Risk of cytomegalovirus infection and subsequent allograft failure after pancreas transplantation.

Cytomegalovirus (CMV) is a common cause of infection after transplantation, but few studies have evaluated its epidemiology, risk factors, and outcomes among pancreas transplant recipients. We performed a retrospective cohort study of adults who underwent pancreas transplantation from January 1, 2010, through December 31, 2020, at 3 sites in Arizona, Florida, and Minnesota. The primary outcome was clinically significant CMV infection (csCMVi), defined as CMV disease or infection requiring antiviral therapy. The secondary outcome was pancreas allograft failure. Among 471 pancreas transplant recipients, 117 (24.8%) developed csCMVi after a median of 226 (interquartile range 154-289) days. CMV donor (D)+/R- patients had a significantly higher incidence of csCMVi (hazard ratio [HR] 4.01, 95% confidence interval [CI] 2.10-7.64; P < .001). In adjusted analysis, a lower absolute lymphocyte count (ALC) was associated with a greater risk of csCMVi among seropositive recipients (HR 1.39 per 50% decrease, 95% CI 1.13-1.73; P = .002) but not among D+/R- patients (HR 1.04 per 50% decrease, 95% CI 0.89-1.23; P = .595). csCMVi, lower ALC, and acute rejection (P < .001) were independently associated with pancreas allograft failure. In conclusion, CMV D+/R- was associated with csCMVi in pancreas recipients, although ALC was associated with csCMVi only among seropositive patients. The development of csCMVi in pancreas recipients was associated with poor pancreas allograft outcomes.

Adjunctive glucocorticoid therapy for Pneumocystis jirovecii pneumonia in solid organ transplant recipients: A multicenter cohort, 2015-2020.

Solid organ transplant recipients (SOTRs) frequently receive adjunctive glucocorticoid therapy (AGT) for Pneumocystis jirovecii pneumonia (PJP). This multicenter cohort of SOTRs with PJP admitted to 20 transplant centers in Canada, the United States, Europe, and Australia, was examined for whether AGT was associated with a lower rate of all-cause intensive care unit (ICU) admission, 90-day death, or a composite outcome (ICU admission or death). Of 172 SOTRs with PJP (median [IQR] age: 60 (51.5-67.0) years; 58 female [33.7%]), the ICU admission and death rates were 43.4%, and 20.8%, respectively. AGT was not associated with a reduced risk of ICU admission (adjusted odds ratio [aOR] [95% CI]: 0.49 [0.21-1.12]), death (aOR [95% CI]: 0.80 [0.30-2.17]), or the composite outcome (aOR [95% CI]: 0.97 [0.71-1.31]) in the propensity score-adjusted analysis. AGT was not significantly associated with at least 1 unit of the respiratory portion of the Sequential Organ Failure Assessment score improvement by day 5 (12/37 [32.4%] vs 39/111 [35.1%]; P = .78). We did not observe significant associations between AGT and ICU admission or death in SOTRs with PJP. Our findings should prompt a reevaluation of routine AGT administration in posttransplant PJP treatment and highlight the need for interventional studies.

Trimethoprim-sulfamethoxazole dosing and outcomes of pulmonary nocardiosis.

BACKGROUND: Nocardia often causes pulmonary infection among those with chronic pulmonary disease or immunocompromising conditions. Trimethoprim-sulfamethoxazole (TMP-SMX) is recommended as first-line treatment, though little data exists regarding outcomes of different dosing regimens. METHODS: We performed a multicenter retrospective cohort study of adult patients with non-disseminated pulmonary nocardiosis initially treated with TMP-SMX monotherapy. Patients' initial TMP-SMX dosing was categorized as high- (> 10 mg/kg/day), intermediate- (5-10 mg/kg/day) or low-dose (< 5 mg/kg/day). Outcomes included one-year mortality, post-treatment recurrence, and dose adjustment or early discontinuation of TMP-SMX. SMX serum concentrations and their effect on management were also assessed. Inverse probability of treatment weighting was applied to Cox regression analyses. RESULTS: Ninety-one patients were included with 24 (26.4%), 37 (40.7%), and 30 (33.0%) treated with high-, intermediate-, and low-dose TMP-SMX, respectively. Patients who initially received low-dose (HR 0.07, 95% CI 0.01-0.68) and intermediate-dose TMP-SMX (HR 0.27, 95% CI 0.07-1.04) had lower risk of one-year mortality than the high-dose group. Risk of recurrence was similar between groups. Nineteen patients had peak SMX serum concentrations measured which resulted in 7 (36.8%) dose changes and was not associated with one-year mortality or recurrence. However, 66.7% of the high-dose group required TMP-SMX dose adjustment/discontinuation compared to 24.3% of the intermediate-dose and 26.7% of the low-dose groups (p = 0.001). CONCLUSIONS: Low- and intermediate-dose TMP-SMX for non-disseminated pulmonary nocardiosis were not associated with poor outcomes compared to high-dose therapy, which had a higher rate of dose adjustment/early discontinuation. Historically used high-dose TMP-SMX may not be necessary for management of isolated pulmonary nocardiosis.

