Citations

Infective endocarditis (IE) remains a diagnostic challenge, particularly in cases where microbiological diagnosis is not established. Advances in molecular diagnostics have expanded the ability to identify causative pathogens beyond traditional culture-based methods. This review explores the role of molecular assays, including pathogen-specific PCR, multiplex PCR, broad-range PCR, and shotgun metagenomic sequencing, in diagnosing IE. These molecular techniques enhance pathogen detection, especially in patients with prior antibiotic exposure, and improve diagnostic accuracy in culture-negative IE. Broad-range PCR assays and metagenomic sequencing offer the untargeted detection of a wide spectrum of organisms. Despite their advantages, limitations such as availability, interpretation challenges, and a lack of antimicrobial susceptibility testing remain. A multimodal approach integrating molecular diagnostics with conventional methods is essential to optimize patient management. Further research is needed to refine diagnostic algorithms and improve cost-effectiveness in clinical practice.

Background: The relationship between vegetation characteristics in Staphylococcus aureus infective endocarditis (IE) and blood culture time to positivity (TTP) has not been investigated. This study evaluates the correlation between vegetation length and TTP in patients with S. aureus IE. Methods: A retrospective cohort study was conducted that included 164 definite cases S. aureus IE. Vegetation length was determined by transesophageal echocardiography (TEE), and TTP was measured in hours from the initial time of blood culture incubation to positivity. Correlations between vegetation characteristics and TTP were analyzed using Spearman’s rank correlation coefficient. Results: A modest but statistically significant negative correlation was observed between vegetation length and TTP (Spearman ρ = −0.18, p = 0.020), suggesting that larger vegetations were associated with shorter TTP. No significant correlations were found for other vegetation characteristics (e.g., vegetation mobility, location, or number) and TTP. Conclusions: Larger vegetation size in S. aureus IE was associated with shorter TTP. These findings highlight the importance of vegetation size in the pathophysiology of S. aureus IE and its role in bacteremia dynamics.

Abstract Purpose Data regarding the incidence, onset, and management of complex outpatient antimicrobial therapy–induced neutropenia (COIN) are limited, and pharmacist involvement in COIN management has not been reported. This report describes the incidence, onset, and management of COIN at a large academic medical center. Methods This multisite retrospective cohort study examined adult patients undergoing serum laboratory monitoring for antimicrobials over a 4-year period. Patients receiving chemotherapy or immunosuppressants were excluded. Data collected included the antimicrobial regimen, complete blood count, duration of antimicrobial therapy until outcome occurrence, infectious syndrome, type of intervention, outcome, and pharmacist involvement. Logistic regression was used to assess risk factors for COIN incidence. The primary outcome was the incidence of COIN by antimicrobial drug. Results From 4,261 treatment episodes, 161 cases of COIN were identified (3.8% COIN incidence). The most common antimicrobials associated with COIN were intravenous piperacillin/tazobactam, cefepime, and meropenem. The majority of COIN events were attributed to a combination of at least 2 antimicrobials. Piperacillin/tazobactam was significantly associated with higher odds of developing COIN (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.04-3.34; P = 0.038), whereas ertapenem was associated with significantly lower odds of COIN (OR, 0.43; 95% CI, 0.24-0.77; P = 0.005). The median time to neutropenia diagnosis was 22 days (interquartile range, 14-29 days) from the time of inpatient antimicrobial start. Intervention for COIN occurred in 66.5% of cases, with neutrophil count recovering in 96.9% of these patients. Clinical pharmacists initiated 74.8% of interventions. Conclusion COIN can be effectively identified and managed by a multidisciplinary team reviewing routine laboratory monitoring, enabling most patients to safely complete antimicrobial treatment.

Abstract Background There is a lack of comprehensive, large cohort studies investigating the predictors for severity and hospitalization in human granulocytic anaplasmosis (HGA). Methods We conducted a retrospective cohort study including all cases of HGA identified by positive blood Anaplasma polymerase chain reaction (PCR) at the Mayo Clinic Laboratory, Rochester between 2011 and 2021. Multivariable logistic regression was performed to evaluate risk factors associated with hospitalization. Results A total of 465 cases were identified. Of those, 67% (n = 312) were managed in the outpatient setting. Hospitalized patients (n = 153, 33%) were more likely to be older (median age of 71 vs 61; P ≤ .001) and immunocompromised (17% vs 7%; P ≤ .001). The triad of leukopenia, thrombocytopenia, and transaminitis was observed in 24% of the cases, but was associated with risk of hospitalization (odds ratio [OR] 1.78, 95% confidence interval [CI]: 1.05–3.03; P ≤ .033). The presence of a coinfection did not impact mortality or hospitalization. Conclusions The risk factors for hospitalization in patients with HGA include altered mental status, higher absolute neutrophil count (ANC), advanced age, comorbidities, and immunosuppression. The classic hematological and biochemical profile may be absent in the majority of cases. Co-testing may be of higher benefit in select cases.

