bluuebunny/crossref_metadata_2025_split huggingface dataset:
P-2073. COVID-19 Vaccine Effectiveness in Patients with Lung Cancer and Mesothelioma in the Omicron Era
Authors: Hosseini-Moghaddam Seyed M , Shepherd Frances A , Swayze Sarah , Kwong Jeffrey 
Published: January 2025

Abstract

Background
Since the Omicron variant emerged, uptake of booster doses of COVID-19 vaccines has gradually decreased both in the general population and among individuals at increased risk of severe COVID-19, such as patients with lung cancer. COVID-19 vaccine effectiveness (VE) has not been estimated in patients with lung cancer in the Omicron era.

Methods
In this test-negative design study using linked population-based cancer registry, health administrative, vaccination, and public health surveillance databases, we included all patients with active lung cancer or mesothelioma living in Ontario, Canada, who were tested for SARS-CoV-2 by RT-PCR from January 2, 2022, to August 31, 2023. We estimated VE against COVID-19-related severe outcomes (hospitalization or death) 7-179 days and ≥180 days following vaccination.

Results
During the study period, 13,622 patients with active lung cancer or mesothelioma underwent SARS-CoV-2 testing, with 1,371 (10.1%) positive. After exclusions, we analyzed 6,037 testing episodes, including 1,354 test-positive and 4,683 randomly selected test-negative episodes. Overall, COVID-19-associated hospitalization and mortality rates were 7.3% and 4.0%, respectively. Across both groups, 126/439 hospitalized patients (28.7%) and 116/5,598 non-hospitalized patients died (2.1%) (p=0.001). After multivariable adjustment, VE against severe COVID-19 was 56% (95%CI, 29%, 72%) 7-179 after vaccination and 10% (-45%, 44%) ≥180 days after vaccination.

Conclusion
Overall, COVID-19 VE against severe outcomes appears to be considerably lower for patients with active lung cancer or mesothelioma than the general population and decreases substantially beyond 180 days after vaccination. Our finding supports administration of COVID-19 booster doses in patients with lung cancer and mesothelioma every 6 months.

Disclosures
All Authors: No reported disclosures
P-2082. Shifting Susceptibility: MIC Assessment in RPMI versus MHB for Daptomycin Non-Susceptible MRSA Isolates
Authors: Bleick Callan , Vader Samantha , Lawal Aminah , Avery Shaylyn , Rybak Michael J 
Published: January 2025

Abstract

Background
Traditional minimum inhibitory concentration (MIC) screening, widely adopted in clinical microbiology labs, utilize Mueller-Hinton broth (MHB) to determine susceptibility breakpoints for bacterial organisms. The Roswell Park Memorial Institute (RPMI) medium supplemented with 5% Luria-Bertani Broth (LB) is commonly used in cell culture research to maintain cell health and improve viability. Additionally, it has been demonstrated to better mimic physiological conditions in humans. This study seeks to elucidate differences in MICs in 25 daptomycin non-susceptible (DNS) methicillin-resistant Staphylococcus aureus (MRSA) isolates.

Methods
Twenty-five DNS-MRSA bacterial strains were utilized. Variations in daptomycin MICs between RPMI and MHB were determined via triplicate microbroth dilution (MBD). After 24 hours, 50 µL of resazurin was added to each 96-well plate, and MICs recorded. Both RPMI and MHB were supplemented with 50 mg/L of calcium, and pH levels verified (pH 7.30-7.50). We assessed differences in MICs between RPMI and MHB using the Mann-Whitney U test (P &lt; 0.05).

Results
The comparison of daptomycin MICs between RPMI and MHB revealed significant differences (P &lt; 0.05) for the 25 DNS-MRSA bacterial strains examined. Specifically, in RPMI, MIC values ranged from 0.0125 to 2, whereas in MHB, MIC values ranged from 2 to 4. This suggests a notable impact of culture medium on the effectiveness of daptomycin against the tested bacterial strains. The study's findings underscore the importance of considering culture conditions when evaluating antimicrobial susceptibility, particularly for DNS-MRSA strains.

