Hematopoietic Stem Cell Recipients Research Articles

Bacterial bloodstream infections in pediatric allogeneic hematopoietic stem cell recipients before and after implementation of a central line-associated bloodstream infection protocol: A single-center experience.

There are only few reports describing the influence of central line-associated bloodstream infection (CLABSI) prevention strategies on the incidence of bacterial bloodstream infections (BBSIs). We performed a retrospective cohort study among pediatric recipients of allogeneic hematopoietic stem cell transplantation (allo-HCT) to assess potential changes in BBSI rates during 3 time periods: pre-CLABSI prevention era (era 1, 2004-2005), CLABSI prevention implementation era (era 2, 2006-2009), and maintenance of CLABSI prevention era (era 3, 2010-2012). BBSI from day 0-365 following allo-HCT were studied. The comparison of person-years incidence rates among different periods was carried out by Poisson regression analysis. The mean age of patients was 10.0 years. During the study period, 126 (65%) of 190 patients had at least a single BBSI. From day 0-30, day 31-100, day 101-180, and day 181-365, 20%, 28%, 30%, and 17% of patients, respectively, experienced BBSIs. The rate of Staphylococcus epidermidis and gram-negative pathogens significantly declined from 3.16-0.93 and 6.32-2.21 per 100 person-months during era 1 and era 3, respectively (P = .001). Patients undergoing allo-HCT during era 3 were associated with decreased risk of BBSI (P = .012). Maintenance of CLABSI protocols by nursing staff and appropriate education of other care providers is essential to lower incidence of BBSI in this high-risk population, and further strategies to decrease infection burden should be studied.

Reconstitution of cytomegalovirus-specific T-cell response in allogeneic hematopoietic stem cell recipients: the contribution of six frequently recognized, virus-encoded ORFs.

The reactivation of human cytomegalovirus (HCMV) in immunosuppressed patients is associated with significant morbidity. Testing HCMV-specific T-cell responses can help determine which patients are at high risk of HCMV disease. We optimized selection of HCMV antigens for detection of T-cell response of patients after allogeneic hematopoietic stem cell transplantation (HSCT) with the aim of identifying patients with insufficient control of HCMV reactivation. T-cell immune response to HCMV was monitored in 30 patients during the first year after HSCT. The HSCT recipients were classified according to their anti-HCMV T-cell response and the presence of HCMV DNA in the blood. We observed an inverse relationship between the magnitude of HCMV-specific T-cell responses against CMV lysate, phosphoprotein (pp) 65, immediate early-1 (IE-1), UL36, and UL55, but not to US3 and US29 detected by interferon-gamma (IFNγ)- ELISPOT and the level of HCMV DNA in the blood of patients during the 30 days following sampling. The study has revealed that patients who received a graft from a seronegative donor have a lower T-cell response against HCMV and increased probability of HCMV reactivation in comparison to the patients who had received their graft from a seropositive donor. The individual peptide pools and native HCMV antigens were useful for monitoring the time course of the anti-HCMV response by IFNγ-ELISPOT, which proved to have a prognostic value. Besides widely employed peptide pools of pp65 and IE-1, the use of antigens UL36 and UL55, but not US3 or US29, increased sensitivity of the test.

Symptomatic BK Virus Infection Is Associated With Kidney Function Decline and Poor Overall Survival in Allogeneic Hematopoietic Stem Cell Recipients.

Nephropathy due to BK virus (BKV) infection is an evolving challenge in patients undergoing hematopoietic stem cell transplantation (HSCT). We hypothesized that BKV infection was a marker of kidney function decline and a poor prognostic factor in HSCT recipients who experience this complication. In this retrospective study, we analyzed all patients who underwent their first allogeneic HSCT at our institution between 2004 and 2012. We evaluated the incidence of persistent kidney function decline, which was defined as a confirmed reduction in estimated glomerular filtration rate of at least 25% from baseline using the Chronic Kidney Disease Epidemiology equation. Cox proportional hazard regression was used to model the cause-specific hazard of kidney function decline, and the Fine-Gray method was used to account for the competing risks of death. Among 2477 recipients of a first allogeneic HSCT, BK viruria was detected in 25% (n = 629) and kidney function decline in 944 (38.1%). On multivariate analysis, after adjusting for age, sex, acute graft-versus-host disease (GVHD), chronic GVHD, preparative conditioning regimen, and graft source, BK viruria remained a significant risk factor for kidney function decline (p < 0.001). In addition, patients with BKV infection and kidney function decline experienced worse overall survival. After allogeneic HSCT, BKV infection was strongly and independently associated with subsequent kidney function decline and worse patient survival after HSCT.

