Healthy Human T-Cell Responses to Aspergillus fumigatus Antigens

Aspergillus fumigatus is associated with both invasive and allergic pulmonary diseases, in different hosts. The organism is inhaled as a spore, which, if not cleared from the airway, germinates into hyphal morphotypes that are responsible for tissue invasion and resultant inflammation. Hyphae secrete multiple products that function as antigens, evoking both a protective (T(H)1-T(H)17) and destructive allergic (T(H)2) immunity. How Aspergillus allergens (Asp f proteins) participate in the development of allergic sensitization is unknown.To determine whether Asp f proteins are strictly associated with T(H)2 responses, or represent soluble hyphal products recognized by healthy hosts, human T cell responses to crude and recombinant products were characterized by ELISPOT. While responses (number of spots producing IFN-gamma, IL-4 or IL-17) to crude hyphal antigen preparations were weak, responses to recombinant Asp f proteins were higher. Recombinant allergens stimulated cells to produce IFN-gamma more so than IL-4 or IL-17. Volunteers exhibited a diverse CD4+ and CD8+ T cell antigen recognition profile, with prominent CD4 T(H)1-responses to Asp f3 (a putative peroxismal membrane protein), Asp f9/16 (cell wall glucanase), Asp f11 (cyclophilin type peptidyl-prolyl isomerase) and Asp f22 (enolase). Strong IFN-gamma responses were reproduced in most subjects tested over 6 month intervals.Products secreted after conidial germination into hyphae are differentially recognized by protective T cells in healthy, non-atopic individuals. Defining the specificity of the human T cell repertoire, and identifying factors that govern early responses may allow for development of novel diagnostics and therapeutics for both invasive and allergic Aspergillus diseases

Recurrent Events Analysis With Data Collected at Informative Clinical Visits in Electronic Health Records

Although increasingly used as a data resource for assembling cohorts, electronic health records (EHRs) pose many analytic challenges. In particular, a patient's health status influences when and what data are recorded, generating sampling bias in the collected data. In this paper, we consider recurrent event analysis using EHR data. Conventional regression methods for event risk analysis usually require the values of covariates to be observed throughout the follow-up period. In EHR databases, time-dependent covariates are intermittently measured during clinical visits, and the timing of these visits is informative in the sense that it depends on the disease course. Simple methods, such as the last-observation-carried-forward approach, can lead to biased estimation. On the other hand, complex joint models require additional assumptions on the covariate process and cannot be easily extended to handle multiple longitudinal predictors. By incorporating sampling weights derived from estimating the observation time process, we develop a novel estimation procedure based on inverse-rate-weighting and kernel-smoothing for the semiparametric proportional rate model of recurrent events. The proposed methods do not require model specifications for the covariate processes and can easily handle multiple time-dependent covariates. Our methods are applied to a kidney transplant study for illustration

Incidence and outcome of Staphylococcus aureus bacteremia in hemodialysis patients

Incidence and outcome of Staphylococcus aureus bacteremia in hemodialysis patients.Background. Staphylococcus aureusbacteremia is frequently associated with metastatic complications and infective endocarditis (IE). The Duke criteria for the diagnosis of IE utilize echocardiographic techniques and are more sensitive than previous criteria. The documentation of IE in patients undergoing hemodialysis (HD) has become increasingly important in order to avoid the overuse of empiric vancomycin and the emergence of antibiotic resistance.MethodsPatients who developed S. aureus bacteremia while undergoing HD at a tertiary medical center or one of four affiliated outpatient HD units were identified. Clinical outcome (death, metastatic complications, IE, and microbiologic recurrence) was assessed during hospitalization and at three months after discharge. Transthoracic and transesophageal echocardiograms were performed and the Duke criteria were used to diagnose IE. Pulse field gel electrophoresis was performed to confirm genetic similarity of recurrent isolates.ResultsFour hundred and forty-five patients underwent hemodialysis for 5431.8 patient-months. Sixty-two developed 65 episodes of S. aureus bacteremia (1.2 episodes/100 patient-months). Complications occurred in 27 (44%) patients. Bacteremia recurred in patients who dialyzed through polytetrafluorethylene grafts (44.4% vs. 7.1%, P = 0.0.01), and there was a trend to increased recurrence in patients who received only vancomycin (19.5% vs. 7.1%, P = 0.4). IE was diagnosed in 8 patients (12%), six of whom had normal transthoracic echocardiograms.ConclusionsSensitive echocardiographic techniques and the Duke criteria for the diagnosis of IE should be used to determine the proper duration of antibiotic therapy in hemodialysis patients with S. aureus bacteremia. This diagnostic approach, coupled with early removal of hardware, may assist in improving outcomes

Pretransplant neutropenia is associated with poor-risk cytogenetic features and increased infection-related mortality in patients with myelodysplastic syndromes.

