bluuebunny/crossref_metadata_2025_split huggingface dataset:
229. IDSA FEATURED ORAL ABSTRACT: MVA-BN Induces a Low Avidity, Non-Durable Humoral Response Against Mpox Virus
Authors: Kottkamp Angelica C , Oom Aaron , Wilson Kesi K , Yonatan Miilani E , Rettig Stephanie , Youn Heekoung , Tuen Michael , Belli Hayley , Zucker Jane R , Rosen Jennifer , Samanovic Marie I , Duerr Ralf , Mulligan Mark J 
Published: January 2025

Abstract

Background
The 2022 global outbreak of clade IIb mpox, the first significant occurrence outside Africa, led to vaccination campaigns using the third-generation orthopoxvirus vaccine modified vaccinia Ankara, Bavarian Nordic (MVA-BN or JYENNEOS vaccine). In the US, a one-fifth dose of an intradermal regimen of the MVA-BN was authorized as a dose-sparing alternative to the two-dose subcutaneous regimen licensed in 2019. During the vaccination campaign, we launched the New York City Observational Study of Mpox Immunity (NYC OSMI) which enrolled participants who received the MVA-BN vaccine during the outbreak in NYC. Here we report the antibody data at one-year post vaccination.

Methods
We initiated the New York City Observational Study of Mpox Immunity (NYC OSMI), a longitudinal study involving 171 MVA-BN vaccinees, some with prior smallpox vaccination and mpox convalescents. Study participants had blood drawn prior to vaccination, after one dose, and after two doses. We performed Immunofluorescence-based Mpox virus (MPXV) clade IIb microneutralization assays, Multiplexed immunoassay for binding antibodies and avidity, and Anti-MPXV H3 Enzyme-Linked Immunosorbent Assay (ELISA). Paired measurements in figures were analyzed by Wilcoxon matched-pairs signed rank test. Comparisons of multiple sample groups in figures were conducted by Kruskal-Wallis test with Dunn’s method for multiple comparisons. Linear mixed-effects regressions (LMER) were used to model neutralizing titer durability with repeated measurements.

Results
Our findings indicate that neutralizing titers in naïve individuals return to baseline in less than a year, while those with prior smallpox vaccination maintain elevated titers. Both groups generate robust IgG responses against MPXV H3 and A35, but the response in naïve vaccinees, characterized by lower avidity, is short-lived.

Conclusion
These results highlight the necessity for further investigation into MVA-BN's long-term protection, potential need for booster doses, and the development of next-generation orthopoxvirus vaccines.

Disclosures
Mark J. Mulligan, M.D., HilleVax: Advisor/Consultant|Meissa Vaccines: Advisor/Consultant|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Sanofi: Grant/Research Support
293. Association of a Hospital Stress Indicator with Device Associated Infections
Authors: Parriott Andrea , Barahmani Nadia , Epson Erin 
Published: January 2025

Abstract

Background
Hospital surges during the COVID-19 pandemic provided an opportunity to assess the effects of strained hospital resources on patient safety outcomes and identify predictors of resilience. We sought to examine the relationship between a composite indicator of hospital stress and device-associated infections (DAI) including central-line associated bloodstream infections (CLABSI) and catheter-associated urinary tract infections (CAUTI) in California acute-care hospitals.

Methods
We used data from the California Hospital Association daily survey to create a composite variable indicating hospital stress. Hospitals were considered stressed on a given day if they reported patients in surge beds, ventilated COVID-19 patients in the emergency department, or a critical staffing shortage. We matched data from the National Healthcare Safety Network (NHSN) on CLABSI and CAUTI occurring between June 2020 and December 2021 to inpatient discharge data from the California Office of Healthcare Access and Information (HCAI) by sex, birthdate, admission date, and hospital. Patients were considered exposed to hospital stress if the hospital was stressed on any day between their admission and infection onset or discharge. We used propensity score weighting for risk adjustment for patient characteristics including month of admission, age, sex, race, expected payer, principal diagnosis, type of admission (emergency/urgent, trauma, or elective) and comorbidities from linked HCAI records (Table 1). Odds ratios were calculated using logistic regression with the generalized estimating equation to account for clustering within facilities.