Risk factors for positive follow-up blood cultures in Gram-negative bacteremia among immunocompromised patients with neutropenia.

INTRODUCTION: Gram-negative bacillary bloodstream infection (GN-BSI) is a frequent clinical challenge among immunocompromised hosts and is associated with a high mortality. The utility of follow-up blood cultures (FUBCs) for GN-BSI in this population, particularly in the setting of neutropenia, is poorly defined. METHODS: We conducted a single-center, retrospective cohort study between the period of July 2018 and April 2022 to investigate the utility of FUBCs and delineate risk factors for positive cultures among neutropenic patients with monomicrobial GN-BSI. Univariate logistic regression was performed to assess risk factors associated with positive FUBCs. RESULTS: Of 206 patients, 98% had FUBCs performed, and 9% were positive. Risk factors for positive FUBCs included multidrug-resistant GN infection (OR 3.26; 95% confidence interval [CI] 1.22-8.72) and vascular catheter source (OR 4.82; CI 1.76-13.17). Among patients lacking these risk factors, the prevalence of positive FUBCs was low (2.8%) and the negative predictive value was 92%. Those with positive and negative FUBCs had similar rates of all-cause mortality (16.7% vs. 16.6%; p = .942) and microbiologic relapse (11.1% vs. 6.0%; p = .401) within 90-days of treatment completion. However, positive FUBCs were associated with prolonged hospitalization and longer duration of antimicrobial therapy. CONCLUSION: Positive FUBCs were infrequent in neutropenic patients with GN-BSI, and their occurrence did not significantly impact mortality or microbiologic relapse. Risk factors for positive FUBCs included multidrug resistant Gram-negative infection and vascular catheter source. Prospective studies will be necessary to elucidate the benefits and risks of FUBCs when managing GN-BSI in patients with underlying immune compromise.

Comparison of Oral and Intravenous Definitive Antibiotic Therapy for Beta-Hemolytic Streptococcus Species Bloodstream Infections from Soft Tissue Sources: a Propensity Score-Matched Analysis.

Beta-hemolytic streptococci are common causes of bloodstream infection (BSI). There is emerging data regarding oral antibiotics for BSI but limited for beta-hemolytic streptococcal BSI. We conducted a retrospective study of adults with beta-hemolytic streptococcal BSI from a primary skin/soft tissue source from 2015 to 2020. Patients transitioned to oral antibiotics within 7 days of treatment initiation were compared to those who continued intravenous therapy, after propensity score matching. The primary outcome was 30-day treatment failure (composite of mortality, infection relapse, and hospital readmission). A prespecified 10% noninferiority margin was used for the primary outcome. We identified 66 matched pairs of patients treated with oral and intravenous antibiotics as definitive therapy. Based on an absolute difference in 30-day treatment failure of 13.6% (95% confidence interval 2.4 to 24.8%), the noninferiority of oral therapy was not confirmed (P = 0.741); on the contrary, the superiority of intravenous antibiotics is suggested by this difference. Acute kidney injury occurred in two patients who received intravenous treatment and zero who received oral therapy. No patients experienced deep vein thrombosis or other vascular complications related to treatment. In patients treated for beta-hemolytic streptococcal BSI, those who transitioned to oral antibiotics by day 7 showed higher rates of 30-day treatment failure than propensity-matched patients. This difference may have been driven by underdosing of oral therapy. Further investigation into optimal antibiotic choice, route, and dosing for definitive therapy of BSI is needed.