A retrospective cohort analysis was performed to determine the impact of neutropenia on the outcome of hematopoietic cell transplantation (HSCT) in patients with myelodysplasia (MDS). Among 291 consecutive patients, 178 (61%) had absolute neutrophil counts (ANCs) or =1500/microL within 2 weeks before HSCT. Neutropenic patients more often had poor-risk karyotypes (34% versus 12%, P < .0001) and high-risk International Prognostic Scoring System scores (37% versus 18%, P = .0006). After HSCT, the rate of infections caused by Gram-positive bacteria and invasive fungal infections was significantly increased among neutropenic patients (rate ratio [RR] 1.77, P = .02 and RR = 2.56, P = .03, respectively), whereas infections caused by Gram-negative bacteria were not affected (RR 1.33, P = .53). The hazards of nonrelapse mortality (NRM) (hazard ratio [HR] = 1.62 [1.1-2.4], P = .01), overall mortality (HR = 1.55 [1.1-2.1], P = 0.007), and infection-related mortality (HR = 2.22 [1.2-4.2], P = .01) were increased in neutropenic patients, whereas relapse, engraftment, and graft-versus-host-disease were not affected. After adjusting for cytogenetic risk and marrow myeloblast percentages, neutropenic patients remained at significant hazard for infection-related mortality (HR = 1.94 [1.0-3.8], P = .05), but not for overall mortality or NRM. We propose that intensified strategies to prevent infections should be implemented in MDS patients with preexisting neutropenia who undergo HSCT

Epidemiology and outcomes of candidemia in 2019 patients: data from the prospective antifungal therapy alliance registry.

BACKGROUND: Candidemia remains a major cause of morbidity and mortality in the health care setting, and the epidemiology of Candida infection is changing. METHODS: Clinical data from patients with candidemia were extracted from the Prospective Antifungal Therapy (PATH) Alliance database, a comprehensive registry that collects information regarding invasive fungal infections. A total of 2019 patients, enrolled from 1 July 2004 through 5 March 2008, were identified. Data regarding the candidemia episode were analyzed, including the specific fungal species and patient survival at 12 weeks after diagnosis. RESULTS: The incidence of candidemia caused by non-Candida albicans Candida species (54.4%) was higher than the incidence of candidemia caused by C. albicans (45.6%). The overall, crude 12-week mortality rate was 35.2%. Patients with Candida parapsilosis candidemia had the lowest mortality rate (23.7%; P CONCLUSIONS: The epidemiology and choice of therapy for candidemia are rapidly changing. Additional study is warranted to differentiate host factors and differences in virulence among Candida species and to determine the best therapeutic regimen

Aspergillus ustus Infections among Transplant Recipients

This is the first report of clustered Aspergillus ustus causing systemic disease in transplant patients

Plasminogen Alleles Influence Susceptibility to Invasive Aspergillosis

Invasive aspergillosis (IA) is a common and life-threatening infection in immunocompromised individuals. A number of environmental and epidemiologic risk factors for developing IA have been identified. However, genetic factors that affect risk for developing IA have not been clearly identified. We report that host genetic differences influence outcome following establishment of pulmonary aspergillosis in an exogenously immune suppressed mouse model. Computational haplotype-based genetic analysis indicated that genetic variation within the biologically plausible positional candidate gene plasminogen (Plg; Gene ID 18855) correlated with murine outcome. There was a single nonsynonymous coding change (Gly110Ser) where the minor allele was found in all of the susceptible strains, but not in the resistant strains. A nonsynonymous single nucleotide polymorphism (Asp472Asn) was also identified in the human homolog (PLG; Gene ID 5340). An association study within a cohort of 236 allogeneic hematopoietic stem cell transplant (HSCT) recipients revealed that alleles at this SNP significantly affected the risk of developing IA after HSCT. Furthermore, we demonstrated that plasminogen directly binds to Aspergillus fumigatus. We propose that genetic variation within the plasminogen pathway influences the pathogenesis of this invasive fungal infection

New Methods To Assess Susceptibilities of Aspergillus Isolates to Caspofungin

Echinocandins are a group of antifungal agents that target 1,3-β-glucan synthase, causing disruption of mold growth at cells compromising tips and branch points. In part because echinocandins do not induce clear growth inhibition end points using broth dilution techniques, methods to test susceptibility have not yet been standardized. We developed a novel susceptibility assay that measures growth of Aspergillus species on solid agar media that contain serial dilutions of caspofungin (agar dilution). Results of agar dilution testing of multiple isolates were compared to results obtained by broth microdilution (MIC), microscopic evaluation (minimal effective concentration [MEC]), and a new method to measure fungal burden, quantification of secreted hyphal antigen. MICs obtained by the agar dilution method were within 1 dilution of MECs for 85% of the Aspergillus isolates; the highest agreement was observed for isolates of Aspergillus niger (95%), which were particularly susceptible to caspofungin. Agar dilution MICs were also consistent with those obtained by quantifying antigen secretion. MICs obtained by broth microdilution were different than MICs by any other method. Several Aspergillus isolates with decreased susceptibility to caspofungin were identified. Agar dilution is simple and reproducible, and results were consistent with the results of more technically demanding techniques. This method may be appropriate for use in the clinical laboratory