Randall C. Walker

Prospective Surveillance for Invasive Fungal Infections in Hematopoietic Stem Cell Transplant Recipients, 2001–2006: Overview of the Transplant-Associated Infection Surveillance Network (TRANSNET) Database

BACKGROUND The incidence and epidemiology of invasive fungal infections (IFIs), a leading cause of death among hematopoeitic stem cell transplant (HSCT) recipients, are derived mainly from single-institution retrospective studies. METHODS The Transplant Associated Infections Surveillance Network, a network of 23 US transplant centers, prospectively enrolled HSCT recipients with proven and probable IFIs occurring between March 2001 and March 2006. We collected denominator data on all HSCTs preformed at each site and clinical, diagnostic, and outcome information for each IFI case. To estimate trends in IFI, we calculated the 12-month cumulative incidence among 9 sequential subcohorts. RESULTS We identified 983 IFIs among 875 HSCT recipients. The median age of the patients was 49 years; 60% were male. Invasive aspergillosis (43%), invasive candidiasis (28%), and zygomycosis (8%) were the most common IFIs. Fifty-nine percent and 61% of IFIs were recognized within 60 days of neutropenia and graft-versus-host disease, respectively. Median onset of candidiasis and aspergillosis after HSCT was 61 days and 99 days, respectively. Within a cohort of 16,200 HSCT recipients who received their first transplants between March 2001 and September 2005 and were followed up through March 2006, we identified 718 IFIs in 639 persons. Twelve-month cumulative incidences, based on the first IFI, were 7.7 cases per 100 transplants for matched unrelated allogeneic, 8.1 cases per 100 transplants for mismatched-related allogeneic, 5.8 cases per 100 transplants for matched-related allogeneic, and 1.2 cases per 100 transplants for autologous HSCT. CONCLUSIONS In this national prospective surveillance study of IFIs in HSCT recipients, the cumulative incidence was highest for aspergillosis, followed by candidiasis. Understanding the epidemiologic trends and burden of IFIs may lead to improved management strategies and study design.

Invasive fungal infections among organ transplant recipients: results of the transplant-associated infection surveillance network (Transnet)

BACKGROUND Invasive fungal infections (IFIs) are a major cause of morbidity and mortality among organ transplant recipients. Multicenter prospective surveillance data to determine disease burden and secular trends are lacking. METHODS The Transplant-Associated Infection Surveillance Network (TRANSNET) is a consortium of 23 US transplant centers, including 15 that contributed to the organ transplant recipient dataset. We prospectively identified IFIs among organ transplant recipients from March, 2001 through March, 2006 at these sites. To explore trends, we calculated the 12-month cumulative incidence among 9 sequential cohorts. RESULTS During the surveillance period, 1208 IFIs were identified among 1063 organ transplant recipients. The most common IFIs were invasive candidiasis (53%), invasive aspergillosis (19%), cryptococcosis (8%), non-Aspergillus molds (8%), endemic fungi (5%), and zygomycosis (2%). Median time to onset of candidiasis, aspergillosis, and cryptococcosis was 103, 184, and 575 days, respectively. Among a cohort of 16,808 patients who underwent transplantation between March 2001 and September 2005 and were followed through March 2006, a total of 729 IFIs were reported among 633 persons. One-year cumulative incidences of the first IFI were 11.6%, 8.6%, 4.7%, 4.0%, 3.4%, and 1.3% for small bowel, lung, liver, heart, pancreas, and kidney transplant recipients, respectively. One-year incidence was highest for invasive candidiasis (1.95%) and aspergillosis (0.65%). Trend analysis showed a slight increase in cumulative incidence from 2002 to 2005. CONCLUSIONS We detected a slight increase in IFIs during the surveillance period. These data provide important insights into the timing and incidence of IFIs among organ transplant recipients, which can help to focus effective prevention and treatment strategies.