Fecal Microbiota Transplant Is a Potentially Safe and Effective Treatment for Clostridium Difficile Infection in Hematopoietic Stem Cell Recipients

Fecal Microbiota Transplant Is a Potentially Safe and Effective Treatment for Clostridium Difficile Infection in Hematopoietic Stem Cell Recipients

Risk factors for mortality in patients with bloodstream infections during the pre-engraftment period after hematopoietic stem cell transplantation.

BackgroundBloodstream infections (BSI) remain a frequent complication during the pre-engraftment period after hematopoietic stem cell transplantation (HSCT), resulting in high mortality rates. This study evaluated risk factors for mortality in hematopoietic stem cell transplant recipients with BSI in the pre-engraftment period.MethodsThis prospective case control study was performed at the Center of Hematology and Bone Marrow Transplantation in Minsk, Republic of Belarus. Data relating to patient age and gender, date and type of transplantation, conditioning chemotherapy regimen, microorganisms isolated from blood, and antibacterial therapy were prospectively collected from all hematopoietic stem cell recipients with microbiologically proven cases of BSI in the pre-engraftment period. The primary outcome was all-cause 30-day mortality after onset of febrile neutropenia.ResultsA total of 135 adult patients with microbiologically proven BSI after HSCT were studied, with 65.2% of cases caused by gram-negative microorganisms and 21.5% by non-fermenting bacteria. Inadequate empiric antibacterial therapy and isolation of carbapenem-resistant non-fermenting gram-negative bacteria (Acinetobacter baumannii and Pseudomonas aeruginosa) were independently associated with increased all-cause 30-day mortality in these patients.ConclusionThe risk factors for mortality in adult patients with BSI in the pre-engraftment period after HSCT were inadequacy of empirical antibacterial therapy and isolation of carbapenem-resistant A. baumannii or P. aeruginosa.

Generation of Immunodeficient Mice Bearing Human Immune Systems by the Engraftment of Hematopoietic Stem Cells.

Immunodeficient mice are being used as recipients of human hematopoietic stem cells (HSC) for in vivo analyses of human immune system development and function. The development of several stocks of immunodeficient Prkdc (scid) (scid), or recombination activating 1 or 2 gene (Rag1 or Rag2) knockout mice bearing a targeted mutation in the gene encoding the IL2 receptor gamma chain (IL2rγ), has greatly facilitated the engraftment of human HSC and enhanced the development of functional human immune systems. These "humanized" mice are being used to study human hematopoiesis, human-specific immune therapies, human-specific pathogens, and human immune system homeostasis and function. The establishment of these model systems is technically challenging, and levels of human immune system development reported in the literature are variable between laboratories. The use of standard protocols for optimal engraftment of HSC and for monitoring the development of the human immune systems would enable more direct comparisons between humanized mice generated in different laboratories. Here we describe a standard protocol for the engraftment of human HSC into 21-day-old NOD-scid IL2rγ (NSG) mice using an intravenous injection approach. The multiparameter flow cytometry used to monitor human immune system development and the kinetics of development are described.

Case Report on the Prevention of an Endemic Outbreak of Influenza B on an Allogeneic Transplant Ward

Respiratory tract infections pose a threat to hematopoietic stem cell recipients, increasing morbidity and mortality rates. To address this, preventive measures are of great importance. We describe the early detection of influenza B in a patient who received a recent hematopoietic transplantation, and elucidation of the transmission path using a point-of-care multiplex polymerase chain reaction panel, leading to prevention of viral spread. The use of risk-score systems and point-of-care testing should be further evaluated.

