Changing microbial epidemiology in hematopoietic stem cell transplant recipients: increasing resistance over a 9-year period

Immunoglobulin replacement vs prophylactic antibiotics for hypogammaglobulinemia secondary to hematological malignancy

ABSTRACT

Immunoglobulin replacement and prophylactic antibiotics are commonly used to prevent infections in patients with secondary hypogammaglobulinemia due to hematological malignancies but have never been directly compared. In this randomized controlled feasibility trial conducted in 7 hospitals in Australia and New Zealand, we enrolled patients with secondary hypogammaglobulinemia with either a history of recurrent/severe infection or an immunoglobulin G level <4 g/L. Participants were randomized in a 1:2 ratio to immunoglobulin (0.4 g/kg per 4 weeks IV) or daily antibiotics (trimethoprim-sulfamethoxazole 160 mg/800 mg or, if contraindicated, 100 mg doxycycline) for 12 months. Participants allocated to antibiotics were allowed to crossover after grade ≥3 infections. The primary outcome was proportion of patients alive on the assigned treatment 12 months after randomization. Between August 2017 and April 2019, 63 patients were randomized: 42 to antibiotics and 21 to immunoglobulin. Proportion of participants alive on allocated treatment at 12 months was 76% in the immunoglobulin and 71% in the antibiotic arm (Fisher exact test P=.77; odds ratio, 0.78; 95% CI, 0.22-2.52). The lower quartile for time to first major infection (median, not reached) was 11.1 months for the immunoglobulin and 9.7 months for the antibiotic arm (log-rank test, P=.65). Three participants in the immunoglobulin and 2 in the antibiotic arm had grade ≥3 treatment-related adverse events. A similar proportion of participants remained on antibiotic prophylaxis at 12 months to those on immunoglobulin, with similar rates of major infections. Our findings support the feasibility of progressing to a phase 3 trial. Trial registration #ACTRN12616001723471.

The addition of doxycycline to fluoroquinolones for bacterial prophylaxis in autologous stem cell transplantation for multiple myeloma

BACKGROUND

Bacterial prophylaxis with a fluoroquinolone (FQ) during autologous stem cell transplant (ASCT) is common, although not standardized among transplant centers. The addition of doxycycline (doxy) to FQ prophylaxis was previously linked to reduced neutropenic fever and bacteremia in multiple myeloma (MM) patients undergoing ASCT although several confounders were present. We compared the incidence of neutropenic fever and bacteremia between MM patients variably receiving prophylaxis with FQ alone and FQ-doxy during ASCT.

METHODS

Systematic retrospective chart review of MM patients who underwent ASCT between January 2016 and December 2021. The primary objective was to determine the effect of bacterial prophylaxis on neutropenic fever and bacteremia within 30 days of ASCT. Multivariable logistic regression for neutropenic fever and univariate logistic regression for bacteremia accounted for differences in subject characteristics between groups.

RESULTS

Among 341 subjects, 121 received FQ and 220 received FQ-doxy for prophylaxis. Neutropenic fever developed in 67 (55.4%) and 87 (39.5%) subjects in the FQ and FQ-doxy groups, respectively (p = .005). Bacteremia was infrequent, with 5 (4.1%) and 5 (2.3%) cases developing in the FQ and FQ-doxy groups, respectively (p = .337). Among Gram-negative bacteremia events, 7/7 Escherichia coli strains were FQ-resistant, and 5/7 were ceftriaxone-resistant.

CONCLUSION

The FQ-doxy prophylaxis group had fewer cases of neutropenic fever than the FQ group, however, there was no significant difference in bacteremia. High rates of antibiotic resistance were observed. An updated randomized controlled trial investigating appropriate prophylaxis for ASCT in the context of current oncology standards and changing antimicrobial resistance rates is warranted.

The effect of ciprofloxacin prophylaxis during haematopoietic cell transplantation on infection episodes, exposure to treatment antimicrobials and antimicrobial resistance: a single-centre retrospective cohort study

Objectives

Fluroquinolone prophylaxis during haematopoietic cell transplantation (HCT) remains contentious. We aimed to determine its effectiveness and association with exposure to treatment antimicrobials and antimicrobial resistance.

Methods

All admission episodes for HCT (N = 400 , 372 unique patients) in a tertiary centre between January 2020 and December 2022 were studied. Allogeneic HCT (allo-HCT) recipients received prophylaxis with ciprofloxacin during chemotherapy-induced neutropenia, while autologous HCT (auto-HCT) recipients did not.

Results

Allo-HCT was performed for 43.3% (173/400) of patients, auto-HCT for 56.7% (227/400). Allo-HCT was associated with an average of 1.01 fewer infection episodes per 100 admission days (95% CI 0.62-1.40, P < 0.001) compared with auto-HCT. In allo-HCT, the total exposure to all antimicrobials was higher [+24.8 days of therapy (DOT)/100 admission days, P < 0.001], as was exposure to ciprofloxacin (+40.5 DOT/100 admission days, P < 0.001). By contrast, exposure to meropenem (-4.5 DOT/100 admission days, P = 0.02), piperacillin/tazobactam (-5.2 DOT/100 admission days, P < 0.001), aminoglycosides (-4.5 DOT/100 admission days, P < 0.001) and glycopeptides (-6.4 DOT/100 admission days, P < 0.001) was reduced. Enterobacteriaceae isolated during allo-HCT were more resistant to ciprofloxacin (65.5%, 19/29 versus 6.1%, 2/33, P < 0001), ceftriaxone (65.5%, 19/29 versus 9.1%, 3/33, P < 0.001), other antimicrobial classes. Vancomycin-resistant enterococci were more common in allo-HCT recipients (11%, 19/173 versus 0.9%, 2/227, P < 0.001). Inpatient mortality during allo- and auto-HCT was 9.8% (17/173) and 0.4% (1/227). respectively (P < 0.001).

Conclusions

Ciprofloxacin prophylaxis in allo-HCT was associated with fewer infection episodes and reduced exposure to treatment antimicrobials. Mortality in auto-HCT remained low. A significant burden of antimicrobial resistance was detected in allo-HCT recipients.

Epidemiology and outcomes of vancomycin-resistant enterococcus infections: a systematic review and meta-analysis

Vancomycin-resistant enterococci (VRE) cause many infections in the healthcare context. Knowledge regarding the epidemiology and burden of VRE infections, however, remains fragmented. We aimed to summarize recent studies on VRE epidemiology and outcomes in hospitals, long-term-care facilities (LTCFs) and nursing homes worldwide based on current epidemiological reports. We searched MEDLINE/PubMed, the Cochrane Library, and Web of Science for observational studies, which reported on VRE faecium and faecalis infections in in-patients published between January 2014 and December 2020. Outcomes were incidence, infection rate, mortality, length of stay (LOS), and healthcare costs. We conducted a meta-analysis on mortality (PROSPERO registration number: CRD42020146389). Of 681 identified publications, 57 studies were included in the analysis. Overall quality of evidence was moderate to low. VRE incidence was rarely and heterogeneously reported. VRE infection rate differed highly (1-55%). The meta-analysis showed a higher mortality for VRE faecium bloodstream infections (BSIs) compared with VSE faecium BSIs (risk ratio, RR 1.46; 95% confidence interval (CI) 1.17-1.82). No difference was observed when comparing VRE faecium vs VRE faecalis BSI (RR 1.00, 95% CI 0.52-1.93). LOS was higher in BSIs caused by E. faecium vs E. faecalis. Only three studies reported healthcare costs. In contrast to previous findings, our meta-analysis of included studies indicates that vancomycin resistance independent of VRE species may be associated with a higher mortality. We identified a lack of standardization in reporting outcomes, information regarding healthcare costs, and state-of-the-art microbiological species identification methodology, which may inform the set-up and reporting of future studies.

