Bacteremia after hematopoietic stem cell transplantation: incidence and predictive value of surveillance cultures

Reactivation of cytomegalovirus and bloodstream infection and its impact on early survival after allogeneic haematopoietic stem cell transplantation: a multicentre retrospective study

Cytomegalovirus reactivation (CMVr) and bloodstream infections (BSI) are the most common infectious complications in patients after allogeneic haematopoietic stem cell transplantation (allo-HSCT). Both are associated with great high morbidity whilst the BSI is the leading cause of mortality. This retrospective study evaluated the incidence of CMVr and BSI, identified associated risk factors, assessed their impact on survival in allo-HSCT recipients during the first 100 days after transplantation. The study comprised 500 allo-HSCT recipients who were CMV DNA-negative and CMV IgG-positive before allo-HSCT. Amongst them, 400 developed CMVr and 75 experienced BSI within 100 days after allo-HSCT. Multivariate regression revealed that graft failure and acute graft-versus-host disease were significant risk factors for poor prognosis, whereas CMVr or BSI alone were not. Amongst all 500 patients, 56 (14%) developed both CMVr and BSI in the 100 days after HSCT, showing significantly reduced 6-month overall survival (p = 0.003) and long-term survival (p = 0.002). Specifically, in the initial post-transplant phase (within 60 days), BSI significantly elevate mortality risk, However, patients who survive BSI during this critical period subsequently experience a lower mortality risk. Nevertheless, the presence of CMVr in patients with BSI considerably diminishes their long-term survival prospects. This study provides real-world data on the impact of CMVr and BSI following transplantation on survival, particularly in regions such as China, where the prevalence of CMV IgG-positivity is high. The findings underscore the necessity for devising and executing focused prevention and early management strategies for CMVr and BSI to enhance outcomes for allo-HSCT recipients.

What We Learn from Surveillance of Microbial Colonization in Recipients of Pediatric Hematopoietic Stem Cell Transplantation

Infections in hematopoietic stem cell transplant (HSCT) remain one of the major causes for morbidity and mortality, and it is still unclear whether knowledge of microbial colonization is important. In this single-center study, we collected weekly surveillance cultures in pediatric recipients of allogenic HSCT from five different body regions and tested for bacteria and fungi. Between January 2010 and December 2021, we collected 1095 swabs from 57 recipients of allogeneic HSCTs (median age: 7.5 years, IQR 1−3: 2.5−11.9). The incidence of positive microbiological cultures (n = 220; 20.1%) differed according to the anatomic localization (p < 0.001) and was most frequent in the anal region (n = 98), followed by the genital, pharyngeal and nasal regions (n = 55, n = 37 and n = 16, respectively). Gram-positive bacteria (70.4%) were the most commonly isolated organisms, followed by fungi (18.6%), Gram-negative (5.5%), non-fermenting bacteria (1.4%), and other flora (4.1%). No association with increased risk of infection (n = 32) or septicemia (n = 7) was noted. Over time, we did not observe any increase in bacterial resistance. We conclude that there is no benefit to surveillance of microbial colonization by culture-based techniques in pediatric HSCT. Sequencing methods might enhance the detection of pathogens, but its role is still to be defined.

Early antimicrobial prophylaxis in autologous stem cell transplant recipients: Conventional versus an absolute neutrophil count-driven approach

Background

Autologous hematopoietic stem cell transplantation (HSCT) recipients are at increased risk of developing life‐threatening infections. There is discordance in published recommendations for timing of pre‐ and post‐transplant antimicrobial prophylaxis in this patient population, and these recommendations are unsubstantiated by any published comparative analyses.

Methods

An observational, pre‐ and post‐intervention study of consecutive autologous HSCT recipients was conducted over a 2‐year period. In the pre‐intervention cohort, antimicrobial prophylaxis was initiated on the day prior to transplant. In the post‐intervention cohort, antimicrobials were initiated once absolute neutrophil count (ANC) reached ≤500 cells/mm³. The primary outcome assessed was frequency of febrile occurrences. Secondary outcomes included total days of prophylaxis, positive blood cultures, all‐cause mortality, Clostridioides difficile infection rates, and length of stay.

Results

A total of 208 patients were included in the final analysis, with 105 and 103 patients in the pre‐ and post‐intervention cohorts, respectively. The majority of patients included were male. Lower rates of fever occurrences were observed in the post‐intervention cohort (83% pre‐ vs. 69% post‐intervention; p = 0.019). A significant reduction in the mean antibacterial days per patient was identified (9.7 vs. 4.6 days; p < 0.001). Other than lower rates of febrile neutropenia in the post‐intervention cohort, no differences were identified in secondary outcomes. In multivariable analyses, ANC‐driven prophylaxis was independently associated with decreased febrile events.

Conclusions

Delaying prophylaxis until severe neutropenia was not associated with increased febrile events or other secondary clinical outcomes evaluated. This approach is associated with a significant reduction in antimicrobial exposure.

