Preventing opportunistic infections in bone marrow transplant recipients

High incidence of Pneumocystis jirovecii pneumonia in allogeneic hematopoietic cell transplant recipients in the modern era

BACKGROUND

International guidelines for Pneumocystis jirovecii pneumonia (PJP) prevention recommend prophylaxis for ≥6 months following allogeneic hematopoietic cell transplantation, and longer in patients with graft-versus-host disease (GVHD) or on immunosuppressive therapy (IST). These recommendations are based on cohorts of patients who did not routinely receive anti-thymocyte globulin (ATG) for GVHD prophylaxis.

METHODS

We performed a retrospective chart review of 649 patients, all of whom received ATG as part of GVHD prophylaxis.

RESULTS

The cumulative incidence of definite PJP was 3.52% at both 3 and 5 years (median follow up, 1648 days for survivors). PJP occurred in 13 non-GVHD patients between days 207 and 508, due in part to low CD4 T-cell counts (<200 CD4 T cells/µL). PJP occurred in eight GVHD patients between days 389 and 792, due in part to non-adherence to PJP prophylaxis guidelines (discontinuation of PJP prophylaxis at <3 months after discontinuation of IST). Breakthrough PJP infection was not observed in patients receiving prophylaxis with cotrimoxazole, dapsone or atovaquone, whereas three cases were observed with inhaled pentamidine.

DISCUSSION

In conclusion, for non-GVHD patients receiving ATG-containing GVHD prophylaxis, 6 months of PJP prophylaxis is inadequate, particularly if the CD4 T-cell count is <200 cells/µL or if there is a high incidence of PJP in the community. For patients with GVHD receiving ATG-containing GVHD prophylaxis, continuing PJP prophylaxis until ≥3 months post-discontinuation of IST is important. Cotrimoxazole, dapsone and atovaquone are preferred over inhaled pentamidine.

Overview of Infections in the Immunocompromised Host

Understanding the components of the immune system that contribute to host defense against infection is key to recognizing infections that are more likely to occur in an immunocompromised patient. In this review, we discuss the integrated system of physical barriers and of innate and adaptive immunity that contributes to host defense. Specific defects in the components of this system that predispose to particular infections are presented. This is followed by a review of primary immunodeficiency diseases and secondary immunodeficiencies, the latter of which develop because of a specific illness or condition or are treatment-related. The effects of treatment for neoplasia, autoimmune diseases, solid organ and stem cell transplants on host defenses are reviewed and associated with susceptibility to particular infections. In conclusion, an approach to laboratory screening for a suspected immunodeficiency is presented. Knowledge of which host defects predispose to specific infections allows clinicians to prevent, diagnose, and manage infections in their immunocompromised patients most effectively.

Vaccination in Multiple Myeloma: Review of Current Literature

Multiple myeloma is a cancer of the immune system. Infection is a major cause of morbidity and mortality in patients with multiple myeloma. Some of these infections are preventable by vaccines available to the general population. However, little is known about the clinical effectiveness of these vaccines in patients with multiple myeloma, and the cellular and humoral immune response to vaccination has not been well characterized, especially in conjunction with modern myeloma therapies. The present report reviews the basics of multiple myeloma and the immune system, the available evidence on the immunologic response of patients with multiple myeloma after vaccination, and current practice recommendations regarding specific vaccines. Understanding the immune response to vaccines could help us understand how immuno-oncology-based therapies work in multiple myeloma and provide future directions for research.

The incidence, mortality and timing of Pneumocystis jiroveci pneumonia after hematopoietic cell transplantation: a CIBMTR analysis

Pneumocystis jiroveci pneumonia (PJP) is associated with high morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Little is known about PJP infections after HSCT because of the rarity of disease given routine prophylaxis. We report the results of a Center for International Blood and Marrow Transplant Research study evaluating the incidence, timing, prophylaxis agents, risk factors and mortality of PJP after autologous (auto) and allogeneic (allo) HSCT. Between 1995 and 2005, 0.63% allo recipients and 0.28% auto recipients of first HSCT developed PJP. Cases occurred as early as 30 days to beyond a year after allo HSCT. A nested case cohort analysis with supplemental data (n=68 allo cases, n=111 allo controls) revealed that risk factors for PJP infection included lymphopenia and mismatch after HSCT. After allo or auto HSCT, overall survival was significantly poorer among cases vs controls (P=0.0004). After controlling for significant variables, the proportional hazards model revealed that PJP cases were 6.87 times more likely to die vs matched controls (P<0.0001). We conclude PJP infection is rare after HSCT but is associated with high mortality. Factors associated with GVHD and with poor immune reconstitution are among the risk factors for PJP and suggest that protracted prophylaxis for PJP in high-risk HSCT recipients may improve outcomes.

