Thoendel, Matthew

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 VEXAS is a relatively newly described immunocompromising condition with hematopoietic stem cell transplant increasingly being used. Little is known regarding infections in this high‐risk population. Methods We conducted a retrospective review of ten adult patients diagnosed with VEXAS who underwent HSCT in the Mayo Clinic Rochester and the Arizona medical record system. Results Nine out of ten individuals developed bacterial infection with bacteremia found in eight individuals despite being on prophylaxis at the time of infection. Six of the ten individuals were found to have viral infection; there were no documented invasive fungal infections and only one individual had a parasitic infection. Conclusion Providers should have a high suspicion for infection, especially bacterial, in this patient population, regardless of prophylaxis use. Patients should also be educated on signs and symptoms of infection.

AbstractIntroductionCytomegalovirus (CMV) reactivation is one of the most common complications after allogeneic hematopoietic stem cell transplantation (HSCT). Letermovir is approved for CMV prophylaxis among high‐risk recipients. However, delayed‐onset post‐prophylaxis clinically significant CMV infection (csCMVi) has been observed, suggesting the potential for extending letermovir prophylaxis beyond the first one hundred days post‐HSCT.MethodsRetrospective multicenter cohort study of allogeneic HSCT patients from August 2018 to March 2023. The primary aim of this study was to identify the risk factors at day 100 associated with delayed onset csCMVi, in patients who received letermovir prophylaxis up to day 100. Competing risk analysis was used to evaluate incidence with specific risk factors, using Gray's Test comparing groups for each event.ResultsAmong 166 eligible allogeneic HSCT recipients, the most common primary hematological diagnosis was acute myelogenous leukemia (AML) (42.2%). Twenty‐six (15.7%) developed a breakthrough csCMVi. Delayed‐onset csCMVi occurred in 23.5%, at a median time of 133 days after SCT. On multivariate analysis, having a matched unrelated donor (odds ratio [OR] 2.46) and a CMV donor negative/recipient positive status (OR 3.47) were associated with delayed onset csCMVi. In contrast, AML had a lower odd of having delayed‐onset csCMVi (OR 0.23).ConclusionsHaving a matched unrelated donor, a CMV donor negative/recipient positive status, and a non‐AML underlying disease were associated with delayed onset csCMVi. Prospective studies are needed to evaluate whether extended letermovir prophylaxis is beneficial for these patients. image

Abstract Background Letermovir (LTMV) is approved for CMV prophylaxis during the first 100 days after HSCT. Thereafter, CMV reactivation (CMVr) may still occur. This study aims to evaluate the incidence and risk factors for any CMVr and clinically significant CMV infection (csCMVi) in patients who received LTMV prophylaxis. Methods Retrospective multicenter cohort study of HSCT patients who received 100 days of LTMV prophylaxis from 08/2018 to 09/2022. Categorical and continuous variables were compared with Fisher’s exact and Kruskal-Wallis test respectively. Logistic regression was used to identify risk factors. Results Of 115 HSCT patients, 28 had CMVr after LTMV prophylaxis (Table 1), including 21 with csCMVi (Table 2). Of note, 29 (25.2%) patients had breakthrough CMV during LTMV prophylaxis. Among 28 cases of post-LTMV CMVr, DNAemia occurred with a median of 38.5 (31.3 – 47) days after stopping LTMV. The median absolute lymphocyte count (ALC) at diagnosis was 1.29 (0.41 – 2.04) x109cells/L. Median peak CMV DNAemia at was 482 (100.5 – 2600) IU/mL, with a duration of 29 (20- 35) days; none had end organ disease. All were receiving immunosuppression for graft-versus-host disease treatment (n=18) or prophylaxis (n=10). Risk factors for CMVr and csCMVi are listed in Table 3. For CMVr, univariate analysis showed that CMV D-/R+ status is associated with increased risk, while having CMV D+ donors or acute myeloid leukemia (AML) had lower risk. Multivariable analysis showed D-/R+ status and breakthrough viremia while on LTMV were associated with increased risk. csCMVi in 21 patients were treated with valganciclovir (n=15) or IV ganciclovir (n=6) for a median duration of 37 (25.5 – 50) days. Univariate analysis showed that acute lymphoblastic leukemia (ALL) and reduced intensity conditioning were associated with increased risk, while AML had lower risk of csCMVi. On multivariable analysis, ALL, and D-/R+ had higher risk while AML had lower risk. Demographics and clinical characteristics of allogeneic hematopoietic stem cell recipients with or without late clinically significant CMV infection Conclusion One in four allogeneic HSCT patients who received LTMV developed post-prophylaxis CMVr within 100 to 200 days post-transplant. CMV D-/R+ status had a higher risk for CMVr and csCMVi after LTMV discontinuation. Patients with AML had a lower risk for CMVr and csCMVi. Disclosures Raymund R. Razonable, MD, Allovir: Endpoint Adjudication Committee|American Society of Transplantation: Board Member|Gilead: Grant/Research Support|Novartis: DSMB|Regeneron: Grant/Research Support|Roche: Grant/Research Support

