bluuebunny/crossref_metadata_2025_split huggingface dataset:
P-2166. Sensitivity and Specificity of Nanopore Sequencing for Detection of Methicillin-Resistant Staphylococcus aureus and Methicillin-Resistant Staphylococcus epidermidis in Positive Blood Culture Samples
Authors: Mangkalamanee Onjira , Kawang Kornthara , Cholsaktrakool Pornsawan , Maita Supakorn , Prasertmanakit Tongsorn , Pollapong Kraiwit , Srichomthong Chalurmpon , Shotelersuk Vorasuk , Punakabutra Napawan , Chatsuwan Tanittha , Nilaratanakul Voraphoj 
Published: January 2025

Abstract

Background
Nanopore sequencing enables rapid DNA/RNA analysis without amplification. Implementing this for point-of-care diagnostics reduces time delays in traditional AST methods, potentially enhancing patient outcomes. We aim to evaluate the performance of Oxford Nanopore Technologies sequencing from positive blood culture for bacterial identification and antimicrobial susceptibility prediction in S. aureus and S. epidermidis by detecting the mecA gene.

Methods
We conducted a cross-sectional descriptive study on individuals with positive blood cultures identifying S. aureus and S. epidermidis over a 12-month period from April 2023 to March 2024. Bacterial DNA was extracted from the blood culture specimens, and then sequenced using the PromethION Flow Cell to identify the organisms and mecA genes, comparing the results to routine blood cultures and standard AST.

Results
108 blood culture samples were initially collected. After applying the exclusion criteria, 80 samples qualified for DNA extraction and sequencing. 45 samples were identified as S. aureus (6 MRSA and 39 MSSA) and 35 as S. epidermidis (27 MRSE and 8 MSSE). Notably, 67.5% of samples contained less than 0.5 ng/μl of DNA. Sensitivity and specificity of mecA gene detection were 35.5% (95% CI: 18.6%–52.3%) and 83.7% (95% CI: 73.3%–94.0%), respectively, with an accuracy of 65.0% (95% CI: 54.5%–75.5%). Upon excluding samples with DNA less than 0.5 ng/μl accuracy improved to 73.1% (95% CI: 56.0%–90.1%). The specimen that showed a false-positive result will proceed to phenotypic confirmation using methicillin-infused mannitol-salt agar. After phenotypic confirmation, the accuracy improved to of 88.5% (95% CI: 76.2%–100.0%). In this study, we also found 5 samples in which the mecA gene was shown to be genotypically oxacillin-sensitive after phenotypic confirmation. The median time for detecting the mecA gene was 198 minutes (IQR: 37.5–458.7) after the onset of sequencing.

Conclusion
Our study on nanopore sequencing for MRSA and MRSE detection from blood cultures found promising but limited sensitivity and specificity in detecting mecA gene. Challenges in DNA extraction from Gram-positive bacteria affected overall accuracy. Further improvements are needed for enhanced diagnostic reliability.

Disclosures
All Authors: No reported disclosures
P-2167. "Clinical Utility of Cell-free Next-generation Sequencing, Single Center Experience"
Authors: Ibrahim Osama , Rogers Ralph , Farmakiotis Dimitrios 
Published: January 2025

Abstract

Background
Timely diagnosis of infectious diseases is crucial, but it can be challenging. The literature about impact of Karius in clinical care is still insufficient. Overall, Karius has been very effective on selected patients but the clinical impact is difficult to assess due to absence of gold standard comparator. In addition, a negative result doesn’t always mean a “true negative” but means that the organism’s DNA wasn’t detected. Also, Identification of non-relevant results has been reported.

Methods
This is a retrospective cohort study of patients who received a Karius testing between January 2018 until March 2023 at Lifespan institution in Rhode Island. Clinical and demographic data was abstracted from the electronic medical record. Quality checks were applied to the data to remove duplicates and errors. Descriptive statistics were reported using Microsoft excel. Clinical impact was abritrated after review of each case by three independent investigators. We predefined clinical impact categories criteria based on criteria from previous studies. Each case was reviewed by each investigator independently and disparities were solved via consensus and discussions. inter-rater reliability was assessed using Cohen's Kappa coefficient.