Conclusion
Our comparative assessment of MICs using RPMI versus MHB revealed statistically significant differences in antimicrobial activity. These differences warrant further investigation across additional strains and antibiotics. Notably, while the breakpoint for daptomycin is 1 mg/liter for S. aureus, our MICs done in RPMI indicated susceptibility of previously recorded DNS strains with a MIC &lt; 1 mg/L according to CLSI guidelines. These findings highlight the importance of considering potential shifts in MICs based on testing media differences and suggest a need for reevaluation of traditional susceptibility testing methods.

Disclosures
Michael J. Rybak, PharmD, PhD, MPH, Abbvie, Melinta, Sionogi, Merck, T2Biosystems: Advisor/Consultant|Abbvie, Melinta, Sionogi, Merck, T2Biosystems: Grant/Research Support|Abbvie, Melinta, Sionogi, Merck, T2Biosystems: Speaker
P-2085. Optimizing GAIHN-AR Network Microbiology Laboratory Assets for Early Detection of Carbapenemase-Producing Organisms in Limited Resources Settings: Argentine Experience
Authors: Corso Alejandra , Pasteran Fernando , Marchetti Paulina , Appendino Andrea , Pereda Rosana , Menocal Alejandra , Sangoy Ana , Kuzawka Marilina , Tocho Eugenia , Cioffi Antonela , de Mendieta Juan Manuel , Lucero Celeste , Colque Angel M , Alonso Laura , Iantorno Paula , Pagano Irene , Barcelona Laura 
Published: January 2025

Abstract

Background
The Global Action in Healthcare Network-Antimicrobial Resistance Module (GAIHN-AR), led by the U.S. CDC, enhances prevention, detection and response in low-resource hospital settings (LRS) against emerging antimicrobial resistance (AR) threats, with an initial focus on carbapenemase-producing organisms. GAIHN-AR includes a lab. component for improving early AR detection, an infection prevention and control program, and a communication platform for rapid response coordination. We describe the implementation verification/validation of new AR diagnostic methods and their integration into clinical workflow
Table

Methods
Prior to GAIHN-AR initiation in two hospitals in Argentina in January 2023, validation of CPO diagnostic techniques was conducted. For this, reference strains characterized by WGS from the CDC & FDA AR-Bank and Argentina-NRL repository were used. Evaluation followed manufacturer specifications, with GeneXpert also tested with alternative Dacron swabs. Pure colonies were used for validation of all methods, except for GENEXPERT®Carba-R where contrived fecal sample were also used. Methodologies were acceptable with sensitivity, specificity, and precision values ≥ 95%.The following methodologies were verified for carbapenemase detection in Enterobacterales, P. aeruginosa, and Acinetobacter spp. (ACI): (i) GENEXPERT®Carba-R; (ii) NG-Test®CARBA-5 lateral flow (ACI excluded); (iii) CHROMagar mSuperCARBA® chromogenic medium for carbapenem resistance detection; (iv) RAPIDEC® CARBA-NP. Additionally, the GENEXPERT®Carba-R was validated for: i) KPC variants with ceftazidime/avibactam resistance, ii) local circulation metallo-β-lactamase IMP variants

Results
The methodologies under evaluation achieved performance between 95-100%, except for the IMP variants with GenXpert Carba-R where sensitivity was reduced to 44% (Table).

Conclusion
Verification/validation process demonstrated that most methods had acceptable performance, allowing integration into lab workflows to facilitate prompt diagnosis and rapid communication with IPC teams. Results benefited not only GAIHN-AR hospitals but also other LRS facilities with whom they were shared through the NRL, offering valuable lessons for similar settings

Disclosures
All Authors: No reported disclosures
P-2086. The Clinical Profile of Patients with Indeterminate Xpert Rifampin Resistance Results in a Single Tertiary Level Institution
Authors: Tenorio Bettina Gabrielle V , Uayan Danielle Josefa F , Lumunsad Kriselle Felicia , Estuart Andrea S , Javier Jose Carlos Ruben R , Abad Cybele Lara R 
Published: January 2025

