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Background: There are limited oral treatment options available for resistant Gram-negative bacterial (GNB) infections. Minocycline, a second-generation tetracycline antibiotic, offers good bioavailability and broad-spectrum coverage that may be an option for GNB infections. Methods: We conducted a retrospective review of minocycline susceptibility testing performed on GNB isolates at the Mayo Clinic reference lab between 2013 and 2022. Minocycline susceptibility was evaluated with a focus on difficult-to-treat organisms and relevant anatomic source. Organisms included resistant isolates of Escherichia coli and Klebsiella pneumoniae ; high-risk ampC-derepressors, including Citrobacter freundii, Enterobacter cloacae, and K. aerogenes; and clinically challenging non-Enterobacterales, Acinetobacter species, Achromobacter species, and Stenotrophomonas maltophilia . Results: Of 217,206 GNB isolates, 18,148 Enterobacterales (EB) and 8,190 non- Enterobacter isolates were tested for minocycline susceptibility. Of these, 80% of all EB and 92% of non-EB isolates were susceptible. Among E. coli isolates with ceftriaxone, ciprofloxacin, meropenem, or multidrug resistance, minocycline susceptibility was 78%, 76%, 70%, and 70.9%, respectively. Among the K. pneumoniae isolates with ceftriaxone, ciprofloxacin, meropenem, or multidrug resistance, minocycline susceptibility was 46%, 38%, 37%, and 39.3%, respectively. 85% of C. freundii , 81% of E. cloacae, and 85% of K. aerogenes isolates were susceptible to Minocycline. 83.5% of Achromobacter species isolates, 66% of Acinetobacter species isolates, and 99.1% of S. maltophilia isolates were susceptible. Conclusions: Our study reports the largest collection of minocycline susceptibility findings in GNB. Minocycline showed in vitro activity against many difficult-to-treat GNB isolates, including ceftriaxone- and multidrug-resistant E. coli and some K. pneumoniae isolates, common Amp-C-producing species, and non-fermenting GNB, including Stenotrophomonas , Acinetobacter , and Achromobacter .

Abstract The practice patterns of fluorine 18–labeled fluorodeoxyglucose positron emission tomography/computed tomography ([18F] FDG PET/CT) use in cardiac implantable electronic device infection remain undefined. Among 258 Emerging Infections Network respondents, 69% reported never or rarely using [18F] FDG PET/CT. Limited access and insurance barriers were the most common obstacles.

Abstract Background Intravesical Mycobacterium bovis bacillus Calmette-Guérin (BCG) is standard therapy for high-risk nonmuscle-invasive bladder cancer. However, M bovis infections can occur and are not well understood. We aimed to characterize clinical phenotypes, diagnosis, management, and outcomes of culture-confirmed M bovis BCG infections following intravesical therapy for urothelial carcinoma. Methods A retrospective single-center review of adults with culture-confirmed M bovis infection after intravesical BCG (May 2009–July 2024) was conducted, abstracting clinical, microbiologic, treatment, and outcome data. Results Twenty-two White male patients (median age, 77 years) were included; 8 (36.4%) had localized genitourinary infection, 6 (27.3%) had dissemination limited to blood, and 8 (36.4%) had dissemination to other organs. Patients with bloodstream-only infection presented acutely (median 1.5 days after last BCG), whereas those with localized or organ-disseminated disease presented months to years after BCG, with the longest diagnostic delays in organ-disseminated infection. Despite all cases had culture-proven M bovis BCG infection, acid-fast smear, Mycobacterium tuberculosis complex polymerase chain reaction, and histopathology had limited sensitivity. All isolates were susceptible to rifampin, isoniazid, and ethambutol; all were resistant to pyrazinamide. Median treatment duration exceeded 9 months, 94.7% achieved cure, and attributable mortality was 5.0% (1 vascular graft infection). Conclusions M bovis BCG infections following intravesical therapy have favorable outcomes but are often associated with diagnostic delays and prolonged treatment. Early suspicion, comprehensive diagnostic evaluation, and timely surgical source control when indicated are critical. Management strategies should be tailored based on the extent of disease dissemination and individual host factors.

Abstract Patent foramen ovale (PFO) has a prevalence of approximately 25%. Its association with pyogenic brain abscess (PBA) is unclear. We reviewed adults with PBA and known PFO status from 1 January 2009 through 31 December 2021 at Mayo Clinic. High PFO prevalence (40.5%) was seen. PBA patients with PFO had distinct abscess characteristics but unchanged 1-year, all-cause mortality.

