Citations

ABSTRACT Background Babesia microti , a parasite transmitted by the Ixodes scapularis tick, can cause infections ranging in presentation from asymptomatic to fulminant, life-threatening disease. Ocrelizumab, an anti-CD20 B-lymphocyte monoclonal antibody used to treat multiple sclerosis, increases the risk of severe or relapsing infections with tick-borne pathogens. In rare cases, babesiosis may trigger hemophagocytic lymphohistiocytosis (HLH). Case Summary We report a case of babesiosis manifesting in a subacute fashion with secondary HLH in a 51-year-old female on B cell-depleting therapy. She presented in December with generalized weakness and fever and was found to have pancytopenia, transaminitis, and hyperinflammatory markers consistent with HLH. A microbial cell-free DNA next-generation sequencing test detected Babesia microti , with subsequent confirmation by blood PCR and smear demonstrating <0.01% parasitemia. The patient improved following treatment with atovaquone and azithromycin, along with corticosteroids for HLH. Conclusion This case highlights the heterogeneity of babesiosis and its potential to present with minimal parasitemia, yet severe systemic inflammation in immunocompromised hosts. Additionally, this case underscores the importance of maintaining a broad differential in patients on B cell-depleting agents who present with new pancytopenia and systemic inflammatory symptoms. Early utilization of microbial cell-free DNA next-generation sequencing tests may aid in timely diagnosis and treatment.

ABSTRACT Background Cytomegalovirus (CMV) infection remains one of the most prevalent and consequential post solid organ transplant (SOT) infections. Treatment is often challenging, especially when dealing with refractory and resistant CMV infections. Methods We performed a retrospective multicenter cohort study of SOT recipients with clinically significant CMV infection (csCMVi) during 2010–2016. The primary outcome was early refractory CMV infection and secondary outcomes were drug resistance, CMV recurrence, and mortality. Analysis was done with Kaplan‐Meier, univariable logistic regression analysis, and multivariable Cox regression. Results We included 145 SOT recipients with csCMVi, majority were liver transplant (49%). Most common induction was an anti‐IL‐2 antibody (43.9%). The majority ( n = 82; 56.5%) were CMV D+/R‐ mismatch and presented asymptomatic infection (50.3%). After the initial 3 weeks of antiviral therapy, 13 (8.9%) patients had probable refractory csCMVi; most of them (10 [76.9%]) were CMV D+/R‐ mismatch. Longer time after transplant had lower risk (OR 0.68; CI 0.48–0.95, p = 0.029) while lower absolute lymphocyte count (ALC) had a higher risk of early refractory csCMVi (OR 1.54; CI 1.01–2.44, p = 0.048). Drug‐resistant csCMVi occurred in 7 patients (4.8%); a high initial CMV DNA level was associated with resistant csCMVi (OR 2.00; CI 1.08–3.93, p = 0.031). 25 patients (17.2%) experienced recurrent csCMVi within 6 months. 30 patients (20.7%) died; refractory, resistant or recurrent CMV infections were not associated with mortality. Conclusion Refractory csCMVi is associated with a low ALC and an earlier onset after transplant. Resistant csCMVi is associated with high initial CMV DNA levels. Recurrence of csCMVi is common and potentially associated with low ALC at the end of antiviral treatment.

ABSTRACT Introduction Cytomegalovirus (CMV) causes substantial morbidity after solid organ transplantation. Valganciclovir (VGCV) remains a first‐line prophylactic agent, but it has significant myelosuppressive effect. Letermovir is approved for CMV prophylaxis in high‐risk kidney transplant recipients, but data on its use outside of that population are limited. We describe characteristics and outcomes of letermovir prophylaxis in non‐kidney transplant recipients. Methods We performed a retrospective, multi‐center study of all adult non‐kidney solid organ transplant recipients (SOTr) who received letermovir (March 2018–June 2024) for CMV prophylaxis. Outcomes included breakthrough and post‐prophylaxis delayed‐onset CMV infections, adverse events, and survival. Results A total of 64 patients were included in the final analysis. Of those, letermovir was used for primary prophylaxis in 56.2% of patients, while the remainder received it for secondary prophylaxis. The main rationale behind selecting letermovir was myelosuppression related to VGCV. During the median follow‐up of 361 days (IQR, 190–536), 40.6% remained on letermovir (median, 387 days); 25.0% completed prophylaxis (median, 116 days); and 34.3% discontinued prematurely (median, 49 days), mainly for cost barriers or adverse effects. Breakthrough infections occurred in 9 patients (14.1%), but only three (4.7%) were clinically significant. After stopping letermovir, 39.5% (15/38 among those who discontinued letermovir) developed post‐prophylaxis delayed‐onset CMV infection. Overall survival was 81.2%; there was one death attributed to CMV. Conclusion In this cohort of non‐kidney solid organ recipients, letermovir was well tolerated with low rates of clinically significant breakthrough infections. Early discontinuation was commonly cost‐driven. Post‐prophylaxis delayed‐onset CMV infections remain common. Large‐scale registry studies are needed to provide evidence for use of letermovir in non‐kidney transplant recipients.