Results
2,843 CLABSI and 2,870 CAUTI were successfully matched to patient records. Forty seven percent of patients were exposed to hospital stress. Risk-adjusted odds ratios were between 2 and 3 and significant at α=0.05 for all DAI, CLABSI, and CAUTI (Table 2).

Conclusion
These findings validate that our measure of hospital stress was associated with increased risk of individual patient-level DAIs in 2020-2021. Further research will focus on generalizing results beyond 2020-2021 and assessing facility-level factors that mitigate the stress-patient outcome association.

Disclosures
All Authors: No reported disclosures
P-815. Clinical Impact of BioFire® Blood Culture Identification 2 Implementation in Patients with Staphylococcal Bacteremia
Authors: Duell Colin , Ackley Tyler , Linder Kristin E , Kuti Joseph L , Castle Alivia , Li Rosanna 
Published: January 2025

Abstract

Background
The BioFire® Blood Culture Identification 2 (BCID2) PCR panel aids in rapid identification of blood pathogens, including coagulase-negative Staphylococci (CoNS) and methicillin susceptible Staphylococcus aureus (MSSA). BCID2 was implemented at all Hartford HealthCare hospitals in September 2022. The objective of this study was to evaluate how BCID2 impacted vancomycin use, clinical outcomes, and pharmacist intervention.

Methods
This was a multi-center, retrospective study of adult patients admitted to Hartford HealthCare hospitals with MSSA or CoNS positive blood cultures. The primary endpoint, days of vancomycin therapy, was compared between the pre- (3/7/22 – 9/7/22) and post-BCID2 periods (10/7/22 – 4/7/23). Secondary endpoints included duration of MSSA positive blood cultures, intensive care unit (ICU) length of stay, hospital mortality, and pharmacist interventions accepted.

Results
Of the 617 patients included in the primary analysis, MSSA bacteremia accounted for 37.0% (110/297) and 31.6% (101/320) of the patients in the pre- and post-BCID2 group, respectively (p=0.178). The median duration of vancomycin was 1.3 and 0.3 days in the pre- and post-BCID2 group, respectively (absolute difference, 1.0 days; p&lt; 0.001). The duration of MSSA BSI was 3.1 and 2.4 days in the pre- and post-BCID2 group, respectively (absolute difference, 0.7 days; p=0.096). Hospital mortality was not different between periods [7.1% (21/297) vs 10.6% (34/320), p=0.16]. In patients with MSSA bloodstream infection (BSI), ICU LOS was 4.4 days shorter in the post-BCID2 period (7.8 vs 3.4 days, p&lt; 0.001). Pharmacists successfully intervened to reduce vancomycin duration in 7.1% (21/297) and 16.3% (52/320) of patients in the pre- and post-BCID2 group, respectively (p&lt; 0.001).

Conclusion
BCID2 implementation shortened the duration of vancomycin in patients with MSSA or CoNS bacteremia and facilitated pharmacist intervention to stop vancomycin in non-pathogenic CoNS positive blood cultures or switch to MSSA-targeted therapy in MSSA BSI. These data support BCID2 as a critical tool to improve appropriate antibiotic selection and shorten the time to safer and more effective treatment for patients with CoNS and MSSA bacteremia.