SARS-CoV-2 spike codon mutations and risk of hospitalization after antispike monoclonal antibody therapy in solid organ transplant recipients.

Neutralizing antispike monoclonal antibody (mAb) therapies were highly efficacious in preventing coronavirus disease 2019 (COVID-19) hospitalization. While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants may harbor spike protein mutations conferring reduced in vitro susceptibility to these antibodies, the effect of these mutations on clinical outcomes is not well characterized. We conducted a case-control study of solid organ transplant recipients who received an antispike mAb for treatment of mild-to-moderate COVID-19 and had an available sample from initial COVID-19 diagnosis for genotypic sequencing. Patients whose SARS-CoV-2 isolate had at least one spike codon mutation conferring at least fivefold decreased in vitro susceptibility were classified as resistant. Overall, 9 of 41 patients (22%) had at least one spike codon mutation that confers reduced susceptibility to the antispike mAb used for treatment. Specifically, 9 of 12 patients who received sotrovimab had S371L mutation that was predicted to confer a 9.7-fold reduced susceptibility. However, among 22 patients who required hospitalization, 5 had virus with resistance mutation. In contrast, among 19 control patients who did not require hospitalization, 4 also had virus-containing resistance mutations (p > 0.99). In conclusion, spike codon mutations were common, though mutations that conferred a 9.7-fold reduced susceptibility did not predict subsequent hospitalization after treatment with antispike mAb.

Clinical utility of a cytomegalovirus-specific T cell assay in assessing the risk of post-prophylaxis cytomegalovirus infection and post-treatment relapse.

INTRODUCTION: Cytomegalovirus (CMV) causes significant morbidity in solid organ transplant recipients (SOTR). Measuring cell-mediated immunity (CMI) may inform the risk of CMV infection after antiviral prophylaxis and predict relapse after CMV treatment. METHODS: We serially assessed CMV CMI using the QuantiFERON-CMV assay (QF-CMV; Qiagen, Germantown, MD) in two cohorts of SOTRs: during valganciclovir prophylaxis and during treatment of CMV viremia. Results of CMI were correlated with post-prophylaxis CMV infection and post-treatment relapse, respectively. RESULTS: Only one (4.2%) of 24 CMV D+/R- patients demonstrated positive QF-CMV by the end of valganciclovir prophylaxis. Four (16.6%) patients developed post-prophylaxis CMV infection; all four had undetectable QF-CMV at end of prophylaxis. Among 20 patients treated for CMV infection, 18 (90%) developed QF-CMV levels >.2 IU/mL by end of antiviral treatment and none developed CMV relapse. In contrast, the single patient who relapsed after completing treatment had a CMV CMI <.2 IU/ml (p = .0036). CONCLUSION: Since CMV D+/R- SOTRs are unlikely to develop adequate CMV CMI while receiving valganciclovir prophylaxis, the utility of CMV CMI monitoring for risk stratification during time of prophylaxis had limited value. Conversely, CMV CMI testing may be a useful marker of the risk of CMV relapse after antiviral treatment.

Risk factors and outcomes of Pneumocystis pneumonia in solid organ transplant recipients: Impact of posttransplant lymphoproliferative disorder.

