Barbara D Alexander

Duke University Medical Center, Durham, North Carolina, United States

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Publications (117)481.25 Total impact

  • Journal of clinical microbiology. 11/2014; 52(11):4119.
  • Clinical Infectious Diseases 09/2014; · 9.37 Impact Factor
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    ABSTRACT: Research to develop and validate novel methods for diagnosis of aspergillosis based on detection of galactomannan requires use of clinical specimens that have been stored frozen. Data that galactomannan remains stable when frozen are scant. The objective of this study was to determine the stability of galactomannan in clinical specimens stored at -20°C that were resulted positive in the Platelia™ Aspergillus enzyme immunoassay when initially tested. Prospective real-time testing of serum and bronchoalveolar lavage (BAL) fluid pools from positive and negative patient specimens showed no decline in galactomannan index (GMI) over 11 months at -20° C, and no development of positive reactions in the negative control pool. Retrospective testing of positive specimens that had been stored at -20° C for 5 years showed that 28 of 30 serum (N=15) or BAL (N=15) specimens remained positive. These findings support the use of frozen serum or BAL specimens stored for at least five years in evaluation of diagnostic tests based on detection of galactomannan.
    Journal of clinical microbiology 04/2014; · 4.16 Impact Factor
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    ABSTRACT: Candida albicans can cause candidemia in neutropenic and critically ill patients and oropharyngeal candidiasis in human immunodeficiency virus (HIV)-positive patients with low CD4(+) counts. Because all patients at risk do not develop Candida infections, it is possible that a patient's genetic background might play a role in his or her susceptibility to infection. Autophagy mediates pathogen clearance and modulation of inflammation. Our aim was to assess the effect of genetic variations in the ATG16L1 and IRGM autophagy genes on the susceptibility of patients with candidemia and oropharyngeal candidiasis. We assessed genetic variations in the ATG16L1 and IRGM genes in a cohort of candidemia patients of both African and European origin. In addition, we evaluated the effect of these polymorphisms on the susceptibility to oropharyngeal candidiasis of an HIV-positive cohort from Tanzania. Functional studies have been performed to assess the effect of the ATG16L1 and IRGM genetic variants on both in vitro and in vivo cytokine production. The results indicate that ATG16L1 variants modulate production of tumor necrosis factor-alpha, but not other cytokines, while no effects were seen in the presence of IRGM polymorphisms. In addition, no significant associations between the single-nucleotide polymorphisms in the ATG16L1 and IRGM genetic variants and the incidence of candidemia or oropharyngeal candidiasis were identified.Despite moderate effects on the modulation of proinflammatory cytokine production, genetic variation in the autophagy genes ATG16L1 and IRGM has a minor impact on the susceptibility to both mucosal and systemic Candida infections.
    Medical mycology: official publication of the International Society for Human and Animal Mycology 04/2014; · 2.13 Impact Factor
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    ABSTRACT: Invasive mold infections (IMIs) are a major source of morbidity and mortality among lung transplant recipients (LTRs), yet information regarding the epidemiology of IMI in this population is limited. From 2001 to 2006, multicenter prospective surveillance for IMIs among LTR was conducted by the Transplant-Associated Infection Surveillance Network. The epidemiology of IMI among all LTRs in the cohort is reported. Twelve percent (143/1173) of LTRs under surveillance at 15 US centers developed IMI infections. The 12-month cumulative incidence of IMIs was 5.5%; 3-month all-cause mortality was 21.7%. Aspergillus caused the majority (72.7%)of IMIs; non-Aspergillus infections (39, 27.3%) included Scedosporium (5, 3.5%), mucormycosis (3, 2.1%) and “unspecified” or “other” mold infections (31, 21.7%). Late-onset IMI was common: 52% occurred within 1 year posttransplant (median 11 months, range 0–162 months). IMIs are common late-onset complications with substantial mortality in LTRs. LTRs should be monitored for late-onset IMIs and prophylactic agents should be optimized based on likely pathogen.