Disclosures
Joseph L. Kuti, PharmD, Abbvie: Advisor/Consultant|bioMerieux: Grant/Research Support|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi Inc: Advisor/Consultant|Shionogi Inc: Grant/Research Support|Shionogi Inc: Honoraria|Venatorx: Grant/Research Support
P-817. Can We Stop Taking Follow-Up Blood Cultures for Brucella Melitensis in Hospitalized Adults?
Authors: Grupel Daniel , Cherniak Meir , Cohen Matan 
Published: January 2025

Abstract

Background
Brucella melitensis is an important zoonotic pathogen causing human disease worldwide. Blood cultures are often essential in establishing the diagnosis in hospitalized patients.
The need for repeated blood cultures is well established in gram-positive bacteremia and is still debated in gram-negative bacteremia. There is scant data regarding the need for repeated blood cultures in brucellosis. Follow-up blood cultures (FUBCs) may direct physicians to cryptogenic focal infection but are also associated with multiple venipunctures, prolonged hospitalization, and contamination. Moreover, repeatedly positive blood cultures can cause clinicians to pursue excessive workups.

Methods
We retrospectively collected data on all positive cultures growing Brucella sp. collected between 1/10 and 12/22 in adults at the Hadassah Medical Center campuses.
The primary outcome was brucellosis relapse or treatment failure. Hospitalization resource utilization, treatment modifications and length of stay were also recorded.
Three groups were defined- patients with 1) a single blood culture positive for Brucella without FUBC; 2) a first positive blood culture with negative FUBCs; and 3) positive FUBCs. Subgroup analysis was performed according to the positivity of the last culture taken during hospitalization.

Results
We found 525 cultures taken from 176 patients positive for Brucella sp. 68 patients met the exclusion criteria. 7.5% of the cohort had a single culture, 17.8% had negative FUBCs, and 74.8% had positive FUBCs.
No significant difference was observed in the primary outcome between the groups with positive or negative FUBCs (15.8% and 11.3%, respectively, p=0.695). The clinical presentation, length of stay, number of imaging modalities used, and rates of treatment modification also did not differ between the groups (Table 1).

Conclusion
In our brucellosis cohort, FUBC positivity was not associated with an increased rate of complications or adverse events despite similar baseline characteristics and clinical course.
Furthermore, the groups with FUBCs did not fare differently than those without FUBCs.
With the caveats of an observational study, these data suggest that discontinuing FUBCs in hospitalized brucellosis patients should be considered as it seems reasonable and safe.

Disclosures
All Authors: No reported disclosures
P-824. A Tertiary Care Hospital's Eight-Year Experience with Acinetobacter Bloodstream Infections in the Pediatric Population
Authors: Erci Ece , Avcu Gulhadiye , Bilen Nimet Melis , Arslan Sema Yıldırım , Guner Gizem , Özkaya Pınar Yazıcı , Cilli Feriha , Sahbudak Bal Zumrut 
Published: January 2025

Abstract

Background
Acinetobacter spp has emerged as an important nosocomial pathogen causing life-threatening infections in hospitalized patients. Since carbapenem-resistant Acinetobacter bloodstream infections have been increasingly reported in the pediatric population worldwide in recent years, we aimed to evaluate the clinical characteristics and identify possible risk factors in hospitalized patients with carbapenem-resistant bloodstream infections.

Methods
We retrospectively analyzed the results of blood-stream infections caused by Acinetobacter spp. in hospitalized children between 2014-2022. Demographic features and clinical and laboratory findings were evaluated.

Results
Bloodstream infections due to Acinetobacter spp. were detected in 70 hospitalized children. Carbapenem resistance was present in 38 (54.2%) of the patients. The mean age of patients with carbapenem-resistant (CR) Acinetobacter bloodstream infection (21 males and 17 females) was 5.7±0.95 years and 3.9±0.74 years in the carbapenem-susceptible (CS) group (13 males and 19 females) (p&lt; 0.005). The most common pathogen in the CR group (97.4%) and CS group (56.3%) was Acinetobacter baumannii. While 15.3% of the CR patients were previously healthy, 3.1% of the CS group had no history of previous diseases. The most important predisposing risk factors for the development of carbapenem resistance were invasive mechanical ventilation (p&lt; 0.005), previous antibiotic use (p&lt; 0.005), and history of meropenem use (p&lt; 0.005). Combination therapy was initiated in 64.6% of patients in the CR group and 53.1% in the CS group. The most frequently used antibiotic regimens in the CR group were meropenem-colistin (15.8%), colistin-amikacin (10.5%), and colistin-sulfamethoxazole and trimethoprim (SMZ-TMP) (7.9%). The mean treatment duration for the groups was 13.3±0.98 days for the CR group and 11.3±1 days for the CS group (p:0.523). The infection-related mortality rates for the CR and the CS groups were 36.8% and 21.9%, respectively, and there was no statistically significant difference between the groups (p:0.136).