BACKGROUND: Pneumocystis jirovecii pneumonia (PJP) is a potentially fatal infection afflicting the immunocompromised population, including solid organ transplant (SOT) recipients. Several risk factors have been described; however, little is known regarding the risk of PJP in SOT recipients with posttransplant lymphoproliferative disorder (PTLD). METHODS: We performed a nested case-control study of SOT recipients diagnosed with PJP from 2000 to 2020. PJP was defined as positive microscopy or polymerase chain reaction testing with compatible symptoms and radiographic findings. Control patients were matched 2:1 by year of first transplant, first transplanted organ, transplant center, and sex. Multivariable conditional logistic regression was performed to test associations with PJP and Cox regression analyzed post-PJP outcomes. RESULTS: Sixty-seven PJP cases were matched to 134 controls. The most common transplant was kidney (55.2%). Fourteen patients had a history of PTLD, 12 of whom developed PJP. After adjusting for age, acute rejection, cytomegalovirus infection, PJP prophylaxis, and lymphopenia (lymphocyte count < .5 × 109 /L), PTLD was independently associated with PJP (OR 14.0, 95% CI 1.7-114.5; p = .014). Lymphopenia was also a significant association (OR 8.2, 95% CI 3.2-20.7; p < .001). PJP was associated with mortality within 90 days of diagnosis (p < .001), but not after 90 days (p = .317). PJP was also associated with 90-day death-censored renal allograft loss (p = .026). CONCLUSIONS: PTLD is independently associated with PJP after adjustment for recognized risk factors. This is likely influenced by PTLD-directed chemotherapy, particularly rituximab-containing regimens. PJP is associated with early mortality, but this effect is not persistent after 90 days. PJP prophylaxis should be considered in SOT recipients with PTLD.

Risk factors and prophylaxis for nocardiosis in solid organ transplant recipients: A nested case-control study.

BACKGROUND: Nocardia is an opportunistic pathogen that primarily affects immunocompromised individuals, including solid organ transplant (SOT) recipients. Up to 2.65% of SOT recipients develop nocardiosis; however, few studies have examined risk factors and prophylaxis for nocardiosis. METHODS: We performed a multicenter, matched nested case-control study of adult SOT recipients with culture-confirmed nocardiosis from 2000 through 2020. Controls were matched up to 2:1 by sex, first transplanted organ, year of transplant, transplant center, and adequate post-transplant follow-up. Multivariable conditional logistic regression was performed to analyze associations with nocardiosis. Cox proportional hazards regression compared 12-month mortality between infection and uninfected patients. RESULTS: One hundred and twenty-three SOT recipients were matched to 245 uninfected controls. Elevated calcineurin inhibitor level, acute rejection, cytomegalovirus infection, lymphopenia, higher prednisone dose, and older age were significantly associated with nocardiosis while trimethoprim-sulfamethoxazole prophylaxis was protective (odds ratio [OR] .34; 95% confidence interval [CI] .13-.84). The effect of prophylaxis was similar, though not always statistically significant, in sensitivity analyses that only included prophylaxis dosed more than twice-per-week (OR .30; 95% CI .11-.80) or restricted to years 2015-2020 (OR .33, 95% CI .09-1.21). Nocardiosis was associated with increased 12-month mortality (hazard ratio 5.47; 95% confidence interval 2.42-12.35). CONCLUSIONS: Multiple measures of immunosuppression and lack of trimethoprim-sulfamethoxazole prophylaxis were associated with nocardiosis in SOT recipients. Effectiveness of prophylaxis may be related to trimethoprim-sulfamethoxazole dose or frequency. Trimethoprim-sulfamethoxazole should be preferentially utilized over alternative agents in SOT recipients with augmented immunosuppression or signs of heightened immunocompromise.

BK polyomavirus DNAemia in pancreas transplant recipients compared to pancreas-kidney recipients.

BACKGROUND: BK polyomavirus (BKV) infection is a common complication of kidney transplantation. While BKV has been described in non-kidney transplant recipients, data are limited regarding its epidemiology and outcomes in pancreas transplant recipients. METHODS: We conducted a retrospective cohort study of adults who underwent pancreas transplantation from 2010-2020. The primary outcome was BKV DNAemia. Secondary outcomes were estimated glomerular filtration rate (eGFR) reduction by 30%, eGFR < 30 mL/min/1.73 m2 , endstage kidney disease, and pancreas allograft failure. Cox regression with time-dependent variables was utilized. RESULTS: Four hundred and sixty-six patients were analyzed, including 74, 46, and 346 with pancreas transplant alone (PTA), pancreas-after-kidney, or simultaneous pancreas-kidney transplants, respectively. PTA recipients experienced a lower incidence of BKV DNAemia (8.8% vs. 32.9%; p < .001) and shorter duration of DNAemia (median 28.0 vs. 84.5 days). No PTA recipients with BKV DNAemia underwent kidney biopsy or developed endstage kidney disease. Lymphopenia, non-PTA transplantation, and older age were associated with BKV DNAemia, which itself was associated with pancreas allograft failure (adjusted hazard ratio 2.14, 95% confidence interval 1.27-3.60; p = .004). Among PTA recipients, BKV DNAemia was not associated with eGFR reduction or eGFR < 30 mL/min/1.73 m2 . CONCLUSIONS: BKV DNAemia was common among PTA recipients, though lower than a comparable group of pancreas-kidney recipients. However, BKV DNAemia was not associated with adverse native kidney outcomes and no PTA recipients developed endstage kidney disease. Conversely, BKV DNAemia was associated with pancreas allograft failure. Further studies are needed to estimate the rate of BKV nephropathy in this population, and further evaluate long-term kidney outcomes.