Abstract Background Adenovirus is a ubiquitous dsDNA virus with potential for end-organ disease. End-organ or disseminated adenoviral disease (EOD) occurs more frequently in hematopoietic stem cell transplant (HSCT) and solid organ transplant (SOT) recipients. We aim to characterize the clinical manifestations and outcome of adenovirus viremia in adults, including HSCT and SOT recipients. We describe severity of illness, organ-involvement, and graft and patient survival. Methods This retrospective, multi-site, study enrolled adults patients with positive adenovirus PCR in blood and other clinical specimens from January, 2010 through April, 2025. We excluded patients with insufficient medical records, follow up less than 30 days, and isolated conjunctivitis without viremia. EOD was defined by the presence of clinical signs or symptoms consistent with organ involvement, confirmed by a positive adenovirus PCR or by histopathology. Descriptive and comparative statistics were performed using R. Results Fifty patients with adenovirus viremia were included in this study. The most common immunocompromising conditions were corticosteroid use (84%, n = 42), HSCT (40%, n = 20) and SOT (34%, n = 17) (Table 1). Only 3 patients (6%) had no known immunocompromising condition. 20 patients (40%) had EOD while 30 patients (60%) had isolated viremia. Lungs were the most affected organ, followed by the gastrointestinal tract and liver (Figure 1). EOD was more prevalent in older patients (60 vs. 41 years, p =0.03) and in those with higher initial plasma viral load (673364 vs. 6593, p=0.005). The most common treatment was reduction in immunosuppression (Table 2). Cidofovir was more often used in patients with EOD. Adenovirus-related outcomes were worse in patients with EOD [higher rates of mortality (45% vs. 13.3%) and ICU admission (60% vs. 20%)] vs. without EOD (Table 3). Conclusion Adenovirus viremia is associated with high mortality in a cohort of mostly immunocompromised adults, particularly those with EOD. Older age and a higher initial plasma viral load are associated with EOD. Patients with EOD had worse clinical outcomes such as ICU admission and adenovirus-related mortality. Disclosures All Authors: No reported disclosures

Abstract Background Persistent candidemia (PC) occurs in a minority of Candida bloodstream infections (BSIs) but is associated with increased morbidity. Comparative data on patient profile, species distribution and outcomes are limited.Table 1Clinical profile and outcomes of patients with persistent candidemia in the primary study cohort. ANC = absolute neutrophil count. SD = standard deviation.Table 2Comparative analysis of persistent candidemia and non-persistent candidemia cases. Methods All candidemia episodes at three academic medical centers (2018-2025) were reviewed. Persistence was defined as ≥72 hours of positive blood cultures after appropriate antifungal initiation. Each PC case was matched 1:2 to non-PC controls who survived ≥72 hours. Demographics, Charlson Comorbidity Index (CCI), Candida species distribution, and outcomes were used for comparative analysis. Continuous variables were summarized as median (interquartile range [IQR]) and compared with Wilcoxon rank-sum, while categorical data (n%) were analyzed by Fisher’s exact test (species by χ²), yielding odds ratios (ORs) with 95% confidence intervals (CIs). Two-tailed p < 0.05 denoted significance. Results Each PC case (n = 46) was matched 1:2 to non-PC controls (n = 92). Clinical profiles and outcomes of PC cases are presented in Table 1. Most PC patients (54.3%) had an immunocompromising condition, and non-urinary intra-abdominal sources were the most frequently suspected infection source (21/46; 45.7%). All but one of 46 PC cases had antibiotic exposure within the preceding 90 days. Comparative demographics and outcomes for PC cases and non-PC controls are displayed in Table 2. PC patients were younger (median 62 yr, IQR 45–69 vs 68 yr, 57–76; p = 0.01), more often female (59% vs 30%; OR 3.3, 95% CI 1.5–7.1; p = 0.002), and had higher comorbidity (CCI 5, IQR 3–8 vs 3, 1–4; p < 0.001). Species distribution differed (χ² p = 0.04), driven by C. guilliermondii over-representation in PC cases (9% vs 0%) (Figures 1 and 2). Hospital stay was longer in PC cases (median 36 d, 24–54 vs 16 d, 8–28; p < 0.001) and time from admission to first culture greater (12 d, 3–26 vs 3 d, 1–10; p = 0.003). 90-day mortality was 54.3% (25/46) in PC cases versus 31.5% (29/92) in controls (OR 2.57, 95% CI 1.17–5.71; p = 0.016). Conclusion In this 7-year multicenter study, there were significant differences in demographics, microbiology, and clinical outcomes between PC and non-PC cases, including higher short-term mortality rates with PC in univariate analysis. Disclosures Paschalis Vergidis, MD, MSc, Current Fungal Infection Reports: Honoraria|F2G: Grant/Research Support|Merck Manuals: Honoraria|Mundipharma: Grant/Research Support|Scynexis: Advisor/Consultant|Scynexis: Grant/Research Support