Abstract Background Next-generation sequencing (NGS) is increasingly used for periprosthetic joint infection (PJI) diagnosis, but its clinical utility is poorly defined. Shotgun metagenomic sequencing (sNGS) has been reported to identify PJI pathogens undetected by culture in sonicate fluid. However, sNGS is complex and costly. Here, 16S ribosomal RNA (rRNA) gene-based targeted metagenomic sequencing (tNGS) was compared to sNGS of sonicate fluid for microbial detection and identification in patients with total hip arthroplasty (THA) and total knee arthroplasty (TKA) failure. Methods A convenience sample of sonicate fluids derived from patients who had undergone THA or TKA removal, enriched with culture negative PJI cases, was tested. Samples had been previously tested by sNGS. For tNGS, samples were extracted, amplified by polymerase chain reaction targeting the V1 to V3 regions of the 16S rRNA gene, and sequenced on an Illumina MiSeq. Results A total of 395 sonicate fluids, including 208 from subjects with PJI, were studied. Compared with sonicate fluid culture, tNGS had higher positive percent agreement (72.1 vs 52.9%, P &lt; .001), detecting potential pathogens in 48.0% of culture-negative PJIs. There was no difference between the positive percent agreement of tNGS (72.1%) and sNGS (73.1%, P = .83). Conclusions 16S rRNA gene-based tNGS is a potential diagnostic tool for PJI pathogen identification in sonicate fluid from failed THAs and TKAs in culture-negative cases, with similar performance characteristics to sNGS.

e19049 Background: Prognosis of COVID-19 is poor in the setting of immunosuppression. Casirivimab/imdevimab (REGEN-COV), bamlanivimab, and sotrovimab are investigational monoclonal antibodies (MoAbs) authorized for treatment of mild/moderate COVID-19 for patients (pts) 12 years or older and who are at high-risk for progression to severe COVID-19. These neutralizing antibodies, against SARS-CoV-2 spike proteins, have been shown to decrease risk of progression to severe disease. Recipients of allogeneic stem cell transplants (allo-SCT) or chimeric antigen T cell therapy (CAR T cell) represent a high risk population. However, treatment outcomes with these MoAbs in these pts are not well described. Methods: This retrospective study included 33 consecutive adult pts who developed mild/moderate COVID-19 and received anti-spike SARS-CoV-2 MoAbs between December 2020 and November 2021. Allo-SCT (N=27) or CAR T cell (N=6) recipients were included, and outcomes were analyzed separately. Pts received REGEN-COV (N=19), bamlanivimab (N=11), or sotrovimab (N=1), missing (N=2). Results: In the allo-SCT cohort (N=27), median age at time of COVID-19 was 55 (23-76) years. Median time from allo-SCT to COVID-19 was 31 (22-64) months. Two pts received CAR T-cell therapy prior to allo-SCT. Diagnoses included leukemia or myeloid diseases (82%), lymphoma (11%), or myeloma (7%). Transplant characteristics are summarized (Table). Thirteen pts were vaccinated against SARS-CoV-2 prior to breakthrough COVID-19. Events considered included hospitalization due to COVID-19, disease progression, or death from any cause. The 6-month event-free and overall survivals were 81% and 91%, respectively. In the CAR T cell recipients cohort (N=6), 4 pts received axicabtagene ciloleucel for diffuse large B-cell or follicular lymphoma and 2 received brexucabtagene autoleucel for mantle cell lymphoma. The median follow-up was 8 (1-11) months. Two pts received autologous SCT prior to COVID-19. Median time from CAR T cell therapy to COVID-19 was 10 (3-24) months. Three pts were vaccinated prior to COVID-19. Only 1 pt was hospitalized due to severe COVID-19 requiring mechanical ventilation leading to death. Conclusions: These results show a potential benefit of MoAbs in high-risk pts, namely allo-SCT or CAR T cell recipients. Future studies should evaluate the role of prophylactic use MoAbs in these populations. A comparative analysis with a matched control cohort (who did not receive MoAbs) will be provided at the meeting. [Table: see text]

Abstract Background Conventional blood cultures were compared to plasma cell-free DNA–based 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR)/next-generation sequencing (NGS) for detection and identification of potential pathogens in patients with sepsis. Methods Plasma was prospectively collected from 60 adult patients with sepsis presenting to the Mayo Clinic (Minnesota) Emergency Department from March through August 2019. Results of routine clinical blood cultures were compared to those of 16S rRNA gene NGS. Results Nineteen (32%) subjects had positive blood cultures, of which 13 yielded gram-negative bacilli, 5 gram-positive cocci, and 1 both gram-negative bacilli and gram-positive cocci. 16S rRNA gene NGS findings were concordant in 11. For the remaining 8, 16S rRNA gene NGS results yielded discordant detections (n = 5) or were negative (n = 3). Interestingly, Clostridium species were additionally detected by 16S rRNA gene NGS in 3 of the 6 subjects with gastrointestinal sources of gram-negative bacteremia and none of the 3 subjects with urinary sources of gram-negative bacteremia. In the 41 remaining subjects, 16S rRNA gene NGS detected at least 1 potentially pathogenic organism in 17. In 15, the detected microorganism clinically correlated with the patient’s syndrome. In 17 subjects with a clinically defined infectious syndrome, neither test was positive; in the remaining 7 subjects, a noninfectious cause of clinical presentation was identified. Conclusions 16S rRNA gene NGS may be useful for detecting bacteria in plasma of septic patients. In some cases of gram-negative sepsis, it may be possible to pinpoint a gastrointestinal or urinary source of sepsis based on the profile of bacteria detected in plasma.

Tick-borne disease pathogen identification remains a diagnostic challenge due to the multiple tests necessary for diagnosis. Targeted metagenomic sequencing is an evolving method to detect multiple different pathogens with a single test. In this issue of the Journal of Clinical Microbiology , L. Kingry, S. Sheldon, S. Oatman, B. Pritt, et al. (J Clin Microbiol 58:e00147-20, 2020, https://doi.org/10.1128/JCM.00147-20 ) explore 16S rRNA gene-targeted metagenomics to identify bacterial pathogens in 881 of more than 13,000 specimens submitted for tick-borne pathogen testing, giving new insights into suspected tick-borne pathogens.