Clinical characteristics and mortality risk factors of mixed bacterial infections in hematopoietic stem cell transplantation recipients

Background and objective

Mixed bacterial infections (MBI) is one of the complications after hematopoietic stem cell transplantation (HSCT) and increases the risk of patient death. However, there are few reports specifically on this topic. The purpose of this study was to investigate the clinical characteristics and mortality risk factors of MBI in HSCT recipients.

Methods

The electronic medical records of patients undergoing HSCT were collected. The epidemiological features and antibiotic resistance of patients with and without MBI were compared. Logistic regression and Cox regression were used to identify the risk factors for MBI acquisition and death. R language was used to construct a prediction model for the overall survival of HSCT recipients with MBI.

Results

The cumulative incidence of MBI was 6.3% and the mortality was 48.8%. Time interval from diagnosis to transplantation > 180 days (HR=2.059, 95% CI 1.042-4.069, P=0.038) and ICU admission after transplantation (HR=2.271, 95% CI 1.053-4.898, P=0.036) were independent risk factors for MBI acquisition. Engraftment period > 20 days (HR=2.273, 95% CI 1.028-5.027, P=0.043), continuous renal replacement therapy (HR=5.755, 95% CI 1.691-19.589, P=0.005) and septic shock (HR=4.308, 95% CI 2.085-8.901, P=0.000) were independent risk factors associated with mortality.

Conclusions

MBI has become a serious problem that cannot be ignored after HSCT. It is urgent for clinicians to pay high attention to it and formulate reasonable monitoring and treatment plans to improve the prognosis of patients.

Dose-dependent impact of enrofloxacin on broiler chicken gut resistome is mitigated by synbiotic application

Fluoroquinolone agents are considered critical for human medicine by the World Health Organization (WHO). However, they are often used for the treatment of avian colibacillosis in poultry production, creating considerable concern regarding the potential spread of fluoroquinolone resistance genes from commensals to pathogens. Therefore, there is a need to understand the impact of fluoroquinolone application on the reservoir of ARGs in poultry gut and devise means to circumvent potential resistome expansion. Building upon a recent dose optimization effort, we used shotgun metagenomics to investigate the time-course change in the cecal microbiome and resistome of broiler chickens receiving an optimized dosage [12.5 mg/kg body weight (bw)/day], with or without synbiotic supplementation (PoultryStar^®, BIOMIN GmbH), and a high dosage of enrofloxacin (50 mg/kg bw/day). Compared to the high dose treatment, the low (optimized) dose of enrofloxacin caused the most significant perturbations in the cecal microbiota and resistome of the broiler chickens, demonstrated by a lower cecal microbiota diversity while substantially increasing the antibiotic resistance genes (ARGs) resistome diversity. Withdrawal of antibiotics resulted in a pronounced reduction in ARG diversity. Chickens receiving the synbiotic treatment had the lowest diversity and number of enriched ARGs, suggesting an alleviating impact on the burden of the gut resistome. Some Proteobacteria were significantly increased in the cecal metagenome of chickens receiving enrofloxacin and showed a positive association with increased ARG burden. Differential abundance (DA) analysis revealed a significant increase in the abundance of ARGs encoding resistance to macrolides-lincosamides-streptogramins (MLS), aminoglycosides, and tetracyclines over the period of enrofloxacin application, with the optimized dosage application resulting in a twofold higher number of affected ARG compared to high dosage application. Our results provide novel insights into the dose-dependent effects of clinically important enrofloxacin application in shaping the broiler gut resistome, which was mitigated by a synbiotic application. The contribution to ameliorating the adverse effects of antimicrobial agents, that is, lowering the spread of antimicrobial resistance genes, on the poultry and potentially other livestock gastrointestinal microbiomes and resistomes merits further study.

Do weekly surveillance cultures contribute to antibiotic stewardship and correlate with outcome of HSCT in children - a multicentre real-world experience of 5 years from Indian subcontinent?

BACKGROUND

The utility of weekly rectal swab surveillance cultures (RSSC) as a resource to identify gut colonisation with Extended Spectrum Beta-Lactamase (ESBL)-producing E Coli or Klebsiella pneumoniae carbapenemase (KPC) producing organisms, to guide empirical antibiotic therapy in HSCT patients continues to be a subject of interest. There is urgency to assess and justify modifications to empirical antibiotics based upon regional epidemiology and patient groups.

OBJECTIVE

To study the utility of weekly rectal swab surveillance cultures (RSSC) to guide empirical antibiotics therapy and the impact of gut colonisation on transplant outcomes.

STUDY DESIGN

This is a retrospective analysis of 317 successive first transplants done in three pediatric bone marrow transplant centres in Indian sub-continent, mainly for hemoglobinopathies, between April 2016 and April 2021. Transplantation, infection control and febrile neutropenia management protocols are identical among the three centres. First line antibiotics were chosen based on RCCS reports i.e. meropenem and high dose meropenem with colistin for ESBL and carbapenemase resistant colonisation respectively for first half of the study and no adjustment was made in the second half. Clinical response to antibiotics, long term outcomes, antibiotic-resistant bacteraemia and acute GVHD were analysed. Log-rank test, Chi-squared test and Wilcoxon test were used to compare data using R Statistical software.

RESULTS

Of all 871 weekly RSSC done, 162 were positive for ESBL- or KPC-resistant organism. RCCS were ESBL-positive in 106 patients (33%) and KPC-positive in 10 patients (3%). Within 97 ESBL-positive patients for whom antimicrobial susceptibility testing (AST) report was available, only 22 (25%) demonstrated clinical resistance of Pip-Taz. Within the 10 KPC-positive patients' clinical resistance was observed only in 4 (40%) to Pip-Taz and 3 (30%) to meropenem. For ESBL-positive RSSC where 1st line empirical antibiotics were used, 66% of the patients responded clinically. Even within the 15 who were resistant to 1st line empirical antibiotics (Pip-Taz) on RSSC reports, 67% responded to Pip-Taz clinically. Within these patients 27 (56%) never needed any carbapenems. Using Pip-Taz empirically in ESBL-positive patients did not prolong meropenem use within 100 days of transplantation (p=0.18). For KPC-positive RSSC where 1st line empirical antibiotics were used, all patients clinically responded, including 4 who were resistant to Pip-Taz and 3 patients who were meropenem resistant on RCCS. Comparing patients who were ESBL-positive, KPC-positive and neither, no statistically significant difference was seen in overall survival (p=0.95), disease free survival (p=0.45), transplant related mortality (p=0.97), rejection (p=0.68) and rate of acute GVHD grade II-IV (p=0.78). Comparing the ESBL-positive patients who did and did not get higher-level empirical antibiotics, no statistical difference was seen in overall survival (p=0.32), disease free survival (p=0.64), transplant related mortality (p=0.65), rejection (p=0.46), acute GVHD grade II-IV (p=0.26) or antibiotic resistant bacteraemia (p=0.3).

CONCLUSIONS

In context of transplantation for non-malignant HSCTs, empiric antibiotic choice based on rectal swab surveillance cultures is not justified, even in regions with a high prevalence of antimicrobial resistance. Antimicrobial susceptibility testing (AST) reports in surveillance cultures did not correlate with in-vivo clinical response. Colonisation reported on weekly surveillance rectal swab cultures showed no correlation with clinical outcomes.

Analysis of incidence and risk factors of the multidrug resistant gastrointestinal tract infection in children and adolescents undergoing allogeneic and autologous hematopoietic cell transplantation: a nationwide study

The aim of this multi-center study was to evaluate the incidence, clinical course, and risk factors for bacterial multidrug-resistant (MDR) gastrointestinal tract infections (GTI) among children undergoing allogeneic and autologous hematopoietic cell transplantation. A total number of 175 pediatric patients (aged 1–18 years), transplanted between January 2018 and December 2019, who were tested for bacterial colonization/infection were enrolled into this multi-center analysis. Episodes of MDR GTI occurred in 77/175 (44%) patients. In multivariate analysis for higher GTI incidence, the following factors were significant: matched-unrelated donor (MUD) transplantation, HLA mismatch, presence of graft-versus-host disease (GVHD), and gut GVHD. The most common GTI were Clostridium difficile (CDI), multidrug-resistant Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli extended-spectrum β-lactamase), and Enterococcus HLAR (high-level aminoglycoside-resistant). No MDR GTI–attributed deaths were reported. MDR GTI is a frequent complication after HCT among children, causes prolonged hospitalization, but rarely contributes to death. We identified risk factors of MDR GTI development in children, with focus on GVHD and unrelated donor and HLA mismatch. We conclude that the presence of Clostridiales plays an important anti-inflammatory homeostatic role and decreases incidence of GVHD or alleviate its course.