    American Journal of Transplantation 04/2014; · 6.19 Impact Factor
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    ABSTRACT: Paecilomyces species are emerging fungal pathogens. Morphological identifications are complicated by similarities among the members of the P. variotii complex as well as to some Rasamsonia and Hamigera species. The purpose of this study was to compare matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) with molecular diagnostic standards (i.e., multilocus DNA sequencing of the internal transcribed spacer regions 1 and 2, D1/D2 regions, and part of the β-tubulin gene) for the identification of Paecilomyces spp. encountered in two clinical mycology laboratories. A total of 77 clinical isolates identified morphologically as P. variotii (n = 21), P. lilacinus (n = 52), and Paecilomyces spp. not otherwise specified (n = 4) were included. In accord with the most recent taxonomy, all P. lilacinus isolates were confirmed as Purpureocillium lilacinum by both sequencing and MALDI-TOF MS. Fungi phenotypically resembling P. variotii or Paecilomyces spp. were identified by molecular techniques as P. variotii sensu stricto (n = 12), P. formosus (n = 3), P. dactylethromorphus (n = 3), Rasamsonia argillacea (n = 4), or R. piperina (n = 1) and at the genus level as an isolate of a Hamigera sp. and a Paecilomyces sp. There was 92.2% (71/77) agreement between the molecular and proteomic methods only after supplementation of the MALDI-TOF MS database with type strains. Paecilomyces variotii-like organisms required multilocus DNA interrogations for differentiation and account for all of the fungi whose identification was missed by MALDI-TOF MS. Overall, MALDI-TOF MS was a rapid and reliable alternative to multilocus sequencing. However, significant augmentation of the commercially available database was required to reproducibly identify this group of important human pathogens.
    Medical mycology: official publication of the International Society for Human and Animal Mycology 03/2014; · 2.13 Impact Factor
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    ABSTRACT: 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. Fifteen institutions belonging to the Transplant-Associated Infection Surveillance Network prospectively enrolled SOT and HCT recipients with histoplasmosis, blastomycosis, or coccidioidomycosis occurring between March 2001 and March 2006. A total of 70 patients (64 SOT recipients and 6 HCT recipients) had infection with an endemic mycosis, including 52 with histoplasmosis, 9 with blastomycosis, and 9 with coccidioidomycosis. The 12-month cumulative incidence rate among SOT recipients for histoplasmosis was 0.102%. Occurrence of infection was bimodal; 28 (40%) infections occurred in the first 6 months post transplantation, and 24 (34%) occurred between 2 and 11 years post transplantation. Three patients were documented to have acquired infection from the donor organ. Seven SOT recipients with histoplasmosis and 3 with coccidioidomycosis died (16%); no HCT recipient died. This 5-year multicenter prospective surveillance study found that endemic mycoses occur uncommonly in SOT and HCT recipients, and that the period at risk extends for years after transplantation.
    Transplant Infectious Disease 03/2014; · 1.98 Impact Factor
  • Frédéric Lamoth, Barbara D. Alexander
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    ABSTRACT: Diagnosis of invasive fungal pneumonias by conventional culture methods is difficult to assess and often delayed. Nonmolecular fungal markers have emerged as an important adjunctive tool to support their diagnosis in combination with other clinical, radiologic, and microbiological criteria of invasive fungal diseases. Concerns about the sensitivity and specificity of some tests in different patient populations should lead to warnings about their widespread use. None can identify the emerging and particularly deadly fungal pathogens responsible for mucormycosis. The role of nonmolecular fungal markers should be better defined in combination with other microbiological and radiologic tools in preemptive antifungal strategies.
