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Background Identifying a microorganism in patients with native vertebral osteomyelitis presents diagnostic challenges. Microorganism identification through culture-based methods is constrained by prolonged processing times and sensitivity limitations. Despite the availability of molecular diagnostic techniques for identifying microorganisms in native vertebral osteomyelitis, there is considerable variability in reported sensitivity and specificity across studies, leading to uncertainty in their clinical utility. Questions/purposes What are the sensitivity, specificity, and diagnostic odds ratios for 16S broad-range PCR followed by Sanger sequencing (16S) and metagenomic next-generation sequencing (NGS) for detecting bacteria in native vertebral osteomyelitis? Methods On June 29, 2023, we searched Cochrane, Embase, Medline, and Scopus for results from January 1970 to June 2023. Included studies involved adult patients with suspected native vertebral osteomyelitis undergoing molecular diagnostics—16S bacterial broad-range PCR followed by Sanger sequencing and shotgun or targeted metagenomic NGS—for bacteria detection. Studies involving nonnative vertebral osteomyelitis and cases of brucellar, tubercular, or fungal etiology were excluded. The reference standard for the diagnosis of native vertebral osteomyelitis was a composite clinical- and investigator-defined native vertebral osteomyelitis diagnosis. Diagnostic performance was assessed using a bivariate random-effects model. Risk of bias and diagnostic applicability were evaluated using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. After a manual screening of 3403 studies, 10 studies (5 on 16S, 5 on NGS) were included in the present analysis, from which 391 patients were included from a total of 958 patients overall. Quality assessment via QUADAS-2 criteria showed moderate risk of bias and good applicability. Results 16S showed 78% (95% confidence interval [CI] 95% CI 31% to 96%) sensitivity and 94% (95% CI 73% to 99%) specificity, whereas NGS demonstrated 82% (95% CI 63% to 93%) sensitivity and 71% (95% CI 37% to 91%) specificity. In addition, the diagnostic ORs were 59 (95% CI 9 to 388) and 11 (95% CI 4 to 35) for 16S and NGS, respectively. Summary receiver operating characteristic curves showed high test performance for 16S (area under the curve for 16S 95% [95% CI 93% to 97%] and for NGS 89% [95% CI 86% to 92%]). Certainty in estimates was moderate because of sample size limitations. Conclusion This meta-analysis found moderate-to-high diagnostic performance of molecular methods on direct patient specimens for the diagnosis of native vertebral osteomyelitis. When used as a complementary test to microbiological analyses, a positive 16S result rules in the diagnosis of native vertebral osteomyelitis, while further studies are needed to understand the role of NGS in the diagnosis of native vertebral osteomyelitis. When available, these tests should be used in addition to conventional microbiology, especially in complex cases with extensively negative standard microbiological test results, to detect fastidious bacteria or to confirm the causative bacteria when their isolation and pathogenicity are unclear. A large sample size is needed in future research to understand the use of these techniques as standalone tests for diagnosis. Level of Evidence Level III, diagnostic study.

ABSTRACT A total of 1,925 Corynebacterium isolates were tested for antimicrobial susceptibility at the Mayo Clinic Microbiology laboratory (Rochester, Minnesota) from January 2012 to March 2023, with C. striatum (35.6%) and C. amycolatum (24.4%) identified as the predominant species. Species known to potentially carry diphtheria toxin were excluded. Common sources of isolation included skin and soft tissue (56.8%), bone and/or native joint synovial fluid (14.2%), urine (13.1%), sputum (6.1%), and blood (5.9%). For penicillin, susceptibility decreased from 47.5% (58 of 122) in 2012 to 20.6% (14 of 68) in 2023. Isolates also showed a decrease in susceptibility to erythromycin from 22.4% (26 of 116) in 2012 to 13.2% (9 of 68) in 2023. Susceptibility to trimethoprim-sulfamethoxazole averaged around 50% throughout the period. Notably, linezolid and vancomycin were universally effective in vitro against all species. The highest susceptibility rates among tested oral agents were to linezolid and doxycycline for non- C . striatum species. Daptomycin minimal inhibitory concentrations (MICs) of >256 µg/mL were observed for one C. amycolatum isolate, one C. tuberculostearicum isolate, and for seven C. striatum isolates, all from patients with prior daptomycin exposure. Daptomycin MICs of 2 µg/mL (nonsusceptible) were observed in one C. striatum isolate recovered from a daptomycin-naïve patient and in six C. jeikeium isolates, from both daptomycin-exposed and non-exposed patients. Significant variation in susceptibility profiles across different Corynebacterium species underscores the importance of performing antimicrobial susceptibility testing to guide effective treatment. Moreover, multidrug resistance observed in C. striatum poses substantial therapeutic challenges especially in patients requiring prolonged or chronic antibiotic suppression.