Abstract Background Infective endocarditis (IE) is a life-threatening infection often challenging to diagnose, particularly in culture-negative cases. Plasma microbial cell-free DNA (mcfDNA) sequencing has shown potential for detecting pathogens in IE. However, its clinical utility, diagnostic impact, and limitations remain debated. This study evaluates its use in diagnosing and managing IE in a tertiary care setting. Methods This single-center retrospective cohort study included adult patients (≥18 years) who underwent mcfDNA sequencing via the Karius test for suspected IE at Mayo Clinic Rochester between December 2019 and February 2024. Diagnostic classification followed the 2023 Duke–International Society of Cardiovascular Infectious Diseases criteria. Data on demographics, clinical features, routine microbiologic workup, and mcfDNA sequencing results were collected. Statistical analysis was conducted to evaluate diagnostic utility and treatment impact. Results Among 141 patients, 66 had a diagnosis of IE, with mcfDNA sequencing identifying pathogens in 60.6% of them, compared with 39.4% with routine workup. mcfDNA sequencing was the sole microbiologic test with positive results in 33.3% of patients, leading to antimicrobial adjustments in 50.0% of that group. Clinically insignificant mcfDNA sequence detection occurred in 28.6% of patients without a diagnosis of IE. Conclusions mcfDNA sequencing is a valuable adjunctive tool for diagnosing culture-negative IE and guiding antimicrobial therapy when clinical suspicion is high. However, its utility depends on appropriate clinical context, highlighting the need for careful test interpretation and further prospective studies to assess patient-centered outcomes and cost-effectiveness.

Abstract Background Plasma microbial cell-free DNA (mcfDNA) sequencing, commercially available from Karius® (Redwood City, CA), has been increasingly utilized in diagnosing endovascular infections. The 2023 updated Duke criteria incorporated detection of pathogen via metagenomic sequencing in its microbiologic criteria. We analyzed the clinical impact of mcfDNA sequencing in the diagnosis and treatment of suspected infective endocarditis (IE) cases. Methods We performed retrospective review of patients with suspected IE who underwent Karius® test at Mayo Clinic, MN, between 2017 to 2023. Results We preformed preliminary analysis of 25 patients. Analysis of baseline characteristics (table 1) revealed that these patients had significant predisposing factors for IE. Before accounting for mcfDNA sequencing, 3 (12%) met criteria for definite IE, 10 (40%) met criteria for possible IE, and 12 (48%) were rejected per 2023 Duke criteria. After incorporating mcfDNA sequencing result, 1 patient who was classified as possible IE was escalated to definite IE. This patient had previous infection of implantable cardioverter-defibrillator (ICD) with Streptococcus dysgalactiae. ICD was removed. She had development of endophthalmitis and stroke, 1 week and 2 weeks after the completion of IV antibiotics, respectively, with echocardiogram showing new tricuspid valve vegetation. Routine work-up was negative despite that she was not on any systemic antibiotics at the time of blood culture collection. mcfDNA sequencing detected Streptococcus dysgalactiae, making definite diagnosis of IE, leading to the physician’s decision to extend the IV antibiotic treatment (treatment escalation). Overall, after mcfDNA sequencing result, treatment decision was not impacted in 14 (56%), ongoing treatment was escalated in 4 (16%), de-escalated in 5 (20%), and antimicrobials was newly initiated in 2 (8%) (figure 1). Positive mcfDNA sequencing result often led to treatment escalation or initiation; negative result often led to treatment de-escalation (figure 2). Conclusion In challenging cases of suspected IE, mcfDNA sequencing led to alteration of antimicrobial treatment in 44% of cases. Further data collection and final analysis will include larger number of patients. Disclosures All Authors: No reported disclosures

Abstract Background Vascular graft infection (VGI) is a rare but serious condition. Pathogen identification can be difficult given the deep-seated nature. Microbial cell-free DNA next-generation sequencing (mcfDNA NGS) is an emerging tool in non-invasive microbiologic workup. One commercially available mcfDNA is the Karius Test (KT). There is a paucity of data regarding utility and impact of mcfDNA NGS testing in the evaluation of VGI. Methods We retrospectively evaluated adult patients who underwent KT for evaluation of VGI at our institution. Only patients who met the Management of Aortic Graft Infection Collaboration (MAGIC) classification for suspected or confirmed VGI were included. We investigated the concordance between KT and conventional microbiologic workup. Conventional workup (CW) included pathogen identification through blood cultures, peri-graft/graft cultures, or histopathology. Concordance was defined by identical pathogen identification on KT and CW. We examined the influence of the KT result on clinical management.Figure 1.KT Results for Confirmed and Suspected VGI. Results We identified 25 patients who met criteria for either suspected or confirmed VGI per the MAGIC criteria. Microbiology was undefined in 8 patients who had negative KT and negative CW. A total of 17 patients had positive workup with 6 having positive KT and negative CW, 3 having negative KT and positive CW, and 8 having both positive KT and positive CW (Table 1). KT was less likely to be positive for patients who met criteria for suspected infection (4/10; 40%) as opposed to confirmed infection (10/15; 66.67%), albeit non-significant (OR 0.33, p=0.188) (Figure 1). The KT led to antimicrobial de-escalation in 27.3% of patients with positive CW and 35.7% of patients with negative CW (Figure 2). Full concordance of KT and CW was noted in 3 patients (Table 2).Figure 2.Influence of KT on VGI cases with positive and negative conventional work-up. Treatment escalation was defined as the broadening of antimicrobial coverage due to KT results. Treatment de-escalation was defined as narrowing/discontinuation of antimicrobial coverage due to KT results. Conclusion We found that the positivity rate for KT was 56%. KT impacted management in 40% of cases. Patients with confirmed VGI had a higher likelihood of having a positive KT. KT was the only positive microbiological definitive test in one case. Further studies are needed to explore the utility and impact of KT in the workup of VGI. Disclosures All Authors: No reported disclosures