    Clinics in Laboratory Medicine. 01/2014;
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    ABSTRACT: Systemic Candida albicans infection causes high morbidity and mortality and is associated with neutropenia; however, the roles of other innate immune cells in pathogenesis are poorly defined. Here, using a mouse model of systemic candidiasis, we found that resident macrophages accumulated in the kidney, the main target organ of infection, and formed direct contacts with the fungus in vivo mainly within the first few hours after infection. Macrophage accumulation and contact with Candida were both markedly reduced in mice lacking chemokine receptor CX3CR1, which was found almost exclusively on resident macrophages in uninfected kidneys. Infected Cx3cr1-/- mice uniformly succumbed to Candida-induced renal failure, but exhibited clearance of the fungus in all other organs tested. Renal macrophage deficiency in infected Cx3cr1-/- mice was due to reduced macrophage survival, not impaired proliferation, trafficking, or differentiation. In humans, the dysfunctional CX3CR1 allele CX3CR1-M280 was associated with increased risk of systemic candidiasis. Together, these data indicate that CX3CR1-mediated renal resident macrophage survival is a critical innate mechanism of early fungal control that influences host survival in systemic candidiasis.
    The Journal of clinical investigation 11/2013; · 15.39 Impact Factor
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    ABSTRACT: Background. Fluconazole (FLC) resistance is common in C. glabrata and echinocandins are often used as first line therapy. Resistance to echinocandin therapy has been associated with FKS1 and FKS2 gene alterations. Methods. We reviewed records of all patients with C. glabrata bloodstream infection at Duke Hospital over the past decade (2001-10) and correlated treatment outcome with MIC results and the presence of FKS gene mutations. For each isolate, MICs to FLC and echinocandins (anidulafungin [ANF], caspofungin [CSF], and micafungin [MCF]) and FKS1 and FKS2 gene sequences were determined. Results. Two hundred ninety-three episodes (313 isolates) of C. glabrata bloodstream infection were analyzed. Resistance to echinocandins increased from 4.9% to 12.3% and to FLC from 18% to 30% between 2001 and 2010, respectfully. Among the 78 FLC resistant isolates, 14.1% were resistant to one or more echinocandins. Twenty-five (7.9%) isolates harbored a FKS mutation. The predictor of a FKS mutant strain was prior echinocandin therapy (stepwise multivariable analysis, OR 19.647, 95% CI 7.19-58.1). Eighty percent (8/10) of patients infected with FKS mutants demonstrating intermediate or resistant MICs to an echinocandin and treated with an echinocandin failed to respond or responded initially but recurred. Conclusions. Echinocandin resistance is increasing, including among FLC resistant isolates. The new CLSI clinical breakpoints differentiate wild-type from C. glabrata strains bearing clinically significant FKS1/FKS2 mutations. These observations underscore the importance of knowing the local epidemiology and resistance patterns for Candida within institutions and susceptibility testing of echinocandins for C. glabrata to guide therapeutic decision making.
    Clinical Infectious Diseases 03/2013; · 9.37 Impact Factor
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    ABSTRACT: Twelve laboratories evaluated candidate material for an Aspergillus DNA calibrator. The DNA material was quantified using limiting dilution analysis; the mean concentration was determined to be 1.73 × 1010 units/mL. The calibrator can be used to standardize aspergillosis diagnostic assays which detect and/or quantify nucleic acid
    Journal of Clinial Microbiology. 01/2013;
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    ABSTRACT: BK polyomavirus (BKV) infection continues to be a significant source of allograft dysfunction in kidney transplant recipients. The optimal screening method to detect BKV remains undetermined. In this retrospective analysis of 347 consecutive kidney transplant recipients, we compare the diagnostic and screening performance of urine electron microscopy (EM) with plasma polymerase chain reaction (PCR) in testing for BKV, using biopsy-proved polyomavirus-associated nephropathy (PVAN) as the gold standard. Sixty-nine of 347 recipients had a positive screening test for BKV infection. Twenty-nine patients underwent biopsy, and 11 were diagnosed with PVAN. Sensitivity rates of urine EM and plasma PCR were 88% and 100%, respectively. Specificity rates of urine EM and plasma PCR were 91% and 78%. There was no statistical difference in the operating characteristics of the two tests. The majority of both plasma PCR and urine EM tests were positive in the six months prior to a diagnostic biopsy confirming PVAN. In those patients who had evidence of BKV infection but did not have PVAN, the percentage of positive screening tests decreased with aggressive lowering of immunosuppression. We conclude that urine EM and plasma PCR both function well in screening for BKV infection and in the diagnosis of PVAN. There is an opportunity to detect viral replication, lower immunosuppression, and to prevent PVAN in this population.
