Aliyah Baluch

Early identification and control of carbapenemase-producing Klebsiella pneumoniae, originating from contaminated endoscopic equipment

Klebsiella producing carbapenemase is an emerging pathogen. We report transmission of this organism by contaminated endoscopic instruments. Quick identification of source, staff education, contact precautions, and emphasis on hand and environmental hygiene led to case control and prevention of outbreak.

Randomized Controlled Trial of High-Dose Intradermal Versus Standard-Dose Intramuscular Influenza Vaccine in Organ Transplant Recipients

The immunogenicity of standard intramuscular (IM) influenza vaccine is suboptimal in transplant recipients. Also, recent studies suggest that alloantibody may be upregulated due to vaccination. We evaluated a novel high‐dose intradermal (ID) vaccine strategy. In conjunction, we assessed alloimmunity. Transplant recipients were randomized to receive IM or high‐dose ID vaccine. Strain‐specific serology and HLA alloantibody production was determined pre‐ and postimmunization. In 212 evaluable patients (105 IM, 107 ID), seroprotection to H1N1, H3N2 and B strains was 70.5%, 63.8% and 52.4% in the IM group, and 71.0%, 70.1%, 63.6% in the ID group (p = ns). Seroconversion to ≥1 antigen was 46.7% and 51.4% in the IM and ID groups respectively (p = 0.49). Response was more likely in those ≥6 months posttransplant (53.2% vs. 19.2%; p = 0.001). Use of mycophenolate mofetil was inversely associated with vaccine response in a dose‐dependent manner (p < 0.001). Certain organ subgroups had higher response rates for influenza B in the ID vaccine group. Differences in anti‐HLA antibody production were detected in only 3/212(1.4%) patients with no clinical consequences. High‐dose intradermal vaccine is an alternative to standard vaccine and has potential enhanced immunogenicity in certain subgroups. In this large cohort, we also show that seasonal influenza does not result in significant alloantibody production.

IL-28B is a Key Regulator of B- and T-Cell Vaccine Responses against Influenza

Influenza is a major cause of morbidity and mortality in immunosuppressed persons, and vaccination often confers insufficient protection. IL-28B, a member of the interferon (IFN)-λ family, has variable expression due to single nucleotide polymorphisms (SNPs). While type-I IFNs are well known to modulate adaptive immunity, the impact of IL-28B on B- and T-cell vaccine responses is unclear. Here we demonstrate that the presence of the IL-28B TG/GG genotype (rs8099917, minor-allele) was associated with increased seroconversion following influenza vaccination (OR 1.99 p = 0.038). Also, influenza A (H1N1)-stimulated T- and B-cells from minor-allele carriers showed increased IL-4 production (4-fold) and HLA-DR expression, respectively. In vitro, recombinant IL-28B increased Th1-cytokines (e.g. IFN-γ), and suppressed Th2-cytokines (e.g. IL-4, IL-5, and IL-13), H1N1-stimulated B-cell proliferation (reduced 70%), and IgG-production (reduced>70%). Since IL-28B inhibited B-cell responses, we designed antagonistic peptides to block the IL-28 receptor α-subunit (IL28RA). In vitro, these peptides significantly suppressed binding of IFN-λs to IL28RA, increased H1N1-stimulated B-cell activation and IgG-production in samples from healthy volunteers (2-fold) and from transplant patients previously unresponsive to vaccination (1.4-fold). Together, these findings identify IL-28B as a key regulator of the Th1/Th2 balance during influenza vaccination. Blockade of IL28RA offers a novel strategy to augment vaccine responses.

An Analysis of Regulatory T-Cell and Th-17 Cell Dynamics during Cytomegalovirus Replication in Solid Organ Transplant Recipients