Abstract

Background
Tuberculosis (TB) is one of the leading causes of morbidity and mortality globally. Since the development of point-of-care tests such as the Xpert MTB/RIF assay, TB diagnosis has improved dramatically. However, the clinical profile of patients and significance of indeterminate rifampin resistance (RR) results remain unclear.Table 1.Clinical profile of Xpert RIF-Indeterminate patients

Methods
Hospital and TB clinic databases from January 1, 2016–April 30, 2023 were reviewed to identify patients with both Xpert MTB/RIF positive TB and indeterminate RR results. The electronic health record and paper charts of cases with indeterminate RR were then retrieved for detailed review. Relevant demographic characteristics and laboratory results were collected for analysis. Descriptive statistics was performed using SPSS.Table 2.Concordance of Xpert and culture rifampin resistance results

Results
Of 4339 records, only 31 cases (0.7%) fulfilled the criteria for study inclusion. The median age was 46 (range 22–97) years. Twenty-two patients were male (70.97%). The most common symptoms were cough (n=15, 48.39%), dyspnea (n=14, 45.16%), and malaise (n=10, 32.26%). Notably, only four had fever (12.90%). Four were asymptomatic. Majority were newly diagnosed TB (28/31, 90.32%) and had comorbidities (23/31, 74.2%), most commonly hypertension (n=15, 48.39%), diabetes mellitus (n=10, 32.26%), end-stage renal disease (n=3, 9.68%), and dyslipidemia (n=3, 9.68%). Eighteen patients reported alcohol use (58.06%). The most frequent chest x-ray findings were apical opacification (n=15, 48.39%), reticular or nodular infiltrates (n=9, 29.03%), and pleural effusion (n=7, 22.58%) (Table 1). Out of 31 patients, ten had rifampin-susceptible cultures (32.3%), two were rifampin resistant (6.4%), and the rest had unknown results (61.3%) (Table 2). Majority of patients were treated with standard 2HRZE/4HR regimen (28/31, 90.32%) and were alive (26/31, 83.87%) on the last follow up.

Conclusion
Majority of patients with Xpert MTB/RIF indeterminate RR results had clinical symptoms and radiographic findings consistent with active TB. Patients with indeterminate RR results can have either susceptible or drug-resistant M. tuberculosis on culture. Indeterminate Xpert MTB/RIF RR results should be interpreted with caution, and final results of TB culture should be followed up.

Disclosures
All Authors: No reported disclosures
P-2089. Transition of Lyme Serological Testing to the Modified Two Tiered-Testing Algorithm (MTTT): Observations from a Commercial Laboratory
Authors: Gillim Laura , Grover Ajay , Walworth Charles M , Alfego David 
Published: January 2025

Abstract

Background
2019 FDA clearance of Lyme disease serologic assays with new indications for use in a modified two-tiered testing (MTTT) algorithm marked the first significant change in Lyme serologic testing in over 20 years. In 2022 Labcorp® fully transitioned Lyme serological testing from the standard two-tiered testing (STTT) algorithm to the MTTT algorithm.

Methods
Retrospective analysis of results reported for Lyme serological testing March through October to correlate with warmer months consistent with tick exposure, comparing samples received in 2019 and 2021 assessed with the STTT algorithm and samples received in 2022 and 2023 with the MTTT algorithm. Algorithm interpretation was based on APHL guidance.