Symptomatic BK virus infection is associated with kidney function decline and poor overall survival in allogeneic hematopoietic stem cell recipients

Symptomatic BK virus infection is associated with kidney function decline and poor overall survival in allogeneic hematopoietic stem cell recipients

High pre-transplant TREC levels indicate good prognosis after hematopoietic stem cell transplantation

BackgroundThymus-dependent T-cell reconstitution plays a role in immune recovery after stem cell transplantation (HSCT). High pre-HCST thymic function has been associated with higher survival, lower incidence of acute and chronic graft versus host disease (GVHD) and lower incidence of infections. The aim of this study was to analyze the relationship between pre-HSCT peripheral blood levels of T-cell receptor excision circles (TREC) and post-HSCT clinical events in recipients of HLA-identical hematopoietic stem cell transplants.MethodDelta deletion signal joint TRECs (sjTRECs) formed by the dREC-yJa rearrangement were quantified by real time PCR in peripheral blood lymphocytes of 62 HSCT recipients.ResultsUnivariate analysis revealed an association between low TREC levels and a higher incidence of grade II-IV acute GVHD (p=0.026), bacterial infection (p=0.005) and cytomegalovirus infection (p=0.033), whereas high TREC levels were associated with higher overall survival (p=0.028). In the multivariate analysis, low pre-HSCT TREC levels remained independently associated with lower survival (p=0.032; RR 2.6), occurrence of grade II-IV acute GVHD (p=0.031; RR: 2.5), bacterial infection (p=0.006, RR: 6.6) and cytomegalovirus infection (p=0.039; RR:2.8).ConclusionOur results corroborate the concept that pre-HSCT recipient´s thymic function is an important predictor of risk for acute grade II-IV GVHD and infection.

A Phase II Study Evaluating the Safety and Efficacy of Subcutaneous Plerixafor for the Mobilization and Transplantation of HLA-Matched Sibling Donor Hematopoietic Stem Cells in Recipients with Hematological Malignancies

▪The optimal source of donor hematopoietic stem cells (HSC) is controversial. Granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood (G-PB) has replaced bone marrow (BM) as the most common allograft source in adults but is associated with donor morbidity and higher rates of chronic graft versus host disease (GVHD) compared to BM. The CXCR4 antagonist plerixafor (Px) mobilizes HSC into the PB (Px-PB) faster than G-CSF and preliminary data suggest both quantitative and qualitative differences in allograft content that may impact clinical outcomes. We sought to assess the efficacy and safety of transplanted allografts collected following mobilization with Px alone in HLA-identical sibling transplantation. This was a Phase II, two-strata, multi-center prospective trial (NCT01696461) to evaluate Px-PB allografts prior to reduced intensity conditioning (RIC) and myeloablative conditioning (MAC) based hematopoietic cell transplantation (HCT). Patients aged 18-65 years with an HLA-ID sibling donor and a hematological malignancy suitable for HCT were eligible. The primary objective was to determine the proportion of donors whose cells could be successfully mobilized and collected with a sufficient CD34+ cell dose using Px as the sole mobilizing agent. Px mobilization was considered successful if ≥ 2.0x10^6 CD34+ cells/kg recipient weight were collected in no more than two leukapheresis (LP) collections. All donors receiving Px were included in the analysis of the primary objective based on the intention-to-treat principle. Secondary objectives included the incidence of acute and chronic adverse events in donors, rates of hematopoietic engraftment, donor chimerism, rates of acute and chronic GVHD, non-relapse mortality (NRM), progression free survival (PFS) and overall survival (OS) for the recipients. From July 2013 to December 2014, 64 donor/recipient pairs were enrolled at 12 centers. Donors received Px at 240μg/kg subcutaneously 4 hours prior to LP. LP was performed processing at least 4X blood volume for up to two consecutive days (a third day was allowed for low CD34+ cell yields after 2 LP procedures) to achieve a target CD34+ cell dose of ≥ 4.0 x 10^6/kg recipient weight with a minimum goal of ≥ 2.0 x 10^6/kg. All allografts were cryopreserved. GVHD prophylaxis included cyclosporine or tacrolimus in combination with methotrexate, mycophenolate mofetil, or sirolimus. G-CSF was given routinely post HCT only to MAC recipients. Patient demographics are provided in Table 1. The median donor age was 56 years (18-65). 64% of the donors were male. Donors underwent one (23%), two (72%), or three (5%) LP procedures. 63 of 64 (98%) donors achieved the primary objective. The median total CD34+ cell dose/kg recipient weight collected within 2 days was 4.6 (0.9-9.6). Maximal donor toxicity following Px injection and LP was grades 0 (30%), 1 (52%), 2 (17%), and 3 (2%). Bloating, flatulence, abdominal pain, headache, paresthesisas, injection site reaction, and dizziness were the most commonly observed toxicities. Bone pain was not observed. The one grade 3 toxicity was a vasovagal episode felt related to LP and unlikely to Px. Toxicities typically resolved within a week of LP. The median follow up is 6.3 months. Median days to ANC (>0.5 x10^9/L) and Platelet count (>20 x 10^9/L) recovery were 13.5 (10-148) and 19 (1-76) after MAC and 14.5 (0-25) and 18 (0-141) after RIC, respectively. The cumulative incidence of acute GVHD grades 2-4 and 3-4 at day 100 were 47% (95% CI: 30-64) and 9% (95% CI: 2-22) after MAC and 19% (95% CI: 6-38) and 5% (95% CI: 0-18) after RIC. Probability of NRM at day 100 was 4% (95% CI: 0-13) and 0% after MAC and RIC, respectively. The probability of OS at day 100 was 97% (95% CI: 88-100) and 90% (95% CI: 78-98) after MAC and RIC, respectively. In conclusion, this is the first multi-center trial to demonstrate that as an alternative to G-CSF, Plerixafor rapidly, safely, and effectively mobilizes sufficient numbers of CD34+ cells from HLA-ID sibling donors for HCT following both RIC and MAC regimens. Engraftment was generally prompt and early results of secondary endpoints in recipients are encouraging. Longer follow-up and more extensive analysis of donor allografts and recipient outcomes will be presented at the time of the meeting. Research support was provided in part by Genzyme, a Sanofi Company. [Display omitted] DisclosuresChen:Bayer: Consultancy, Research Funding. Devine:Genzyme: Research Funding.