Abstract Background Outpatient parenteral antimicrobial therapy (OPAT) is effective and cost-efficient, but 12%–63% of patients experience adverse events, requiring close monitoring. Therapeutic drug monitoring (TDM) is routinely used for vancomycin and aminoglycosides but is underutilized for beta-lactams (BLs) due to limited access, logistical barriers, and clinician inexperience. This study evaluated its use and clinical impact within a high-volume OPAT program. Methods This retrospective, single-center cohort included adult patients (≥18 years) enrolled in an OPAT program who received cefepime (CEF), piperacillin/tazobactam (TZP), or meropenem (MEN) and underwent BL TDM between April 2023 and April 2025. BL TDM was not protocolized within the OPAT program; however, institutional guidance supported its use in carefully selected patients. We aimed to describe TDM indications, lab trends, microbiological profiles, and the impact of TDM on treatment. Results During the study period, 25 OPAT patients underwent BL TDM. TDM was performed in patients receiving CEF (64%), TZP (20%), and MEN (16%). The most common indication for TDM was suspected beta-lactam toxicity (32%) (Figure 1). Post-TDM therapy adjustments were made in 52% (n = 13), including changes in dosing frequency (38.5%) and dosage strength (30.8%). Additional changes included infusion strategy modification or agent substitution (15.4% each). Subtherapeutic levels were the most common reason for adjustment (46.2%), followed by adverse effects, supratherapeutic levels, and changes in renal function (23.1% each). Skin, soft tissue, and musculoskeletal infections were most common (Figure 2). Positive cultures were present in 80%, with Pseudomonas spp most frequently isolated. Therapy was completed in 17 patients; 7 discontinued early, and 1 had treatment ongoing. Reasons for therapy discontinuation are detailed in Table 1. Conclusion BL TDM is contributing to a paradigm shift in OPAT practice by improving both efficacy and safety. While inpatient TDM typically targets efficacy, safety concerns more commonly motivate TDM in the OPAT setting. Although this review involved a small cohort, our experience adds to the growing body of evidence supporting BL TDM as a tool to enhance patient outcomes in the OPAT setting. Disclosures All Authors: No reported disclosures

Abstract Background Leishmaniasis is a rare protozoan parasitic disease transmitted through the bite of infected Phlebotomus and Lutzomyia sandflies. Clinical presentation is variable due to numerous species and host immunity differences. We present our clinical experiences with CL to guide timely diagnosis and treatment in returning travelers. Methods We retrospectively analyzed a cohort of adult patients 18+ years old who were diagnosed with CL from 2005 and 2025. We describe the demographic, clinical, and diagnostic features of CL. Results Biopsy-confirmed CL was diagnosed in 20 returning travelers (Table 1) from various endemic regions, most commonly Costa Rica (Fig. 1). The median time from travel to symptom onset was 36.5 days (SD 102), with an additional 75.5 days (SD 87) prior to biopsy diagnosis. All patients were evaluated by dermatology and 70% were evaluated by infectious disease (n=14). On initial presentation, lesions were described as ulcerated (50%, n=10), nodular (30%, n=6), painful (20%, n=4), and necrotic (10%, n=2; Fig. 2). Most lesions were located on the upper extremity (55%, n=11), followed by the face (35%, n=7), lower extremity (30%, n=6), and trunk (15%, n=3). 15% of individuals (n=3) had constitutional symptoms. No patients had definitive mucosal involvement, however, 10% (n=2) endorsed lip edema. No patients had visceral involvement. Species level identification occurred in 14 cases (70%), of which the most common was L.V. panamensis (50%), L.L. mexicana (21%), L. V. guyanensis (14%), L. L. tropica (7%), and L. V. braziliensis (7%). Initial treatments included azoles, liposomal amphotericin B (AmBisome), and miltefosine (each 20%); cryotherapy and parenteral pentamidine (each 10%); with compounded topical paromomycin added in 15% of cases. 35% of individuals (n=7) failed initial treatment and required additional treatment courses due to persistent lesions (57%) or relapse following initial resolution (14%). 10% (n=2) required a third treatment course due to persistent/recurrent lesions. Conclusion While CL in travelers has a variety of clinical manifestations, travel history, knowledge of key clinical features, and lesion patterns can aid in early diagnosis and treatment. CL is associated with early treatment failure rate for uncertain reasons. Disclosures All Authors: No reported disclosures