Modelling and Simulation of the Effect of Targeted Decolonisation on Incidence of Extended-Spectrum Beta-Lactamase-Producing Enterobacterales Bloodstream Infections in Haematological Patients

Introduction

Haematological patients are at higher risk of bloodstream infections (BSI) after chemotherapy. The aim of this study was to develop a simulation model assessing the impact of selective digestive decontamination (SDD) of haematological patients colonised with extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) on the incidence of ESBL-E BSI after chemotherapy.

Methods

A patient population was created by a stochastic simulation model mimicking the patients’ states of colonisation with ESBL-E during hospitalisation. A systematic literature search was performed to inform the model. All ESBL-E carriers were randomised (1:1) to either the intervention (targeted SDD) or the control group (placebo). ESBL-E BSI incidence was the outcome of the model. Sensitivity analyses were performed by prevalence of ESBL-E carriage at hospital admission (low: < 10%, medium: 10–25%, high: > 25%), duration of neutropenia after receiving chemotherapy, administration of antibiotic prophylaxis with quinolones, and time interval between SDD and chemotherapy.

Results

The model estimated that the administration of targeted SDD before chemotherapy reduces the incidence of ESBL-E BSI in the hospitalised haematological population up to 27%. The greatest benefit was estimated in high-prevalence settings, regardless of the duration of neutropenia, the time interval before chemotherapy, and the administration of antibiotic prophylaxis with quinolones (p < 0.05). In medium-prevalence settings, SDD was effective in patients receiving quinolone prophylaxis, with either 1-day time interval before chemotherapy and a neutropenia duration > 6 days (p < 0.05) or 7-day time interval before chemotherapy and a neutropenia duration > 9 days (p < 0.05). No benefit was observed in low-prevalence settings.

Conclusions

Our model suggests that targeted SDD could decrease the rate of ESBL-E BSI in haematological carriers before chemotherapy in the setting of high ESBL-E prevalence at hospital admission. These estimates require confirmation by well-designed multicentre RCTs, including the assessment of the impact on resistance/disruption patterns of gut microbiome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00550-3.

Update in clinical and mouse microbiota research in allogeneic haematopoietic cell transplantation

PURPOSE OF REVIEW

The intestinal microbiota plays a critical role in intestinal homeostasis and immune regulation and has been recognized as a predictor of clinical outcome in patients undergoing allogeneic haematopoietic cell transplantation (allo-HCT) and specifically a determinant of the severity of graft-versus-host disease (GVHD) in mouse models. As GVHD is the most important cause of nonrelapse mortality (NRM) after allo-HCT, understanding the mechanisms by which modifying the microbiota may prevent or decrease the severity of GVHD would represent an important advance.

RECENT FINDINGS

Microbiota injury was observed globally and higher diversity at peri-engraftment was associated with lower mortality. Lactose is a dietary factor that promotes post-allo-HCT Enterococcus expansion, which is itself associated with mortality from GVHD in patients and exacerbates GVHD in mice. Bacterial and fungal bloodstream infections are preceded by intestinal colonization with a corresponding organism, supporting the gut as a source for many bloodstream infections. Metabolomic profiling studies showed that GVHD is associated with changes in faecal and plasma microbiota-derived molecules.

SUMMARY

In this review, we highlight some of the most recent and important findings in clinical and mouse microbiota research, as it relates to allo-HCT. Many of these are already being translated into clinical trials that have the potential to change future practice in the care of patients.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host: An Update

This article reviews antibiotic resistance and treatment of bacterial infections in the growing number of patients who are immunocompromised: solid organ transplant recipients, the neutropenic host, and persons with human immunodeficiency virus and AIDS. Specific mechanisms of resistance in both gram-negative and gram-positive bacteria, as well as newer treatment options are addressed elsewhere and are only briefly discussed in the context of the immunocompromised host.

Bacteriophage therapy as a treatment option for transplant infections

PURPOSE OF REVIEW

Since initial description of the successful use of intravenous bacteriophage therapy in the United States in 2017, there is widespread interest in using bacteriophage therapy for multidrug-resistant (MDR) infections.

RECENT FINDINGS

Recent published cases of bacteriophage therapy in transplant candidates and recipients are reviewed highlighting its safety and potential efficacy when used as an adjunct to systemic antibiotics for a variety of clinical indications. An overview of access to bacteriophage therapy in the United States is also provided.

SUMMARY

The reviewed cases form the basis for ongoing compassionate use of bacteriophage therapy in transplant candidates and recipients with life-threatening MDR infections until data from clinical trials are available to guide therapy.

Antibiotic prophylaxis and the gastrointestinal resistome in paediatric patients with acute lymphoblastic leukaemia: a cohort study with metagenomic sequencing analysis

BACKGROUND

Although antibiotic prophylaxis with levofloxacin can reduce the risk of serious infection in immunocompromised patients, the potential contribution of prophylaxis to antibiotic resistance is a major drawback. We aimed to identify the effects of levofloxacin prophylaxis, given to paediatric patients with acute lymphoblastic leukaemia to prevent infections during induction chemotherapy, on antibiotic resistance in gastrointestinal microbiota after completion of induction and consolidation therapy.

METHODS

This prospective, single-centre (St Jude Children's Research Hospital, Memphis, TN, USA) cohort study included children (≤18 years) receiving therapy for newly diagnosed acute lymphoblastic leukaemia and who received either primary levofloxacin prophylaxis or no antibacterial prophylaxis (aside from Pneumocystis jirovecii prophylaxis with trimethoprim-sulfamethoxazole) and provided at least two stool samples, including one after completion of induction therapy. We used metagenomic sequencing to identify bacterial genes that confer resistance to fluoroquinolones, trimethoprim-sulfamethoxazole, or other antibiotics, and to identify point mutations in bacterial topoisomerases (gyrA, parC) that confer resistance to fluoroquinolones. We then used generalised linear mixed models to compare the prevalence and relative abundance of antibiotic resistance gene groups after completion of induction and consolidation therapy between participants who had received levofloxacin and those who received no prophylaxis.

FINDINGS

Between Feb 1, 2012, and April 30, 2016, 118 stool samples (32 baseline, 49 after induction, and 37 after consolidation) were collected from 49 evaluable participants; of these participants, 31 (63%) received levofloxacin prophylaxis during induction therapy and 18 (37%) received no antibacterial prophylaxis. Over the course of induction therapy, there was an overall increase in the relative abundance of trimethoprim-sulfamethoxazole resistance genes (estimated mean fold change 5·9, 95% CI 3·6-9·6; p<0·0001), which was not modified by levofloxacin prophylaxis (p=0·46). By contrast, the prevalence of topoisomerase point mutations increased over the course of induction therapy in levofloxacin recipients (mean prevalence 10·4% [95% CI 3·2-25·4] after induction therapy vs 3·7% [0·2-22·5] at baseline) but not other participants (0% vs 0%; p<0·0001). There was no significant difference between prophylaxis groups with respect to changes in aminoglycoside, β-lactam, vancomycin, or multidrug resistance genes after completion of induction or consolidation therapy.

INTERPRETATION

Analysing the gastrointestinal resistome can provide insights into the effects of antibiotics on the risk of antibiotic-resistant infections. In this study, antibiotic prophylaxis with trimethoprim-sulfamethoxazole or levofloxacin during induction therapy for acute lymphoblastic leukaemia appeared to increase the short-term and medium-term risk of colonisation with bacteria resistant to these antibiotics, but not to other drugs. More research is needed to determine the longer-term effects of antibacterial prophylaxis on colonisation with antibiotic-resistant bacteria.

