical implications of HMV-Kp isolates in Japan, highlighting the need for further investigation and monitoring.

Disclosures
Kazuko Yamamoto, MD, PhD, Fisher & Paykel Healthcare: Grant/Research Support|Kirin Holdings Co.: Grant/Research Support
311. Heterologous immunity and host susceptibility to emerging alphaviral infections
Authors: Vittor Amy Y , Pu Ruiyu , Paul Carrera Jean , Long Maureen T , Lopez Sandra , Weaver Scott , Morris John G , Pascual David 
Published: November 2023

Abstract

Background
In 2010, Madariaga virus (MADV) newly emerged in Darien, Panama, where Venezuelan equine encephalitis virus (VEEV) is endemic. We noted an inverse relationship between VEEV and MADV seroprevalence in humans, prompting the study of heterologous immunity in alphaviral infection.

Methods
Using patient samples from Panama, we examined antibody-dependent cell mediated cytotoxicity (ADCC) and antibody-dependent cell mediated lysis assays (ADCL) to three viruses: Mayaro virus (MAYV), Madariaga virus (MADV), and the vaccine strain of Venezuelan equine encephalitis virus (TC83). We developed an ADCC assay using adherent target cells (human dermal fibroblasts), and high-throughput immunofluorescence microscopy. We determined ADCL activity using alphavirus-infected K562 cells and flow cytometry. We further defined the specificity of antibodies by plaque reduction neutralization tests, whole viral antigen and virus-specific recombinant glycoprotein (rGP) ELISAs.

Results
Sera from alphavirus-exposed individuals demonstrated significantly greater ADCC and ADCL activity compared to alphavirus-naïve sera. Blocking CD16 abrogated this effect, confirming the role of natural killer cells in inducing ADCC and ADCL. The relationship is asymmetric; prior VEEV exposure yields a high degree of homologous and heterologous ADCC and ADCL activity, whereas MADV and MAYV exposure results in heterologous ADCC and ADCL activity no different than alphavirus-negative controls. We observed a strong association between ADCC/ADCL activity and whole viral antigen ELISA titers, but not rGP ELISA nor neutralization titers, suggests that the viral antigens that elicit ADCC and ADCL may be nonstructural proteins.

Conclusion
Here we demonstrate that VEEV antibodies are active against heterologous alphaviral infections in vitro by ADCC and ADCL, but not by neutralization. This has implications for vaccine development. Eliciting an antibody response that is not only neutralizing, but also generates antibodies with ADCC and ADCL activity may produce broader protection against viral variants or antigenically similar viruses. Additionally, these results provide insight into immunological mechanisms underlying the emergence potential of a novel virus.

Disclosures
All Authors: No reported disclosures
312. Strain Engraftment and Gene Transfer in a Fecal Microbiota Transplantation Cohort
Authors: Brink Catherine , Conrad Roth , Babiker Ahmed , Hatt Janet , Barrios-Steed Danielle , Kraft Colleen S , Woodworth Michael H , Konstantinidis Konstantinos 
Published: November 2023

Abstract

Background
Fecal microbiota transplantation (FMT) is a procedure that has gained popularity due to the high efficacy in treating recurrent Clostridioides difficile infections (RCDI) and other conditions associated with a dysbiotic gut microbiome. Despite the widespread acceptance of the technique, repeating its success in RCDI treatment in other diseases has been difficult due to the individual-level variation in disease effects on the gut and the emphasis on taxonomic, rather than functional, microbiome analyses. We present a metagenomic analysis of the use of FMT to treat renal transplant patients infected with multidrug-resistant organisms (MDROs).

Methods
DNA was extracted from longitudinally collected participant stool samples before and after FMT. Reads were assembled and binned into metagenome assembled genomes (MAGs), which were then mapped back to the reads to calculate relative abundance, breadth and sequencing depth in each patient sample. This allowed us to assess the species-level changes in the composition of patient microbiomes after FMT treatment.

Results
We identified four MAGs, representing close relatives of Akkermansia muciniphila, Dakarella massiliensis, Mesosutterella multiformis and Waltera intestinalis, that showed a pattern of engraftment (absent or undetectable before FMT, but present for at least two consecutive timepoints after treatment) in FMT-treated patients. We also observed clear evidence of a donor MAG closely related to Faecalibacterium gallinarum replacing patient MAGs identified as Faecalibacterium hattori, revealing a potential mechanism of successful FMT treatment though a resistant strain in the patient microbiome likely being outcompeted by a drug-susceptible strain of the same species from the donor.

Conclusion
Herein we elucidated the taxonomic changes that take place in renal transplant patient gut microbiomes with reduced MDRO colonisation in response to FMT treatment. Future efforts will aim to identify the shifts in the functional gene profiles of the patient microbiomes to allow for a deeper understanding of the mechanisms underlying successful FMT treatments and further the rational design of live biotherapeutic consortia to treat antibiotic-resistant colonisation.

Disclosures
Ahmed Babiker, MBBS, Roche: Advisor/Consultant