Results
Overall, 65 patient had Karius testing and included 35 male and 30 female. 30 patients were immunocompromised and 16 of them had hematologic malignancy. Mean age was 46.7 and the study included 12 pediatric and 53 adult patient. The most common infectious syndrome was Pneumonia/pulmonary followed by osteoarticular and endovascular. Management was changed in 11/65 patients. The Karius testing had positive impact in 12 patients, negative impact in 1 patient and no impact in 52 patients. Positive percent agreement with conventional testing was 0.49 and negative percent agreement was 0.83

Conclusion
Cell-free next-generation sequencing has a valuable role in diagnosis and management of infections in challenging cases especially in patients with high pretest probability. Further research is needed to define the population who would benefit most from it.

Disclosures
All Authors: No reported disclosures
P-2181. Cardiac MRI Identifies Heart Disease Risk in Individuals with Hepatitis C Regardless of Myocardial Damage Markers or Fibrosis Stage
Authors: D’Amore Aaron , Sirajuddin Arlene , George Nivya , Gharib Ahmed M , Mathur Poonam 
Published: January 2025

Abstract

Background
Infection with hepatitis C virus (HCV) increases the risk of extrahepatic manifestations, including cardiovascular disease (CVD). Cardiac magnetic resonance (CMR) remains the gold standard test for non-invasive structural and functional assessment of the heart and can be used to detect CVD. We sought to determine the CVD risk in patients with HCV prior to therapy using CMR.Table 1.Baseline Demographic Features of HCV CMR Cohort

Methods
Individuals with chronic HCV infection were prospectively enrolled in the CHROME study (NCT 03823911). A subset of 10 HCV-infected individuals were enrolled in the MRI sub-study from March to September 2019. HCV antibody and RNA, liver fibrosis score, and markers of inflammation and myocardial damage were obtained.
CMR was performed prior to the initiation of DAA treatment. ECV fraction was calculated using the equation: ECV = 100% x (1-hematocrit) x [(1/T1myocardium post) – (1/T1myocardium pre)]/[(1/T1blood post) – (1/T1 blood pre)]. An ECV fraction &gt; 30% was considered abnormally increased. 10 age-matched, HCV-negative volunteers were included in the analysis so that T-test was used to compare ECV fraction in both groups.Figure 1.Extracellular Volume (ECV) of HCV-infected individuals and Healthy Volunteers. ECV fraction in the HCV-infected individuals was significantly increased (0.30 ±0.03 vs. 0.26±0.03, p=0.0036).

Results
Demographics are shown in Table 1. CMR showed that 8 of 10 HCV-infected individuals had an abnormal ECV fraction ( &gt;30%)7 (average=0.30, range 29-38%). When compared with age-matched normal volunteers, ECV fraction in the HCV-infected individuals was significantly increased (0.30 ±0.03 vs. 0.26±0.03, p=0.0036) (Figure 1). Three of 10 HCV-infected individuals had non-ischemic patterns of gadolinium enhancement on the LGE images (Figure 2). For HCV-infected individuals, markers of inflammation and myocardial damage were within laboratory reference range for all subjects in the CMR cohort, and ECV fraction was elevated regardless of myocardial damage markers or liver fibrosis stage.Figure 2.A) Short axis late gadolinium enhancement image shows a midwall pattern of enhancement within the basal septal wall (arrow), compatible with an area of midwall fibrosis. B) Native T1 map and C) post contrast T1 map show a corresponding area of abnormal T1 measurements within the basal septum (arrows).

Conclusion
Our findings suggest that myocardial changes secondary to HCV infection can occur without measurable changes in inflammatory or myocardial biomarkers, and ECV fraction via CMR may be a sensitive screening tool to detect these changes. This has important implications for the necessity of early HCV treatment, since cardiovascular changes can precede the development of advanced liver fibrosis in HCV-infected individuals.