FUNDING

Children's Infection Defense Center at St Jude Children's Research Hospital, American Lebanese Syrian Associated Charities, and National Institutes of Health.

Quality of inpatient antimicrobial use in hematology and oncology patients

OBJECTIVES

To compare antimicrobial prescribing practices in Australian hematology and oncology patients to noncancer acute inpatients and to identify targets for stewardship interventions.

DESIGN

Retrospective comparative analysis of a national prospectively collected database.

METHODS

Using data from the 2014-2018 annual Australian point-prevalence surveys of antimicrobial prescribing in hospitalized patients (ie, Hospital National Antimicrobial Prescribing Survey called Hospital NAPS), the most frequently used antimicrobials, their appropriateness, and guideline concordance were compared among hematology/bone marrow transplant (hemBMT), oncology, and noncancer inpatients in the setting of treatment of neutropenic fever and antibacterial and antifungal prophylaxis.

RESULTS

In 454 facilities, 94,226 antibiotic prescriptions for 62,607 adult inpatients (2,230 hemBMT, 1,824 oncology, and 58,553 noncancer) were analyzed. Appropriateness was high for neutropenic fever management across groups (83.4%-90.4%); however, hemBMT patients had high rates of carbapenem use (111 of 746 prescriptions, 14.9%), and 20.2% of these prescriptions were deemed inappropriate. Logistic regression demonstrated that hemBMT patients were more likely to receive appropriate antifungal prophylaxis compared to oncology and noncancer patients (adjusted OR, 5.3; P < .001 for hemBMT compared to noncancer patients). Oncology had a low rate of antifungal prophylaxis guideline compliance (67.2%), and incorrect dosage and frequency were key factors. Compared to oncology patients, hemBMT patients were more likely to receive appropriate nonsurgical antibacterial prophylaxis (aOR, 8.4; 95% CI, 5.3-13.3; P < .001). HemBMT patients were also more likely to receive appropriate nonsurgical antibacterial prophylaxis compared to noncancer patients (OR, 3.1; 95% CI, 1.9-5.0; P < .001). However, in the Australian context, the hemBMT group had higher than expected use of fluoroquinolone prophylaxis (66 of 831 prescriptions, 8%).

CONCLUSIONS

This study demonstrates why separate analysis of hemBMT and oncology populations is necessary to identify specific opportunities for quality improvement in each patient group.

Microbiology of Bloodstream Infections in Children After Hematopoietic Stem Cell Transplantation: A Single-Center Experience Over Two Decades (1997-2017)

Background

Bloodstream infections (BSIs) occur frequently after hematopoietic stem cell transplantation (HSCT). We examined the microbiology of BSI in pediatric HSCT recipients over a 2-decade period at our institution to inform empirical antimicrobial prescribing and infection prevention strategies.

Methods

We conducted a retrospective cohort study of children (<18 years) who underwent HSCT at Duke University between 1997 and 2015. We used recurrent-event gap-time Cox proportional hazards models to determine the hazards of all-cause and cause-specific BSI according to HSCT year. We compared the median time to BSI by causative organism type and evaluated for temporal trends in the prevalence of antibiotic resistance among causative organisms.

Results

A total of 865 BSI occurred in 1311 children, including 412 (48%) Gram-positive bacterial, 196 (23%) Gram-negative bacterial, 56 (6%) fungal, 23 (3%) mycobacterial, and 178 (21%) polymicrobial BSI. The hazard of all BSIs did not change substantially over time during the study period, but the hazard of fungal BSIs declined over time during the study period (P = .04). Most fungal BSIs (82%) occurred in the first 100 days after HSCT, whereas mycobacterial BSIs occurred later after HSCT than BSIs caused by other organisms (P < .0001). The prevalence of vancomycin resistance among BSIs caused by Enterococcus faecium increased during the study period (P = .0007). The risk of 2-year mortality in children was increased with BSI (P = .02), Gram-negative bacterial BSI (P = .02), and fungal BSI (P < .0001).

Conclusions

Despite expanded practices for BSI prevention over the past several decades, the incidence of BSI remains high in pediatric HSCT recipients at our institution. Additional strategies are urgently needed to effectively prevent BSIs in this high-risk population.

Make Sure You Have a Safety Net: Updates in the Prevention and Management of Infectious Complications in Stem Cell Transplant Recipients

Hematopoietic stem cell transplant recipients are at increased risk of infection and immune dysregulation due to reception of cytotoxic chemotherapy; development of graft versus host disease, which necessitates treatment with immunosuppressive medications; and placement of invasive catheters. The prevention and management of infections in these vulnerable hosts is of utmost importance and a key “safety net” in stem cell transplantation. In this review, we provide updates on the prevention and management of CMV infection; invasive fungal infections; bacterial infections; Clostridium difficile infection; and EBV, HHV-6, adenovirus and BK infections. We discuss novel drugs, such as letermovir, isavuconazole, meropenem-vaborbactam and bezlotoxumab; weigh the pros and cons of using fluoroquinolone prophylaxis during neutropenia after stem cell transplantation; and provide updates on important viral infections after hematopoietic stem cell transplant (HSCT). Optimizing the prevention and management of infectious diseases by using the best available evidence will contribute to better outcomes for stem cell transplant recipients, and provide the best possible “safety net” for these immunocompromised hosts.

Febrile Neutropenia in Acute Leukemia. Epidemiology, Etiology, Pathophysiology and Treatment

Acute leukemias are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. An important cause of both the latter is infectious complications. Patients with acute leukemia are highly susceptible to infectious diseases due to factors related to the disease itself, factors attributed to treatment, and specific individual risk factors in each patient. Patients with chemotherapy-induced neutropenia are at particularly high risk, and microbiological agents include viral, bacterial, and fungal agents. The etiology is often unknown in infectious complications, although adequate patient evaluation and sampling have diagnostic, prognostic and treatment-related consequences. Bacterial infections include a wide range of potential microbes, both Gram-negative and Gram-positive species, while fungal infections include both mold and yeast. A recurring problem is increasing resistance to antimicrobial agents, and in particular, this applies to extended-spectrum beta-lactamase resistance (ESBL), Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and even carbapenemase-producing Enterobacteriaceae (CPE). International guidelines for the treatment of sepsis in leukemia patients include the use of broad-spectrum Pseudomonas-acting antibiotics. However, one should implant the knowledge of local microbiological epidemiology and resistance conditions in treatment decisions. In this review, we discuss infectious diseases in acute leukemia with a major focus on febrile neutropenia and sepsis, and we problematize the diagnostic, prognostic, and therapeutic aspects of infectious complications in this patient group. Meticulously and thorough clinical and radiological examination combined with adequate microbiology samples are cornerstones of the examination. Diagnostic and prognostic evaluation includes patient review according to the multinational association for supportive care in cancer (MASCC) and sequential organ failure assessment (SOFA) scoring system. Antimicrobial treatments for important etiological agents are presented. The main challenge for reducing the spread of resistant microbes is to avoid unnecessary antibiotic treatment, but without giving to narrow treatment to the febrile neutropenic patient that reduce the prognosis.

Multidrug-resistant bacterial infections in children undergoing haematopoietic stem cell transplantation over a 6-year period: analysis of the Polish Pediatric Group for Hematopoietic Stem Cell Transplantation

AIMS

Multidrug-resistant (MDR) bacteria are an emerging cause of morbidity and mortality after haematopoietic stem cell transplantation (HSCT). The aim of the study was to analyse the incidence, clinical characteristics and survival from bacterial infections (BI) caused by MDR pathogens in paediatric HSCT recipients.