Coagulase negative Staphylococcus bacteremia in hematopoietic stem cell transplant recipients: Clinical features and molecular characterization

The purpose of our study was to investigate the epidemiology of coagulase negative staphylococci (CoNS) responsible for bacteremia in hematopoietic stem cell transplant (HSCT) recipients and to determine the prevalence and the genetic background of methicillin resistance. The prevalence of CoNS bacteremia was 7.4% (54/728), higher in allograft (10.7%) than in autograft (4.7%) recipients. A sepsis or a septic shock were observed in 9% of cases. No deaths were attributable to CoNS bacteremia. The methicillin resistance rate was 81%. All MR-CoNS, harbored mecA gene and 90% were typeable with SCCmec typing using PCR amplification. The SCCmec type IV was the most frequent (44%). Clonal dissemination of MR- Staphylococcus epidermidis strains was limited. Our study showed a low prevalence and favorable outcome of CoNS bacteremia in HSCT recipients with limited clonal diffusion. However, they were associated with a significant rate of severe infections and a high rate of methicillin resistance, mediated by SCCmec IV element in most cases.

The role of microbiota in allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (Allo-HSCT) is commonly performed to treat a variety of benign and malignant hematological diseases. Acute graft-versus-host disease (GVHD) is a major life-threatening complication that often occurs following allo-HSCT. Recently, improvements in methods to characterize the microbiota have led to a greater appreciation for how frequently and profoundly an alteration in microbial composition, or dysbiosis, can occur in allo-HSCT recipients to better decipher the complex interplay between microbiota and allo-HSCT outcomes.

AREAS COVERED

This article reviews the current knowledge of the microbiota's impact on allo-HSCT outcomes, including effects of microbiota-derived metabolites, and crosstalk between commensals and the allogeneic immune response. This article also summarizes the effects of HSCT and transplant-related procedures on microbiota, and recent developments in interventional strategies.

EXPERT OPINION

A growing body of literature indicates that the composition of the intestinal microbiota can function as a predictive biomarker for the risk and severity of acute GVHD, as well as overall survival, in patients undergoing allo-HSCT. Mechanisms underpinning these associations, however, are not well understood, and clinical strategies that modulate the microbiome to improve outcomes have yet to be fully developed. There is an unmet need to determine mechanisms to improve the efficacy of allo-HSCT.

Bloodstream Infections and Delayed Antibiotic Coverage Are Associated With Negative Hospital Outcomes in Hematopoietic Stem Cell Transplant Recipients

BACKGROUND

Bloodstream infections (BSIs) are common after hematopoietic stem cell transplantation (HSCT) and are associated with increased long-term morbidity and mortality. However, short-term outcomes related to BSI in this population remain unknown. More specifically, it is unclear whether choices related to empiric antimicrobials for potentially infected patients are associated with patient outcomes.

RESEARCH QUESTION

Are potential delays in appropriate antibiotics associated with hospital outcomes among HSCT recipients with BSI?

STUDY DESIGN AND METHODS

We conducted a retrospective cohort study at a large comprehensive inpatient academic cancer center between January 2014 and June 2017. We identified all admissions for HSCT and prior recipients of HSCT. We defined potential delay in appropriate antibiotics as > 24 h between positive blood culture results and the initial dose of an antimicrobial with activity against the pathogen.

RESULTS

We evaluated 2,751 hospital admissions from 1,086 patients. Of these admissions, 395 (14.4%) involved one or more BSIs. Of these 395 hospitalizations, 44 (11.1%) involved potential delays in appropriate antibiotics. The incidence of mortality was higher in BSI hospitalizations than in those without BSI (23% vs 4.5%; P < .001). In multivariable analysis, BSI was an independent predictor of mortality (OR, 8.14; 95% CI, 5.06-13.1; P < .001). Mortality was higher for admissions with potentially delayed appropriate antibiotics than for those with appropriate antibiotics (48% vs 20%; P < .001). Potential delay in antibiotics was also an independent predictor of mortality in multivariable analysis (OR, 13.8; 95% CI, 5.27-35.9; P < .001).

INTERPRETATION

BSIs were common and independently associated with increased morbidity and mortality. Delays in administration of appropriate antimicrobials were identified as an important factor in hospital morbidity and mortality. These findings may have important implications for our current practice of empiric antibiotic treatment in HSCT patients.

Risk Factors for Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections and Outcomes

Purpose

The incidence of carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections (BSIs) is increasing globally; however, little has been reported on the risk factors and outcomes of CRKP BSIs in central China. This study aimed to determine the clinical risk factors for CRKP BSIs and the outcomes of CRKP BSIs.

Patients and Methods

We performed a case-control study of 239 patients with K. pneumoniae BSIs who were treated at Henan Provincial People’s Hospital between July 2017 and July 2018. The cases (n=98, 41%) had CRKP BSIs, and the controls (n=141, 59%) had non-carbapenem-resistant K. pneumoniae (non-CRKP) BSIs. Antimicrobial sensitivity was determined using automated broth microdilution and an agar disk diffusion method. Data were obtained from clinical and laboratory records. Multivariate logistic regression and Pearson chi-square tests were used to identify clinical factors and outcomes associated with carbapenem resistance.