Abstract Background Catheter-associated urinary tract infection (CAUTI) is one of the most prevalent nosocomial infection reported and is associated with significant resource expenditure across health care facilities. Methods We conducted a retrospective review of newly catheterized patients at a tertiary hospital over 12-months period. Demographic, clinical, and diagnostic data were collected. Based on the National Health Safety Network (NHSN) criteria, patients were divided into two groups: health care associated infection (HAI) and criteria not met (CNM). Outcome measures included secondary bloodstream infections, hospital re-admission, death, and microbiological relapse at 30 days of hospital discharge. These outcomes were compared between groups. Results A total of 314 patients were identified, of whom 55 (17.5%) met the criteria for HAI. Demographic, clinical and microbiological data are summarized in Tables 1-3. In comparison to the CNM group, the HAI group showed higher rates of fever, urinary frequency, bladder pain or tenderness, costovertebral angle tenderness, positive blood cultures, growth of urinary microorganisms &gt;100,000 colony forming units (CFU), and imaging evidence of infection (p&lt; 0.01). Blood stream infections were observed in 20 (6.6%) patients, with 12 of these in the HAI group, and were attributed to a urinary source in 7 cases. Composite outcomes were affected by fever (p&lt; 0.01), imaging evidence of infection (p&lt; 0.01) and presence of renal abscess, whereas the age of catheter, dysuria, bladder tenderness, urinary frequency, urinary CFU threshold didn't achieve statistical significance. After adjusting for the Charlson Comorbidity Index, the HAI group showed higher rates of re-occurrence of blood stream infections, re-admission and mortality within 30 days (Table 4). Conclusion Fever, imaging evidence of infection, and renal abscess were significant predictors of adverse composite outcomes, whereas catheter age, dysuria, bladder tenderness, urinary frequency, and urinary CFU threshold were not. Refinement of the NHSN surveillance definition of CAUTI may enhance targeted resource allocation for prevention efforts. Disclosures All Authors: No reported disclosures

Abstract Background Cytomegalovirus (CMV) infection remains one of the most prevalent and important infections following solid organ transplant (SOT). Treatment is often challenging, especially when dealing with refractory and resistant CMV infections.Table 1:Univariable logistic regression analyses of associations with early refractory CMV infectionTable 2:Univariable logistic regression analyses of associations with resistant CMV infection Methods We performed a retrospective cohort study of SOT recipients with clinically significant CMV infection (csCMVi) at a tertiary transplant center in the US during 2010-2016. The primary outcome was early refractory CMV infection and secondary outcomes were drug resistance, CMV recurrence, and mortality. Kaplan-Meier estimation, univariable logistic regression analysis, and multivariable Cox regression were used for outcome analysis.Table 3:Multivariable Cox regression analysis of associations with recurrent CMV infection after primary treatment endedNote: Refractory CMV was not included in the model for recurrent CMV as no patients with refractory infection had recurrence. Results A total of 145 SOT recipients with csCMVi were included. Most patients were recipients of liver (49%), followed by kidney (22.1%), heart (6.9%), lung (5.5%), and pancreas (4.1%). Multiple organ transplants accounted for 12.4% of the cohort. Most common induction was an anti-IL-2 antibody (43.9%) followed by ATG (29.5%). 82 (56.5%) had CMV D+/R- mismatch. In total, 34 (23.4%) had CMV syndrome, 38 (26.2%) had tissue-invasive CMV disease, while the rest (50.3%) were asymptomatic. After the initial 3 weeks of antiviral therapy, 13 (8.9%) patients had probable refractory csCMVi; most of them (10 [76.9%]) were CMV D+/R- mismatch. Longer time after transplant had lower risk (OR 0.68; CI 0.48-0.95, p=0.029) while lower absolute lymphocyte count (ALC) was higher risk of early refractory csCMVi (OR 1.54; CI 1.01-2.44, p=0.048) (Table 1). Drug-resistant CMV occurred in 7 patients (4.8%); a high initial CMV DNA level was associated with resistant csCMVi (OR 2; CI 1.08-3.93, p=0.031) (Table 2). Of 144 patients with post-treatment follow-up, 25 (17.2%) experienced recurrent csCMVi within 6 months. Table 3 shows the associations with recurrence of csCMVi after initial treatment. 30 patients (20.7%) died during a median follow-up of 4 years, but refractory, resistant or recurrent CMV were not associated with mortality. Conclusion Refractory csCMVi is associated with low ALC and an earlier onset post-transplant. Resistant csCMVi is associated with high levels of initial CMV DNA. Recurrence of csCMVi is common and possibly associated with low ALC at the end of antiviral treatment. Disclosures All Authors: No reported disclosures