METHODS AND RESULTS

Among 971 transplanted patients, BI were found in 416 children between the years 2012 and 2017. Overall, there were 883 bacterial episodes, which includes 85·8% after allo-HSCT and 14·2% after auto-HSCT. MDR strains were responsible for half of the total number of bacterial episodes. Over 50% of MDR pathogens were Enterobacteriaceae causing mainly gut infections or urinary tract infections.

CONCLUSIONS

Regarding HSCT type, we did not find differences in the profile of MDR BI between allo- and auto-HSCT recipients. However, survival in MDR and non-MDR infections was comparable.

SIGNIFICANCE AND IMPACT OF THE STUDY

The large sample size enables unique analysis and makes our data more applicable to other paediatric HSCT centres. In the absence of local epidemiological data, presented clinical characteristics of MDR-caused infections may be used to optimize the prophylactic strategies, early identification of infectious complications of MDR aetiology and thus promptly initiate adequate antibiotic therapy and further improve patients' outcome.

Gut resistome plasticity in pediatric patients undergoing hematopoietic stem cell transplantation

The gut microbiome of pediatric patients undergoing allo-hematopoietic stem cell transplantation (HSCT) has recently been considered as a potential reservoir of antimicrobial resistance, with important implications in terms of patient mortality rate. By means of shotgun metagenomics, here we explored the dynamics of the gut resistome - i.e. the pattern of antibiotic resistance genes provided by the gut microbiome - in eight pediatric patients undergoing HSCT, half of whom developed acute Graft-versus-Host Disease (aGvHD). According to our findings, the patients developing aGvHD are characterized by post-HSCT expansion of their gut resistome, involving the acquisition of new resistances, as well as the consolidation of those already present before HSCT. Interestingly, the aGvHD-associated bloom in resistome diversity is not limited to genes coding for resistance to the antibiotics administered along the therapeutic course, but rather involves a broad pattern of different resistance classes, including multidrug resistance, as well as resistance to macrolides, aminoglycosides, tetracyclines and beta-lactams. Our data stress the relevance of mapping the gut resistome in HSCT pediatric patients to define the most appropriate anti-infective treatment post HSCT.

Febrile Neutropenia in Transplant Recipients

Febrile neutropenic patients are at increased risk of developing infections. During the initial stages of neutropenia, most of these infections are bacterial. The spectrum of bacterial infections depends to some extent on whether or not patients receive antimicrobial prophylaxis when neutropenic. Since most transplant recipients do, Gram-positive organisms predominate, due to the fact prophylaxis is directed primarily against Gram-negative organisms. Staphylococcus species (often methicillin-resistant), Streptococcus species (viridans group streptococci, beta-hemolytic streptococci), and Enterococcus species (including vancomycin-resistant strains) are isolated most often. Therefore, potent empiric Gram-positive coverage is recommended by many in this setting. Escherichia coli, Pseudomonas aeruginosa, and Klebsiella species are the most common Gram-negative pathogens isolated. Non-fermentative Gram-negative bacilli (Stenotrophomonas maltophilia, Acinetobacter species) are emerging as important pathogens. Many of these organisms acquire multiple mechanisms of resistance that render them multidrug resistant. The administration of prompt, broad-spectrum, empiric, antimicrobial therapy is essential and is generally based on local epidemiology and susceptibility/resistance patterns. Response rate to the initial regimen is generally in the range of 75–85%. Fungal infections develop in patients with prolonged neutropenia (greater than 7–10 days). Candida species and Aspergillus species are the predominant fungal pathogens, although many other fungi are opportunistic pathogens in this setting. Fungal infections are seldom documented microbiologically or on histopathology, and the administration of empiric antifungal therapy, when such infections are suspected, is the norm. Therapy is often prolonged, and outcomes are still suboptimal. The importance of infection control and antimicrobial stewardship cannot be overemphasized.

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.

Incidence, Risk Factors and Outcome of Pre-engraftment Gram-Negative Bacteremia After Allogeneic and Autologous Hematopoietic Stem Cell Transplantation: An Italian Prospective Multicenter Survey

Background

Gram-negative bacteremia (GNB) is a major cause of illness and death after hematopoietic stem cell transplantation (HSCT), and updated epidemiological investigation is advisable.

Methods

We prospectively evaluated the epidemiology of pre-engraftment GNB in 1118 allogeneic HSCTs (allo-HSCTs) and 1625 autologous HSCTs (auto-HSCTs) among 54 transplant centers during 2014 (SIGNB-GITMO-AMCLI study). Using logistic regression methods. we identified risk factors for GNB and evaluated the impact of GNB on the 4-month overall-survival after transplant.

Results

The cumulative incidence of pre-engraftment GNB was 17.3% in allo-HSCT and 9% in auto-HSCT. Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most common isolates. By multivariate analysis, variables associated with GNB were a diagnosis of acute leukemia, a transplant from a HLA-mismatched donor and from cord blood, older age, and duration of severe neutropenia in allo-HSCT, and a diagnosis of lymphoma, older age, and no antibacterial prophylaxis in auto-HSCT. A pretransplant infection by a resistant pathogen was significantly associated with an increased risk of posttransplant infection by the same microorganism in allo-HSCT. Colonization by resistant gram-negative bacteria was significantly associated with an increased rate of infection by the same pathogen in both transplant procedures. GNB was independently associated with increased mortality at 4 months both in allo-HSCT (hazard ratio, 2.13; 95% confidence interval, 1.45-3.13; P <.001) and auto-HSCT (2.43; 1.22-4.84; P = .01).

Conclusions

Pre-engraftment GNB is an independent factor associated with increased mortality rate at 4 months after auto-HSCT and allo-HSCT. Previous infectious history and colonization monitoring represent major indicators of GNB.

Clinical Trials registration

NCT02088840.

Epidemiology, risk factors and outcomes of multi-drug-resistant bloodstream infections in haematopoietic stem cell transplant recipients: importance of previous gut colonization

BACKGROUND

Bloodstream infections (BSI) are a major complication in the early phase of a haematopoietic stem cell transplant (HSCT).

AIM

To describe the incidence and risk factors for BSI occurring in the pre-engraftment phase of HSCT, and its impact on mortality.

METHODS

Clinical variables of 232 HSCT patients were analysed retrospectively between 2014 and 2015. Univariate Cox regression analyses were performed to test the association between each covariate and the outcome. Covariates with P < 0.10 on univariate analysis were included in a multiple Cox regression analysis using a backward elimination method.

FINDINGS

The cumulative incidence of BSI was 25.4%, mainly caused by Gram-negative bacteria (GNB) (55.2%). Approximately 40.5% of the patients had gut colonization by multi-drug-resistant (MDR) bacteria (vancomycin-resistant enterococcus and carbapenem-resistant GNB). Among patients colonized by MDR GNB, 20% developed an overt BSI due to MDR bacteria with the same pattern of sensitivity. Of the 13 deaths related to infection, 10 were patients with BSI caused by MDR GNB. The independent risk factors for BSI were gut colonization by MDR bacteria including GNB (P < 0.001) and duration of neutropenia >10 days (P = 0.005), and those associated with BSI caused by MDR bacteria were age >62 years (P = 0.03), use of total parenteral nutrition (TPN) (P < 0.001) and previous gut colonization by MDR GNB (P = 0.002).

CONCLUSIONS

Previous gut colonization by MDR was an independent risk factor for BSI, together with TPN and age, and had an impact on outcome. These findings suggest that gut decolonization may be a potential strategy to prevent BSI.

Changes in bacterial epidemiology and antibiotic resistance among veterans with spinal cord injury/disorder over the past 9 years

OBJECTIVE

Patients with spinal cord injury and disorder (SCI/D) have an increased risk of infection with multidrug-resistant (MDR) bacteria. We described bacterial epidemiology and resistance in patients with SCI/D at Veterans Affairs Medical Centers (VAMCs) for the past 9 years.

DESIGN

Retrospective cohort.

SETTING

One hundred thirty VAMCs.

PARTICIPANTS

Veterans with SCI/D and bacterial cultures with antibiotic susceptibility testing performed between 1/1/2005-12/31/2013. Single cultures with contaminants and duplicate isolates within 30 days of initial isolates were excluded.