Background CMV-specific T-cells are crucial to control CMV-replication post-transplant. Regulatory T-cells (T-regs) are associated with a tolerant immune state and may contribute to CMV-replication. However, T-cell subsets such as T-regs and IL-17 producing T-cells (Th-17) are not well studied in this context. We explored T-regs and Th-17 frequencies during CMV-replication after transplantation. Methods We prospectively evaluated 30 transplant patients with CMV-viremia. We quantified CMV-specific CD4+ and CD8+ T-cells, T-regs (CD4+CD25+FoxP3+) and Th-17 frequencies using flow-cytometry and followed patients requiring anti-viral treatment. Two subsets were compared: anti-viral treatment requirement (n = 20) vs. spontaneous clearance of viremia (n = 10). Results Higher initial CMV-specific CD4+ T-cells and lower T-regs were observed in patients with spontaneous clearance (p = 0.043; p = 0.021 respectively). Using a ratio of CMV-specific CD4+ T-cells to T-regs allowed prediction of viral clearance with 80% sensitivity and 90% specificity (p = 0.001). One month after stop of treatment, the same correlation was observed in patients protected from CMV-relapse. The ratio of CMV-specific CD4+ T-cells to T-regs allowed prediction of relapse with 85% sensitivity and 86% specificity (p = 0.004). Th-17 responses were not correlated with virologic outcomes. Conclusions This study provides novel insights into T-regs and Th-17 subpopulations during CMV-replication after transplantation. These preliminary data suggest that measurement of CMV-specific CD4+ T-cells together with T-regs has value in predicting spontaneous clearance of viremia and relapse.

Long term immune responses to pandemic influenza A/H1N1 infection in solid organ transplant recipients.

In solid organ transplant (SOT) recipients it is unknown if natural infection with influenza confers protection from re-infection with the same strain during the next influenza season. The purpose of this study was to determine if infection with pandemic influenza A/H1N1 (pH1N1) resulted in a long-term immunologic response. Transplant recipients with microbiologically proven pH1N1 infection in 2009/2010 underwent humoral and cell-mediated immunity (CMI) testing for pH1N1 just prior to the next influenza season. Concurrent testing for A/Brisbane/59/2007 was done to rule-out cross-reacting antibody. We enrolled 22 adult transplant patients after pH1N1 infection. Follow up testing was done at a median of 7.4 months (range 5.8–15.4) after infection. After excluding those with cross-reactive antibody, 7/19 (36.8%) patients were seroprotected. Detectable pH1N1-specific CD4+ and CD8+ interferon-γ producing T-cells were found in 11/22 (50%) and 8/22 (36.4%) patients respectively. Humoral immunity had a significant correlation with a CD4 response. This is the first study in transplant patients to evaluate long-term humoral and cellular response after natural influenza infection. We show that a substantial proportion of SOT recipients with previous pH1N1 infection lack long-term humoral and cellular immune responses to pH1N1. These patients most likely are at risk for re-infection.

Nocardiosis following hematopoietic stem cell transplantation

Nocardia species are ubiquitous environmental organisms that can cause a diverse spectrum of disease. Clinical manifestations range from localized skin and soft tissue infections to life‐threatening pulmonary, central nervous system, and/or disseminated infections. Patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT) are at risk for nocardiosis, and further data in regard to characteristics of disease in this population are warranted.

Effect of Immunosuppression on T-Helper 2 and B-Cell Responses to Influenza Vaccination.

BACKGROUND Influenza vaccine immunogenicity is suboptimal in immunocompromised patients. However, there are limited data on the interplay of T- and B- cell responses to vaccination with simultaneous immunosuppression. METHODS We collected peripheral blood mononuclear cells from transplant recipients before and 1 month after seasonal influenza vaccination. Before and after vaccination, H1N1-specific T- and B-cell activation were quantified with flow cytometry. We also developed a mathematical model using T- and B-cell markers and mycophenolate mofetil (MMF) dosage. RESULTS In the 47 patients analyzed, seroconversion to H1N1 antigen was demonstrated in 34%. H1N1-specific interleukin 4 (IL-4)-producing CD4(+) T-cell frequencies increased significantly after vaccination in 53% of patients. Prevaccine expression of H1N1-induced HLA-DR and CD86 on B cells was high in patients who seroconverted. Seroconversion against H1N1 was strongly associated with HLA-DR expression on B cells, which was dependent on the increase between prevaccine and postvaccine H1N1-specific IL-4(+)CD4(+) T cells (R(2) = 0.35). High doses of MMF (≥ 2 g/d) led to lower seroconversion rates, smaller increase in H1N1-specific IL-4(+)CD4(+) T cells, and reduced HLA-DR expression on B cells. The mathematical model incorporating a MMF-inhibited positive feedback loop between H1N1-specific IL-4(+)CD4(+) T cells and HLA-DR expression on B cells captured seroconversion with high specificity. CONCLUSIONS Seroconversion is associated with influenza-specific T-helper 2 and B-cell activation and seems to be modulated by MMF.