Disclosures
All Authors: No reported disclosures
P-2182. Assessing Hepatitis A Virus (HAV) and Hepatitis B Virus (HBV) Screening, Immunity, and Vaccination in People Living with Human Immunodeficiency Virus (HIV) in the Illinois Department of Corrections (IDOC)
Authors: Truong Nicholas T , Dang Alex , Debs Hillary , Morrow Jennifer , Kalota Huda , Patel Mahesh C , Borgetti Scott , Drwiega Emily N , Badowski Melissa E 
Published: January 2025

Abstract

Background
Individuals in custody are highly susceptible to vaccine-preventable diseases, including hepatitis A virus (HAV) and hepatitis B virus (HBV). In the Illinois Department of Corrections (IDOC) HIV Telemedicine Clinic, people are screened for HAV/HBV, providing an opportunity to recommend vaccines in those without immunity.

Methods
This retrospective cohort pre-post study included adults living with HIV who followed in the IDOC HIV Telemedicine Clinic during two time periods, 01/01/2019 - 12/31/2019 and 01/01/2022 – 12/31/2022, with a 9-month follow-up period to account for screening and vaccination recommendations. Patients were excluded from primary endpoint analysis if they had chronic HBV infection. The primary objective was to compare the rates of vaccination and immunity to HAV and/or HBV among individuals in custody living with HIV in 2022 to prior data in 2019, where standardized recommendations for serologic screening and vaccination were not routinely performed. Secondary endpoints included the number of individuals receiving HAV/HBV screening, acceptance of vaccination if recommended, and documented barriers to vaccination. Statistical analysis included descriptive statistics, Chi-squared test, and Student’s t-test.

Results
A total of 436 patients were included in the 2019 cohort and served as historical control data. Of 341 patients screened for inclusion in the 2022 cohort, 300 were included. Baseline characteristics are presented in Table 1. 79% and 70% of patients were immune to HAV in 2019 and 2022, respectively (p = 0.02). 65% and 71% of patients were immune to HBV in 2019 and 2022, respectively (p = 0.12). Overall, the number of patients immune to both HAV and HBV were similar between the two cohorts with 52% in 2019 and 53% in 2022 (p = 0.89). On the other hand, the percentage of patients who had no immunity to both HAV and HBV was 8% in 2019 and 12% in 2022 (p = 0.08). Patient refusal was the main barrier to vaccination. Other secondary outcomes for 2022 are outlined in Table 2.

Conclusion
Overall, HAV and HBV immunity did not significantly increase in 2022. Results suggest that a major opportunity still exists to screen and provide vaccination to individuals in custody, but routine serologic screening can lead to improved HAV and HBV immunity rates.

Disclosures
Scott Borgetti, MD, GSK: Grant/Research Support
P-2259. Incidence, Treatment, and Outcomes of Urinary Tract Infections Caused by Extended-Spectrum Beta-Lactamase Producing Bacteria in Kidney Transplant Recipients
Authors: Gerdes Elise N , Wynd Michael A , Chaung Melissa 
Published: January 2025

Abstract

Background
Urinary tract infections (UTI) are the most common bacterial infection in kidney transplant recipients (KTR) during the first year post transplant. The objective of this study was to determine the incidence of UTI caused by extended-spectrum beta-lactamase (ESBL) producing bacteria in KTR and compare their outcomes to KTR with UTI caused by non-ESBL producing pathogens.
Index Urinary Tract Infections (2013-2022)

Methods
This was a single-center, retrospective, chart review including adults who received their first, kidney-alone transplant from January 2013 through December 2022 and had a UTI within the first year post-transplant. A UTI was defined as a positive urine culture treated with antibiotics and presence of ESBL-producing bacteria was confirmed by susceptibility patterns. Patients were excluded if they had a rejection or received augmented immunosuppression prior to index UTI, received treatment for positive donor cultures, or were dialysis-dependent at 90 days post-transplant. Primary outcomes: incidence of index UTI caused by ESBL producing bacteria, location of treatment, and length of stay. Key secondary outcomes: patient and allograft survival, incidence of biopsy-proven rejection after treatment of index UTI, and number of UTI in the first year post-transplant.
Primary Outcome: Hospitalizations