Invasive Non-Aspergillus Mold Infections in Transplant Recipients, United States, 2001-2006

Recent reports describe increasing incidence of non-Aspergillus mold infections in hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. To investigate the epidemiology of infections with Mucorales, Fusarium spp., and Scedosporium spp. molds, we analyzed data from the Transplant-Associated Infection Surveillance Network, 23 transplant centers that conducted prospective surveillance for invasive fungal infections during 2001-2006. We identified 169 infections (105 Mucorales, 37 Fusarium spp., and 27 Scedosporium spp.) in 169 patients; 124 (73.4%) were in HCT recipients, and 45 (26.6%) were in SOT recipients. The crude 90-day mortality rate was 56.6%. The 12-month mucormycosis cumulative incidence was 0.29% for HCT and 0.07% for SOT. Mucormycosis incidence among HCT recipients varied widely, from 0.08% to 0.69%, with higher incidence in cohorts receiving transplants during 2003 and 2004. Non-Aspergillus mold infections continue to be associated with high mortality rates. The incidence of mucormycosis in HCT recipients increased substantially during the surveillance period.

Prognostic Analysis for Survival in Adult Solid Organ Transplant Recipients With Post-Transplantation Lymphoproliferative Disorders

PURPOSE The objective of this study was to determine prognostic factors for overall survival in patients with post-transplantation lymphoproliferative disorders (PTLDs). PATIENTS AND METHODS This study focused on the 107 adult solid organ transplantation patients who were diagnosed with PTLDs at Mayo Clinic (Rochester, MN) between December 1970 and May 2003. RESULTS The median age at the time of diagnosis was 48 years (range, 15 to 75 years). Extranodal disease including grafted organ involvement was present in 85 patients (80%). The graft organ was involved in 30 patients (28%). At the time of these analyses, 62 patients (58%) had died. The median survival for the entire cohort was 31.5 months (95% CI, 10.7 to 72.5 months). The median follow-up of living patients was 51.8 months (range, 5.6 to 202.6 months). In univariate analyses for overall survival from the time of PTLD diagnosis, the following poor prognostic factors were identified: poor performance status with Eastern Cooperative Oncology Group levels 3 and 4 (P < .0001), grafted organ involvement (P = .0005), the presence of one or more extranodal sites (P = .005), both nodal and extranodal disease (P = .002), high International Prognostic Index (P = .006), advanced stage (P = .001), and elevated lactate dehydrogenase (P = .03). A final multivariable model for survival was constructed using three factors: poor performance status (3 to 4), monomorphic disease, and graft organ involvement. CONCLUSION A prognostic model has been developed for PTLD patients using one centers 30 years of experience. We propose additional confirmation and validation of these prognostic factors in larger prospective studies.

Differences between early and late posttransplant lymphoproliferative disorders in solid organ transplant patients: are they two different diseases?

Background. The objective of the authors’ study was to characterize the clinical and pathologic differences between patients who develop posttransplant lymphoproliferative disorders (PTLD) early or late after transplantation and to assess the overall survival in these two groups. Methods. One hundred seven adult solid organ transplant patients were identified at the Mayo Clinic between December 1970 and May 2003. Results. Forty-nine patients developed PTLD within the first year (early PTLD, 1–11.8 months) and 58 patients developed PTLD after 1 year (late PTLD, 14 months–17 years). Patients with early PTLD more commonly had the following characteristics: positive Epstein-Barr virus (EBV) in situ hybridization status (P<0.0001), CD20-positive status (P=0.002), and involvement of the grafted organ (P=0.02). Overall survival did not differ between the two groups (P=0.25). PTLD may occur in two different settings with different characteristics. Conclusions. Early PTLD is more commonly EBV in situ hybridization-positive and CD20-positive, and more commonly involves the grafted organ.

Systemic histoplasmosis: a 15-year retrospective institutional review of 111 patients.

