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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., (© 2023 Wiley Periodicals LLC.)

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., (© 2023 Wiley Periodicals LLC.)

Background: Neutropenia is a risk factor for development of infections; however, the direct effect of neutropenia on development of bloodstream infection (BSI) is not known. D-index, which is area between the neutrophil time curve and a neutrophil count of 0.5 × 10 9 /L, incorporates the combined effect of severity and duration of neutropenia. We aimed to evaluate whether D-index can be used as a marker for BSI in patients with allogeneic stem cell transplantation., Method: We conducted a retrospective cohort study of patients undergoing allogeneic stem cell transplantation between January 1, 2005, and September 30, 2015. The primary outcome measure was the development of BSI within 30 days of transplantation., Results: A total of 714 patients were included in the study of whom 101 developed BSI. Patients with BSI had a significantly higher median D-index value compared with patients who did not have BSI (4990 vs. 3570, P < .001). As a marker, the performance of the D-index was similar to that of the duration of profound neutropenia (P = .18) and significantly better than the total duration of neutropenia (P = .001)., Conclusion: The D-index performed better than the total duration of neutropenia as a marker for BSI in patients with allogeneic stem cell transplantation. There was no difference between D-index and, a more easily calculable indicator, duration of profound neutropenia., (© 2021 Wiley Periodicals LLC.)

The D-index assesses neutropenia dynamics. Prolonged neutropenia is a major risk for invasive fungal infection (IFI); we hypothesized that D-index is predictive of IFI risk. We retrospectively reviewed 789 adults who underwent allogeneic hematopoietic transplant (HSCT) from 1/1/2005 to 9/30/2015. Medical records were reviewed from transplant (D0) through Day 100. The D-index was calculated as area over the neutrophil curve until engraftment. 714 patients were included for analysis. Sixteen (2%) developed probable (11) or proven (5) IFI. Median time to IFI was 40 days (range 8-98) after HSCT. Groups with and without IFI did not differ significantly in duration of mild or profound neutropenia. Median D-index of those with IFI was 4293 days neutrophil/µl compared to 3590 days neutrophil/µl for those without IFI (P = 0.17). Patients who were neutropenic on D0 showed higher rates of IFI than those who were not (10/123 [8%] vs 6/591 [1%]; P < 0.001). Only 2% developed IFI, likely due to mold-active antifungal prophylaxis. The D-index was not significantly higher in those with IFI. Duration of profound neutropenia and neutropenia at D0 may be better markers for IFI among HSCT recipients during the first 30 and 100 days after transplant.

While lymphopenia is a well-defined risk factor for severe influenza, the effect of neutropenia is unknown. This was a retrospective single centre study of adult patients with documented neutropenia and influenza between 2005 and 2013. Forty patients were included with a median follow-up of 2 years (IQR 0.8-4.0). Median ANC at influenza diagnosis was 0.3 × 10 9 /L (IQR 0.1-0.4 × 10 9 /L). Outcomes included hospitalization (N = 28, 70%), pneumonia (N = 9, 23%), ICU admission (N = 9, 23%) and mechanical ventilation (N = 7, 18%). Three deaths (7.5%) were attributed to influenza, all of whom had lower respiratory tract infection (LRTI). Patients with LRTI (N = 18, 45%) also had a higher 30-day mortality (37 versus 0%) and 90-day mortality (42 versus 0%) than those with upper respiratory tract infection. In summary, neutropenic patients have high rates of influenza complications. Our study highlights the need for early diagnosis and aggressive management of influenza in this population.

Background The epidemiology of fungal infections in hematologic malignancies has changed in the past decade. Triazole prophylaxis has decreased Candida spp infections while infections due to other molds such as Aspergillus and Fusarium species have increased. Fusariosis has very poor prognosis, and after aspergillosis, is the most common invasive fungal infection in this patient population. We sought to describe fusariosis in patients with hematologic malignancy at the Mayo Clinic. Methods We performed a retrospective review of patients with culture-positive Fusarium infection from January 2003 to October 2016 at the Mayo Clinic, Rochester, MN. The records of patients were reviewed for demographics, diagnosis, treatment, and outcomes including mortality. Patients without a diagnosis of hematologic malignancy were excluded. Patients were classified with proven or probable Fusariosis based on the Revised Definitions of Invasive Fungal Disease from the EORTC/MSG Consensus Group. Results We identified 14 patients with hematologic malignancies (age range 17–76 years; median 60 years) with a confirmed culture diagnosis of Fusarium infection classified as proven (9 patients) or probable (5 patients). Two cases were isolated pulmonary infections, 3 extra-pulmonary, and 9 disseminated cases. Two patients had previously undergone stem cell transplantation. Eight patients (57%) were receiving antifungal prophylaxis at the time of diagnosis: 2 on voriconazole, 1 on posaconazole, 1 on fluconazole, 3 on echinocandins, and 1 on Amphotericin B. Nine patients (64%) were neutropenic at the time of diagnosis. Amphotericin was the initial treatment in 7 (50%) patients, with voriconazole added for 4 patients for combination therapy the first week. Voriconazole monotherapy was given initially in 5 patients. Seven patients (50%) were deceased at 6 weeks after culture positivity, with an additional 2 patients deceased by 12 weeks. Conclusion Fusarium infection outcomes in patients with hematologic malignancies are poor. Neutropenia was common in those diagnosed, and infections were more likely to be disseminated, with high mortality rates. Amphotericin was commonly used as initial treatment, with many physicians recommending combination therapy with two agents, commonly voriconazole. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]