Results
Of 178 patients included, 21 (11.8%) had a UTI due to ESBL-producing bacteria and 157 (88.2%) had a UTI caused by a non-ESBL producing organism. The incidence of ESBL-UTIs increased from 0 to 18.5% during the observation period. No differences were identified in baseline characteristics except for receipt of a donation-after-cardiac-death kidney, 8 (38.1%) in the ESBL-UTI group and 28 (17.8%) in the non-ESBL UTI group, p = 0.03. Compared to the non-ESBL-UTI group, the ESBL-UTI group was more likely to be admitted for treatment 11/21 (52.2%) vs 40/157 (25.5%), p = 0.01, and had more UTIs in the first post-transplant year, mean (range) 2.7 (1-6) vs 1.8 (1-7), p = 0.003. No differences were identified in other outcomes.
Empiric Therapy in Patients with Extended-Spectrum β-lactamase Urinary Tract Infections

Conclusion
The incidence of index UTI due to ESBL-producing bacteria is increasing while the UTI rate remains consistent, creating the need to identify optimal treatment and prevention strategies in KTR.
Secondary Outcome: Total Urinary Tract Infections in the First Year Post-Transplant

Disclosures
All Authors: No reported disclosures
P-2281. Impact of Immunosuppression on Clinical Outcomes in Critically Ill Pneumonia Patients
Authors: Sanabria-Herrera Natalia , Torres Antoni , Martin-Loeches Ignacio , Reyes Luis Felipe F 
Published: January 2025

Abstract

Background
Nosocomial lower respiratory infections (nLRTI) are linked to poorer clinical outcomes and a significant healthcare cost. Nevertheless, there remains uncertainty regarding the risk factors for mortality among critically ill individuals, particularly those with varying degrees of immunosuppression. Thus, this study aims to comprehensively describe immunocompromised patients, assess its impact on clinical outcomes, and conduct a comparative survival analysis.
Figure 1
Identified microorganisms in A) the Immunosuppression group and B) Non- the Immunosuppression group

Methods
This analysis used data from the prospective, multicenter, and multinational cohort developed by the European Network for ICU-related respiratory infections (ENIRRI), including 1060 adult patients diagnosed with nLRTI. Descriptive statistics were utilized to compare the immunosuppressed group against the non-immunosuppressed group, while also detailing the microorganisms predominantly identified in both groups. A survival analysis adjusted for infection severity using a Cox proportional hazards model was performed to explore mortality within these subgroups further.
Figure 2
Kaplan-Meier survival curve stratified by Immunosuppression status: Probability of survival from ICU admission

Results
Immunosuppression was observed in 25% of the patients (264/1060). In both cohorts, Pseudomonas aeruginosa was the predominant microorganism, particularly affecting immunosuppressed patients, (25.3% vs. 16.7%, p = 0.032), followed by Klebsiella spp and Acinetobacter baumanii (Figure 1). Interestingly, the survival analysis revealed a lower probability of survival in the non-immunosuppressed after admission to the ICU (Figure 2). Additionally, the Cox regression analysis adjusted by disease severity found that no-immunosuppressed patients had lower mortality.
Figure 3
Adjusted Kaplan-Meier Survival Curve following Cox Regression: Survival Probability Adjusted for SAPS II Score.

Conclusion
This description sheds light on the intricate relationship between immunosuppression, microbial etiology, and clinical outcomes in patients with nLRTI. Interestingly, immunosuppression was not associated with worse clinical outcomes, even after adjusting for disease severity.