    Clinical Transplantation 12/2012; · 1.63 Impact Factor
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    ABSTRACT: To determine the true institutional cost of treating invasive fungal infections in light of recent advances in diagnostic techniques and antifungal therapies for both treatment and prophylaxis of these infections. Economic analysis. Academic medical center. A total of 200 patients discharged from the hospital during 2004-2005 with a diagnosis of proven, probable, or possible aspergillosis, cryptococcosis, invasive candidiasis, or zygomycosis (cases). Patients were matched in a 1:1 fashion with patients having similar underlying disease states but no invasive fungal infections (controls). Data on demographic and clinical characteristics were collected from patients' medical records. In addition, information concerning each patient's hospitalization was recorded. Resource utilization data for a patient's entire hospitalization were collected from the hospital's charge databases and converted to costs. These data were compared between the cases and the controls. After adjusting for race-ethnicity, sex, age, and comorbid illnesses, mean total hospital cost for cases was $32,196 more than for controls (p<0.0001). Nonpharmacy costs accounted for the majority (63%) of this difference, and an additional $3996 was attributed to systemic antifungal drugs. The mean length of hospital stay was longer for cases than controls (25.8 vs 18.4 days). Treatment of patients with invasive fungal infections was associated with a significantly higher inpatient hospital cost compared with controls. However, due to new diagnostic techniques and effective antifungal therapy, the relative cost of these infections appears to be at least stable compared with the previous decade. These findings can help assess the utility of cost-avoidance strategies such as antifungal prophylaxis and application of appropriate treatment.
    Pharmacotherapy 10/2012; 32(10):890-901. · 2.31 Impact Factor
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    ABSTRACT: STUDY OBJECTIVE: To determine the true institutional cost of treating invasive fungal infections in light of recent advances in diagnostic techniques and antifungal therapies for both treatment and prophylaxis of these infections. DESIGN: Economic analysis. SETTING: Academic medical center. PATIENTS: A total of 200 patients discharged from the hospital during 2004-2005 with a diagnosis of proven, probable, or possible aspergillosis, cryptococcosis, invasive candidiasis, or zygomycosis (cases). Patients were matched in a 1:1 fashion with patients having similar underlying disease states but no invasive fungal infections (controls). MEASUREMENTS AND MAIN RESULTS: Data on demographic and clinical characteristics were collected from patients' medical records. In addition, information concerning each patient's hospitalization was recorded. Resource utilization data for a patient's entire hospitalization were collected from the hospital's charge databases and converted to costs. These data were compared between the cases and the controls. After adjusting for race-ethnicity, sex, age, and comorbid illnesses, mean total hospital cost for cases was $32,196 more than for controls (p<0.0001). Nonpharmacy costs accounted for the majority (63%) of this difference, and an additional $3996 was attributed to systemic antifungal drugs. The mean length of hospital stay was longer for cases than controls (25.8 vs 18.4 days). CONCLUSION: Treatment of patients with invasive fungal infections was associated with a significantly higher inpatient hospital cost compared with controls. However, due to new diagnostic techniques and effective antifungal therapy, the relative cost of these infections appears to be at least stable compared with the previous decade. These findings can help assess the utility of cost-avoidance strategies such as antifungal prophylaxis and application of appropriate treatment.
