Early bacteremia in pediatric hematopoietic stem cell transplant patients on oral antibiotic prophylaxis

Risk factors for bloodstream infection in paediatric haematopoietic stem cell transplantation: a systematic review and meta-analysis

BACKGROUND

Haematopoietic stem cell transplantation (HSCT), a standard treatment for paediatric haematological diseases, is highly associated with bloodstream infection (BSI), which may increase mortality.

AIM

To explore the risk factors for BSI in paediatric HSCT recipients.

METHODS

Three English databases and four Chinese databases were searched from inception to March 17th, 2022. Eligible studies included randomized controlled trials, cohort studies, and case-control studies that enrolled HSCT recipients aged ≤18 years and reported BSI risk factors. Two reviewers independently screened studies, extracted data, and assessed the risk of bias. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), certainty of body of evidence was assessed.

FINDINGS

Fourteen studies involving 4602 persons were included. The incidences of BSI and associated mortality in paediatric HSCT recipients were approximately 10-50% and 5-15%, respectively. Meta-analysis of all studies revealed that previous BSI before HSCT (relative effect (RE): 2.28; 95% confidence interval (CI) 1.19-4.34, moderate certainty) and receiving an umbilical cord blood transplant (RE: 1.55; 95% CI: 1.22-1.97, moderate certainty) were probably associated with an increased risk of BSI. Meta-analysis of studies with low risk of bias reassured that previous BSI before HSCT probably increased the risk of BSI (RE: 2.28; 95% CI: 1.19-4.34, moderate certainty), and revealed that steroid use (RE: 2.72; 95% CI: 1.31-5.64, moderate certainty) was likely a risk factor whereas autologous HSCT was probably a protective factor of BSI (RE: 0.65; 95% CI: 0.45-0.94, moderate certainty).

CONCLUSION

These findings could inform the management of paediatric HSCT recipients, helping identify who may benefit from prophylactic antibiotics.

Bloodstream bacterial infections in thalassemic pediatric and adolescent patients after hematopoietic stem cell transplantation

BACKGROUND

Thalassemic patients usually require regular blood transfusions; however, HSCT can provide a cure. Incidence of IBI in pediatric patients post-HSCT is still scant.

OBJECTIVES

This study aimed to explore whether thalassemic patients had a different incidence of post-HSCT IBI compared with patients with other underlying diseases. Factors associated with IBI in the pediatric population undergoing HSCT were also investigated.

METHODS

In this retrospective cohort study, clinical data of pediatric patients who underwent HSCT during the period from 2011 to 2016 were reviewed and analyzed. The primary outcome was incidence of IBI within 1-year post-HSCT.

RESULTS

Of 123 patients, 53 were thalassemic. IBI was diagnosed in 23 patients within 1 year after HSCT (incidence: 19.5 episodes/1000 patients/month). The IBI incidence was lower in thalassemic patients than in patients with other underlying diseases (6.9 vs. 31.6 episodes/1000 patients/month). Having thalassemia as an underlying disease was the only factor associated with lower IBI in pediatric post-HSCT patients (hazard ratio: 0.245; 95% confidence interval, 0.080-0.748). In post-HSCT thalassemic patients, IBI mostly occurred within 100 days after HSCT, and most of these cases had catheter-related blood stream infection. The risk of IBI tended higher for haploidentical HSCT, but this difference was not statistically significantly different.

CONCLUSION

The IBI incidence after HSCT was lower in thalassemic patients than in those with other underlying diseases. Catheter-related blood stream infection was the major IBI in these patients. IBI was not a major complication in thalassemic pediatric patients undergoing HSCT.

The gut microbiome in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation

The gut microbiome (GM) has been associated with different clinical outcomes in the context of allogeneic hematopoietic stem cell transplantation (HSCT). Large multicenter cohort studies in adults have found significant correlations with overall survival, relapse, and incidence of complications. Moreover, GM is already a promising target for therapeutic interventions. However, few data are available in children, a population presenting unique features and challenges. During childhood, the GM evolves rapidly with large structural fluctuations, alongside with the maturation of the immune system. Furthermore, the HSCT procedure presents significant differences in children. These considerations underline the importance of a specific focus on the pediatric setting, and the role of GM and its age-dependent trajectory in influencing the immunity reconstitution and clinical outcomes. This review provides a comprehensive overview of the available evidence in the field of GM and pediatric HSCT, highlighting age-specific issues and discussing GM-based therapeutic approaches.