Disclosures
All Authors: No reported disclosures
P-2302. Efficacy of Universal vs Targeted Antifungal Prophylaxis for the Prevention of Invasive Fungal Infections after Lung Transplant
Authors: Claire Ashmead-Meers , Miceli Marisa H , Linder Kathleen A , Kauffman Carol A , Richards Blair 
Published: January 2025

Abstract

Background
IFI are associated with high morbidity and mortality among LTx patients (pt). Preventive strategies are commonly used, but the optimal AP approach is unclear. Over the last 10 years, our LTx program has transitioned from universal AP with itraconazole (ITR), to targeted AP, and now universal AP with posaconazole (POS). We compared the efficacy of these strategies.

Methods
All adult LTx pt at U Michigan from 7/1/2014-2/28/2023 were followed for 12 months (mo) post-LTx. Pt were divided into 3 cohorts based on AP regimen: cohort 1 - universal ITR for 6 mo; cohort 2 - targeted voriconazole (VOR) for 3 mo if colonized with Aspergillus or fluconazole (FLU) for 14 days (d) if colonized with Candida; cohort 3 - universal POS for 6 mo. Demographics, LTx characteristics, IFI defined by MSGERC criteria, breakthrough IFI (B-IFI) defined by MSGERC/ECMM criteria, and mortality were noted.

Results
Of 134 pt, 86 (64%) were men, and 101 (75%) had double-LTx. Pulmonary fibrosis was the most common reason for LTx (47,35%). There were 59 (44%), 29 (22%), and 46 (34%) pt in the universal ITR, universal POS, and targeted cohorts, respectively. A total of 23 proven/probable IFI occurred: 14 invasive pulmonary aspergillosis (IPA), 7 invasive candidiasis (IC), 1 cryptococcal pneumonia (CP) and 1 hyaline mold IFI. IFI occurred at a median of 98 d (range 1–322 d). IFI occurred in 6/59 (10%) receiving universal ITR (all but one of whom had IPA, all B-IFI); 5/29 (17%) receiving universal POS (3 IC and 2 IPA, all B-IFI); and 12/46 (26%) in the targeted AP cohort (7 IPA, 4 IC, 1 CP). Of the 12 pt with IFI in the targeted cohort, 10 did not meet criteria for use of AP and thus were not given VOR or FLU; 7/10 developed IPA and 2/10 IC. No IPA occurred in 5 pt who received VOR AP, but 2 pt on FLU AP developed breakthrough IC. Kaplan-Meier curve showed a trend toward IFI-free survival at 12 mo to be greater among pt receiving universal ITR (0.89) and universal POS (0.83) vs. targeted AP (0.73), p=0.16. All-cause mortality was 10% (14/134) and did not differ among the 3 AP cohorts, p=.49. Only 1 death (IC) was caused by IFI.

Conclusion
Universal AP using POS or ITR may be a more effective strategy than targeted AP for prevention of IFI post-LTx, but this comes with an increased risk for harder-to-treat B-IFI.

Disclosures
Marisa H. Miceli, MD, AN2: PI in clinical trial|F2G: PI in clinical trial|Pulmocide: PI in clinical trial|Scynexis: Advisor/Consultant|Scynexis: PI in clinical trial
P-2303. Active Surveillance and Antimicrobial Prophylaxis to Prevent Hyperammonemia Syndrome in Lung Transplant Recipients: A Single Center Cohort Study
Authors: Charles Drew , Lee Sara , Charya Ananth , Eberlein Michael , Saharia Kapil K 
Published: January 2025

Abstract

Background
Hyperammonemia syndrome (HS) is a life-threatening complication primarily affecting lung transplant recipients (LTR) and is associated with M. hominis and/or Ureaplasma spp infection. We implemented an active surveillance and prophylaxis protocol to improve outcomes associated with HS in LTR. Herein, we evaluate the impact of our protocol on outcomes of HS.

Methods
This is a single-center retrospective cohort study of adult LTR performed from 1/1/2019 to 1/31/2024. Our surveillance and prophylaxis protocol was implemented on 8/1/2022 and included PCR testing for M. hominis and Ureaplasma spp on post-operative bronchoscopy samples, measurement of serum ammonia levels, and azithromycin prophylaxis in our LTR. Comparisons between groups were performed using Chi-square or Fischer’s exact test for categorical variables and Student’s t test or Mann-Whitney U for continuous variables.