Results
In 2019 and 2021, a combined total of 314,409 individuals were tested from March through October using the Lyme STTT algorithm while a combined total of 597,142 individuals were tested in 2022 and 2023 using MTTT during the same time frame. The populations of individuals tested by STTT and MTTT did not differ significantly in sex (STTT: 57.2% female, MTTT: 57.4%), age (STTT: mean 51 ± 29.0 years, MTTT: 51.0 ± 30.0 years) or geographic distribution (by U.S. census bureau region). An overall increase in positivity was observed with the MTTT (6.4%) compared to the STTT (3.2%) and was specifically observed in the percentage of individuals with results consistent with recent or remote past infection (tier 1+/tier 2 IgG+ or both IgG+ IgM+). A decrease in the percentage of results consistent with acute or recent infection (tier 1+/tier 2 IgM+) was observed with MTTT (1.1%) versus STTT (1.5%). 11.6% of Lyme MTTT orders included a concurrent order for Lyme immunoblot. MTTT and immunoblot results were discordant for 9.1% of samples. Of the discordant samples 43% had detectable IgG and/or IgM on the 2nd tier MTTT but were negative by immunoblot.

Conclusion
The transition from the STTT to MTTT algorithm revealed higher rates of serological positivity for Lyme disease. Analysis of samples tested by both MTTT and immunoblot indicates that MTTT assays exhibit greater sensitivity, aligning with findings in peer-reviewed literature. Some clinicians ordered both MTTT and immunoblot tests, suggesting a need for education on updated Lyme testing recommendations.

Disclosures
Laura Gillim, PhD, Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company) Charles M. Walworth, MD, Labcorp: Employee|Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company) David Alfego, PhD, Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company)
P-2091. Potential Impact of Targeted Sequencing on Central Line-associated Bloodstream Infection (CLABSI) at Stanford Health Care, 2015–2024
Authors: Rodriguez-Nava Guillermo , Egoryan Goar , Fu Kyle , Shepard John , McIntyre Karen , Sampson Mindy M , Salinas Jorge 
Published: January 2025

Abstract

Background
Central line-associated bloodstream infection (CLABSI) remains a key quality measure. However, the CLABSI surveillance definition attributes bloodstream infections in patients with central venous access devices to the central line if no other sources are found, potentially overestimating true line-related cases. Incorporating non-culture based microbiologic testing, such as next-generation sequencing, into the CLABSI surveillance definition may further skew these estimates. We aimed to review the organisms identified in 16S rRNA sequencing tests from blood samples to determine if they were typically associated with CLABSI.

Methods
We retrieved all 16S rRNA sequencing orders from Stanford Hospitals & Clinics from May 2015– May 2024. We identified orders obtained from blood specimens and categorized those patients with and without central venous access devices. We compared the identified organisms with those included in the NSHN CLABSI definition (https://www.cdc.gov/nhsn/pdfs/pscmanual/17pscnosinfdef_current.pdf).

Results
Of the 3,830 16S rRNA tests ordered, 225 were from blood specimens. Among these, 40% (65/225) had a central venous access device at some point during admission. Eight tests were positive: two from patients with a device during collection, identifying Bartonella quintana and Ureaplasma urealyticum—both not excluded from the NHSN definition. Other positives included two cases of Borrelia hermsii, Paracoccus spp., Leptospira spp., Legionella spp., and coagulase-negative Staphylococcus, with only the latter typically associated with central venous access device infection. Only organisms from the genera Blastomyces, Histoplasma, Coccidioides, Paracoccidioides, Cryptococcus, and Pneumocystis are excluded from the NHSN CLABSI definition.

Conclusion
The increasing use of next-generation sequencing tests, such as 16S rRNA targeted sequencing, introduces unique scenarios where non-culturable organisms can be detected in blood specimens. There may be some risk of unfairly penalizing institutions for reporting organisms not associated with CLABSI. The list of organisms included in the NHSN CLABSI surveillance definition should be continuously updated to reflect the adoption of new non-culture-based testing methods.

Disclosures
All Authors: No reported disclosures
P-2094. Difference in Detection Rates of Coagulase-negative Staphylococci between BACTECTM FX (BD) and BACT/ALERT® VIRTUO® (bioMérieux)
Authors: Taylor Jeremy J , Whalen Allison , Colic Stephanie , Ozbolt Patrick , Antonara Stella 
Published: January 2025

Abstract

Background
Blood cultures (BCxs) with skin flora make interpretation of results difficult, impacting patient (pt) care on multiple levels. OhioHealth (OH), a large health care system in central Ohio, transitioned from BACTECTM FX (BD) to a new BCx detection system, BACT/ALERT® VIRTUO® (bioMérieux) in September 2022 and an increase in coagulase negative staphylococci (CoNS) isolates was noted. We compared detection rates of the most common contaminant, CoNS, between two BCx systems during 3 month pre-and post-implementation periods (March-May 2022 and March-May 2023).