INTERVENTIONS

None.

OUTCOMES

Trends in microbial epidemiology and antibiotic resistance.

RESULTS

Included were 216,504 isolates from 19,421 patients. Urine was the most common source and Gram-negative bacteria (GNB) were isolated most often, with 36.1% of GNB being MDR. Logistic regression models clustered by patient and adjusted for location at an SCI/D center and geographic region showed increased odds over time of vancomycin resistance in Enterococcus [adjusted odds ratio (aOR) 1.67, 95% confidence interval (CI) 1.30-2.15], while methicillin resistance in Staphylococcus aureus remained unchanged (aOR 0.90, 95% CI 0.74-1.09). There were also increased odds of fluoroquinolone resistance (aOR 1.39, 95% CI 1.31-1.47) and multidrug resistance (aOR 1.46, 95% CI 1.38-1.55) in GNB, with variability in the odds of MDR bacteria by geographic region.

CONCLUSIONS

GNB are isolated frequently in Veterans with SCI/D and have demonstrated increasing resistance over the past 9 years. Priority should be given to controlling the spread of resistant bacteria in this population. Knowledge of local and regional epidemiologic trends in antibiotic resistance in patients with SCI/D may improve appropriate antibiotic prescribing.

Rates of Microbiologically Diagnosed Infection and Pathogen Detection in Hematopoietic Stem Cell Transplant Patients

Infections remain a significant cause of mortality in hematopoietic stem cell transplant patients. Evaluations of causes of infection are often unrevealing, and at some sites, increasing rates of antimicrobial resistance have been noticed. We performed a retrospective analysis of infection rates and microbiologic testing yield, or percent of tests ordered to diagnose an infection, in the first 100 days of 30 allogeneic and 56 autologous stem cell transplants performed at San Antonio Military Medical Center from July 2011 to April 2014. Blood stream infections were diagnosed in 11.6% with a yield of 6%. Urinary tract infections were diagnosed in 2.3% with a yield of 3%. Clostridium difficile infections were diagnosed in 9.3% and testing yield was 6%. Incidence of respiratory viruses was 5.8% with 4 rhinoviruses/enteroviruses and 1 influenza virus identified. One Proteus mirabilis urinary isolate was an extended spectrum beta-lactamase producer. Five patients, 13% of allogeneic and 4% of autologous patients, died within the first 100 days post-transplantation. History of bacteremia was present in 60% of patients who died; however, only one died due to a microbiologically diagnosed infection. Improved diagnostic tests and methods are needed to increase yield of detection of infection in hematopoietic stem cell transplant patients.

Distribution and clinical determinants of time-to-positivity of blood cultures in patients with neutropenia

OBJECTIVES

Blood cultures (BCs) are essential in the evaluation of neutropenic fever. Modern BC systems have significantly reduced the time-to-positivity (TTP) of BC. This study explores the probability of bacteraemia when BCs have remained negative for different periods of time.

METHODS

All adult patients with neutropenia and bacteraemia were included (January 2012-February 2016). Predictive clinical factors for short (≤16 hours) and long (>24 hours) TTP were determined. The residual probability of bacteraemia was estimated for the scenario of negative BC 24 hours after collection.

RESULTS

The cohort consisted of 154 patients, accounting for 190 episodes of bacteraemia. Median age of 61 years, 60.5% were male. In 123 (64.7%) episodes, BC yielded a single Gram-positive micro-organism and in 49 (25.8%) a Gram-negative micro-organism (median TTP 16.7, 14.5 hours respectively, P < .01). TTP was ≤24 hours in 91.6% of episodes. Central line-associated bacteraemia was associated with long TTP. The probability of bacteraemia if BC had remained negative for 24 hours was 1%-3%.

CONCLUSIONS

The expected TTP offers guidance in the management of patients with neutropenia and suspected bacteraemia. The knowledge of negative BC can support a change in working diagnosis, and impact clinical decisions as soon as 24 hours after BC collection.

High Levels of Morbidity and Mortality Among Pediatric Hematopoietic Cell Transplant Recipients With Severe Sepsis: Insights From the Sepsis PRevalence, OUtcomes, and Therapies International Point Prevalence Study

OBJECTIVES

Pediatric severe sepsis is a major cause of morbidity and mortality worldwide, and hematopoietic cell transplant patients represent a high-risk population. We assessed the epidemiology of severe sepsis in hematopoietic cell transplant patients, describing patient outcomes compared with children with no history of hematopoietic cell transplant.

DESIGN

Secondary analysis of the Sepsis PRevalence, OUtcomes, and Therapies point prevalence study, comparing demographics, sepsis etiology, illness severity, organ dysfunction, and sepsis-related treatments in patients with and without hematopoietic cell transplant. The primary outcome was hospital mortality. Multivariable logistic regression models were used to determine adjusted differences in mortality.

SETTING

International; 128 PICUs in 26 countries.

PATIENTS

Pediatric patients with severe sepsis prospectively identified over a 1-year period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In patients with severe sepsis, 37/567 (6.5%) had a history of hematopoietic cell transplant. Compared with patients without hematopoietic cell transplant, hematopoietic cell transplant patients had significantly higher hospital mortality (68% vs 23%; p < 0.001). Hematopoietic cell transplant patients were more likely to have hospital acquired sepsis and had more preexisting renal and hepatic dysfunction than non-hematopoietic cell transplant patients with severe sepsis. History of hematopoietic cell transplant, renal replacement therapy, admission from inpatient floor, and number of organ dysfunctions at severe sepsis recognition were independently associated with hospital mortality in multivariable analysis; hematopoietic cell transplant conferred the highest odds of mortality (odds ratio, 4.00; 95% CI, 1.78-8.98). In secondary analysis of hematopoietic cell transplant patients compared with other immunocompromised patients with severe sepsis, history of hematopoietic cell transplant remained independently associated with hospital mortality (odds ratio, 3.03; 95% CI, 1.11-8.27).

CONCLUSIONS

In an international study of pediatric severe sepsis, history of hematopoietic cell transplant is associated with a four-fold increased odds of hospital mortality after adjustment for potential measured confounders. Hematopoietic cell transplant patients more often originated from within the hospital compared to children with severe sepsis without hematopoietic cell transplant, possibly providing an earlier opportunity for sepsis recognition and intervention in this high-risk population.

Levofloxacin Prophylaxis During Induction Therapy for Pediatric Acute Lymphoblastic Leukemia

BACKGROUND

Infection is the most important cause of treatment-related morbidity and mortality in pediatric patients treated for acute lymphoblastic leukemia (ALL). Although routine in adults with leukemia, antibacterial prophylaxis is controversial in pediatrics because of insufficient evidence for its efficacy or antibiotic choice and concerns about promoting antibiotic resistance and Clostridium difficile infection.

METHODS

This was a single-center, observational cohort study of patients with newly diagnosed ALL, comparing prospectively collected infection-related outcomes in patients who received no prophylaxis, levofloxacin prophylaxis, or other prophylaxis during induction therapy on the total XVI study. A propensity score-weighted logistic regression model was used to adjust for confounders.

RESULTS

Of 344 included patients, 173 received no prophylaxis, 69 received levofloxacin prophylaxis, and 102 received other prophylaxis regimens. Patients receiving prophylaxis had longer duration of neutropenia. Prophylaxis reduced the odds of febrile neutropenia, likely bacterial infection, and bloodstream infection by ≥70%. Levofloxacin prophylaxis alone reduced these infections, but it also reduced cephalosporin, aminoglycoside, and vancomycin exposure and reduced the odds of C. difficile infection by >95%. No increase in breakthrough infections with antibiotic-resistant organisms was seen, but this cannot be excluded.

CONCLUSIONS

This is the largest study to date of antibacterial prophylaxis during induction therapy for pediatric ALL and the first to include a broad-spectrum fluoroquinolone. Prophylaxis prevented febrile neutropenia and systemic infection. Levofloxacin prophylaxis also minimized the use of treatment antibiotics and drastically reduced C. difficile infection. Although long-term antibiotic-resistance monitoring is needed, these data support using targeted prophylaxis with levofloxacin in children undergoing induction chemotherapy for ALL.