Post-treatment outcomes of ceftriaxone versus antistaphylococcal penicillins or cefazolin for definitive therapy of methicillin-susceptible Staphylococcus aureus bacteremia.

Methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia is associated with poor outcomes. Ceftriaxone offers logistical advantages over other standard therapies, though in vitro studies have questioned its efficacy and clinical studies of ceftriaxone in MSSA bacteremia are conflicting.We performed a multicenter, retrospective cohort study of adult patients who received ceftriaxone, cefazolin, or antistaphylococcal penicillins as definitive therapy for MSSA bacteremia from 2018 to 2019. Definitive therapy was defined as the antibiotic used in the outpatient setting. Patients were excluded if they received less than 7 days of outpatient therapy. Follow-up started on the date of definitive therapy completion. The primary outcome was 90-day treatment failure, defined as a composite of mortality and microbiologic recurrence. This was analyzed with multivariable Cox regression. A total of 223 patients were included, 37 (16.6%) of whom received ceftriaxone. The most common ceftriaxone dose was 2 g daily (83.8%). The most common primary site of infection was skin/soft tissue (37.2%), unknown (21.1%), and catheter-related (15.2%). Twenty-six (11.7%) developed infective endocarditis. Median total duration of treatment was 31.0 days, and median outpatient duration was 24.0 days. Twenty-six (11.7%) developed 90-day treatment failure. After adjusting for Charlson comorbidity index, duration of therapy, and use of transesophageal echocardiography, definitive treatment with ceftriaxone was associated with treatment failure (hazard ratio 2.66, 95% confidence interval 1.15-6.12; p=0.022). Among patients with MSSA bacteremia, definitive treatment with ceftriaxone was associated with a higher risk of treatment failure within 90 days as compared to cefazolin or antistaphylococcal penicillins.

Clinical characteristics and outcomes of pancreatic fungal infection in patients with necrotizing pancreatitis.

Pancreatic fungal infection (PFI) in patients with necrotizing pancreatitis can lead to significant morbidity and mortality. The incidence of PFI has increased during the past decade. Our study aimed to provide contemporary observations on the clinical characteristics and outcomes of PFI in comparison to pancreatic bacterial infection and necrotizing pancreatitis without infection. We conducted a retrospective study of patients with necrotizing pancreatitis (acute necrotic collection or walled-off necrosis), who underwent pancreatic intervention (necrosectomy and/or drainage) and had tissue/fluid culture between 2005 and 2021. We excluded patients with pancreatic procedures prior to hospitalization. Multivariable logistic and Cox regression models were fitted for in-hospital and 1-year survival outcomes. A total of 225 patients with necrotizing pancreatitis were included. Pancreatic fluid and/or tissue was obtained from endoscopic necrosectomy and/or drainage (76.0%), CT-guided percutaneous aspiration (20.9%), or surgical necrosectomy (3.1%). Nearly half of the patients had PFI with or without concomitant bacterial infection (48.0%), while the remaining patients had either bacterial infection alone (31.1%) or no infection (20.9%). In multivariable analysis to assess the risk of PFI or bacterial infection alone, only previous pancreatitis was associated with an increased odds of PFI vs. no infection (OR 4.07, 95% CI 1.13-14.69, p = .032). Multivariable regression analyses revealed no significant differences in in-hospital outcomes or one-year survival between the 3 groups. Pancreatic fungal infection occurred in nearly half of necrotizing pancreatitis. Contrary to many of the previous reports, there was no significant difference in important clinical outcomes between the PFI group and each of the other two groups.