Abstract Objective This study aimed to conduct a scoping review of machine learning (ML) techniques in outpatient parenteral antimicrobial therapy (OPAT) for predicting adverse outcomes and to evaluate their validation, implementation and potential barriers to adoption. Materials and methods This scoping review included studies applying ML algorithms to adult OPAT patients, covering techniques from logistic regression to neural networks. Outcomes considered were medication intolerance, toxicity, catheter complications, hospital readmission and patient deterioration. A comprehensive search was conducted across databases including Cochrane Central, Cochrane Reviews, Embase, Ovid MEDLINE and Scopus, from 1 January 2000 to 1 January 2024. Results Thirty-two studies met the inclusion criteria, with the majority being single-centre experiences primarily from North America. Most studies focused on developing new ML models to predict outcomes such as hospital readmissions and medication-related complications. However, there was very little reporting on the performance characteristics of these models, such as specificity, sensitivity and C-statistics. There was a lack of multi-centre or cross-centre validation, limiting generalizability. Few studies advanced beyond traditional logistic regression models, and integration into clinical practice remains limited. Discussion ML shows promise for enhancing OPAT outcomes by predicting adverse events and enabling pre-emptive interventions. Despite this potential, significant gaps exist in development, validation and practical implementation. Barriers include the need for representative data sets and broadly applicable, validated models. Conclusion Future research should address these barriers to fully leverage ML’s potential in optimizing OPAT care and patient safety. Models must deliver timely, accurate and actionable insights to improve adverse event prediction and prevention in OPAT settings.

Abstract Cardiac implantable electronic device infection in the context of corynebacterial bloodstream infection (BSI) remains poorly understood. From 2012 to 2023 at Mayo Clinic, 4 of 12 patients with corynebacterial BSI had cardiac implantable electronic device infection: 1 patient was diagnosed during a relapsing BSI episode. Undefined source, persistent BSI, and the presence of a prosthetic cardiac valve were common characteristics.

Background: While criteria for the diagnosis of nosocomial pneumonias exist, objective definitions are a challenge and there is no gold standard for diagnosis. We analyzed the impact of the implementation of a logical, consensus-based diagnostic and treatment protocol for managing nosocomial pneumonias in the cardiovascular surgery intensive care unit (CVS-ICU). Methods: We conducted a quasi-experimental, interrupted time series analysis to evaluate the impact of a diagnostic and treatment protocol for nosocomial pneumonias in the CVS-ICU. Impacts were measured relative to patient outcomes, diagnostic processes, and antimicrobial stewardship improvement. Descriptive statistics were used to analyze results. Results: Overall, 35 pre-protocol and 39 post-protocol patients were included. Primary clinical variables suggesting pneumonia in pre- and post-protocol patients were new lung consolidation (50% vs. 71%), new leukocytosis (59% vs. 64%), and positive culture (32% vs. 55%). Appropriate diagnostic testing improved (23% vs. 54%, p = 0.008) after protocol implementation. The proportion of patients meeting the criteria for nosocomial pneumonia (77% vs. 87%) was not statistically significant, though more patients in the post-protocol group met probable diagnostic criteria (51% vs. 77%). Duration of therapy was not significantly different (6 days [IQR = 5.0, 10.0] vs. 7 days [IQR = 6.0, 9.0]). Conclusions: The implementation of a diagnostic and treatment protocol for management of nosocomial pneumonias in the CVS-ICU resulted in improved diagnostic accuracy, advanced antimicrobial and diagnostic stewardship efforts, and laboratory cost savings without an adverse impact on patient-centered outcomes.

Abstract Background Recent advances in shotgun metagenomic sequencing (sMGS) for detecting microbial cell-free DNA (mcfDNA) in peripheral blood have shown promise across various patient populations. This study evaluates the application of sMGS for diagnosing osteoarticular infections (OAIs), a condition with significant diagnostic challenges. Methods We conducted a retrospective analysis on 73 patients suspected of OAIs at the Mayo Clinic from 2019 to 2023, incorporating mcfDNA sMGS (Karius test [KT]) into their diagnostic evaluation. We categorized the clinical impact of KT on OAI diagnoses and management into 4 distinct outcomes. (1) KT was able to confirm an established diagnosis, (2) KT supported noninfectious diseases diagnosis, (3) KT established an unsuspected diagnosis, (4) KT did not add relevant information. Results In our cohort, KT was performed in 73 patients. Among the infected individuals, KT yielded positive results in 22 of 43 (51.2%) cases. Of these 22 cases, 11 (50%) showed agreement with conventional diagnostic workup, whereas in 5 (22.7%) cases, the KT established an unsuspected diagnosis. Native vertebral osteomyelitis diagnosis (P < .001) or OAIs with concomitant presence of endocarditis or endovascular infection (P = .005) were statistically associated with a definite, probable, or possible diagnostic certainty of KT result. Conclusions In complex OAIs, KT enhanced diagnostic accuracy by 11.6%, proving especially beneficial in diagnosing native vertebral osteomyelitis and infections with concurrent endocarditis or endovascular complications. Our findings underscore the utility of KT in the diagnostic workflow for challenging OAI cases, potentially altering clinical management for a significant subset of patients.