CLINICAL TRIALS REGISTRATION

NCT00549848.

Fluoroquinolone prophylaxis in haematological cancer patients with neutropenia: ECIL critical appraisal of previous guidelines

OBJECTIVES

Fluoroquinolone (FQ) prophylaxis was recommended in 2005 by European Conference on Infections in Leukemia (ECIL) for patients with prolonged neutropenia. In consideration of a worldwide increase in antibiotic resistance, the issue of FQ prophylaxis during neutropenia was re-evaluated.

METHODS

Literature review of randomised controlled trials (RCT) and observational studies published in years 2006-2014 was performed. Their results were analysed in meta-analysis. Meta-regression model was applied to evaluate whether the rates of FQ resistance in community and hospital settings influenced the efficacy of FQ prophylaxis. The impact of FQ prophylaxis on colonisation and infection with resistant bacteria was reviewed.

RESULTS

Two RCTs and 12 observational studies were identified. FQ prophylaxis did not have effect on mortality (pooled OR 1.01, 95%CI 0.73-1.41), but was associated with lower rate of bloodstream infections (BSI) (pooled OR 0.57, 95%CI 0.43-0.74) and episodes of fever during neutropenia (pooled OR 0.32, 95%CI 0.20-0.50). No effect of the background rate of FQ resistance on the efficacy of FQ prophylaxis was observed. In few studies, FQ prophylaxis resulted in an increased colonisation or infection with FQ- or multi-drug resistant strains.

CONCLUSIONS

The possible benefits of FQ prophylaxis on BSI rate, but not on overall mortality, should be weighed against its impact in terms of toxicity and changes in local ecology in single centres.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host

This article reviews antibiotic resistance and treatment of bacterial infections in the growing number of patients who are immunocompromised: solid organ transplant recipients, the neutropenic host, and persons with human immunodeficiency virus and AIDS. Specific mechanisms of resistance in both gram-negative and gram-positive bacteria, as well as newer treatment options are addressed elsewhere, and are only briefly discussed in the context of the immunocompromised host.

Temporal changes in neutropenic blood culture isolates and disease associations: a single centre series of 1139 episodes

Neutropenic infections are life-threatening and require empiric antibiotic treatment. We examined 1139 blood culture isolates from our institution over a 36-year period from neutropenic patients to examine temporal trends and disease associations. Positive associations were found between viridans streptococci and acute myeloid leukaemia, coagulase negative staphylococci and acute lymphoblastic leukaemia and Pseudomonas aeruginosa and indolent B-cell malignancies.

Complications of hematopoietic stem cell transplantation: Bacterial infections

Bacterial infections remain a common complication of hematopoietic stem cell transplantation (HSCT), especially in the pre-engraftment phase. The risk of bacterial infections is mainly related to neutropenia, mucositis, and the presence of vascular lines. Most parts of the world have witnessed a shift in epidemiology toward Gram-negative bacteria; a large proportion of which are resistant to fluoroquinolones, extended-spectrum beta-lactams, carbapenems, and in some units even colistin. Meticulous infection control practices are essential for prevention of bacterial infections in HSCT. The role of routine prophylactic antibiotics is limited in settings with high rates of bacterial resistance. If used, prophylactic antibiotics should be limited to high-risk patients, and the agents are selected based on local resistance profiles. Neutropenic fever is a medical emergency in most HSCT recipients. Prompt clinical evaluation is paramount, along with the intravenous administration of appropriate empiric antimicrobials, typically an antipseudomonal beta-lactam agent. Glycopeptides should only be considered if the patient is hemodynamically unstable or Gram-positive infection is suspected. Additional Gram-negative agents, such as colistin or aminoglycosides, may be added if extensive Gram-negative resistance is expected. To mitigate increasing bacterial resistance, empiric antibiotic regimens should be rationalized or discontinued as soon as possible.

Secular trends of bloodstream infections during neutropenia in 15 181 haematopoietic stem cell transplants: 13-year results from a European multicentre surveillance study (ONKO-KISS)

OBJECTIVES

Antibacterial resistance is emerging in patients undergoing haematopoietic stem cell transplantation (HSCT), and most data on the epidemiology of bloodstream infections (BSI)-causing pathogens come from retrospective single-centre studies. This study sought to investigate trends in the epidemiology of BSI in HSCT patients from a prospective multicentre cohort.

METHODS

We investigated changes in the incidence of causative organisms of BSI during neutropenia among adult HSCT patients for 2002-2014. The data were collected from a prospective cohort for infection surveillance in 20 haematologic cancer centres in Germany, Austria and Switzerland (ONKO-KISS).

RESULTS

A total of 2388 of 15 181 HSCT patients with neutropenia (1471 allogeneic (61.6%) and 917 autologous (38.4%) HSCT) developed BSI (incidence 15.8% per year). The incidence of Gram-negative BSI increased over time both in patients after allogeneic HSCT (allo-HSCT) and autologous HSCT (auto-HSCT). BSI caused by Escherichia coli in allo-HSCT patients increased from 1.1% in 2002 to 3.8% in 2014 (3/279 vs. 31/810 patients, p <0.001), and the incidence of BSI caused by enterococci increased from 1.8% to 3.3% (5 vs. 27 patients, p <0.001). In contrast, the incidence of BSI due to coagulase-negative staphylococci decreased in allo-HSCT patients from 8.2% to 5.1%, (23 vs. 40 patients, p <0.001) and in auto-HSCT patients from 7.7% to 2.0% (13/167 vs. 30/540 patients; p = 0.028 for period 2002-2011). No significant trends were observed for the incidence of BSI due to methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci or extended-spectrum β-lactamase-producing Enterobacteriaceae. The BSI case fatality remained unchanged over the study period (total of 477 fatalities, 3.1%).

CONCLUSIONS

The incidence of Gram-negative BSI significantly increased over time in this vulnerable patient population, providing evidence for reevaluating empiric therapy for neutropenic fever in HSCT patients.

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.

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.

Bacterial infections in pediatric hematopoietic stem cell transplantation recipients: incidence, epidemiology, and spectrum of pathogens: report of the Polish Pediatric Group for Hematopoietic Stem Cell Transplantation

BACKGROUND

Infectious complications are a significant cause of hematopoietic stem cell transplantation (HSCT) failure, especially allogeneic HSCT (allo-HSCT) because of delayed immune reconstitution and graft-versus-host disease (GVHD) occurrence. Identifying the factors responsible for bacterial infections (BI) in patients undergoing HSCT will provide much more effective empirical antimicrobial treatment in this group of patients.

OBJECTIVE

The aim of this study was to evaluate the epidemiology and profile of BI in patients after HSCT in 5 centers of the Polish Pediatric Group for Hematopoietic Stem Cell Transplantation in 2012-2013.

PATIENTS AND METHODS

In 308 HSCT recipients, we retrospectively analyzed 273 episodes of BI in 113 (36.7%) children aged 0.02-22 years (median age: 7 years), 92 after allo-HSCT and 22 after autologous HSCT (auto-HSCT). We assessed incidence of BI in different HSCT types by calculating the Index of Bacterial Infection (IBI) as a ratio of patients with at least 1 BI to all patients who underwent this type of HSCT in the analyzed period. We assessed the profile of BI with particular emphasis on multidrug-resistant organisms, and impact of underlying disease and of graft-versus-host disease on BI episodes.