Successful management of Mycobacterium haemophilum lower extremity cutaneous infection in a matched‐unrelated donor stem cell transplant recipient

Nontuberculous mycobacterial infections can often occur in individuals with adequate immune function. Such infections typically have cutaneous involvement and are caused by rapidly growing mycobacterium. Other nontuberculous mycobacteria species, like Mycobacterium haemophilum, almost always present as opportunistic infections occurring in severely immunocompromised hosts. Here, we present a complicated and protracted course of diagnosing M. haemophilum lower extremity cutaneous infection in a matched‐unrelated donor stem cell transplant recipient.

Early Antimicrobial De-escalation and Stewardship in Adult Hematopoietic Stem Cell Transplantation Recipients: Retrospective Review

Abstract Background Antimicrobial stewardship in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients remains underutilized in North America. European guidelines advise de-escalation of broad-spectrum therapy after 72 hours in select patients with neutropenic fever of unknown origin. This is not commonplace in the United States, as current guidelines recommend broad-spectrum therapy until neutrophil engraftment. If de-escalating after at least 5 days of broad-spectrum therapy and defervescence in neutropenic allo-HSCT recipients does not predispose them to recurrent fever or infection, the practice could afford several benefits. Methods The primary end point was rate of recurrent fever. Secondary outcomes included Clostridium difficile–associated infections, length of stay, intensive care unit (ICU) admission incidence, in-hospital mortality rate, need for re-escalation of therapy, rate of positive blood cultures for patients who had recurrent fevers, overall antimicrobial utilization from neutropenic fever onset, and pharmacoeconomic impact. Results A total of 120 patients were assessed in 2 groups as cohort 1 (n = 46), which received early de-escalation, and cohort 2 (n = 74), which did not. The primary end point met criteria for noninferiority, as 7 patients (15%) in cohort 1 had recurrent fever within the specified time frame compared with 14 (19%) in cohort 2 (90% CI, –0.0878 to 0.1629, P = .026). Patients in cohort 1 received significantly less gram-positive broad-spectrum antimicrobials, with trends toward lower use of broad-spectrum gram-negative agents and lower associated costs and no differences in length of stay, ICU admission incidence, need for re-escalation of therapy, rate of culture-positive bacteremia after de-escalation or discontinuation of broad-spectrum therapy, or in-hospital mortality rate. Conclusions De-escalating after at least 5 days of broad-spectrum therapy and defervescence did not appear to affect the rate of recurrent fever. This allowed for significant reductions in gram-positive broad-spectrum antimicrobial utilization, with trends toward lower use of broad-spectrum gram-negative agents and associated costs and no difference in clinical outcomes compared with those continuing such therapy until neutrophil engraftment.

Baseline serum interleukin-6 to interleukin-2 ratio is associated with the response to seasonal trivalent influenza vaccine in solid organ transplant recipients

BACKGROUND The analysis of pre- and post-vaccination B-cell-associated cytokines might be useful in predicting the immunogenicity of seasonal trivalent influenza vaccine (TIV) in solid organ transplant (SOT) recipients. METHODS We performed a subanalysis of a clinical trial that compared the safety and efficacy of high-dose intradermal (ID) versus intramuscular (IM) TIV in SOT recipients. Serum levels of selected cytokines (interferon [IFN]-γ, interleukin [IL]-2, IL-4, IL-5, IL-6, IL-12 and IL-21, and tumor necrosis factor [TNF]-α) were measured pre- and one month post-vaccination in 155 patients (with 84 and 71 receiving the ID and IM vaccines, respectively). Cytokine profiles were compared according to vaccine response (seroconversion [≥4-fold increase in hemagglutination inhibition antibody titers] to ≥1 influenza vaccine antigen). RESULTS Mean baseline IL-6 levels were higher (1.20 versus 0.65pg/mL; P-value=0.021) and IL-2 levels were lower (0.01 versus 0.50pg/mL; P-value=0.051) in patients achieving vaccine response. After adjusting for clinical variables, baseline IL-6/IL-2 ratio remained predictive of vaccine response (odds ratio per 10-unit increment: 1.06; 95% confidence interval: 1.02-1.10; P-value=0.002). Vaccination induced an increase in TNF-α (P-value <0.0001) and a decrease in IL-5 levels (P-value=0.0007). There were no significant differences in cytokine kinetics between vaccine responders and non-responders. Mean baseline TNF-α levels were higher in patients experiencing moderate-to-severe adverse events after vaccination (1.93 versus 1.72pg/mL; P-value=0.009). CONCLUSIONS Baseline serum IL-6 and IL-2 levels, two cytokines that modulate the role of CD4(+) T follicular helper cells and the terminal differentiation of B-cells, predict vaccine response in SOT recipients.