Epidemiological surveillance of health care-associated infections in a pediatric hematopoietic stem cell transplantation unit in South Brazil

BACKGROUND

Pediatric hematopoietic stem cell transplantation (HSCT) recipients represent a vulnerable population with regard to health care-associated infections (HAI) with a differentiated profile of etiologic agents.^1,2 There are few reports in the literature regarding HAI in the pediatric population submitted to HSCT.

METHODS

This is a retrospective study conducted in a pediatric HSCT unit in Curitiba, Brazil between February 2013 and December 2017 that evaluated 109 pediatric patients. The variables analyzed were: age, gender, baseline disease, type of transplantation, infection topography, etiologic agent, time of HAI occurrence, antimicrobial prophylaxis, period of neutropenia, length of stay, and outcomes RESULTS: Of 113 HSCT procedures, 91 (83.5%) were allogenic and 18 were autologous (16.5%). The mean age of the patients was 7.9 years, with a median of 8.1 years (4.0 months-17.3 years); 71 (65.1%) were male; 55 (50.5%) presented with an oncologic diagnosis, 32 (29.4%) with a hematological diagnosis, 17 (15.6%) with immunodeficiencies, and 5 (4.6%) with other causes. During hospitalization after HSCT, 86 episodes of HAI were detected in 66 patients, with an infection density of 16.5 infections/1000 patient days, 86% of which occurred after allogeneic transplants, appearing, on average, 15.3 days after transplantation. The main topographies were bloodstream infection (BSI), with 24 (27.9%) cases, and central line-associated bloodstream infection (CLABSI), with 11 (12.8%). Gram-positive bacteria predominated in cultures and HAI was more frequent in patients diagnosed with immunodeficiencies and other non-oncologic and non-hematologic conditions. Among the Gram-positive bacteria, Staphylococcus epidermidis was the main agent identified (77.7%), possibly because of colonization. However, Gram-negative bacteria, with a resistance profile, comprised 40% of the cases of bacterial infections, most of them represented by Klebsiella pneumoniae (66.6%). Of the 66 patients who presented HAI, 59 patients (89.4%) were discharged, and 7 (10.6%) died.

CONCLUSION

The main topographies were CLABSI and BSI. Patients with immunodeficiencies presented a higher risk for HAI Staphylococcus epidermidis was the main agent identified. However, Klebsiella pneumoniae posed a higher risk for Pediatric Intensive Care Unit admission and death.

Levofloxacin prophylaxis in hospitalized children with leukemia: A cost-utility analysis

BACKGROUND

Infections are common and are a major cause of morbidity and mortality during treatment of childhood leukemia. We evaluated the cost effectiveness of levofloxacin antibiotic prophylaxis, compared to no prophylaxis, in children receiving chemotherapy for acute myeloid leukemia (AML) or relapsed acute lymphoblastic leukemia (ALL).

PROCEDURES

A cost-utility analysis was conducted from the perspective of the single-payer health care system using a lifetime horizon. A comprehensive literature review identified available evidence for effectiveness, safety, costs of antibiotic prophylaxis in children with leukemia, and health utilities associated with the relevant health states. The effects of levofloxacin prophylaxis on health outcomes, quality-adjusted life-years (QALY), and direct health costs were derived from a combined decision tree and state-transition model. One-way deterministic and probabilistic sensitivity analyses were performed to test the sensitivity of results to parameter uncertainty.

RESULTS

The literature review revealed one randomized controlled trial on levofloxacin prophylaxis in childhood AML and relapsed ALL, by Alexander et al, that showed a significant reduction in rates of fever and neutropenia (71.2% vs 82.1%) and bacteremia (21.9% vs 43.4%) with levofloxacin compared to no prophylaxis. In our cost-utility analysis, levofloxacin prophylaxis was dominant over no prophylaxis, resulting in cost savings of $542.44 and increased survival of 0.13 QALY. In probabilistic sensitivity analysis, levofloxacin prophylaxis was dominant in 98.8% of iterations.

CONCLUSIONS

The present analysis suggests that levofloxacin prophylaxis, compared to no prophylaxis, is cost saving in children receiving intensive chemotherapy for AML or relapsed ALL.