RESULTS

In the studied group, 273 episodes of BI were diagnosed, including 237 episodes after allo-HSCT and 36 after auto-HSCT. Among allo-HSCT recipients diagnosed with at least 1 BI, the IBI was 0.4 (matched sibling donor-HSCT 0.3; matched donor-HSCT 0.4; mismatched unrelated donor [MMUD]-HSCT 0.8; P = 0.027) and after auto-HSCT 0.3 per 1 transplanted patient. In patient after allo-HSCT because of myelo- or lymphoproliferative diseases and bone marrow failures, the major cause of infections was Enterobacteriaceae, while gram-positive bacteria predominated in the group with primary immunodeficiencies. In all patients after auto-HSCT, the dominant pathogen of BI were Enterobacteriaceae (P = 0.011). Time from each type of HSCT to infection caused by different pathogens did not differ significantly.

CONCLUSIONS

The risk of BI does not depend on the underlying disease, but only on HSCT donor type and is the highest after MMUD-HSCT procedure. The profile of BI depends on the underlying disease and HSCT donor type, but does not depend on the occurrence of acute GVHD. Gram-negative bacteria predominated in patients with myelo- and lymphoproliferative diseases, while in patients with primary immunodeficiencies gram-positive strains were predominant.

Increasing Rates of Fluoroquinolone Resistance in Escherichia coli Isolated From the Blood and Urine of Patients with Hematologic Malignancies and Stem Cell Transplant Recipients

Fluoroquinolone (FQ) antibiotics have been shown to reduce mortality and the number of febrile episodes when used as prophylaxis during neutropenia. Prior studies suggest that prophylaxis may result in increasing rates of FQ resistance. Fluoroquinolone non-susceptibility trends in Escherichia coli isolated from blood and urine cultures were evaluated over a 16-year period during which prophylaxis was initiated in patients with hematologic malignancies and stem cell transplants. Non-susceptibility rates increased after the introduction of prophylaxis, with yearly non-susceptibility rates rising from 30%–33% to 40%–88% in blood isolates. The high rates of non-susceptibility now observed raise concerns about the continued efficacy of FQ prophylaxis. This concern exists particularly in those patients undergoing stem cell transplants where the total FQ non-susceptibility rates over the study period were 82.3%. Further evaluation of the effect of FQ prophylaxis on antibiotic resistance and its efficacy in the setting of increased rates of resistance is warranted.

Current State of Antimicrobial Stewardship at Solid Organ and Hematopoietic Cell Transplant Centers in the United States

OBJECTIVE To assess the extent of antimicrobial stewardship programs (ASPs) at solid organ transplant (SOT) and hematopoietic cell transplant (HCT) centers in the United States. DESIGN An 18-item voluntary survey was developed to gauge current antimicrobial stewardship practices in transplant patients, examine the availability and perceived usefulness of novel diagnostics and azole levels to guide therapy, and identify challenges for implementation of ASPs at these centers. PARTICIPANTS The survey was distributed electronically to infectious disease physicians and pharmacists at adult and pediatric SOT and HCT centers during May 1-22, 2015. Facilities were deidentified. RESULTS After duplicate removal, 71 (56%) of 127 unique transplant centers in 32 states were analyzed. Forty-four sites (62%) performed at least 100 SOT annually, and 40 (56%) performed at least 100 HCT annually. Top 5 stewardship activities encompassing transplant patients were formulary restriction, guideline development, prospective audit and feedback, education, and dose optimization. Respiratory viral panels (66/66 [100%]), azole levels (64/66 [97%]), and serum/bronchoalveolar lavage galactomannan (58/66 [88%]) were perceived as most useful to guide therapy. Apparent challenges to antimicrobial stewardship included undefined duration for certain infections (53/59 [90%]), diagnostic uncertainty (47/59 [80%]), the perception that antibiotic-resistant infections required escalation (42/59 [71%]), prescriber opposition (41/59 [69%]), and costly drugs (37/59 [63%]). CONCLUSIONS ASP activities were performed at many adult and pediatric SOT and HCT centers in the United States. Diagnostic and therapeutic uncertainty in transplant patients is challenging for ASPs. Collaborative research should examine the impact of antimicrobial stewardship practices in SOT and HCT. Infect Control Hosp Epidemiol 2016;1-6.

The challenge of antibiotic resistance in haematology patients

Bacterial infections were once a major obstacle to the treatment of acute leukaemia. Improvement in management strategies, including the use of broad-spectrum antibacterial drugs targeting Gram-negative bacteria, has reduced the mortality in neutropenic patients developing blood stream infections and other severe infections. In many countries these achievements are threatened by development of multi-resistant bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. This review addresses the epidemiology, clinical importance and possible management of these multi-resistant organisms.

Impact of Prophylactic Levofloxacin on Rates of Bloodstream Infection and Fever in Neutropenic Patients with Multiple Myeloma Undergoing Autologous Hematopoietic Stem Cell Transplantation

Few studies have evaluated the role of antibacterial prophylaxis during neutropenia in patients with multiple myeloma undergoing autologous hematopoietic stem cell transplantation (HSCT). At our center, levofloxacin prophylaxis was initiated in June 2006 in patients with myeloma who were undergoing autologous HSCT. We compared the incidence of bloodstream infection (BSI) and fever and neutropenia (FN) within 30 days of transplantation before (January 2003 to May 2006) and after (June 2006 to April 2010) the initiation of levofloxacin prophylaxis in patients undergoing autologous HSCT for myeloma. We also compared rates of BSI and FN during the same time periods in autologous HSCT recipients with lymphoma who did not receive antibacterial prophylaxis during either time period. After the initiation of levofloxacin prophylaxis, the BSI rate decreased from 41.2% (49 of 119) to 14.7% (23 of 156) and the rate of FN decreased from 91.6% to 60.9% in patients with myeloma (P < .001, for each). In contrast, rates of BSI (43.1% versus 47.3%; P = .50) and FN (98.8% versus 97.1%; P = .63) did not change in patients with lymphoma. Levofloxacin prophylaxis was independently associated with decreased odds of BSI (odds ratio, .27; 95% confidence interval, .14 to .51; P < .001) and FN (odds ratio, .18; 95% confidence interval, .09 to .36; P < .001) in multivariate analysis. Patients with myeloma had a nonsignificant increase in the risk of BSI due to levofloxacin-resistant Enterobacteriaceae (5% versus 1%, P = .08) and Clostridium difficile infection (7% versus 3%, P = .12) after the initiation of levofloxacin prophylaxis but did not have higher rates of BSI due to other resistant bacteria. Levofloxacin prophylaxis is associated with decreased risk of BSI and FN in patients with myeloma undergoing autologous HSCT.

Bacterial Infections in Hematopoietic Stem Cell Transplant Recipients

Bacterial infections are major complications after Hematopoietic Stem Cell Transplant (HSCT). They consist mainly of bloodstream infections (BSI), followed by pneumonia and gastrointestinal infections, including typhlitis and Clostridium difficile infection. Microbiological data come mostly from BSI. Coagulase negative staphylococci and Enterobacteriaceae are the most frequent pathogens causing approximately 25% of BSI each, followed by enterococci, P. aeruginosa and viridans streptococci. Bacterial pneumonia is frequent after HSCT, and Gram-negatives are predominant. Clostridium difficile infection affects approximately 15% of HSCT recipients, being more frequent in case of allogeneic than autologous HSCT. The epidemiology and the prevalence of resistant strains vary significantly between transplant centres. In some regions, multi-drug resistant (MDR) Gram-negative rods are increasingly frequent. In others, vancomycin-resistant enterococci are predominant. In the era of increasing resistance to antibiotics, the efficacy of fluoroquinolone prophylaxis and standard treatment of febrile neutropenia have been questioned. Therefore, a thorough evaluation of local epidemiology is mandatory to decide the need for prophylaxis and the choice of the best regimen for empirical treatment of febrile neutropenia. For the latter, individualised approach has been proposed, consisting of either escalation or de-escalation strategy. De-escalation strategy is recommended since resistant bacteria should be covered upfront, mainly in patients with severe clinical presentation and previous infection or colonisation with a resistant pathogen. Non-pharmacological interventions, such as screening for resistant bacteria, applying isolation and contact precautions should be put in place to limit the spread of MDR bacteria. Antimicrobial stewardship program should be implemented in transplant centres.