Abstract Advocacy has long been at the core of the infectious diseases (ID) field, with clinicians and researchers advocating to ensure patients can access the care they need on an individual and global scale. The Infectious Diseases Society of America Training Program Directors’ (PD) Committee met in 2024 and discussed ways that advocacy is and should be incorporated into fellowship training, as well as highlighted the role PDs play in advocating for their trainees. Policies with a negative impact on ID clinical care, public health, and research underscore the importance of mobilizing the field of ID to advocate for the patients and communities we serve, as well as for ourselves. This paper presents ideas generated at this meeting and is meant to serve as a reference for ID PDs, as well as the wider ID community, as a call to action for teaching and participating in advocacy work.

ABSTRACT Purpose The purpose of this study was to evaluate the incidence and risk factors for developing recurrent clinically significant cytomegalovirus infections (csCMVi) in heart transplant recipients. Methods We conducted a retrospective cohort study involving adult heart transplant recipients at three large transplant centers in the United States between January 2011 and March 2019. All patients with a history of csCMVi, defined as CMV disease or CMV infection requiring preemptive therapy, were followed from the date of treatment completion for the primary csCMVi episode. Outcomes of interest were recurrent csCMVi and all‐cause mortality. Results Among 98 heart transplant recipients with csCMVi, 22 (22.4%) episodes of recurrent csCMVi occurred. Median time‐to‐recurrent csCMVi was 31.5 (IQR 21.3–59.8) days following treatment completion. A preceding episode of CMV disease (versus infection) was associated with a lower risk of recurrent csCMVi (HR 0.29, 95% CI 0.08–0.98; p = 0.047). Patients with lymphopenia had higher rates of recurrent csCMVi without statistical significance (HR 2.13, 95% CI 0.88–5.13; p = 0.093). Seroconversion by the end‐of‐therapy among CMV D+/R− mismatched patients was associated with a reduced risk of csCMVi recurrence (HR 0.07, 95% CI 0.02–0.30; p < 0.001). Overall, 17 (17.3%) patients died during follow‐up, which was not significantly higher among those with recurrent csCMVi (HR 2.13, 95% CI 0.78–5.79; p = 0.141). Conclusions About one in five heart recipients with csCMVi developed post‐treatment recurrence. A preceding episode of CMV disease and seroconversion was protective against recurrence. Lymphopenia may be a practical biomarker to stratify recurrence risk. Overall, recurrent csCMVi was not significantly associated with mortality.

Abstract Background The underlying cause of fever of unknown origin (FUO) remains unidentified in up to 51% of cases despite systematic evaluation. Microbial cell-free DNA next-generation sequencing (mcfDNA-NGS) offers an agnostic, noninvasive approach to pathogen identification, but the utility and clinical impact of this assay in FUO remain unknown. Methods This retrospective cohort study evaluated adult patients referred for FUO evaluation at a tertiary medical center between November 2019 and November 2023. Patients underwent both standard microbiologic testing (ST) and mcfDNA-NGS. Diagnostic impact was assessed in 4 domains: new diagnoses, earlier time to diagnosis, avoidance of invasive procedures, and non-hypothesis-driven diagnoses. Logistic regression was used to identify predictors of positive mcfDNA-NGS testing. Results Among 176 patients, mcfDNA-NGS was positive in 44.3%, with 49% of these cases considered clinically significant. Infectious cause of FUO was identified in 39% of patients, noninfectious in 35%, and unknown in 26%. mcfDNA-NGS contributed to a positive diagnostic impact in 30% of cases, mainly by earlier diagnosis (16%) and potential for avoidance of invasive procedures (10%). Positive mcfDNA-NGS was significantly associated with higher Charlson comorbidity index score (odds ratio [OR], 1.22; P &lt; .001) and white blood cell (WBC) count ≤4.5 × 109 cells/L (OR, 8.61; P &lt; .001). Conversely, FUO without localization was associated with a decreased likelihood of positive mcfNDA testing (OR, 0.18; P &lt; .001). Conclusions mcfDNA-NGS effectively complements ST in diagnosing FUO, providing earlier detection and minimizing invasive testing. Clinical predictors such as high comorbidity and low WBC count may guide the optimal use of mcfDNA-NGS in FUO. Prospective evaluation of optimal timing and use of mcfDNA-NGS and cost-benefit analysis in FUO is needed.