Incidence, risk factors, and outcome of blood stream infections during the first 100 days post-pediatric allogeneic and autologous hematopoietic stem cell transplantations

Bloodstream infections (BSI) are a frequently observed complication after hematopoietic stem cell transplant (HSCT). Retrospective analysis of clinical and microbiological data during the first 100 days from 302 consecutive pediatric patients who underwent HSCT for a malignant disease at our institute between January 2013 and June 2017. A total of 164 patients underwent autologous and 138 allogeneic HSCT. The overall incidence of BSI was 37% with 92% of infectious episodes occurring during the pre-engraftment phase. Gram-positive bacteria (GPB) accounted for 54.6% of the isolated pathogens, gram-negative bacteria (GNB) for 43.9%, and fungi for 1.4%. Coagulase-negative staphylococci and Escherichia coli were the most commonly isolated GPB and GNB, respectively. Forty-five percent of GNB were extended-spectrum beta-lactamase producers and 21% were multidrug-resistant organisms. Fluoroquinolone resistance was 92% and 68%, among GPB and GNB, respectively. Risk factors for BSI in univariate analysis were allogeneic HSCT, delayed time to engraftment more than 12 days, previous BSI before HSCT, and alternative donor. In multivariate analysis, only HSCT type (allogeneic vs autologous P = .03) and previous BSI within 6 months before HSCT (P = .016) were significant. Overall survival at day 100 was 98% and did not differ significantly between patients with and without BSI (P = .76). BSI is common in children undergoing HSCT for malignant diseases. Allogeneic HSCT recipients and previous BSI within 6 months before HSCT are associated with increased risk of post-transplant BSI. With current supportive measures, BSI does not seem to confer an increased risk for 100-day mortality.

Bacteremia in pediatric patients with hematopoietic stem cell transplantation

BACKGROUND

This study aimed to describe the incidence, microbiological profile, and risk factors associated with bacteremia in pediatric patients with hematopoietic stem cell transplantation (HSCT).

METHODS

A retrospective cohort study was performed on patients under 18 years old who underwent HSCT due to any indication, between January 2012 and January 2017. The patient data were collected from the first 100 days post-HSCT. Bacteremia was defined as the isolation of bacteria from at least one blood culture. The relation between bacteremia and associated risk factors was evaluated using univariate and multivariate analysis.

RESULTS

We enrolled a total of 111 pediatric patients who received HSCT during the period of study. The total number of patients who developed at least one episode of bacteremia was 46 (41.4%), and the total number of bacteremia episodes was 62. Rectal swabs were performed in 44 patients to detect prior colonization and this showed that 25% of them were positive, the main pathogen isolated being carbapenem-resistant enterobacteriaceae. The Gram-negative bacteria cases accounted for 60% of 62 events. The main Gram-negative bacteria isolated were Klebsiella pneumoniae and Escherichia coli and the majority were resistant strains. The mortality rate on day +100 for the whole cohort was 18% (n=20). Regarding the patients with bacteremia, the mortality rate on day +100 was 30% (n=14), and the cause of death was related to infection in 10 of them. We did not find any statistically significant risk factor for the development of bacteremia.

CONCLUSION

Bacteremia is common after HSCT, and there is a high frequency of resistant Gram-negative infections which is related to high mortality.

Antibiotic-Resistant Septicemia in Pediatric Oncology Patients Associated with Post-Therapeutic Neutropenic Fever

Death in cancer patients can be caused by the progression of tumors, their malignity, or other associated conditions such as sepsis, which is a multiphasic host response to a pathogen that can be significantly amplified by endogenous factors. Its incidence is continuously rising, which reflects the increasing number of sick patients at a higher risk of infection, especially those that are elderly, pediatric, or immunosuppressed. Sepsis appears to be directly associated with oncological treatment and fatal septic shock. Patients with a cancer diagnosis face a much higher risk of infections after being immunosuppressed by chemotherapy, radiotherapy, or anti-inflammatory therapy, especially caused by non-pathogenic, Gram-negative, and multidrug-resistant pathogens. There is a notorious difference between the incidence and mortality rates related to sepsis in pediatric oncologic patients between developed and developing countries: they are much higher in developing countries, where investment for diagnosis and treatment resources, infrastructure, medical specialists, cancer-related control programs, and post-therapeutic care is insufficient. This situation not only limits but also reduces the life expectancy of treated pediatric oncologic patients, and demands higher costs from the healthcare systems. Therefore, efforts must aim to limit the progression of sepsis conditions, applying the most recommended therapeutic regimens as soon as the initial risk factors are clinically evident-or even before they are, as when taking advantage of machine learning prediction systems to analyze data.