Results

Risk factors for carbapenem resistance included recent carbapenem use (odds ratio [OR]: 9.98, 95% confidence interval [CI]: 5.2–17.1, P<0.001), invasive procedures (OR: 11.1, 95% CI: 3.3–37.7, P<0.001), and pre-existing diseases of the digestive system (OR: 8.22, 95% CI: 1.73–39.2, P=0.008). Treatment failure was more frequent in the cases (84.7%) than in the controls (32.6%).

Conclusion

Exposure to antibiotics, especially carbapenems, and invasive procedures were the major risk factors for carbapenem resistance among patients with K. pneumoniae BSIs. Strict control measures should be implemented to prevent the emergence and spread of CRKP.

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.

Low pre-transplant levels of mannose-binding lectin are associated with viral infections and mortality after haematopoietic allogeneic stem cell transplantation

BACKGROUND

Mannose-binding lectin (MBL) is a key component of innate immunity. Low serum MBL levels, related to promoter polymorphism and structural variants, have been associated with an increased risk of infection. The aim of this work was to analyse the incidence and severity of infections and mortality in relation to the MBL2 genotype and MBL levels in patients underwent allogeneic haematopoietic stem cell transplantation (Allo-HSCT).

RESULTS

This was a prospective cohort study of 72 consecutive patients underwent Allo-HSCT between January 2007 and June 2009 in a tertiary referral centre. Three periods were considered in the patients' follow-up: the early period (0-30 days after Allo-HSCT), the intermediate period (30-100 days after Allo-HSCT) and the late period (> 100 days after Allo-HSCT). A commercial line probe assay for MBL2 genotyping and an ELISA Kit were used to measure MBL levels. A total of 220 episodes of infection were collected in the 72 patients. No association between donor or recipient MBL2 genotype and infection was found. The first episode of infection presented earlier in patients with pre-transplant MBL levels of < 1000 ng/ml (median 6d vs 8d, p = 0.036). MBL levels < 1000 ng/ml in the pre-transplant period (risk ratio (RR) 2.48, 95% CI 1.00-6.13), neutropenic period (0-30 days, RR 3.28, 95% CI 1.53-7.06) and intermediate period (30-100 days, RR 2.37, 95% CI 1.15-4.90) were associated with increased risk of virus infection. No association with bacterial or fungal disease was found. Mortality was associated with pre-transplant MBL levels < 1000 ng/ml (hazard ratio 5.55, 95% CI 1.17-26.30, p = 0.03) but not with MBL2 genotype.

CONCLUSIONS

Patients who underwent Allo-HSCT with low pre-transplant MBL levels presented the first episode of infection earlier and had an increased risk of viral infections and mortality in the first 6 months post-transplant. Thus, pre-transplant MBL levels would be important in predicting susceptibility to viral infections and mortality and might be considered a biomarker to be included in the pre-transplantation risk assessment.

Limited Utility of Outpatient Surveillance Blood Cultures in Hematopoietic Cell Transplant Recipients on High-Dose Steroids for Treatment of Acute Graft-versus-Host-Disease

Steroids used to treat acute graft-versus-host-disease (GVHD) are believed to blunt clinical symptoms of infection. We aimed to assess the value of weekly surveillance blood cultures (SBCs) drawn in an outpatient setting from hematopoietic cell transplant (HCT) patients receiving high-dose steroids. We hypothesized that most positive outpatient surveillance cultures would be low-pathogenicity, gram-positive organisms and would lead to excess vancomycin therapy. We conducted a retrospective review of blood cultures collected from a cohort of adult HCT patients enrolled in a clinical trial of acute GVHD therapy with high-dose steroids (prednisone-equivalent doses ≥ .5 mg/kg/day) between April 2009 and May 2013. SBCs were defined as those collected weekly from central venous catheters in the outpatient setting while patients were receiving high-dose steroids. Cultures obtained as part of a symptom workup or as follow-up for documented bacteremia were excluded. Clinical data were collected using center databases supplemented by medical record review. One hundred twenty-seven HCT recipients were eligible for inclusion in the study. A total of 1015 SBCs were obtained, with a median of 8 cultures (interquartile range, 5 to 10) per patient. Forty-two organisms were isolated from 36 of 1015 cultures (3.5%) in 30 unique patients, or 1 positive culture per 28 blood cultures drawn. The most frequently detected organisms were coagulase-negative Staphylococci (25/1015 [2.5%]). Gram-negative organisms were rare (4/1015 [.4%]. Antibiotics were administered to most patients with positive surveillance cultures (33/36 [92%]). Six were admitted to the hospital for treatment; none needed intensive care or died from their bacteremia. Vancomycin was the most frequently administered antibiotic, comprising 256 of 376 total days (68%) of antibiotic received by the cohort with a median duration of 10 days ((interquartile range, 7 to 14). Weekly outpatient SBCs obtained from asymptomatic patients on high-dose glucocorticoids for treatment of acute GVHD after allogeneic HCT were infrequently positive, and most organisms were low-pathogenicity organisms. SBCs also led to excess antibiotic exposure and costs, suggesting benefits of such ambulatory screening may be of limited value in this setting.

Rethinking Antimicrobial Prophylaxis in the Transplant Patient in the World of Emerging Resistant Organisms-Where Are We Today?