We examined 225 patients with necrotizing pancreatitis who had tissue/fluid culture available and found that nearly half of the patients had pancreatic fungal infection. Interestingly, there was no difference in clinical outcomes between the fungal infection group and non-fungal infection groups.

Clinical characteristics of central nervous system phaeohyphomycosis: A brief report of 20 years' experience.

Central nervous system (CNS) phaeohyphomycosis is a rare and often fatal fungal infection. Our study reported a case series of eight CNS phaeohyphomycosis cases at our institution over the past 20 years. We did not observe the common pattern of risk factors, abscess location, or number of abscesses among them. Most patients were immunocompetent without classic risk factors for fungal infection. Early diagnosis and aggressive management with surgical intervention and prolonged antifungal therapy can lead to a favorable outcome. The study highlights the need for further research to better understand the pathogenesis and optimal management of this challenging rare infection.

Association of adverse effects with high serum posaconazole concentrations.

Posaconazole therapeutic drug monitoring (TDM) is widely utilized to assess therapeutic efficacy and safety; however, clinical effects of very high serum concentrations are unknown. A retrospective review of 90 patients receiving posaconazole for treatment or prophylaxis of invasive fungal infections with serum concentrations ≥3000 ng/mL from 1/1/2019 to 4/30/2021 evaluated the incidence and type of adverse drug reactions (ADRs). Symptomatic ADRs were very common in patients with posaconazole concentrations of ≥5000 ng/mL and 3000-4999 ng/mL (80% vs. 58.8%; P = 0.31). Posaconazole TDM should be performed for both treatment and prophylaxis indications and dose decrease for serum concentrations >3000 ng/mL should be considered.

Drug level monitoring is commonly used to evaluate appropriate dosing and effectiveness of posaconazole, a medication used to treat fungal infections. Patients with high levels commonly had side effects. Posaconazole monitoring should be completed, and doses reduced when levels are high.

Immunomodulators for severe coronavirus disease-2019 in transplant patients: Do they increase the risk of secondary infection?

BACKGROUND: Current guidelines recommend immunomodulators, tocilizumab or baricitinib, for the management of severe coronavirus disease-2019 (COVID-19) in patients with increasing oxygen requirements. Given their immunosuppressive effects, there is a concern for higher rates of infection among transplant recipients. METHODS: A retrospective cohort study of transplant patients with severe COVID-19 between April 2020 and January 2022 was performed at the Mayo Clinic. The primary outcome was incidence of secondary infections after COVID-19 diagnosis. Secondary outcomes were 90-day mortality, ventilatory days, and thromboembolic events. RESULTS: A total of 191 hospitalized transplant patients were studied, including 77 (40.3%) patients who received an immunomodulator. Overall, 89% were solid organ transplant recipients, with kidney as the most common transplanted organ (50.3%). The majority (89.0%) required oxygen supplementation on admission, and 39.8% of these patients required mechanical ventilation during the hospital course. There was no significant difference in the incidence of secondary infections between those who received or did not receive an immunomodulator (p = .984). Likewise, there was no difference in 90-day mortality between patients who received or did not receive an immunomodulator (p = .134). However, higher mortality was observed among patients that developed a secondary infection (p < .001). CONCLUSION: The use of immunomodulators in transplant patients with severe COVID-19 was not significantly associated with an increased risk of secondary infections. Secondary infections were associated with higher risk of all-cause mortality. Future studies of larger cohorts are needed to explore the effect of immunomodulators on survival among transplant patients with COVID-19.

Outcomes of transplant recipients with pretransplant Nocardia colonization or infection.