Infection surveillance in pediatric hematopoietic stem cell transplantation recipients

OBJECTIVE

To describe the profile of reported healthcare-associated infections (HAIs) in pediatric patients submitted to hematopoietic stem cell transplantation (HSCT) at a reference center.

METHODS

Retrospective cohort of pediatric patients who were submitted to HSCT from 2008 to 2016. The criteria for HAI were based on those established by the National Healthcare Safety Network. Data were collected by active surveillance performed daily by professionals. This study was approved by the institutional research ethics committee.

RESULTS

A total of 86 HSCTs were performed in 81 patients younger than 18 years of age (median, 10 years). Of these, 69 (85%) were males. Aplastic anemia and leukemia were the main diagnoses. A total of 140 HAIs were diagnosed with an incidence density of 28.2 infections/1000 patient-days. The most common HAI was laboratory-confirmed bloodstream infection (46), the majority of which was reported to be central venous catheter-associated (43). Gram-negative bacteria were the most prevalent microorganisms (58.5%). Almost all the infections occurred until 30 days after transplantation, and 17 deaths were observed within 180 days after the procedure.

CONCLUSION

Active surveillance of HAIs in HSCT children allowed the evaluation of the incidence and profile of HAIs, which is essential for the health care of these patients.

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

INTRODUCTION

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).

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Bacteremia during neutropenic episodes in children undergoing hematopoietic stem cell transplantation with ciprofloxacin and penicillin prophylaxis

Bacteremia during neutropenic episodes is a cause of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). We have used oral ciprofloxacin and penicillin V, from the start of the conditioning regimen until engraftment, for the prophylaxis of bacterial infection. The objective of this study was to retrospectively analyze the prevalence of and risk factors for breakthrough bacteremia during neutropenic episodes in autologous and allogeneic HSCT patients. There were 215 patients enrolled, with a median age of 8.32 years (range 0.51-21.64 years) between 2002 and 2014. The common underlying diseases were thalassemia and acute leukemia. Bacteremia was documented in 33 patients (15.3 %), with 39 microorganisms isolated. Escherichia coli (28.2 %) and Streptococcus viridans (12.8 %) were the most commonly isolated Gram-negative and Gram-positive bacteria, respectively. Multidrug resistant strains were found in 32 and 14.3 % of Gram-negative and Gram-positive bacteria, respectively. Risk factors for bacteremia were receiving anti-thymocyte globulin (ATG) [odds ratio (OR) 2.44, 95 % confidence interval (CI) 1.06-5.65, P = 0.037] and umbilical cord blood as a stem cell graft (OR 6.60, 95 % CI 1.04-41.83, P = 0.045). In conclusion, the prevalence of bacteremia was 15.3 % and the use of ATG and cord blood were risk factors for bacteremia during neutropenic episodes.

Antibiotic-mediated modification of the intestinal microbiome in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is curative for many patients with severe benign and malignant hematologic disorders. The success of allogeneic HSCT is limited by the development of transplant-related complications such as acute graft-versus-host disease (GvHD). Early pre-clinical studies suggested that intestinal microflora contribute to the pathogenesis of acute GvHD, and that growth suppression or eradication of intestinal bacteria prevented the development of acute GvHD even in MHC-mismatched transplants. These observations led to the practice of gut decontamination (GD) with oral non-absorbable antibiotics in patients undergoing allogeneic HSCT as a method of acute GvHD prophylaxis. Microbiome studies in the modern sequencing era are beginning to challenge the benefit of this practice. In this review, we provide a historical perspective on the practice of GD and highlight findings from the limited number of clinical trials evaluating the use of GD for acute GvHD prevention in allogeneic HSCT patients. In addition, we examine the role of the gut microbiota in allogeneic HSCT in the context of recent studies linking the microflora to regulation of intestinal immune homeostasis. We discuss the implications of these findings for future strategies to reduce acute GvHD risk by selective manipulation of the microbiota.