PURPOSE OF REVIEW

The use of prophylactic antibiotics during the neutropenic period in hematopoietic stem cell transplantation has been the standard of care at most institutions for the past 20 years. We sought to review the benefits and risks of this practice.

RECENT FINDINGS

Emerging data has highlighted the potential costs of antibacterial prophylaxis, from selecting for antibiotic resistance to perturbing the microbiome and contributing to increase risk for Clostridium difficile and perhaps graft-versus-host-disease, conditions which may lead to poorer outcomes. Though in many studies prophylactic antibiotics improved morbidity and mortality outcomes, the potential harms including antibiotic resistance, Clostridium difficile infection, and alterations of the gut microbiome should be considered. Future studies aimed to better risk-stratify patients and limit the use of broad-spectrum antibiotics are warranted.

The incidence, risk factors and outcomes of early bloodstream infection in patients with malignant hematologic disease after unrelated cord blood transplantation: a retrospective study

BACKGROUND

Bloodstream infection (BSI) is one of the major causes of morbidity and mortality for patients undergoing hematopoietic stem cell transplantation (HSCT). The unrelated cord blood transplantation (UCBT) can provided opportunities for patients without suitable donors for bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT), while few studies have addressed BSI after UCBT. The aim of this study was to analyse the incidence and risk factors of BSI, causative organisms, microbial resistance, and its impact on the clinical outcomes and survival of patients.

METHODS

There are 336 patients, were divided into two groups depending on whether developing BSI. Demographic characteristics, laboratory data, and clinical outcome were compared between different groups. The risk factors of BSI was examined using logistic regression and the survival was examined using the Kaplan-Meier method and log-rank test.

RESULTS

Ninety-two patients (27.4%) developed early BSI with 101 pathogenic bacteria isolated, and the median day of developing initial BSI was 4.5 d. Gram-negative bacteria were the most common isolate (60, 59.4%), followed by Gram-positive bacteria (40, 39.6%) and fungi (1, 1.0%). Thirty-seven (36.6%) isolates were documented as having multiple drug resistance (MDR). Myeloid malignancies, conditioning regimens including total body irradiation (TBI), and prolonged neutropenia were identified as the independent risk factors for early BSI. The 3-year OS was 59.9% versus 69.2% in the BSI group and no-BSI group (P = 0.0574), respectively. The 3-year OS of the MDR group was significantly lower than that of the non-BSI group (51.1% versus 69.2%, p = 0.013).

CONCLUSIONS

Our data indicate that the incidence of early BSI after UCBT was high, especially in patients with myeloid disease and a conditioning regimen including TBI and prolonged neutropenia. Early BSI with MDR after UCBT had a negative impact on long-term survival.

Bacterial bloodstream infections in the allogeneic hematopoietic cell transplant patient: new considerations for a persistent nemesis

Bacterial bloodstream infections (BSI) cause significant transplant-related morbidity and mortality following allogeneic hematopoietic cell transplantation (allo-HCT). This manuscript reviews the risk factors for and the bacterial pathogens causing BSIs in allo-HCT recipients in the contemporary transplant period. In addition, it offers insight into emerging resistant pathogens and reviews clinical management considerations to treat and strategies to prevent BSIs in allo-HCT patients.

Incidence, etiology, and outcome of pleural effusions in allogeneic hematopoietic stem cell transplantation

Pleural effusion is a known entity in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT); however, the incidence, risk factors, and morbidity-mortality outcomes associated with pleural effusions remain unknown. We retrospectively evaluated pleural effusions in 618 consecutive adult patients who underwent allogeneic HSCT from January 2008 to December 2013 at our institution. Seventy one patients developed pleural effusion at a median of 40 days (range, 1 - 869) post-HSCT with the cumulative incidence of 9.9% (95% CI, 7.7 - 12.5%) at 1 year. Infectious etiology was commonly associated with pleural effusions followed by volume overload and serositis type chronic GVHD. In multivariate analysis, higher comorbidity index (P = 0.03) and active GVHD (P = 0.018) were found to be significant independent predictors for pleural effusion development. Higher comorbidity index, very high disease risk index, ≤7/8 HLA matching, and unrelated donor were associated with inferior overall survival (OS) (P < 0.03). More importantly, patients with pleural effusion were noted to have poor OS in comparison to patients without pleural effusion (P < 0.001). Overall, pleural effusion is a frequently occurring complication after allogeneic HSCT, adding to morbidity and mortality and hence, early identification is required. Am. J. Hematol. 91:E341-E347, 2016. © 2016 Wiley Periodicals, Inc.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

Usefulness of daily surveillance blood cultures in allogeneic hematopoietic stem cell transplant recipients on steroids: a 1-year prospective study

BACKGROUND

Bloodstream infections (BSI) are frequent and potentially severe complications in allogeneic hematopoietic stem cell transplant (AHSCT) recipients. In patients on steroids, surveillance blood cultures (SBCs) are routinely performed to detect asymptomatic BSI but their usefulness remains controversial.