Whole Genome Sequencing of Azole-Resistant Aspergillus Fumigatus Strains from Hematopoietic Stem Cell Recipients Identifies Candidate Molecular Targets Potentially Implicated in Novel Resistance Mediating Mechanisms - First Results

IntroductionInvasive aspergillosis (IA) represents a critical complication that frequently emerges during induction chemotherapy for acute leukemia or after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and is associated with high mortality rates. During the last years, routine administration of antimold prophylaxis based on triazole regimens provided a major advance in controlling fungal infections in patients at high risk for IA. However, several studies recently reported azole resistant fungal strains, which are detectable in patients at risk with rapidly increasing frequency. While mutations in the 14α-sterol demethylase (cyp51A) gene have been implicated in mediating azole resistance, in approximately 50% of resistant patient isolates the underlying genetic cause is unknown (van der Linden, Emerging Infectious Diseases, 2015). In view of a rising prevalence of azole resistance in the high risk clinical setting we performed whole genome sequencing (WGS) of azole-resistant cyp51A-wildtype Aspergillus fumigatus (Afu) specimen, the main effector of IA, with the aim to identify novel genetic alterations leading to azole resistance.MethodsAfu clinical strains were isolated from six different patients with IA undergoing intensive chemotherapy for acute leukemia or after allo-HSCT. Phenotypic resistance screening confirmed azole resistance in all samples. Moreover, Sanger sequencing revealed characteristic resistance associated cyp51A mutations ("TR46/Y121F/T289A") in four of the six specimen, while two samples harbored cyp51A wildtype sequences. High molecular weight genomic DNA (gDNA) was isolated using a modified DNeasy Plant Mini Kit protocol (Qiagen). WGS sequencing libraries were prepared utilizing the transposome fragmentation based Nextera XT DNA Library Prep Kit (Illumina) and sequenced on a MiSeq next generation sequencing (NGS) system (Illumina) with V2 sequencing chemistry (2x250bp). Raw paired reads were mapped to the NCBI Af293 (ASM265v1) reference genome using BWA followed by calibration with GATK. Subsequently, genomic variants were identified by GATK Haplotypecaller module and ANNOVAR software was used for functional variant annotation.ResultsWGS of four cyp51A mutated and two cyp51A wildtype samples resulted in an average genomic coverage of 26x (range 21.2x - 30.1x) allowing robust detection of genomic sequence variants. Of note, the presence or absence of cyp51A "TR46/Y121F/T289A" mutational genotype was reliably validated by WGS data using both our variant calling pipeline and manual screening of mapped reads with the IGV browser. In an attempt to screen for novel, previously undocumented candidate genes that are mechanistically involved in azole resistance we first identified all mutations that are exclusively present in the cyp51A wildtype samples and undetectable in the cyp51A mutated cohort. Next, we excluded all variants that have previously been reported as being polymorphic in WGS data from 22 different Afu strains sequenced by the J. Craig Venter Institute. Using this strategy we identified a core candidate cluster of 112 nucleotide variants in 62 genes that were exclusively found in the cyp51A wildtype group and predicted to have an impact on the amino acid sequence of the corresponding translational products. In particular, exemplary identified mutations affected genes coding for glycosyl hydrolase family 31 proteinimplicated in carbohydrate metabolic processes and 3-oxo-5-alpha-steroid 4-dehydrogenase family protein, which is, similar to cyp51A, involved in steroid metabolism.ConclusionThe rapid increase in detection of triazole resistant fungal strains in clinical contexts represents a critical problem, particularly for immunocompromised patients at high risk for IA, and highlights the need to explore the underlying molecular causes. Pending further validation in a larger cohort, our NGS-based approach for sequencing the genomes of azole resistant Afu strains identified several candidate genomic alterations that might pinpoint alternative pathways to acquisition of resistance, independent of the previously described cyp51A mutations. Ultimately, our approach for discovery of previously undescribed resistance pathways in fungal strains might aid in exploration of novel therapeutic targets and identify suitable biomarkers for effective clinical and epidemiological surveillance. DisclosuresBuchheidt:Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Other: travel grant, Research Funding, Speakers Bureau; Astellas: Other: travel grant, Speakers Bureau; Merck Sharp & Dohme: Other: travel grant, Speakers Bureau.