Incidence and risk factors of bacterial infections in children following autologous hematopoietic stem cell transplantation: Single-center experience from Jordan

Bacterial infection is a serious sequela following AHSCT; however, limited data are available regarding pediatric recipients, especially in developing countries. We retrospectively analyzed the incidence and risk factors of bacterial infections during the first 100 days after AHSCT in children at KHCC in Amman, Jordan between January, 2005 and September, 2013. A total of 65 patients were identified, with median age of four yr (1-17). Forty-seven patients (72.3%) had solid tumors and 18 (27.7%) had lymphoma. Bacterial infections were documented in 33 patients (50%), with a total of 63 episodes. Gram-negative infection (57.1%) was more prevalent than Gram-positive infection (38%). The risk of bacterial infections was higher among patients less than five yr of age (p = 0.028) and those who developed hypogammaglobulinemia requiring IVIG replacement (p = 0.001). Patients with solid tumors developed more bacterial infections compared to patients with lymphoma (p = 0.0057). No deaths were attributed to bacterial infection. Bacterial infection rate is high among recipients of AHSCT in Jordan with Gram-negative bacteria being the most common.

Low-dose irradiation affects the functional behavior of oral microbiota in the context of mucositis

The role of host-microbe interactions in the pathobiology of oral mucositis is still unclear; therefore, this study aimed to unravel the effect of irradiation on behavioral characteristics of oral microbial species in the context of mucositis. Using various experimental in vitro setups, the effects of irradiation on growth and biofilm formation of two Candida spp., Streptococcus salivarius and Klebsiella oxytoca in different culture conditions were evaluated. Irradiation did not affect growth of planktonic cells, but reduced the number of K. oxytoca cells in newly formed biofilms cultured in static conditions. Biofilm formation of K. oxytoca and Candida glabrata was affected by irradiation and depended on the culturing conditions. In the presence of mucins, these effects were lost, indicating the protective nature of mucins. Furthermore, the Galleria melonella model was used to study effects on microbial virulence. Irradiated K. oxytoca microbes were more virulent in G. melonella larvae compared to the nonirradiated ones. Our data indicate that low-dose irradiation can have an impact on functional characteristics of microbial species. Screening for pathogens like K. oxytoca in the context of mucosits could be useful to allow early detection and immediate intervention.

Oral mucositis in pediatric patients undergoing hematopoietic stem cell transplantation: clinical outcomes in a context of specialized oral care using low-level laser therapy

OM is a painful inflammatory condition of the oral mucosa, derived from the toxic effects of chemotherapy and radiotherapy. High OM severity is frequently present in HSCT pediatric patients, who exhibit multiple painful ulcers that limit their mastication and swallowing, leading to poor nutritional status. Few studies have demonstrated OM clinical outcomes in young patients undergoing HSCT. Feasibility of oral care and LLLT on OM prophylaxis and treatment is also poorly discussed. The aim of this study was to describe a specialized oral care protocol that included LLLT for pediatric patients undergoing transplantation and to demonstrate the clinical outcomes after OM prevention and treatment. Data from OM-related morbidity were collected from 51 HSCT pediatric patients treated daily with LLLT, followed by standard oral care protocols. All the patients, even infants and young children, accepted the daily oral care and LLLT well. The majority (80.0%) only exhibited erythema in the oral mucosa, and the maximum OM degree was WHO II. Patients who had undergone autologous and HLA-haploidentical transplants showed OM with the lowest severity. The frequency of total body irradiation and methotrexate prescriptions was higher in adolescents when compared with infants (p = 0.044), and adolescents also exhibited OM more severely than infants and young children. We found that good clinical outcomes were obtained using this therapy, mainly in regard to the control of OM severity and pain reduction in the oral cavity. Specialized oral care, including LLLT, is feasible and affordable for HSCT pediatric patients, although some adaptation in the patient's oral hygiene routine must be adopted with help from parents/companions and clinical staff.

Bloodstream infection after stem cell transplantation in children with idiopathic aplastic anemia

Bloodstream infection (BSI) is the most common infectious complication of hematopoietic stem cell transplantation (HSCT) and can cause substantial morbidity and mortality. Identification of risk factors for BSI might be helpful in efforts to reduce transplantation-related death. This study analyzed the incidence of BSI and risk factors for BSI after HSCT in pediatric patients with aplastic anemia (AA). BSI occurred in 39 of the 351 patients with AA (11.1%). Onset of BSI occurred at a median of 8 days after HSCT (range, 0 to 92 days). The 5-year overall survival rate was lower in patients with BSI than in patients without BSI (63.32% ± 7.90% versus 93.35% ± 1.44%; P < .0001). Univariate analysis identified the following variables as associated with BSI: history of immunosuppressive therapy with antithymocyte globulin (ATG), transplantation from an unrelated donor, frequent blood transfusion before transplantation, major or major plus minor ABO type mismatch, graft-versus-host disease prophylaxis with tacrolimus and without cyclosporine, and long interval from diagnosis to transplantation. Among these factors, long interval from diagnosis to transplantation was the sole statistically significant risk factor for BSI on multivariate analysis. In patients who underwent HSCT from a related donor, age ≥14 years at transplantation was risk factor for BSI. In contrast, history of immunosuppressive therapy with ATG, frequent blood transfusion before HSCT, graft failure, and major or major plus minor ABO type mismatch were risk factors for BSI in patients who underwent HSCT from an unrelated donor. Because the overall 5-year survival rate without BSI was >90%, even in patients who were received a transplant from an unrelated donor, control of BSI is very important for successful HSCT in pediatric patients with AA.