METHODS

We performed a 1-year, observational, prospective, single-center study to assess the utility of daily SBCs in AHSCT recipients on steroids and a case-control study to identify risk factors associated with positive SBCs. All blood cultures (BCs) obtained from adults hospitalized in the HSCT unit were prospectively studied throughout 1 year. Characteristics, treatments, and outcome of patients were retrieved from medical charts.

RESULTS

A total of 3594 BCs were obtained in 177 patients, including 1450 SBCs in 82 AHSCT recipients on steroids. In 33 patients, 103 SBCs (7%) were positive. Low-virulence bacteria were identified in 74% of episodes. When analyzing first episode of positive SBCs (28 patients), 6 (21%) true BSI were identified.

CONCLUSIONS

Patients with positive SBCs were receiving antibiotic treatment less frequently at the time of SBCs (P < 0.001) and had more frequently BCs obtained through central venous access (P < 0.04) when compared to patients with negative SBCs. Daily SBCs in AHSCT recipients on steroids only rarely identify BSI and clear benefit for patients could not be demonstrated.

Bacteremia During Early Post-allogeneic Hematopoietic Stem Cell Transplantation Period: A Single Center Experience

Bacteremia is a significant complication of allogeneic hematopoietic stem cell transplantation (HSCT). We aimed to study bacteremia occurring during early post-transplant period at Bone Marrow Transplantation Unit of Ain Shams University regarding its risk factors and impact on survival. Patients performing allogeneic HSCT were followed up for occurrence of bacteremia. Survival status was assessed at 180 days post-transplant. Bacteremia occurred in 53.3 % of patients. On univariate analysis, CD34 +ve cell dose (P = 0.004), duration of neutropenia (P = 0.018), time interval between day of stem cell infusion and day of neutrophil engraftment (P = 0.043) and > 1 apheresis days (P = 0.040) were associated with higher rates of bacteremia. On multivariate analysis, CD34 +ve cell dose (P = 0.002) and apheresis day number (P = 0.038) remained significant. There was significant difference between patients who developed bacteremia and those who did not regarding overall survival (OS) (P = 0.042). Patients developing bacteremia caused by Gram negative bacteria (GNB) had lower OS than Gram positive bacteria (GPB) (P < 0.001). In conclusion, stem cell dose and apheresis day number influence bacteremia risk. Also, Gram negative bacteremia has negative impact on allogeneic transplant recipient survival rates.

Prevalence of Resistant Gram-Negative Bacilli in Bloodstream Infection in Febrile Neutropenia Patients Undergoing Hematopoietic Stem Cell Transplantation: A Single Center Retrospective Cohort Study

Bloodstream infection (BSI) is an important cause of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). To evaluate the causative bacteria and identify risk factors for BSI associated mortality in febrile neutropenia patients undergoing HSCT, we collected the clinical and microbiological data from patients underwent HSCT between 2008 and 2014 and performed a retrospective analysis. Throughout the study period, among 348 episodes of neutropenic fever in patients underwent HSCT, 89 episodes in 85 patients had microbiological defined BSI with a total of 108 isolates. Gram-negative bacteria (GNB) were the most common isolates (76, 70.3%) followed by gram-positive bacteria (GPB, 29, 26.9%) and fungus (3, 2.8%). As to the drug resistance, 26 multiple drug resistance (MDR) isolates were identified. Resistant isolates (n = 23) were more common documented in GNB, mostly Escherichia coli (9/36, 25%) and Klebsiella pneumonia (6/24, 25%). A total of 12 isolated were resistant to carbapenem including 4 K pneumoniae (4/24, 16.7%), 3 Stenotrophomonas maltophilia, and 1 Pseudomonas aeruginosa and other 4 GNB isolates (Citrobacter freumdii, Pseudomonas stutzeri, Acinetobacter baumanii, and Chryseobacterium indologenes). As to the GPB, only 3 resistant isolates were documented including 2 methicillin-resistant isolates (Staphylococcus hominis and Arcanobacterium hemolysis) and 1 vancomycin-resistant Enterococcus faecium. Among these 85 patients with documented BSI, 11 patients died of BSI as primary or associated cause with a BSI-related mortality of 13.1 ± 3.7% and 90-day overall survival after transplantation at 80.0 ± 4.3%. Patients with high-risk disease undergoing allo-HSCT, prolonged neutropenia (≥15 days) and infection with carbapenem-resistant GNB were associated with BSI associated mortality in univariate and multivariate analyses. Our report revealed a prevalence of GNB in BSI of neutropenic patients undergoing HSCT. Patients with high-risk diseases with prolonged neutropenia and carbapenem-resistant GNB were independent risk factors for BSI-related mortality.

Utility of routine surveillance blood cultures in asymptomatic allogeneic hematopoietic stem cell transplant recipients with indwelling central venous catheters at a comprehensive cancer center

BACKGROUND

Many transplant centers obtain surveillance blood cultures (SBCs) from asymptomatic allogeneic hematopoietic stem cell transplant (allo-HCT) recipients with central venous catheters for early detection of potential blood stream infections. The aim of this study was to determine the utility of this practice.

METHODS

We conducted a retrospective study of all patients who underwent allo-HCT to determine the frequency, clinical significance, and costs associated with SBCs.