Tacrolimus and Mini-dose Methotrexate for Prevention of Graft-Versus-Host Disease after Unrelated Hematopoietic Stem Cell Transplantation in Children: A Single-center Study in Korea

Background: Currently, data on the role of tacrolimus and mini-dose methotrexate (MTX) in pediatric unrelated hematopoietic stem cell transplantation (HSCT) is limited. We report the outcomes of unrelated hematopoietic stem cell recipients, evaluating engraftment status, incidence of acute and chronic graft-versus-host disease (GVHD) and toxicities after use of tacrolimus and mini-dose MTX for GVHD prophylaxis.

Prognosis of Allogeneic Haematopoietic Stem Cell Recipients Admitted to the Intensive Care Unit: A Retrospective, Single-Centre Study

Background: Allogeneic haematopoietic stem cell transplantation (HSCT) is a procedure with inherent complications and intensive care may be necessary. We evaluated the short- and long-term outcomes of the HSCT recipients requiring admission to the intensive care unit (ICU). Methods: We retrospectively examined the outcome of 54 adult haematological HSCT recipients admitted to the ICU at the University Hospital Rigshospitalet between January 2007 and March 2012. Results: The overall in-ICU, in-hospital, 6-month and 1-year mortality rates were 46.3, 75.9, 79.6 and 86.5%, respectively. Mechanical ventilation had a statistically significant effect on in-ICU (p = 0.02), 6-month (p = 0.049) and 1-year (p = 0.014) mortality. Renal replacement therapy also had a statistically significant effect on in-hospital (p = 0.038) and 6-month (p = 0.026) mortality. Short ICU admissions, i.e. <10 days, had a statistically significant positive effect on in-hospital, 6-month and 1-year mortality (all p < 0.001). The SAPS II, APACHE II and SOFA scoring systems grossly underestimated the actual in-hospital mortality observed for these patients. Conclusion: The poor prognosis of critically ill HSCT recipients admitted to the ICU was confirmed in our study. Mechanical ventilation, renal replacement therapy and an ICU admission of ≥10 days were each risk factors for mortality in the first year after ICU admission.

Burden of serious fungal diseases in Hungary.