Microbiota and their role in the pathogenesis of oral mucositis

Oral mucositis in patients undergoing cancer therapy is a significant problem. Its prevalence ranges between 20 and 100%, depending on treatment type and protocols and patient-based variables. Mucositis is self-limiting when uncomplicated by infection. Unfortunately, the incidence of developing a local or systemic infection during the course of the treatment is very high. At this stage, it is unclear which role oral microbiota play in the onset, duration, and severity of oral mucositis. Nevertheless, there is growing interest in this underexplored topic, and new studies are being undertaken to unravel their impact on the pathogenesis of mucositis.

Aetiology and resistance in bacteraemias among adult and paediatric haematology and cancer patients

OBJECTIVES

A knowledge of current epidemiology and resistance patterns is crucial to the choice of empirical treatment for bacteraemias in haematology and cancer patients.

METHODS

A literature review on bacteraemias in cancer patients considered papers published between January 1st 2005 and July 6th 2011. Additionally, in 2011, a questionnaire on the aetiology and resistance in bacteraemias, and empirical treatment, was sent to participants of the European Conference on Infections in Leukemia (ECIL) meetings; recipients were from 80 haematology centres.

RESULTS

For the literature review, data from 49 manuscripts were analysed. The questionnaire obtained responses from 39 centres in 18 countries. Compared with the published data, the questionnaire reported more recent data, and showed a reduction of the Gram-positive to Gram-negative ratio (55%:45% vs. 60%:40%), increased rates of enterococci (8% vs. 5%) and Enterobacteriaceae (30% vs. 24%), a decreased rate of Pseudomonas aeruginosa (5% vs. 10%), and lower resistance rates for all bacteria. Nevertheless the median rates of ESBL-producers (15-24%), aminoglycoside-resistant Gram-negatives (5-14%) and carbapenem-resistant P. aeruginosa (5-14%) were substantial, and significantly higher in South-East vs. North-West Europe.

CONCLUSIONS

The published epidemiological data on bacteraemias in haematology are scanty and mostly dated. Important differences in aetiology and resistance exist among centres. Updated analyses of the local epidemiology are mandatory to support appropriate empirical therapy.

Risk factor analysis of bloodstream infection in pediatric patients after hematopoietic stem cell transplantation

Bloodstream infection (BSI) is a recognized cause of morbidity and mortality in children after hematopoietic stem cell transplantation (HSCT). However, there are limited reports on BSI after HSCT in pediatric patients in multiple centers. This study was a retrospective cohort analysis of consecutive patients who underwent allogeneic and autologous HSCT at the Department of Paediatrics, Hokkaido University Hospital, between 1988 and 2009; the Department of Paediatrics, Sapporo Hokuyu Hospital, between 2007 and 2009; and the Department of Paediatrics, Asahikawa Medical University, between 1989 and 2009. A total of 277 patients underwent HSCT during the study period. In this multicenter analysis, cases of BSI after HSCT were recorded in the early posttransplant period (within the first 100 d), and BSI was observed in 24 of 277 HSCT patients. Multivariate analysis showed that nonmalignant disease was an independent factor associated with BSI after HSCT (hazard ratio 6.3 for aplastic anemia or Wiskott-Aldrich syndrome patients; confidence interval, 1.4-12.8; P = 0.012). We conclude that aplastic anemia and Wiskott-Aldrich syndrome were the novel risk factors for BSI in pediatric patients after HSCT.