Conclusion
Our single-center experience aims to emphasize the importance of rational antibiotic use and enhance the awareness of clinicians about the increasing carbapenem resistance.

Disclosures
All Authors: No reported disclosures
P-825. Short Versus Long Treatment Duration for Streptococcal Bloodstream Infections
Authors: Spivak Emily S , Gray Julie , Zhang Chong , Earl Ali 
Published: January 2025

Abstract

Background
The rise in antibiotic resistance, antimicrobial-related harms and emerging data have prompted a shift towards shorter antibiotic durations. However, there is a lack of data to inform durations of therapy for Streptococcal bloodstream infections (BSI). The need for clearer guidance led us to compare outcomes between short and long antibiotic durations for uncomplicated Streptococcal BSI with the goal of informing local and national practice.
Effects of Long vs. Short Antibiotic Durations

Methods
This was a retrospective cohort study of unique adult patients admitted to University of Utah from January 1, 2014 to July 15, 2023 with uncomplicated Streptococcal BSI, defined as negative follow-up blood cultures, clinical resolution by day 3, absence of metastatic foci, source control if indicated, and no other complications. We used inverse probability of treatment weighting to estimate the average treatment effects (ATE) of in vitro active antibiotics administered for &gt; 10 days (long duration) versus &lt; 10 days (short duration), adjusting for pretreatment variables. The primary outcome was a composite of recurrent bacteremia, all-cause mortality, and readmissions at 30 days from end of treatment (EOT). Secondary outcomes were 90-day all-cause mortality and recurrent bacteremia from EOT.

Results
209 patients met criteria for inclusion. The median duration in the long and short groups were 15 (IQR, 14-17) and 8 days (IQR, 7-9.75), respectively. In the propensity score weighted analysis (Table 1), the ATE of long versus short duration was not significant on the composite primary outcome (21% vs 22%; OR= 0.81 [95% CI: 0.34 to 1.91], p=0.62) or any secondary outcomes.

Conclusion
We found no appreciable difference in outcomes between patients treated with &gt;10 days of antibiotics compared to those treated with &lt;10 days for uncomplicated Streptococcal BSI. Given low absolute rates of mortality and recurrent bacteremia, paired with no appreciable difference related to treatment duration, it is reasonable to recommend shorter durations. Given limitations of this retrospective analysis, future research is needed to confirm our findings; however, our data could inform antimicrobial stewardship interventions aimed at decreasing treatment durations for uncomplicated Streptococcal BSI.

Disclosures
All Authors: No reported disclosures
P-827. Epidemiology of Favorable vs. Unfavorable Outcomes in Hospitalized Patients with S. aureus Bacteremia in the US: A Multicenter Retrospective Cohort Study
Authors: Zilberberg Marya D , Nathanson Brian H , Wagenaar Rolf J , Posthumus Jan , Shorr Andrew 
Published: January 2025

Abstract

Background
The incidence of Staphylococcus aureus bacteremia (SAB) remains ∼25 cases/100,000 population, and methicillin-resistant S. aureus (MRSA) causes ∼1/2 of all SAB. Historically, mortality has served as the primary gauge for SAB’s outcomes, potentially neglecting other important unfavorable outcomes (UO) that contribute to its morbidity. We developed a multifaceted definition for UOs in SAB and examined their prevalence and early predictors.