Valid data on the prevalence of serious fungal diseases are difficult to derive as in most countries these conditions are not reportable infections. To assess the burden of these infections in Hungary prevalence estimates from international peer-reviewed papers and population statistics were utilised. In the intensive care unit (ICU) population at least 370 cases of serious yeast and 52 mould infections can be expected yearly. The total number of candidaemia cases may be as high as 1110 annually. In patients with acute leukaemia and recipients of haematopoietic stem cell and solid organ transplants the predicted incidence is more than 55 every year. Recurrent vulvovaginal candidiasis--though not a life-threatening condition--can adversely affect the quality of life of more than 177,000 Hungarian women. According to organisation for economic co-operation and development (OECD), 4.7% of total population older than 15 will suffer from chronic obstructive pulmonary disease (COPD) and 4.4% from asthma, adding another very broad risk group to the aforementioned categories susceptible for mycotic complications. Here more than 17,000 can have severe asthma with fungal sensitisation (SAFS) and more than 13,000 are at risk for developing allergic bronchopulmonary aspergillosis (ABPA). The incidence of dermatomycoses and other superficial fungal infections is even more difficult to assess but--according to international estimations--can affect around 14.3% of the total population. More than 1.6 million Hungarians may suffer from fungal diseases annually, with 33,000 cases being life threatening or very serious. This is an under-recognised problem of special importance for public health.

Mesenchymal stromal cells enhance the engraftment of hematopoietic stem cells in an autologous mouse transplantation model.

IntroductionStudies have proposed that mesenchymal stem cells (MSCs) improve the hematopoietic engraftment in allogeneic or xenogeneic transplants and this is probably due to the MSCs’ immunosuppressive properties. Our study aimed to discern, for the first time, whether MSC infusion could facilitate the engraftment of hematopoietic stem cells (HSCs) in autologous transplantations models, where no immune rejection of donor HSCs is expected.MethodsRecipient mice (CD45.2) mice, conditioned with moderate doses of radiation (5-7 Gy), were transplanted with low numbers of HSCs (CD45.1/CD45.2) either as a sole population or co-infused with increasing numbers of adipose-derived-MSCs (Ad-MSCs). The influence of Ad-MSC infusion on the short-term and long-term engraftment of donor HSCs was investigated. Additionally, homing assays and studies related with the administration route and with the Ad-MSC/HSC interaction were conducted.ResultsOur data show that the co-infusion of Ad-MSCs with low numbers of purified HSCs significantly improves the short-term and long-term hematopoietic reconstitution of recipients conditioned with moderate irradiation doses. This effect was Ad-MSC dose-dependent and associated with an increased homing of transplanted HSCs in recipients’ bone marrow. In vivo and in vitro experiments also indicate that the Ad-MSC effects observed in this autologous transplant model are not due to paracrine effects but rather are related to Ad-MSC and HSC interactions, allowing us to propose that Ad-MSCs may act as HSC carriers, facilitating the migration and homing of the HSCs to recipient bone marrow niches.ConclusionOur results demonstrate that Ad-MSCs facilitate the engraftment of purified HSCs in an autologous mouse transplantation model, opening new perspectives in the application of Ad-MSCs in autologous transplants, including HSC gene therapy.

Effectiveness of BCV for the treatment of digestive diseases and disseminated adenovirus infections in recipients of pediatric hematopoietic stem cells

s / Journal of Clinical Virology 70 (2015) S1–S126 S15 and Sofosbuvir (NS5B inhibitor). 31 treatment-naive HIV-HCV co-infected patient samples were sequenced to measure the prevalence of naturally occurring resistance polymorphisms. Metagenomic sequencing was carried out without the need for primer-specific PCR, RNA was extracted using magnetic beads (Magjet), reverse transcribed (Maxima) and fragmented and indexed using transposon-based chemistry (Nextera XT). Sequencing libraries were run on an in house MiSeq Illumina next generation sequencing platform. Identification of resistance associated variants was performed using an inhouse bioinformatic pipeline. Results: The analysis covered 27 residues. Mutations detected at a frequency higher than 50% included NS3: (Q80), NS5A (M28, H58), but none in the NS5B region. Mutations detected at less than 50% of the total circulating population: NS3: (V36:22%, Q41:31%, F43:27%, T54:20%,V55:7%, Q80:57% V107:3%, R109:7%, I132:24%, R155:11%, A156:11%, V163:11%, D168:22%, NS5A: M28:27%, Q30:39%, L31:18%, P32:11%, H58:43%, E62:28%, Y93:20%, NS5B: L159:29%, S282:35%,L320:15%, V321:11%. Conclusion: The role of resistance mutations in patients with HCV therapy remains an area of active research. In addition to the presence of NS3 polymorphisms that may be associated with resistance, natural polymorphisms conferring resistance to NS5A inhibitorsmay also be associatedwith treatment failure. Resistance to the NS5B inhibitor (sofosbuvir) has been detected both in vitro and in vivo at the S282 locus (S282T) although this variant has not been reported as a majority variant natural polymorphism. As the mutation is associated with reduced replication fitness, it is highly likely to revert towildtype followingwithdrawal of the inhibitor; it may therefore be undetected in clinical trials if sampling is not carried out during or immediately after cessation of therapy. Further study into the role of minority variant polymorphisms associated with resistance will be important as new DAAs are rolled out. http://dx.doi.org/10.1016/j.jcv.2015.07.041