Performing allogeneic and autologous hematopoietic SCT in the outpatient setting: effects on infectious complications and early transplant outcomes

This retrospective single-center study compared the incidence, spectrum and effect of infections in 1045 consecutive allogeneic (allo) and autologous (auto) hematopoietic SCT (HSCT) performed between 1995 and 2006 in the inpatient (IP) or outpatient (OP) setting. We analyzed 374 allo-HSCT (196 IP and 178 OP) and 671 auto-HSCT (163 IP and 508 OP). The incidence of infection was lower both in auto-OP (25% OP vs 33% IP, P=0.042) and allo-OP cohorts (42.7% OP vs 55.6% IP, P=0.012). The mean number of infections per transplant was lower in both auto-OP (0.39 OP vs 0.57 IP, P=0.05) and in allo-OP cohorts (0.78 OP vs 1.09 IP, P=0.018). The 100-day non-relapse mortality (NRM) for OP auto-HSCT was 4.72% and for IP 3.95% (P=0.68). The 100-day NRM for OP allo-HSCT was lower at 14.1% than it was for IP at 22.6% (P=0.041). Time to onset of first infection and spectrum of infections was similar in all groups. We conclude that performing allo- and auto-HSCT in the OP setting results in short-term outcomes, including infections complications that are comparable to the standard IP setting.

[Update on the treatment of genital herpes]

Genital herpes is a chronic infection characterized by periodic reactivation. It can produce symptomatic disease in the host although asymptomatic viral excretion can also occur. It is currently the main cause of genital ulceration and an important public health problem that has substantial clinical, psychological, and economic repercussions. This review analyzes the currently available therapeutic options and regimens, which are based mainly on systemic use of antiviral agents such as aciclovir, valacyclovir, and famciclovir. In addition, special emphasis is placed on the prevention and management of this infection in specific situations, such as pregnant, pediatric, and immunocompromised patients.

Autoimmunity following haematopoietic stem-cell transplantation

Autoimmunity after stem-cell transplantation has been observed over decades. Evidence comes from single case reports or small series. Autoimmune phenomena are known in both the autologous and the allogeneic settings, irrespective of the graft source. Most publications deal with autoantibody production after transplantation; more rarely, the appearance of the associated autoimmune disease is reported. Autoimmune thyroid disease and autoimmune cytopenias are most often described. Homeostatic expansion after transplantation-induced lymphopenia is thought to be a trigger for loss of self-tolerance and proliferation of autoreactive T-cells in these patients. With allogeneic haematopoietic stem-cell transplantation, adoptive transfer of autoimmune disease has been shown, raising the issue of graft quality. Many of the clinical and laboratory features of graft-versus-host disease (GvHD), especially in its chronic form, resemble those of autoimmune diseases, and the pathophysiological mechanisms are similar. Prospective data for a better understanding of autoimmunity and 'altered' immunity after stem-cell transplantation are needed.

The effect of peptide stimulation on haematopoietic stem cell mobilisation including engraftment characteristics and a note on donor side effects

Aplasia or irreversible bone marrow failure and a variety of haematologic malignancies, as well as an increasing number of solid tumours, currently include various forms of marrow or equivalent transplantation in routine management. In both allogeneic and autologous procedures stable recipient immunohaematopoietic reconstitution depends upon infusing the requisite population harvested at a precise time following commencement of a stimulatory peptide. In a first step this prospective study documented the safety of apheresis, defined side effects and enumerated mononuclear, CD34+ and CD3+ cells obtained. In the second stage delivery of the graft, characterised in this way and with the additional measurement of in vitro growth in clonogenic assay, to the suitably conditioned patient was correlated with recovery of neutrophil and platelet numbers appearing in the circulation. In a third and ongoing analysis the influence of passenger T-lymphocytes is being evaluated for impact on infection and a potential anti-tumour effect. The conclusion is that this technology is reliable, has a high degree of patient acceptability without untoward complications, and that local results correspond to international experience thereby providing an important and relevant measure of quality control.