Ranganath, Nischal

Abstract Alternaria spp. are dematiaceous ascomycetes that can cause opportunistic infections in immunocompromised hosts. They are challenging to identify and treat. However, optimal antifungal therapy remains undefined. We retrospectively reviewed antifungal susceptibilities (AST) of all Alternaria spp. isolates from adults at a tertiary care center between 2011 and 2025. We evaluated culture sources, minimum inhibitory concentration (MIC) and minimal effective concentration (MEC) distributions, and MIC₅₀/MIC₉₀ and MEC50/MEC90 values. Clinical characteristics, treatment measures, and outcomes of patients with clinically significant Alternaria spp. infections were described. Forty-one patients had Alternaria spp. isolated, most commonly from skin (n = 13), bone/joint (n = 5), nail (n = 3), or cornea (n = 3). Posaconazole and itraconazole demonstrated low MICs (MIC₅₀/MIC₉₀: 0.06/0.5 and 0.25/0.5 µg/mL, respectively). Voriconazole and isavuconazole showed higher MIC₅₀/MIC₉₀ (1/2 and 2/4 µg/mL). Caspofungin (0.125/0.5 µg/mL) and amphotericin B (0.25/1 µg/mL) had low MICs and MECs.s. Alternaria spp. represented clinically significant infection in 27 cases (66%); 26% were solid organ transplant recipients and 15% had hematologic malignancies. Other risk factors included preceding trauma (22%) and autoimmune disease (15%). Posaconazole was the most frequently used empiric agent (6, 32%). Following AST results, 14 patients (52%) received oral antifungal therapy; posaconazole was used in all 14. In addition, 7 patients (26%) received combination therapy with IV amphotericin B. Adjunctive surgery occurred in 14 cases (52%). Five patients (19%) died before completing therapy; Alternaria infections occurred predominantly in immunocompromised hosts and were frequently managed with posaconazole and surgery. Interpretive criteria for Alternaria spp. are needed to guide empiric and definitive therapy.

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 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 Achromobacter species are Gram-negative bacilli that predominantly affect individuals with cystic fibrosis or those with immunocompromising conditions. Clinical and microbiologic data on Achromobacter species are limited due to the rarity of these organisms and challenges with species-level identification. We conducted a 10-year retrospective analysis (1 January 2013 to 14 March 2023) of all bloodstream and non-bloodstream Achromobacter isolates identified at three tertiary-care Mayo Clinic locations (Minnesota, Arizona, and Florida). Additionally, we examined clinical characteristics of adult patients with Achromobacter bloodstream isolates. A total of 1,598 Achromobacter isolates, encompassing 1,545 non-bloodstream isolates and 53 bloodstream isolates, were identified. The most frequently identified species was Achromobacter xylosoxidans , though species-level identification was not possible for many isolates. Among adult patients with Achromobacter bloodstream infection, the mean age was 58.3 years (standard deviation ± 16.7), 73.1% had a central venous catheter, and 59.6% were immunocompromised. All-cause mortality was 10.2% at 30 days and 18.4% at 90 days. Bloodstream isolates exhibited greater than 90% susceptibility to meropenem, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. The respiratory tract was the most common source of non-bloodstream isolates (57.5%). Non-bloodstream isolates showed high susceptibility to imipenem (94.6%), piperacillin-tazobactam (92.8%), trimethoprim-sulfamethoxazole (92.1%), and meropenem (87.5%) while demonstrating significant resistance to fluoroquinolones and aminoglycosides. Our findings support the use of piperacillin-tazobactam, carbapenems, or trimethoprim-sulfamethoxazole as initial therapy for Achromobacter infections. Further research is needed to better define the clinical and microbiologic characteristics of Achromobacter infections. IMPORTANCE Achromobacter is a rare but important genus of bacteria that tends to cause infection in those with cystic fibrosis, recurrent healthcare exposures, and/or an immunocompromising condition. There is limited data on the clinical profile of Achromobacter infections as well as optimal antibiotic selection for affected patients. We conducted a retrospective study to improve understanding of the microbiologic and clinical characteristics of Achromobacter . Our study consists of a 10-year survey of all Achromobacter isolates processed by three Mayo Clinic tertiary-care centers in Minnesota, Florida, and Arizona from 2013 to 2023. We report multiple findings, including the clinical characteristics of patients with Achromobacter bloodstream infection, the number of different Achromobacter species identified, and the sources of isolates not obtained from blood cultures. We additionally present antimicrobial susceptibility results for Achromobacter isolates. Our study provides guidance to clinicians treating Achromobacter infections and, it is hoped, will facilitate ongoing study of Achromobacter .

Abstract Objectives To compare the efficacy and safety of antibiotic lock therapy (ALT) versus catheter removal in managing central vascular catheter–associated bloodstream infection (CVC-BSI). Methods We conducted a single-centre, retrospective cohort study of adult patients treated with ALT or catheter removal for management of CVC-BSI between 2018 and 2022. The primary outcome was a composite of 90 day microbiological relapse or recurrent BSI. Secondary outcomes included 30 day mortality, CVC-associated complications and Clostridioides difficile infection (CDI). Logistic regression with propensity score-adjustment was used to evaluate differences in outcomes and identify predictors of relapse. Results During the study period, 106 participants received ALT and 181 underwent catheter removal. Patients treated with ALT received shorter courses of systemic antimicrobials (11 versus 14 days; P &lt; 0.001) and had shorter hospital stays (4 versus 10 days; P &lt; 0.001). Median duration of catheter salvage in patients receiving ALT was 28 days (IQR 7–80). Primary composite outcome was similar between both groups, but ALT was associated with a significantly higher risk of microbiological relapse within 90 days (20% versus 7%; adjusted odds ratio 3.93, 95% CI 1.64–9.40; P = 0.002). No significant difference in 30 day mortality, CVC-related complications or CDI was observed. CoNS BSI was an independent predictor of microbiological relapse in patients treated with ALT (OR 2.28; P = 0.05). Conclusions Although ALT offers a non-invasive catheter salvage strategy, its association with higher relapse rates, particularly in CoNS BSI, suggests catheter removal should remain the preferred approach when feasible. ALT could be considered a short-term catheter salvage strategy for pathogens with low virulence when used with close surveillance.

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 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 Introduction With reports of expanding epidemiology of blastomycosis across the United States, the purpose of this study was to evaluate the incidence and outcomes associated with blastomycosis in solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients. Methods We conducted a retrospective case series of adult SOT and HCT recipients at a tertiary care medical center between January 1, 2005 and September 30, 2023. Cases were defined as culture‐proven blastomycosis. We performed descriptive statistical analysis to evaluate diagnosis, management, and outcomes (mortality) of blastomycosis in SOT. Results The cumulative incidence of blastomycosis was 0.11% with a median time to infection following transplant of 743 days. Of the 19 cases, the majority of patients were SOT recipients (90%). Supratherapeutic immunosuppression within 30 days of diagnosis was observed in 42% of cases with documented drug monitoring. Urine antigen testing was highly sensitive (100%). Fourteen (73.7%) patients received induction therapy with liposomal amphotericin B followed by azole therapy for a minimum of 12 months. Despite appropriate treatment, 1‐year mortality was high at 26.3%, with attributable mortality of 21.1%. Conclusions While rates of blastomycosis remain low among SOT and HCT recipients, infection is associated with poor posttransplant outcomes. Antigen testing can aid in timely assessment of disease severity and initiation of appropriate therapy. Among survivors, no relapses were observed while on lifelong secondary suppression. Future studies should aim to better define risk factors associated with developing blastomycosis and establish effective strategies for prevention.