Inflammatory modulation of HSCs: viewing the HSC as a foundation for the immune response

Cells of the innate and adaptive immune systems are the progeny of a variety of haematopoietic precursors, the most primitive of which is the haematopoietic stem cell. Haematopoietic stem cells have been thought of generally as dormant cells that are only called upon to divide under extreme conditions, such as bone marrow ablation through radiation or chemotherapy. However, recent studies suggest that haematopoietic stem cells respond directly and immediately to infections and inflammatory signals. In this Review, we summarize the current literature regarding the effects of infection on haematopoietic stem cell function and how these effects may have a pivotal role in directing the immune response from the bone marrow.

Sequential administration of sargramostim and filgrastim in pediatric allogeneic stem cell transplantation recipients undergoing myeloablative conditioning

G-CSF and GM-CSF both hasten myeloid engraftment post-MA-alloSCT; however, GM-CSF is earlier acting and less expensive. The objective was to evaluate efficacy/safety of sequential administration of GM-CSF followed by G-CSF in children post-MA-alloSCT. From January 2001 to June 2005, 31 children received 32 MA-alloSCT: mean age 6.65 yr; MRD BM or PBSC vs. related or unrelated UCB 11:21; malignant vs. non-malignant disorders 22:10. GM-CSF (250 microg/m(2) IV QD) began on day of stem cell infusion. GM-CSF was switched to G-CSF (10 microg/kg IV QD) when WBC >or= 300/mm(3) x 2 days. G-CSF continued until ANC >or= 2500/mm(3) x 2 days, then tapered to maintain ANC >or= 1000/mm(3). Median time to myeloid engraftment (ANC >or= 500/mm(3) x 3 days) was 17 days [13 days vs. 24 days, MRD BM/PBSC vs. UCB (p < 0.0001)], occurring at a median time of two days after switch to G-CSF. Clinically relevant adverse events were bone pain (n = 8) and large pleural effusion (n = 1). It was estimated that sequential GM-CSF/G-CSF was cost-effective compared with G-CSF alone [cost-savings of $1311/patient ($41,952/study), 2007 Red Book Average Wholesale Price]. In summary, it was demonstrated that sequential administration of GM-CSF/G-CSF post-MA-alloSCT was safe, cost-effective and resulted in prompt myeloid engraftment.

Blood stream infection after hematopoietic stem cell transplantation is associated with increased mortality

Blood stream infection (BSI) is a serious complication of hematopoietic stem cell transplantation (HSCT). The aim of this retrospective cohort analysis was to describe BSI after HSCT, and to assess the predictors and outcomes of BSI after HSCT using multivariable modeling. Of the 243 subjects transplanted, 56% received allogeneic HSCT and 106 (43.6%) developed BSI. Of the 185 isolates, 68% were Gram-positive cocci, 21% were Gram-negative bacilli (GNR) and 11% were fungi. Type of allogeneic HSCT was an independent risk factor for BSI (hazard ratio (HR) 3.26, 95% confidence interval (CI) 1.50, 7.07, P = 0.01), as was the degree of HLA matching (HR 1.84, 95% CI 1.00, 3.37, P = 0.05). BSI was a significant independent predictor of mortality after HSCT (HR 1.79, 95% CI 1.18, 2.73, P = 0.007), after adjusting for acute graft-versus-host disease (GVHD) and allogeneic HSCT (both predicting death < or = 3 months after HSCT). In contrast to the effects of acute GVHD and allogeneic HSCT, the effect of BSI was evident throughout the post-HSCT period. GNR BSI and vancomycin-resistant enterococcal BSI also were significantly associated with death. We concluded that BSI is a common complication of HSCT associated with increased mortality throughout the post-HSCT period.

New agents for the prevention of opportunistic infections in haematopoietic stem cell transplant recipients

Over the past three decades, autologous and allogeneic haematopoietic stem cell transplants (HSCTs) have become effective treatments for a variety of malignant and nonmalignant conditions. Patients who undergo HSCT receive high doses of chemotherapy and/or radiation that induce a prolonged period of profound immunodeficiency, placing them at high risk for infection from a panoply of opportunistic organisms. Although supportive treatment for these patients has markedly improved, 10-20% of allogeneic HSCT recipients will ultimately succumb to infection. Joint guidelines to prevent opportunistic infection were released in 2000 by the Centers for Disease Control, the Infectious Diseases Society of America, and the American Society of Blood and Marrow Transplantation; however, treatment decisions for these patients are often based on limited studies or depend on institution-specific transplant protocols and antibiotic resistance patterns. This paper will discuss new agents for preventing bacterial, fungal and viral infections in HSCT recipients.