Methods
BCx contamination rates were defined as CoNS in 1/2 sets as per microbiology laboratory standard procedures, or clinically as CoNS in 2/2 sets drawn simultaneously from the same site without signs/symptoms of infection. Pts were excluded if: i) pathogenic organisms were identified in prior BCxs (within 1 week of CoNS) or, ii) any organism other than CoNS was present in the same set. Pure CoNS BCxs were then assessed for number of sets positive (POS) on initial collection and follow up BCxs obtained after the first POS set with CoNS.

Results
From March-May 2022, 23,440 sets were collected with overall positivity rate of 9.5% (2,219 sets). CoNS was identified in 2% of total POS (465 sets). Of those, 244 pts had 1/2 initial sets POS resulting in 28% (69 pts) with redraws. In March-May 2023, 25,314 sets were collected with overall positivity rate of 10.1% (2,564 sets). CoNS was identified in 2.6% of total POS (657 sets). Of those, 364 pts had 1/2 initial sets POS with 37.9% (138 pts) with redraws. Pre-implementation, 55 pts had 2/2 sets POS for CoNS, and 5 pts grew the same organism on redraw. Post-implementation, 78 pts had 2/2 sets POS for CoNS, and 13 pts grew the same organism on redraw. Both periods had similar rates of 2/2 CoNS POS sets drawn simultaneously (72% and 70.5% respectively).

Conclusion
Increased rates of CoNS were detected after transition to the VIRTUO® system, including 1/2 POS sets, resulting in increased follow up cultures. Simultaneously timed sets of BCxs 2/2 POS with CoNS made interpretation of contamination difficult, highlighting the need for education on proper BCx collection techniques, including separate time/site draws to clinically assess true contamination events.

Disclosures
All Authors: No reported disclosures
P-2100. Comparison of Fosfomycin MIC Values between Parent and Inner Colonies (IC) of Escherichia coli Arising During Disk Diffusion (DD) Testing
Authors: Malik Khadijah , Salay Jenna , Bixby Morgan L , Bixby Morgan L , Collins Lindsey , Chang Tiffany , Hirsch Elizabeth B 
Published: January 2025

Abstract

Background
Recent studies have documented uropathogenic E. coli displaying the presence of IC during fosfomycin DD testing. These IC often demonstrate increased minimal inhibitory concentrations (MIC) when compared to their parent isolates. Investigating the clinical relevance of these IC and the extent of their resistance is a first step in determining whether they are associated with fosfomycin failure.

Methods
E. coli isolates (n = 69) collected from the University of Minnesota Medical Center (UMMC) that produced ≥ 3 discrete IC during at least one DD test were included. Parent and IC (n = 69) isolates underwent broth microdilution (BMD) testing using fosfomycin concentrations of 0.5-64 µg/mL for parent isolates and 8-1024 µg/mL for IC with incubation at 37°C for 16-20 hours. All susceptibility testing was supplemented with 25 µg/mL glucose-6-phosphate and conducted in duplicate on separate days. E. faecalis ATCC 29212 and E. coli ATCC 25922 were included as quality control strains. The results were evaluated using both CLSI (susceptible [S]: 64 µg/mL) and EUCAST (S: 8 µg/mL) breakpoints. Categorical agreement between the two guidelines were calculated.