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AbstractBackgroundThere are no established clinical breakpoints for antifungal agents against Cryptococcus species; however, epidemiological cut‐off values can help distinguish wild‐type (WT) isolates without any acquired resistance from non‐WT strains, which may harbour resistance mechanisms.Patients/MethodsWe describe the trends of antifungal MICs and percentages of WT C. neoformans species complex (CNSC) isolates processed in our reference laboratory from November 2011 to June 2021. There were only nine isolates in 2011, thus, we included them in the year 2012 for data analysis. Clinical data is also described when available.ResultsWe identified 632 CNSC, the majority collected from blood (n = 301), cerebrospinal fluid (n = 230), and respiratory (n = 71) sources. The overall percentage of WT isolates for amphotericin B (AMB), 5‐flucytosine, and fluconazole was 77%, 98%, and 91%, respectively. We noticed a statistically significant change in the percentage of AMB WT isolates over the years, with 98% of isolates being WT in 2012 compared to 79% in 2021 (p < .01). A similar change was not observed for other antifungal agents. Clinical data was available for 36 patients, primarily non‐HIV immunocompromised patients with disseminated cryptococcosis. There were no statistically significant differences in the clinical characteristics and outcomes between patients with WT (58.3%) versus non‐WT (41.7%) isolates, but we noticed higher mortality in patients infected with an AMB non‐WT CNSC isolate.ConclusionsWe observed an increase in the percentage of AMB non‐WT CNSC isolates in the past decade. The clinical implications of this finding warrant further evaluation in larger studies.

Abstract Background Non-diphtheriae Corynebacterium spp. are important human pathogens responsible for a broad spectrum of clinical syndromes. Data on species-specific susceptibility patterns is limited. In this study we aim to study these susceptibility patterns over time and summarize the species-specific resistance profile that could be used by clinicians to guide therapeutic decisions. Methods We conducted a retrospective review of all the Non-diphtheriae Corynebacterium isolates that were submitted for antimicrobial susceptibility testing (AST) between January-2012 and February of 2023 to our reference lab. Results A total of 1925 Corynebacterium isolates were submitted for susceptibility testing over the study period. The most commonly identified species was C. striatum (35.6%) followed by C. amycolatum (24.4%). Figure-1 outlines the species distribution. Temporal analysis showed decreasing susceptibility rates over the study period from 47.5% to 20.6% for penicillin & from 50% to 7.6% for clindamycin. Linezolid and vancomycin were universally active against all species (Table-1). Daptomycin non-susceptibility was reported in 25% of C. jeikeium isolates (MIC=2). High level resistance to daptomycin with MIC &gt;256 were noted in seven C. striatum and single C. amycolatum isolate. Doxycycline has the highest susceptibility rates among the tested oral agents after linezolid for the non-striatum species. Significant variation in species-specific susceptibility pattern was noted and summarized in Table 1. C. striatum was associated with concerning resistance rates to beta-lactams, tetracyclines, trimethoprim-sulfamethoxazole & fluoroquinolones with limited reliable oral treatment options beside linezolid. C. kroppenstedtii (associated with granulomatous mastitis) showed high susceptibility rate to tetracyclines and trimethoprim-sulfamethoxazole despite prevalent penicillin resistance. Conclusion Non-diphtheriae Corynebacterium spp are commonly isolated from clinical specimens and are associated with various clinical syndromes. Significant variation in resistance profile exists between different species. Prevalent resistance among the most common species such as C. Striatum is associated with therapeutic challenges. Disclosures Christina G. Rivera (O'Connor), Pharm.D, Gilead Sciences: Advisor/Consultant|Gilead Sciences: Board Member|Gilead Sciences: Grant/Research Support|Gilead Sciences: Honoraria Audrey N. Schuetz, MD, Merck: Advisor/Consultant