RESULTS

From 776 patients, 6,801 SBCs were obtained (median, 9 per patient). Most (96.89%) were negative. Of the 211 positive SBCs, 171 (81%) had minimal clinical significance. The remaining 40 positive cultures (19%) were considered potentially significant. The frequency of potentially significant SBCs was 5.1% for the entire cohort and 0.59% of all SBCs drawn.

CONCLUSION

All potentially significant cultures and some that were deemed to have minimal significance led to medical intervention, some of which were probably unnecessary. No adverse outcomes occurred in patients with positive SBCs for the first 30 days following the positive result, regardless of the pathogen isolated or the quantitative colony count. The frequency of clinically significant positive SBCs in asymptomatic adult allo-HCT recipients is very low. Routine use of this practice leads to some unnecessary medical interventions and added costs.

Utility of surveillance blood cultures in patients undergoing hematopoietic stem cell transplantation

Background

Surveillance blood cultures are often obtained in hematopoietic stem cell transplant (HSCT) patients for detection of bloodstream infection. The major aims of this retrospective cohort study were to determine the utility of the practice of obtaining surveillance blood cultures from asymptomatic patients during the first 100 post-transplant days and to determine if obtaining more than one positive blood culture helps in the diagnosis of bloodstream infection.

Methods

We conducted a 17-month retrospective analysis of all blood cultures obtained for patients admitted to the hospital for HSCT from January 2010 to June 2011. Each patient’s clinical course, vital signs, diagnostic testing, treatment, and response to treatment were reviewed. The association between number of positive blood cultures and the final diagnosis was analyzed.

Results

Blood culture results for 205 patients were reviewed. Cultures obtained when symptoms of infection were present (clinical cultures) accounted for 1,033 culture sets, whereas 2,474 culture sets were classified as surveillance cultures (no symptoms of infection were present). The total number of positive blood cultures was 185 sets (5.3% of cultures obtained) and accounted for 84 positive culture episodes. Incidence of infection in autologous, related allogeneic and unrelated allogeneic transplants was 8.3%, 20.0%, and 28.6% respectively. Coagulase-negative staphylococci were the most common organisms isolated. Based on our application of predefined criteria there were 29 infections and 55 episodes of positive blood cultures that were not infections. None of the patients who developed infection were diagnosed by surveillance blood cultures. None of the uninfected patients with positive blood cultures showed any clinical changes after receiving antibiotics. There was a significant difference between the incidence of BSI in the first and second 50-day periods post-HSCT. There was no association between the number of positive blood cultures and the final diagnosis.

Conclusion

Surveillance blood cultures in patients who have undergone HSCT do not identify bloodstream infections. The number of positive blood cultures was not helpful in determining which patients had infection. Patients are at higher risk of infection in the first 50 days post-transplant period.

Surveillance cultures in pediatric allogeneic hematopoietic stem cell transplantation

The value of surveillance cultures in predicting systemic infections and in guiding antimicrobial treatment is controversial. We investigated 57 pediatric allo-SCTs between 2007 and 2009. ALL (34), AML (5), and severe aplastic anemia (4) were the largest patient groups. Conditioning was TBI-based in 87% and 54% developed GVHD (21% grade III-IV). Of the 2594 weekly colonization samples, 24% were positive (fecal bacteria 86%, fecal fungi 16%, Clostridium difficile 16%; throat bacteria 17% and throat fungi 4%). Enterobacteria and enterococci were the most common fecal findings, staphylococci and streptococci in the throat. Of the bacterial stool samples pretransplant, 74% (mostly enterococci) were resistant to our first-line antibiotics (ceftazidime and cloxacillin). Candida species accounted for the majority of the fungal findings: 62% of the fecal and 78% in the throat. A total of 170 clinical infection episodes were recorded, and in 12 of these, the bacterial blood culture was positive. In 4/12 cases, the pathogen was detected in surveillance culture previously, leading to sensitivity and specificity of 33.3 and 47.4%, respectively. Positive predictive value of bacterial surveillance cultures was 0.9%. The antimicrobial treatment was changed in only five cases based on the surveillance culture results. Weekly surveillance cultures seldom provided clinical benefit and were not cost-effective.

Antimicrobial therapy of febrile complications after high-dose chemotherapy and autologous hematopoietic stem cell transplantation--guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

More than 18,000 autolgous transplantation were performed in Europe in the year 2009. It as a routine procedure in experienced centres. Even if there is a low mortality rate, infections are a major issue after transplantation, occurring in more than 60 % of the patients. In this review we discuss all aspects of infections after autologous stem transplantation, including epidemiology, diagnostics, therapeutic algorithms, prophylaxis and supportive therapy.

Infections in Leukemia and Hematopoietic Stem Cell Transplantation

Infections are one of the most common complications in patients diagnosed with leukemia and serve as a major obstacle to treatment. Through the early 1970s, infections were the most common cause of death in patients diagnosed with acute leukemia, but improvement in treatment and supportive care over the past few decades, coupled with expanded prophylaxis and prevention regimens, have led to reduction in both the frequency and severity of infections. Regardless, due in part to an aging cancer population and the diversity of cancer treatments and procedures, infectious diseases remain a major cause of morbidity and mortality in patients with leukemia.