Results
E. coli parent isolates had an MIC range of 1 to &gt;64 µg/mL with a MIC50/90 of 8/32 µg/mL (Table 1). The IC isolates had significantly higher MIC ranges (&lt; 8 and &gt;1024 µg/mL) and MIC50/90 values of 256/ &gt;1024 µg/mL. The parent isolates had 94.2% (n = 65) and 69.6% (n = 48) susceptibility per CLSI and EUCAST breakpoints, respectively. Using the more stringent EUCAST breakpoints, all IC isolates were resistant whereas 65.2% (n = 45) were considered resistant per CLSI breakpoints. Categorical agreement among the parent collection was 75.4% and 65.2% in the IC collection (Table 2).

Conclusion
Our data indicate IC arising from E. coli during fosfomycin DD testing are notably more resistant than their parent isolates, with an MIC50 increase of five, 2-fold dilutions. Future directions for this work include expanding the isolate collection and examining the fitness of these IC in comparison to their parents. Improving the understanding of the frequency, resistance, and fitness of IC arising from fosfomycin DD testing will help determine an optimal interpretation of IC, which may in turn improve patient outcomes.

Disclosures
Elizabeth B. Hirsch, PharmD, FCCP, FIDSA, GSK: Advisor/Consultant|GSK: Honoraria
P-18. Incidence of Pneumococcal Disease and Vaccination Coverage among US Adults by Age and Risk Groups
Authors: Bailey M Doyinsola , Huang Yi-Ling , Ai Lei , Mohanty Salini , McGuinn Valina C , Johnson Kelly D , Cossrow Nicole 
Published: January 2025

Abstract

Background
Older adults and those with underlying medical conditions are at increased risk for illness, hospitalization, and death from pneumococcal disease (PD). The CDC currently recommends pneumococcal vaccination for adults ≥65 years and adults ≥19 years with underlying medical conditions who are at greater risk of PD. Identifying differences in pneumococcal vaccination coverage (VCR) and disease incidence is necessary to develop and implement strategies to improve VCR. We estimated VCR and incidence of PD, by age and risk group, among adults ≥18 years in the United States from 2017-2020.

Methods
This was a retrospective study of administrative claims data from Merative® MarketScan® Commercial Claims and Encounters Database. From 2017-2020, annual incidence rates of invasive pneumococcal disease (IPD), non-bacteremic pneumococcal pneumonia (NBPP) and all-cause pneumonia (ACP) were estimated by age group (18-49, 50-64, ≥65 years) and risk group (healthy, with chronic medical conditions (CMC) and with immunocompromising conditions (IC)) among adults with at least 2.5 years of continuous enrollment. Adults were considered vaccinated if they had at least one pneumococcal vaccine within 2 prior years to their index date. The percentage of pneumococcal vaccination was reported annually from 2017-2020.

Results
From 2017-2020, there were approximately 9-10 million patients annually in the study population. Less than 25% of US adults recommended for pneumococcal vaccination were vaccinated (Figure 1). Vaccination rates were highest among those ≥65 years (Figure 1). Annual incidence rates per 100,000 person-years decreased from 2017 to 2020 for IPD, NBPP and ACP (Figure 2). Each year, the incidence of PD was consistently higher among those ≥65 years, and those with IC or CMC. There was a decrease in the incidence of PD in 2020, coinciding with the COVID-19 pandemic.

Conclusion
Despite ACIP recommendations, vaccination rates remain low in those recommended to receive a pneumococcal vaccine, specifically among older adults and those with underlying conditions. This analysis underscores the opportunity to improve VCR and prevent PD in US adults, especially those at greatest risk.

Disclosures
M. Doyinsola Bailey, PHD, MPH, Merck & Co., Inc., Rahway, NJ, USA: Employee|Merck & Co., Inc., Rahway, NJ, USA: Stocks/Bonds (Public Company) Yi-Ling Huang, PhD, Merck: Stocks/Bonds (Public Company) Salini Mohanty, DrPH, MPH, Merck & Co., Inc.: Employee|Merck & Co., Inc.: Stocks/Bonds (Public Company) Kelly D. Johnson, PhD, Merck & Co., Inc.: Employee|Merck & Co., Inc.: Stocks/Bonds (Public Company) Nicole Cossrow, PhD, Merck: Stocks/Bonds (Public Company)