Abstract Background HIV prevention continues to be a care gap in developing countries, like Dominican Republic. The lack of sufficient programs for prescription and information of general populations are barriers for better control of HIV infection in this country. The knowledge of HIV prevention strategies such as Pre-Exposure Prophylaxis (PrEP) or Post-Exposure Prophylaxis (PEP) among medical professionals and medical students is unknown. The goal of ending HIV Pandemic by 2030 is to rely on prevention strategies. Our study aims to determine the level of knowledge of medical students in a pre-preclinical cycle and in a clinical cycle regarding HIV/AIDS, PrEP and PEP Methods We survey medical students in the Dominican Republic to measure knowledge on HIV, PrEP/PEP. We compared mean knowledge for each topic based on a score out of 10. We analyzed mean scores by using T-Tests and ANOVA with Post Hoc or Tukey Analysis, assuming significance when p&lt; 0.05. Results A total of 503 students participated in the survey. ANOVA results showed that there was a statistically significant difference in mean knowledge scores for HIV, PEP, and PrEP (F (2, 1506) = [196.6], p &lt; 0.001). Post hoc analysis revealed that medical students had a higher mean score for HIV knowledge (M= 8.9) than mean scores for PrEP (M= 7.6, p&lt; 0.01) and PEP (M= 7.1, p&lt; 0.01). Similarly, the difference in knowledge scores for PrEP was significantly higher than for PEP (p&lt; 0.01). We further divided participants into Preclinical Years and Clinical years and found that participants within the Clinical Years of Med School had a significantly increased mean PEP knowledge (m= 7.5) than Preclinical Years participants (m= 6.7) (t (460) = 5.8, p&lt; 0.001). Similar results were not appreciated with PrEP, where Clinical year participants had a non-significant increased mean knowledge (m=7.8) compared to their counterparts (m= 7.5) (t (486) = 1.4, p= 0.79). Conclusion Our findings might suggest that medical students acquire more knowledge about PEP as they progress into clinical training, but that PrEP knowledge may be emphasized equally in both pre-clinical and clinical training. Further studies should focus on identifying points for improvement and implementing strategies to tackle barriers. One of several limitations of this study is a response bias. Disclosures All Authors: No reported disclosures

Abstract Background Antimicrobial resistance (AMR) is a threat to healthcare, and infections with antimicrobial resistant organisms carry significant morbidity and mortality. Owing to high rates of AMR, the Centers for Disease Control and Prevention listed Acinetobacter baumannii as a top priority pathogen for research and development of new antimicrobial agents. Antimicrobial susceptibility testing is challenging for this organism, and susceptibility profiles are variable, leading to need of a potential guidance document with assistance in selecting effective empiric therapeutic regimens. Methods We retrospectively reviewed the microbiology and antimicrobial susceptibility testing (AST) results for Acinetobacter spp. from blood culture isolates submitted to Mayo Clinic Laboratories from December 2012 to 2022. AST was performed using agar dilution and interpretations following Clinical & Laboratory Standards Institute (CLSI) guidelines. Isolates were identified by MALDI mass spectrometry and/or 16S sequencing, as available (Figure 1).Figure 1:Isolate identification Isolate identification description. Isolates were analyzed based on this classification used in out laboratory. Results 804 blood culture isolates were included. A. baumannii/calcoaceticus complex (27%) was most frequently isolated, followed by A. lwoffii (22%), and showed the highest resistance across all antimicrobials (73% susceptible or below) (Figure 2). A. baumannii/calcoaceticus complex showed rising resistance rates over time from 2012 to 2022 for meropenem, minocycline and ampicillin-sulbactam (Figure 3). Cefiderocol non-susceptible rate was 35% for A. baumannii/calcoaceticus complex.Figure 2:Antimicrobial susceptibility profiles for Acinetobacter spp. Description of susceptibility profiles for Acinetobacter spp. isolates, based on the classification used by our laboratory. Antimicrobials are presented at the top and isolates on the left. Number of isolates analyzed are presented in the table with the percentage of the isolates susceptible to each antibiotic class in parenthesis.Figure 3:Acinetobacter baumannii/calcoaceticus complex isolates and resistance, trend Trend of isolates per year and resistance percentage to meropenem, colistin, minocycline and amp-sulb. Number of isolates per year at the base of each bar; percentage of resistance for antimicrobials expressed on lines. Amp-sulb = ampicillin-sulbactam. Conclusion A. baumannii/calcoaceticus complex showed high levels of resistance ( &gt;75%) across multiple antimicrobials and increasing rates of resistance over time from 2012 to 2022. A high number of cefiderocol non-susceptible organisms is also concerning (Figure 2). Disclosures Audrey N. Schuetz, MD, Merck: Advisor/Consultant