Routine surveillance for bloodstream infections in a pediatric hematopoietic stem cell transplant cohort: Do patients benefit?

BACKGROUND

Hematopoietic stem cell transplant (HSCT) recipients are at a high risk for late bloodstream infection (BSI). Controversy exists regarding the benefit of surveillance blood cultures in this immunosuppressed population. Despite the common use of this practice, the practical value is not well established in non-neutropenic children following HSCT.

METHODS

At the IWK Health Centre (Halifax, Nova Scotia), weekly surveillance blood cultures from central lines are drawn from children following HSCT until the line is removed. A retrospective chart review was performed to determine the utility and cost of this practice. Eligible participants were non-neutropenic HSCT recipients with central venous access lines. The cost of laboratory investigations, nursing time, hospital stay and interventions for positive surveillance cultures was calculated.

RESULTS

Forty-three HSCTs were performed in 41 children. Donors were allogenic in 33 cases (77%) and autologous in 10 cases (23%). There were 316 patient contacts for surveillance cultures (mean seven per patient) and 577 central line lumens sampled. Three of 43 patients (7%) had clinically significant positive surveillance blood cultures. Bacteria isolated were Klebsiella pneumoniae (n=2) and Corynebacterium jeikeium (n=1). All follow-up cultures before initiation of antimicrobial therapy were sterile. All three patients were admitted for antimicrobial therapy if they were not already hospitalized and/or had an uncomplicated course. The estimated total cost of BSI surveillance and management of asymptomatic infection over six years was $27,989.

CONCLUSION

The present study suggests that BSI surveillance in children following HSCT engraftment has a very low yield and significant cost. It is unclear whether it contributes to improved patient outcomes.

The utility of routine surveillance blood cultures in asymptomatic hematopoietic stem cell transplant patients

INTRODUCTION

Surveillance blood cultures (BCs) are often obtained in hematopoietic stem cell transplant (HSCT) patients for earlier detection of blood stream infections (BSI). The major aim of this study was to determine the utility of the current practice of obtaining surveillance blood cultures from asymptomatic transplant patients upon admission for the preparative regimen.

METHODS

We conducted an 8-year retrospective study of all patients consecutively admitted to the hospital for a HSCT from 2000 to 2008.

RESULTS

In this retrospective analysis, surveillance BCs from 191 eligible patients were analyzed. The incidence of definitive BSIs was 0.52% (1/191) with 6 BCs from other HSCT patients growing probable contaminants. The overall incidence of positive surveillance BCs was 2.9% (7/238) for the BCs taken and 3.7% (7/191) for patients cultured with coagulase negative staphylococcus being isolated from 6 of the 7 patients. The probability of increased BSI after transplantation in patients with initial positive surveillance BCs compared with those having negative BCs, was not significant (P=0.675). No infection-related mortality was observed during the first 60 days posttransplantation in these patients.

CONCLUSIONS

The frequency of positive surveillance BCs in asymptomatic HSCT patients at the time of hospital admission for transplant seems to be extremely low. These results, if confirmed by larger studies, show the reduced utility of obtaining surveillance BC in asymptomatic patients before administration of the conditioning regimen and the need for re-evaluation of this practice.

Infections after allogeneic hematopoietic stem cell transplantation with a nonmyeloablative conditioning regimen

Hematopoietic cell transplantation (HCT) following nonmyeloablative conditioning (NMSCT) may be associated with a reduced risk of infection compared to standard allogeneic HCT. We retrospectively analyzed incidence and risk factors of infection in 62 patients undergoing NMSCT with low-dose TBI +/- fludarabine and postgrafting CsA and MMF. The proportion of patients with any infection was 77%, but the majority of infectious events occurred beyond day 30. Donor other than sibling, older age, early disease and male gender were significant risk factors. The incidence of bacteremia was 55% at 1 year and the number of bacteremic episodes was 0.9 per patient (0.08 before day 30). The risk of bacteremia increased with older age and the use of a donor other than an HLA-identical sibling, but not with neutropenia. The incidence of infections other than bacteremia correlated with the use of corticosteroids. The risk of CMV infection increased with high-risk CMV serology, and risk of CMV disease with high-risk CMV serology, older age, first transplantation and a diagnosis of lymphoma. In conclusion, after NMSCT, infections are not frequent in the first 30 days post transplant but careful long-term monitoring is necessary thereafter.