    Pharmacotherapy 09/2012; · 2.31 Impact Factor
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    ABSTRACT: Candidemia is a severe invasive fungal infection with high mortality. Recognition of Candida species is mediated through pattern recognition receptors such as Toll-like receptors (TLRs). This study assessed whether genetic variation in TLR signaling influences susceptibility to candidemia. Thirteen mostly nonsynonymous single nucleotide polymorphisms (SNPs) in genes encoding TLRs and signaling adaptors MyD88 and Mal/TIRAP were genotyped in 338 patients (237 white, 93 African American, 8 other race) with candidemia and 351 noninfected controls (263 white, 88 African American). The SNPs significant in univariate analysis were further analyzed with multivariable logistic regression to determine association with clinical outcomes. Functional consequences of these polymorphisms were assessed via in vitro stimulation assays. Analyses of TLR SNPs revealed that 3 TLR1 SNPs (R80T, S248N, I602S) were significantly associated with candidemia susceptibility in whites. This association was not found in African Americans, likely due to lower power in this smaller study population. Furthermore, these TLR1 polymorphisms displayed impaired cytokine release by primary monocytes. No associations with susceptibility to candidemia were observed for SNPs in TLR2, TLR4, TLR6, TLR9, MyD88, or TIRAP. Nonsynonymous SNPs in TLR1 are associated with impaired TLR1 function, decreased cytokine responses, and predisposition to candidemia in whites.
    The Journal of Infectious Diseases 03/2012; 205(6):934-43. · 5.85 Impact Factor
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    ABSTRACT: Species of Candida frequently cause life-threatening infections in neonates, transplant and intensive care unit (ICU) patients, and others with compromised host defenses. The successful management of systemic candidiasis depends upon early, rapid diagnosis. Blood cultures are the standard diagnostic method, but identification requires days and less than half of the patients are positive. These limitations may be eliminated by using real-time polymerase chain reaction (PCR) to detect Candida DNA in the blood specimens of patients at risk. Here, we optimized a PCR protocol to detect 5-10 yeasts in low volumes of simulated and clinical specimens. We also used a mouse model of systemic candidiasis and determined that candidemia is optimally detectable during the first few days after infection. However, PCR tests are often costly, labor-intensive, and inconvenient for routine use. To address these obstacles, we evaluated the innovative microfluidic real-time PCR platform (Advanced Liquid Logic, Inc.), which has the potential for full automation and rapid turnaround. Eleven and nine of 16 specimens from individual patients with culture-proven candidemia tested positive for C. albicans DNA by conventional and microfluidic real-time PCR, respectively, for a combined sensitivity of 94%. The microfluidic platform offers a significant technical advance in the detection of microbial DNA in clinical specimens.
    European Journal of Clinical Microbiology 02/2012; 31(9):2237-45. · 3.02 Impact Factor
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    ABSTRACT: Invasive candidiasis (IC) is a devastating disease. While prompt antifungal therapy improves outcomes, empiric treatment based on the presence of fever has little clinical impact. Β-D-Glucan (BDG) is a fungal cell wall component detectable in the serum of patients with early invasive fungal infection (IFI). We evaluated the utility of BDG surveillance as a guide for preemptive antifungal therapy in at-risk intensive care unit (ICU) patients. Patients admitted to the ICU for ≥ 3 days and expected to require at least 2 additional days of intensive care were enrolled. Subjects were randomized in 3:1 fashion to receive twice weekly BDG surveillance with preemptive anidulafungin in response to a positive test or empiric antifungal treatment based on physician preference. Sixty-four subjects were enrolled, with 1 proven and 5 probable cases of IC identified over a 2.5 year period. BDG levels were higher in subjects with proven/probable IC as compared to those without an IFI (117 pg/ml vs. 28 pg/ml; p<0.001). Optimal assay performance required 2 sequential BDG determinations of ≥ 80 pg/ml to define a positive test (sensitivity 100%, specificity 75%, positive predictive value 30%, negative predictive value 100%). In all, 21 preemptive and 5 empiric subjects received systemic antifungal therapy. Receipt of preemptive antifungal treatment had a significant effect on BDG concentrations (p< 0.001). Preemptive anidulafungin was safe and generally well tolerated with excellent outcome. BDG monitoring may be useful for identifying ICU patients at highest risk to develop an IFI as well as for monitoring treatment response. Preemptive strategies based on fungal biomarkers warrant further study. Clinical Trials.gov NCT00672841.