BACKGROUND: Specific pretransplant infections have been associated with poor posttransplant outcomes. However, the impact of pretransplant Nocardia isolation has not been studied. METHODS: We performed a retrospective study from three centers in Arizona, Florida, and Minnesota of patients with Nocardia infection or colonization who subsequently underwent solid organ or hematopoietic stem cell transplantation from November 2011 through April 2022. Outcomes included posttransplant Nocardia infection and mortality. RESULTS: Nine patients with pretransplant Nocardia were included. Two patients were deemed colonized with Nocardia, and the remaining seven had nocardiosis. These patients underwent bilateral lung (N = 5), heart (N = 1), heart-kidney (N = 1), liver-kidney (N = 1), and allogeneic stem cell transplantation (N = 1) at a median of 283 (interquartile range [IQR] 152-283) days after Nocardia isolation. Two (22.2%) patients had disseminated infection, and two were receiving active Nocardia treatment at the time of transplantation. One Nocardia isolate was resistant to trimethoprim-sulfamethoxazole (TMP-SMX) and all patients received TMP-SMX prophylaxis posttransplant, often for extended durations. No patients developed posttransplant nocardiosis during a median follow-up of 1.96 (IQR 0.90-6.33) years. Two patients died during follow-up, both without evidence of nocardiosis. CONCLUSIONS: This study did not identify any episodes of posttransplant nocardiosis among nine patients with pretransplant Nocardia isolation. As patients with the most severe infections may have been denied transplantation, further studies with larger sample sizes are needed to better analyze any impact of pretransplant Nocardia on posttransplant outcomes. However, among patients who receive posttransplant TMP-SMX prophylaxis, these data suggest pretransplant Nocardia isolation may not impart a heightened risk of posttransplant nocardiosis.

Evaluating antimicrobial duration for Gram-negative bacteremia in patients with neutropenia due to hematologic malignancy or hematopoietic stem cell transplantation.

BACKGROUND: In the management of Gram-negative bloodstream infection (GN-BSI), short antimicrobial courses have been increasingly demonstrated to be non-inferior to prolonged therapy, with lower risk of Clostridioides difficile infection (CDI) and emergence of multi-drug resistant (MDR) organisms. However, immunocompromised hosts were excluded from these studies. We investigated outcomes of short (≤10 days), intermediate (11-14 days), and prolonged (≥15 days) antimicrobial durations for GN-BSI in neutropenic patients. METHODS: A retrospective cohort study was conducted on neutropenic patients with monomicrobial GN-BSI between 2018 and 2022. The primary outcome was a composite of all-cause mortality and microbiologic relapse within 90 days after therapy completion. The secondary outcome was a composite of 90-day CDI and development of MDR-GN bacteria. Cox regression analysis with propensity score (PS) adjustment was used to compare outcomes between the three groups. RESULTS: A total of 206 patients were classified into short (n = 67), intermediate (n = 81), or prolonged (n = 58) duration. Neutropenia was predominantly secondary to hematopoietic stem cell transplantation (48%) or hematologic malignancy (35%). The primary sources of infection included intra-abdominal (51%), vascular catheter (27%), and urinary (8%). Most patients received definitive therapy with cefepime or carbapenem. No significant difference in the primary composite endpoint was observed for intermediate versus short (PS-adjusted hazard ratio [aHR] 0.89; 95% confidence interval [95% CI] 0.39-2.03) or prolonged versus short therapy (PS-aHR 1.20; 95% CI 0.52-2.74). There was no significant difference in the secondary composite endpoint of CDI or MDR-GN emergence. CONCLUSION: Our data suggest that short antimicrobial courses had comparable 90-day outcomes as intermediate and prolonged regimens for GN-BSI among immunocompromised patients with neutropenia.

Breakthrough COVID-19 after SARS-CoV-2 vaccination in solid organ transplant recipients: An analysis of symptomatic cases and monoclonal antibody therapy.

BACKGROUND: Solid organ transplant (SOT) recipients are at increased risk for complications from SARS-CoV-2 infection. Little is known regarding clinical course and outcomes of breakthrough COVID-19 in the fully vaccinated SOT population. We sought to describe our cohort of SOT recipients who developed symptomatic breakthrough COVID-19 after full vaccination. METHODS: We conducted a retrospective review of SOT recipients diagnosed with COVID-19 at least 14 days after completing SARS-CoV-2 vaccination. Patients were analyzed according to those presenting with mild-to-moderate and severe COVID-19, respectively. We described presenting characteristics, COVID-19 therapy, and analyzed outcomes including emergency department (ED) visits, hospitalization, and intensive care unit (ICU) admission. RESULTS: Thirty-five patients met inclusion criteria. These had a mean age of 60.8 years and kidney transplant was the most common SOT type. Five patients presented with severe COVID-19 at diagnosis, all requiring hospitalization without ICU admission. From the 30 patients who presented with mild-to-moderate infection, 28 received casirivimab-imdevimab. Four of these 28 (14.3%) had an ED visit, with one requiring hospital admission (3.4%). No patients required ICU admission. CONCLUSION: Breakthrough COVID-19 may occur in SOT recipients after full vaccination, though they appear to have acceptable outcomes. Anti-spike monoclonal antibody therapy for eligible SOT patients may have mitigated clinical progression and improved the outcomes. Further study with large cohorts is warranted.