Infections after CD34-selected or unmanipulated autologous hematopoietic stem cell transplantation

Immune reconstitution may be delayed after CD34-selected compared with unmanipulated autologous peripheral blood stem cell transplantation (PBSCT), resulting in a theoretically increased risk of infections. In a case-control matched study we compared the incidence of infection in 25 recipients of CD34-selected PBSC (CD34 group) and 75 recipients of unmanipulated PBSC (PBSC group) transplants. The population included 52 males and 48 females suffering from non-Hodgkin's lymphoma (n = 32), Hodgkin's disease (n = 8), multiple myeloma (n = 40) or breast cancer (n = 20). Neutrophil engraftment was comparable in the two groups. The actuarial incidence of infection was similar in the two groups (56% vs. 49% at day 30, and 70% vs. 64% at 1 yr respectively). The proportion of patients with 1, 2 or 3 infections, the number of infectious event per patient (1.32 vs. 1.04; NS), the number of infections before day 15 or 30, between days 31 and 100 or after day 100, the risk of varicella-zoster virus or cytomegalovirus infection or disease, or the use of antibiotic or antifungal therapy, were not increased in the CD34 compared with the PBSC group. The main agents responsible for infection were bacteria, particularly gram-positive cocci, in both groups. Bacteremia accounted for 33% of all infectious events in the CD34 group vs. 16% in the PBSC group (P < 0.05). Fungal infections were rare. In conclusion, our results do not support the notion that CD34-selection of the graft is associated with an increased rate of infection after autologous PBSC transplantation. The role of extended infection prophylaxis should be evaluated.

Pegfilgrastim compared with Filgrastim after autologous hematopoietic peripheral blood stem cell transplantation

In order to assess the effect of Pegfilgrastim on the duration of neutropenia and clinical outcome of patients after autologous peripheral blood stem cell (PBSC) transplantation, we compared 20 consecutive patients with lymphoma or multiple myeloma receiving a single 6-mg dose of Pegfilgrastim on day 1 posttransplant to an historical control group of 60 patients receiving daily Filgrastim 5 microg/kg starting on day 1 posttransplant. The duration of neutropenia was similar in the Pegfilgrastim group compared with the control group. There were no differences in time to neutrophil, erythroid, or platelet engraftment nor in the incidence of fever and infections. The duration of antibiotic therapy, transfusion support, and time to hospital discharge were similar in the two groups. However, after initial hematopoietic reconstitution, we observed significantly higher values of lymphocytes (e.g., 1,660+/-1,000 versus 970+/-460 on day 80, p=0.0002), neutrophils (e.g., 3,880+/-2,030 versus 2,420+/-1,500 on day 25, p=0.0004), reticulocytes (e.g., 148,160+/-90,590 versus 87,140+/-65,920 on day 25, p<0.0001), and platelets (e.g., 210,700+/-116,090 versus 150,240+/-58,230 on day 55, p=0.0052) up to day 100 in the Pegfilgrastim group compared with the Filgrastim group. These observations had no impact on clinical outcome of the patients after day 30 due to the low incidence of infectious events after engraftment in autologous PBSC transplantation. We conclude that the effect of Pegfilgrastim administrated on day 1 posttransplant is comparable to that of daily Filgrastim on initial hematopoietic reconstitution. The possibly superior effect of Pegfilgrastim on cell counts we observed after initial engraftment should be further tested in a prospective randomized trial.

Bloodstream Infections among Heart Transplant Recipients

BACKGROUND

Heart transplant (HT) recipients are prone to life-threatening infections, including bloodstream infection (BSI), but information on this topic is particularly scarce.

METHODS

We studied 309 consecutive HT performed at our institution between 1988 and 2003. We assessed the characteristics of each episode of BSI, prophylaxis and immunosuppression used, and possible related factors.

RESULTS

Sixty episodes of BSI occurred in 15.8% of all HT recipients. Rates of BSI/transplanted patient decreased progressively throughout the study period: 21.2%, 14.3%, and 7.5% in each 5-year period (P=0.03). BSI episodes occurred a median of 51 days after transplantation. The main BSI origins were: lower respiratory tract (23%), urinary tract (20%), and catheter-related-BSI (16%). Gram-negative organisms predominated (55.3%), followed by Gram-positive (44.6%). Mortality was 59.2%, with 12.2% directly attributable to BSI. Independent risk factors for BSI after HT were: hemodialysis (OR 6.5; 95% CI 3.2-13), prolonged intensive care unit stay (OR 3.6; 95% CI 1.6-8.1), and viral infection (OR 2.1; 95% CI 1.1-4). BSI was a risk factor for mortality (OR 1.8; 95% CI 1.2-2.8).

CONCLUSION

BSIs have decreased in HT recipients, but still contribute to mortality, mainly if related to pneumonia or polymicrobial infections. Reduction of early postoperative complications and viral infections are amenable goals that may further reduce BSI in this population.

Inflammatory response to mucosal barrier injury after myeloablative therapy in allogeneic stem cell transplant recipients

We noted a significant increase of interleukin-8 (IL-8), LBP and CRP mirroring the pattern of mucosal barrier injury as measured by gut integrity (lactulose/rhamnose ratio), daily mucositis score (DMS) and serum citrulline concentrations of 32 haematopoietic stem cell transplant (HSCT) recipients following intensive myeloablative therapy. Concentrations of IL-8, LBP and CRP were already significantly elevated before the onset of fever or bacteraemia due to oral viridans streptococci (OVS) in the first week after transplant during profound neutropenia. These markers reached their peak when citrulline concentrations reached their nadir, the highest scores of DMS were attained and when there was significantly decreased gut integrity. This suggests that the degree of mucosal barrier injury rather than bacteraemia due to OVS determines the intensity of the inflammatory response.