Methods
We included adult hospitalized patients with at least one positive blood culture (BC) for S. aureus in a large US database (∼300 hospitals, 2020-2022). We defined UO as at least one of the following: hospital mortality, antibiotic escalation, persistently positive BCs, prolonged post-infection length of stay (LOS), or readmission within 30 days after discharge. All other outcomes were classified as favorable (FO). We used descriptive statistics to compare patients with UO and FO, and applied multiple regression models to identify factors associated with UOs.

Results
Among 4,080 patients with SAB, 2,427 (59.5%) suffered an UO. The most common UOs were disease worsening and need for vasopressors (Figure 1). Those with UOs were more likely to be non-White and suffered from a higher co-morbidity burden (Table 1). During hospitalization and prior to the onset of SAB, those with UOs more frequently required an ICU stay and dialysis. The majority of SABs were community-onset, and similarly distributed in the groups. UOs occurred in 66.1% of patients with MRSA vs. 55.2% with MSSA. Vancomycin was the leading empiric drug administered, followed by cefazolin. Daptomycin was used infrequently, and the rate of delayed therapy was low. The unadjusted post-infection hospital LOS and costs were significantly higher with UOs (Table 1). The variables with the highest odds ratios predicting an UO were the presence of septic shock on admission, empiric treatment with daptomycin, and the presence of complicated SAB (Table 3).

Conclusion
UOs occur frequently in SABs. A broader perspective exploring issues other than mortality demonstrates the substantial implications of SAB both for patients and healthcare systems. Select clinical variables are associated with UOs, some of which may not be modifiable.

Disclosures
Marya D. Zilberberg, MD, MPH, Basilea Pharmaceutica International Ltd, Allschwil, Switzerland: Grant/Research Support Brian H. Nathanson, Ph.D., MERCK: Advisor/Consultant Rolf J. Wagenaar, MS, Basilea: Advisor/Consultant Jan Posthumus, PhD, MBA, Basilea Pharmaceutica International., Alschwil Ltd: Honoraria|Basilea Pharmaceutica International., Alschwil Ltd: Stocks/Bonds (Public Company) Andrew Shorr, MD, MPH, MBA, Basilea: Advisor/Consultant|Basilea: Grant/Research Support
P-841. Empiric Antimicrobial Treatment of Sepsis in Canadian Emergency Rooms: Analysis of Pathogens Causing Bacteremia and Their Susceptibility Rates
Authors: Li Jeremy , Baxter Melanie R , Walkty Andrew , Karlowsky James , Zhanel George 
Published: January 2025

Abstract

Background
An alarming increase in the frequency of ESBL-producing organisms has been reported in Canada, raising concerns about whether empiric regimens used for the treatment of sepsis remain sufficient to cover ER patients with potentially undiagnosed bloodstream infections. Using data from the CANWARD study, we report on the epidemiology of bloodstream infections in Canadian emergency rooms and estimate the susceptibility rate of these pathogens to empiric regimens commonly used for the treatment of sepsis.
Rate of ESBL production in blood culture isolates of Escherichia coli (ER patients, CANWARD 2007-2022).

Methods
As part of the CANWARD national surveillance study, sentinel hospitals across Canada submitted the first 10 clinically significant isolates recovered from blood cultures each month. Isolates underwent antimicrobial susceptibility testing using the broth microdilution method and susceptibility to antibiotics was determined whenever MICs and CLSI breakpoints were available. For Streptococcus and Enterococcus, where piperacillin-tazobactam breakpoints were not available, susceptibility was inferred from penicillin and ampicillin MICs as per EUCAST standards.
Rate of ceftriaxone susceptibility in blood culture Escherichia coli isolates (ER patients, CANWARD 2007-2022).