To our knowledge, an institutional review of systemic histoplasmosis has not been conducted in the United States since the major outbreaks in Indianapolis in 1978-4982. We conducted a retrospective review of all patients with systemic histoplasmosis diagnosed at Mayo Clinic over a 15-year period. The case definitions employed were based on an international consensus statement by the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group (EORTC/IFICG) and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (MSG). One hundred eleven patients with systemic histoplasmosis were identified between January 1, 1991, and December 31, 2005. Of these, 78 patients had disseminated histoplasmosis and 55 patients had Histoplasma capsulatum fungemia. The mean age of patients was 55 years, 66% were male, and 98% were white. Fifty-nine percent of patients were immunocompromised. Fever was the most frequently reported symptom (63%), followed by respiratory complaints (43%) and weight loss (37%). The peripheral white blood cell count was <3000 cells/mm3 in 28%, hemoglobin was <10 g/dL in 29%, and platelet count was <150,000 cells/mm3 in 41% of patients. Liver enzymes were elevated (alanine aminotransferase >60 U/L in 39%, aspartate aminotransferase >60 U/L in 27%), alkaline phosphatase was >200 U/L in 55%, and albumin was <3.5 g/dL in 70%. Serologic and histopathologic examinations were each positive in 75% of cases, Histoplasma urine antigen screening was positive in 80%, and H. capsulatum was culture positive in 84%. Forty-seven percent of patients were sequentially treated with an amphotericin B-containing product followed by itraconazole, 31% received itraconazole alone, and 7% received an amphotericin B-containing product only. Another 13% of patients did not receive antifungal treatment, and the remaining 2% did not have treatment data available. Sixty percent of patients required hospitalization, and in hospital mortality was 6% with a median survival time of 61 days. The relapse rate was 9%, with a median relapse-free survival of 857 days. Systemic histoplasmosis should be suspected in patients who have lived in endemic areas with fever, bone marrow suppression, and elevated hepatic enzymes, particularly if they are immunocompromised. Evaluation including a combination of Histoplasma serologic screening, urine antigen assay, and fungal culture will secure the diagnosis in most cases.Abbreviations: AIDS = acquired immunodeficiency syndrome, AST = aspartate aminotransferase, EORTC/IFICG = European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group, HAART = highly active antiretroviral therapy, HIV = human immunodeficiency virus, IDSA = Infectious Diseases Society of America, MSG = National Institute of Allergy and Infectious Diseases Mycoses Study Group, TNF = tumor necrosis factor.

Prophylaxis of cytomegalovirus infection in liver transplantation: A randomized trial comparing a combination of ganciclovir and acyclovir to acyclovir

BACKGROUND The optimal prophylactic regimen to prevent cytomegalovirus (CMV) infection and disease in orthotopic liver-transplant patients remains to be established. We tested whether a combination of intravenous ganciclovir (GCV) followed by high dosages of oral acyclovir (ACV) for 4 months provided a higher degree of protection from CMV than oral ACV alone. METHODS One hundred sixty-seven liver-transplant recipients were randomized to receive 120 days of antiviral treatment starting at the time of transplantation consisting of either ACV 800 mg orally four times daily (n=84) or 14 days of GCV 5 mg/kg intravenously every 12 hr followed by oral ACV 800 mg four times daily (n=83). Prospective laboratory and clinical surveillance was performed to determine primary endpoints (onset of CMV infection and CMV disease) and secondary endpoints (rates of fungal and bacterial infection, allograft rejection, and survival after transplantation). One-year event rates are presented as cumulative percentages. RESULTS During the first year after transplantation, CMV infection developed in 57% of patients treated with ACV and in 37% of patients treated with GCV + ACV (P=0.001). CMV disease developed in 23% of patients treated with ACV and in 11% of patients treated with GCV + ACV (P=0.03). In seronegative recipients of allografts from CMV-seropositive donors (D+/R-), CMV disease developed in 58% of patients treated with ACV and in 25% of patients treated with GCV + ACV (P=0.04). In the D+/R- group, 54% of patients treated with ACV and 17% of patients treated with GCV + ACV developed infection with Candida albicans (P=0.05). CONCLUSIONS Prophylaxis of CMV infection in liver-transplant patients with 14 days of intravenous GCV followed by high-dosage oral ACV is more effective than high-dosage oral ACV alone at reducing CMV infection and disease, even for patients in the D+/R- CMV serological group.