Control of norovirus outbreak on a pediatric oncology unit

Patients undergoing treatment for cancer with chemotherapy and hematopoietic stem cell recipients are at risk for severe morbidity caused by norovirus (NV). We describe a NV outbreak on the Memorial Sloan Kettering Cancer Center's pediatric oncology unit. Stool testing for diagnosis of NV was performed by real-time polymerase chain reaction (PCR). Twelve NV cases occurred; 7 were hospital acquired. Twenty-five health care workers reported NV compatible illness. Patient-to-patient transmission occurred once. The practices of the Centers for Disease Control and Prevention were supplemented with electronic surveillance, surrogate screening for NV, and heightened cleaning. Two additional cases occurred after implementation of interventions. Long-term shedding was detected in 2 patients. We describe interventions for controlling NV on a pediatric oncology unit. High-risk chronic shedders pose ongoing transmission risks. PCR is a valuable diagnostic tool but may be overly sensitive. Surrogate markers to assess NV burden in stool and studies on NV screening are needed to develop guidelines for high-risk chronic shedders.

Symptomatic BK virus as a significant independent predictor of immune suppression and poor overall survival in allogeneic hematopoietic stem cell recipients.

7025 Symptomatic BK virus as a Significant Independent Predictor of Immune Suppression and Poor Overall Survival in Allogeneic Hematopoietic Stem Cell Recipients Background: BK virus (BKV) infectio...

A systematic review of acute kidney injury in pediatric allogeneic hematopoietic stem cell recipients.

The process of allogeneic HSCT in children is associated with frequent AKI and mortality, but the epidemiology is not widely reported. The aim of this review was to summarize the available evidence on incidence, risk factors, timing, and prognosis of AKI in children following HSCT. We systematically reviewed all observational studies reporting incidence and outcomes of AKI in pediatric allogenic HSCT recipients. The minimum criteria for AKI were defined as an increase in sCr ≥ x1.5 or urine output ≤0.5 mL/kg/min over six h. Medline and Embase were searched until March 2014. From 993 electronic records, five were eligible for inclusion (n = 571 patients). The average incidence of AKI within the first 100 days following HSCT was 21.7% (range 11-42%), and the average time of onset was 4-6 wk post-transplant. Risk factors for AKI included cyclosporine toxicity, amphotericin B and foscarnet, SOS, and having a mismatched donor. There were conflicting reports on whether AKI was associated with the development of CKD. AKI is a common and potentially life-threatening complication following HSCT in children. Further quality observational studies are needed to accurately determine the epidemiology and prognosis of AKI in this population.

Clinical Application of Variation in Replication Kinetics During Episodes of Post-transplant Cytomegalovirus Infections

BackgroundCytomegalovirus (CMV) infection in transplant recipients is reported to replicate with a doubling time of 1.2–2days, and weekly screening is recommended for early diagnosis. We re-evaluated these features in our cohort of transplant recipients. MethodsThe CMV doubling time of the first CMV infection in the first year post-transplant could be calculated for 193 recipients of haematopoietic stem cell or solid organ transplantation. Factors determining the proportion of recipients with a high diagnostic CMV viral load (≥18,200IU/mL) were explored using mathematical simulation. FindingsThe overall median doubling time was 4.3days (IQR 2.5–7.8) and was not influenced by prior CMV immunity, or type of transplantation (p>0.4). Assuming a fixed doubling time of 1.3days and screening intervals of 7 or 10days, 11.1% and 33.3% were projected to have a high CMV viral load at diagnosis, compared to 1.4% and 4.3% if the doubling time varies as observed in our cohort. Consistently, 1.9% of recipients screened weekly had a high diagnostic virus load. InterpretationScreening intervals can be extended to 10days in cohorts with comparable CMV doubling time, whereas shorter than 7days is required in cohorts with shorter doubling times to maintain pre-emptive screening quality.