Results
From 2007 to 2022, 9,178 blood culture isolates were collected from patients presenting to Canadian emergency rooms. The most common organisms isolated were:
1. Escherichia coli (31.7%)
2. Staphylococcus aureus (16.8%)
3. Klebsiella pneumoniae (7.8%)
4. Streptococcus pneumoniae (6.8%)
5. Streptococcus pyogenes (2.9%)
There has been a marked increase in the rate of ESBL production in E. coli (Figure 1). This is associated with a decrease in the susceptibility rate of E. coli to ceftriaxone (Figure 2).
Despite these changes, isolates from blood cultures of ER patients remain susceptible to piperacillin-tazobactam more than 90% of the time and remain susceptible to piperacillin-tazobactam plus vancomycin more than 95% of the time (Table 1).
Susceptibility rates of blood culture isolates from ER patients to commonly prescribed empiric antimicrobial regimens.

Conclusion
Isolates causing bloodstream infections in Canadian ER patients remain susceptible to piperacillin-tazobactam more than 90% of the time. The susceptibility rate to ceftriaxone is less than 85% and ceftriaxone should be used with caution in sepsis when the source of infection is unclear. Individual centers should perform their own assessments based on the most common pathogens causing bacteremia and their local susceptibility rates.

Disclosures
All Authors: No reported disclosures
P-849. Characteristics and Outcomes of Patients with Community-acquired and Nosocomial Klebsiella pneumoniae Bacteremia in a Tertiary Hospital in the Philippines
Authors: Abad Cybele Lara R , Carascal Mark , Ong Justin Allister G 
Published: January 2025

Abstract

Background
Klebsiella pneumoniae (KPN) bacteremia is associated with higher morbidity and mortality, but there is paucity of local data. This study describes the clinical, microbiologic profile, capsular types, and outcomes of individuals with community-acquired and nosocomial KPN bacteremia.

Methods
This study prospectively enrolled patients in a private tertiary hospital from January 1, 2023 to December 31, 2023. Hospitalized patients &gt;/= 18 years old with documented KPN bacteremia were included in the study and isolates subjected to capsular typing. The two-tailed t test was used for continuous variables reported as mean and standard deviation whereas chi-square test was used for categorical variables reported as frequencies and percentages. Descriptive statistics were used and univariate analysis using Medcalc Statistical software.

Results
A total of 25 patients developed KPN bacteremia during the study period; 18 were community-acquired (CA) and 7 were nosocomial. More than half of patients were female (16/25, 64%), with median age 70 (+/- 15) years old. The most common comorbidities were hypertension (15/25, 60%), diabetes mellitus 14/25 (56%), and solid tumor (9/25, 36%). The average intensive care unit stay of 3.4 (+/- 5.9) days for CA KPN bacteremia was significantly shorter than the 13.6 (+/- 16.1) days for those with nosocomial KPN bacteremia. There was no difference in the total length of hospital stay for CA KPN bacteremia (36.7 +/- 85 days) and nosocomial KPN bacteremia (38.6 +/- 23.3 days). Wild-type KPN isolates (15/25, 83.3%) were more commonly found in CA KPN bacteremia, whereas multi-drug resistant isolates were more common for nosocomial KPN. Patients with endotracheal intubation (OR=16, 95% CI 2.2 to 118.3), positive qSOFA (OR=6.42, 95% CI 1.1 to 37.7%), identification of rmpA (OR=9.33, 95% CI 1.5 to 59.5%), and K20 capsular serotype (OR=6.0, 95% CI 1.0 to 35.9%) were more likely to have higher mortality.

Conclusion
In this cohort, KPN bacteremia occurred more frequently among women, and in the older age group. CA-KPN was more common than nosocomial KPN bacteremia, but the latter was associated with multi-drug resistance. Endotracheal intubation, positive qSOFA, rmpA, and K20 capsular serotypes were associated with higher mortality.

Disclosures
All Authors: No reported disclosures