    PLoS ONE 01/2012; 7(8):e42282. · 3.53 Impact Factor
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    ABSTRACT:  Candida bloodstream infections cause significant morbidity and mortality among hospitalized patients. Although clinical and microbiological factors affecting prognosis have been identified, the impact of genetic variation in the innate immune responses mediated by cytokines on outcomes of infection remains to be studied.  A cohort of 338 candidemia patients and 351 noninfected controls were genotyped for single-nucleotide polymorphisms (SNPs) in 6 cytokine genes (IFNG, IL10, IL12B, IL18, IL1β, IL8) and 1 cytokine receptor gene (IL12RB1). The association of SNPs with both candidemia susceptibility and outcome were assessed. Concentrations of pro- and antiinflammatory cytokines were measured in in vitro peripheral blood mononuclear cell stimulation assays and in serum from infected patients.  None of the cytokine SNPs studied were associated with susceptibility to candidemia. Persistent fungemia occurred in 13% of cases. In the multivariable model, persistent candidemia was significantly associated with (odds ratio [95% confidence interval]): total parenteral nutrition (2.79 [1.26-6.17]), dialysis dependence (3.76 [1.46-8.64]), and the SNPs IL10 rs1800896 (3.45 [1.33-8.93]) and IL12B rs41292470 (5.36 [1.51-19.0]). In vitro production capacity of interleukin-10 and interferon-γ was influenced by these polymorphisms, and significantly lower proinflammatory cytokine concentrations were measured in serum from patients with persistent fungemia.  Polymorphisms in IL10 and IL12B that result in low production of proinflammatory cytokines are associated with persistent fungemia in candidemia patients. This provides insights for future targeted management strategies for patients with Candida bloodstream infections.
    Clinical Infectious Diseases 12/2011; 54(4):502-10. · 9.37 Impact Factor
  • Erika D Lease, Barbara D Alexander
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    ABSTRACT: Fungal pneumonia is increasingly common, particularly in highly immunosuppressed patients, such as solid organ or hematopoietic stem cell transplant recipients, and the diagnosis is evolving. Although standard techniques such as microscopy and culture remain the mainstays of diagnosis, relatively recent advances in serological and molecular testing are important additions to the field. This article reviews the laboratory tools used to diagnose fungal respiratory disease.
    Seminars in Respiratory and Critical Care Medicine 12/2011; 32(6):663-72. · 2.75 Impact Factor
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    ABSTRACT: 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.
    Emerging Infectious Diseases 10/2011; 17(10):1855-64. · 6.79 Impact Factor

Publication Stats

4k Citations
481.25 Total Impact Points

Institutions

  • 2001–2014
    • Duke University Medical Center
      • • Division of Infectious Diseases
      • • Department of Medicine
      • • Department of Pediatrics
      Durham, North Carolina, United States
  • 2007–2013
    • Duke University
      • Department of Medicine
      Durham, North Carolina, United States
    • The Children's Hospital of Philadelphia
      • Division of Infectious Diseases
      Philadelphia, Pennsylvania, United States
    • Associates of Cape Cod, Inc.
      East Falmouth, Massachusetts, United States
  • 2012
    • Radboud University Medical Centre (Radboudumc)
      • Department of Human Genetics
      Nymegen, Gelderland, Netherlands
    • University of Utah
      Salt Lake City, Utah, United States
  • 2010
    • State University of New York
      New York City, New York, United States
  • 2009
    • University of Texas MD Anderson Cancer Center
      Houston, Texas, United States
    • University of North Carolina at Chapel Hill
      • Division of Molecular Pharmaceutics
      North Carolina, United States
  • 2003–2009
    • University of Pittsburgh
      Pittsburgh, Pennsylvania, United States
  • 2008
    • University of Houston
      Houston, Texas, United States
  • 2005
    • Mayo Clinic - Rochester
      Rochester, Minnesota, United States
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States