Infectious complications in acute graft-versus-host disease after liver transplantation.

Graft-versus-hostdisease (GVHD) following liver transplantation (LT) is rare but can lead tosignificant mortality. The leading cause of death following GVHD diagnosis isinfectious complications. However, there is a lack of clear descriptions concerning infection and antimicrobial management patterns. Our study aims toprovide the focused details of all infectious complications of acute GVHDfollowing LT. We retrospectively reviewed all adult LT recipients with acute GVHD at Mayo Clinic's Transplant Centers from January 1, 2010, to December 31, 2021. Detailed characteristics of infection in each case were described. Among 4,585 LTs performed during this period, 12 (0.3%) patients developed acuteGVHD. The median time from transplantation to GVHD diagnosis was 49.0 days [IQR 31.5-99.0]. Ten (83.3%) patients developed severe infections leading tomortality. The most common cause of infection was nosocomial bacteremia fromenteric bacteria such as vancomycin-resistant enterococci and gram-negative bacilli. Other infections included breakthrough invasive fungal infections,cytomegalovirus (CMV) reactivation, and Clostridioides difficile colitis. Antimicrobial prophylaxis strategies in most cases were based on the degree of neutropenia-these include levofloxacin for bacterial prophylaxis, nebulized pentamidine for Pneumocystis jiroveci pneumonia prophylaxis, posaconazole for invasive fungal prophylaxis, and valganciclovir based on CMVstatus. All GVHD patients with severe infections succumbed to thesecomplications. Ourstudy reiterates that despite prophylaxis, infectious complications in GVHDfollowing LT are common and lead to exceptionally high mortality. Individualizedantimicrobial treatment, prophylaxis and monitoring strategies remain a criticalcomponent of GVHD management. Further study to optimize these practices isrequired.

Outcomes of bebtelovimab and sotrovimab treatment of solid organ transplant recipients with mild-to-moderate coronavirus disease 2019 during the Omicron epoch.

BACKGROUND: Solid organ transplant recipients (SOTRs) are at high-risk for severe infection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Anti-spike monoclonal antibodies are currently utilized under emergency use authorization to prevent hospitalization in high-risk individuals with coronavirus disease 2019 (COVID-19), including SOTRs. However, clinical data for bebtelovimab, the sole currently available anti-spike monoclonal antibody for COVID-19, is limited. METHODS: We conducted a retrospective cohort study of adult SOTRs diagnosed with mild-to-moderate COVID-19 from January 2022 through May 2022 who received either bebtelovimab or sotrovimab. The primary outcome was COVID-19-related hospitalization within 30 days of COVID-19 diagnosis. Data were analyzed with Fisher's exact test. RESULTS: Among 361 SOTRs, 92 (25.5%) received bebtelovimab and 269 (74.5%) received sotrovimab. The most common organ transplant was a kidney (42.4%). SOTRs who received bebtelovimab had a higher proportion who had received a booster SARS-CoV-2 vaccine dose and had received their last vaccination dose more recently. Eleven (3.0%) SOTRs were hospitalized, and rates of hospitalization were similar between monoclonal antibody groups (3.3% versus 3.0%; p > .99). Three patients required admission to an intensive care unit, all of who received sotrovimab. Four (1.1%) patients died within 30 days of COVID-19 diagnosis, two from each group. CONCLUSIONS: SOTRs with mild-to-moderate COVID-19 who received bebtelovimab had similar rates of COVID-19-related hospitalization as those who received sotrovimab. While differences in vaccination rates and viral subvariants could act as confounders, bebtelovimab appears to be of similar effectiveness as sotrovimab.