Cardiac xenotransplantation: progress toward the clinic.

Background. Animal organs could satisfy the demand for solid organ transplants, which currently exceeds the limited human donor supply. Hyperacute rejection, the initial immune barrier to successful xenotransplantation, has been overcome with pig donors transgenic for human complement regulatory proteins. Delayed xenograft rejection, thought to be mediated by anti-pig antibodies predominantly to Gal antigens, is currently regarded as the major barrier to successful xenotransplantation. A median graft survival of 90 days in the life-supporting position is considered a reasonable initial standard for consideration of entry to the clinic. Methods. A series of 10 heterotopic heart transplants from CD46 transgenic pigs to baboons was completed. Immunosuppression consisted of splenectomy, Rituximab (Anti-CD20), tacrolimus, sirolimus, corticosteroids, and TPC. Thymoglobulin (Rabbit Anti-Thymocyte Globulin) was used to treat putative rejection episodes. Results. Median graft survival was 76 days (range 56–113 days, n=9). Only three grafts were lost to rejection. The remaining grafts lost were due to recipient mortality with baboon cytomegalovirus (BCMV) being the major cause (n=4). No cellular infiltrates were present as a manifestation of rejection. Three hearts showed chronic graft vasculopathy. Conclusions. The median survival of 76 days in this group of heterotopic porcine-to-baboon cardiac xenografts represents a major advance over the median 27-day survival reported in the literature. Cellular rejection may not constitute a direct major barrier to xenotransplantation. A median survival of 90 days may be achievable with better control of BCMV infection. If further studies in the orthotopic position replicate these outcomes, criteria considered appropriate for clinical application of cardiac xenotransplantation would be approached.

Clinical Manifestations and Management of Left Ventricular Assist Device–Associated Infections

BACKGROUND Infection is a serious complication of left ventricular assist device (LVAD) therapy. Published data regarding LVAD-associated infections (LVADIs) are limited by single-center experiences and use of nonstandardized definitions. METHODS We retrospectively reviewed 247 patients who underwent continuous-flow LVAD implantation from January 2005 to December 2011 at Mayo Clinic campuses in Minnesota, Arizona, and Florida. LVADIs were defined using the International Society for Heart and Lung Transplantation criteria. RESULTS We identified 101 episodes of LVADI in 78 patients (32%) from this cohort. Mean age (± standard deviation [SD]) was 57±15 years. The majority (94%) underwent Heartmate II implantation, with 62% LVADs placed as destination therapy. The most common type of LVADIs were driveline infections (47%), followed by bloodstream infections (24% VAD related, and 22% non-VAD related). The most common causative pathogens included gram-positive cocci (45%), predominantly staphylococci, and nosocomial gram-negative bacilli (27%). Almost half (42%) of the patients were managed by chronic suppressive antimicrobial therapy. While 14% of the patients had intraoperative debridement, only 3 underwent complete LVAD removal. The average duration (±SD) of LVAD support was 1.5±1.0 years. At year 2 of follow-up, the cumulative incidence of all-cause mortality was estimated to be 43%. CONCLUSION Clinical manifestations of LVADI vary on the basis of the type of infection and the causative pathogen. Mortality remained high despite combined medical and surgical intervention and chronic suppressive antimicrobial therapy. Based on clinical experiences, a management algorithm for LVADI is proposed to assist in the decision-making process.

Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant-Associated Infection Surveillance Network (TRANSNET)

Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients, but few data have been reported on the epidemiology of endemic fungal infections in these populations.