Abstract Background Good syndrome (GS) is an under-recognized adult-onset immunodeficiency characterized by the coexistence of thymoma and hypogammaglobulinemia. It is marked by recurrent infections, combined B- and T-cell immunodeficiency, and frequent autoimmune manifestations. Its rarity, unclear pathogenesis, and often delayed diagnosis contribute to its clinical complexity.Distribution of Infections by pathogen type in patients with Good Syndrome: the microbiological spectrumDemographics, clinical characteristics, thymoma classification with staging and management Methods We conducted a retrospective review of adults diagnosed with good syndrome at Mayo Clinic up until 2024. We assessed baseline characteristics, clinical features with a particular focus on infectious complications, immunological lab parameters, thymoma histopathology with staging, and management. Descriptive statistics were utilized for analysis.Immunological lab parameters and management of Good syndrome Results During the study period, Good syndrome was diagnosed in 32 patients; 78% were male, with a median age at diagnosis of 62 years (Table 1). All patients had thymoma, the majority of which were stage I (localized), and most underwent thymectomy as part of management. The median delay in GS diagnosis following thymoma diagnosis was 1,486 days (interquartile range IQR: 406.75–1,992.75). Infectious complications were observed in 30 of 32 patients (97%), most commonly sinopulmonary infections (87%) (Figure 1). Bacterial infections were documented in 29 patients (94%), viral in 14 (45%), fungal in 13 (42%), and mycobacterial in 3 (10%) (Figure 2). Immunologic data were available for 22 patients. Reduced CD4+ T-cell counts and severe B-cell lymphopenia were observed in 77%. IgM and IgG deficiencies were the most prevalent, present in 82% of cases. Most patients received monthly immunoglobulin replacement; additionally, 59% were prescribed oral antimicrobial prophylaxis due to their elevated risk of infections. All-cause mortality was 31% (n=10); among these, 3 deaths (10%) were directly attributable to complications of Good syndrome. Conclusion We observed a significant delay (Median of 4.07 years) in the diagnosis of Good syndrome following thymoma detection. Given the high risk of infectious complications and associated mortality, clinicians should maintain a high index of suspicion and consider early immunologic evaluation in adults with recurrent or opportunistic infections, particularly in the context of a known thymoma. Disclosures All Authors: No reported disclosures

Abstract Background Beta-lactam pharmacokinetics can be significantly altered in patients with malignancy. Therapeutic drug monitoring (TDM; i.e., drug level testing) may facilitate pharmacokinetic/pharmacodynamic (PK/PD) target attainment, but the data are limited. This study aimed to characterize PK/PD target attainment of anti-pseudomonal beta-lactams in hematology/oncology patients.Table 1:Case DescriptionGraph 1:Distribution of Beta-Lactam TDM Indications Methods We conducted a retrospective review of beta-lactam TDM performed between June 2022 and June 2024 in hospitalized adults with hematologic or solid organ malignancies. We included patients who underwent beta-lactam TDM during clinical care, typically for extracorporeal membrane oxygenation (ECMO), extremes of body weight, suspected augmented renal clearance, multidrug-resistant infection, or suspected dose-dependent beta-lactam toxicity. Primary outcomes were (1) the proportion achieving target beta-lactam concentrations and (2) the proportion undergoing antibiotic dose adjustment based on TDM results.Table 2:Institutional Dosing Guidelines Results There were 47 TDM episodes in 20 unique patients. Considering only the first TDM per patient, 10 (50%) patients achieved target concentrations, 2 (10%) were below target, and 6 (30%) were above target. Antibiotic dose adjustments were made in 8 (40%) patients in response to TDM results. The most common indication for beta-lactam TDM was concerns regarding accurate renal clearance, followed by extremes of weight. Conclusion Retrospective findings suggest that beta-lactam TDM facilitated individualization of therapy in 40% of patients with either hematological or solid organ malignancy, with dose adjustments often intended to improve antibiotic safety. Future studies should refine the criteria for beta-lactam TDM use in this population and determine the need for tailored PK/PD targets in patients with impaired host response to infection. Disclosures All Authors: No reported disclosures