Results
One hundred and thirty-four adults received a lung transplant during the study period. Baseline characteristics are shown in Table 1. In total, 9 LTR (6.7%) were diagnosed with M. hominis or Ureaplasma spp. infection (Table 2). Of these, 3 LTR met criteria for definite HS (3/134, 2.2%) of whom two died. An additional 3 LTR had disseminated infection due to M. hominis without evidence of HS.
Following protocol implementation, 31/37 (83.8%) LTR had PCR testing for M. hominis and Ureaplasma spp. (Table 2). Ammonia levels were sent within 3 days of transplantation in 20/37 (54.1%) LTR. All patients received prophylaxis with azithromycin (or alternative agent) for at least 5 days or until PCR returned negative. Three LTR had either M. hominis or Ureaplasma spp infection detected following protocol implementation; none developed HS. One LTR developed disseminated M. hominis infection. However, screening was delayed by 10 days and prophylaxis was stopped after 5 days, prior to screening results being known.

Conclusion
The prevalence of HS in our cohort is similar to published reports. Adherence to our protocol was high for azithromycin prophylaxis and PCR testing, but low for ammonia levels. Importantly, no case of definite HS occurred following protocol implementation. Additional studies to determine optimal screening and prophylaxis strategies for HS are needed.

Disclosures
Kapil K. Saharia, MD, MPH, Eurofins Viracor: Advisor/Consultant
P-2308. Effect of Antibiotic Therapy on Preventing Subsequent Urinary Tract Infection in Early Kidney Transplant Recipients with Asymptomatic Bacteriuria
Authors: Kim Geonui , Chang Eui Jin , Bae Seongman , Jung Jiwon , Kim Min Jae , Chong Yong Pil , Lee Sang-Oh , Choi Sang-Ho , Kim Sung-Han 
Published: January 2025

Abstract

Background
The efficacy of treating asymptomatic bacteriuria during the early peri-transplantation period in kidney transplant (KT) recipient has not been properly assessed. In this study, we assessed the effectiveness of treating asymptomatic bacteriuria in first three months after KT and one month before, including bladder irrigation specimen obtained from operating room.

Methods
A single center retrospective cohort study was conducted on patient who underwent KT. KT recipient with asymptomatic bacteriuria within 30 days before and 90 days after the transplantation between January 2020 and January 2023 were included. The frequency of subsequent urinary tract infection (UTI) within 90 days of detecting asymptomatic bacteriuria was compared between antibiotic-treated and untreated groups.

Results
A total of 112 KT recipients with asymptomatic bacteriuria were included; of these, 33 (29 %) received antibiotic treatment while 79 (71 %) did not. Nineteen patients (17%) developed symptomatic UTIs within 90 days of detecting asymptomatic bacteriuria; 21% (7/33) in the antibiotic-treated group and 15% (12/79) in the untreated group (odds ratio, 1.53; 95% confidence interval, 0.53 to 4.24). Untreated asymptomatic bacteriuria was not significantly associated with subsequent UTI in multivariable logistic regression analysis (adjusted odds ratio, 1.32, 95% confidence interval, 0.45 to 3.85; p=0.61) after adjusting gender, vesicoureteral reflux, malignancy, type of donated kidney and induction immunosuppressive drug.

Conclusion
We found that antibiotic therapy for patients with asymptomatic bacteriuria during the early peri-transplantation period did not confera significant advantage in preventing subsequent UTIs. Prescribing antibiotics for asymptomatic bacteriuria in KT recipients should be approached with caution due to the potential risk of colonization or infection by resistant bacteria.
Figure 1.
Kaplan-Meier estimates of UTI incidence in patients with asymptomatic bacteriuria after KT ; Log-rank test showed that treated group showed that UTI occurred later than untreated group. (p=0.37)

Disclosures
All Authors: No reported disclosures