Evolution, incidence, and susceptibility of bacterial bloodstream isolates from 519 bone marrow transplant patients

Shifting trends in bloodstream infection-causing microorganisms and their clinical impact in patients with haematologic malignancies in South Korea: A propensity score-matched study

BACKGROUND

This study aimed to identify recent trends in the epidemiology of bloodstream infection (BSI)-causing microorganisms among patients with haematologic malignancies (HMs) between 2011 and 2021, and to determine their impact on patient outcomes.

METHODS

This retrospective study included 6792 patients with HMs, of whom 1308 (19.3%) developed BSI within 1 y of diagnosis. The incidence of BSI-causing microorganisms was determined, and a propensity score-matched study was performed to identify risk factors for 28-d all-cause mortality in patients with HM.

RESULTS

A total of 6792 patients with HMs were enrolled. The cumulative incidence of BSI and neutropenia was significantly higher in the acute myeloid leukaemia and acute lymphoblastic leukaemia groups compared to other groups, and neutropenia and type of HMs were risk factors for the development of BSI. The annual incidence of coagulase-negative staphylococci (CoNS)-BSI decreased significantly (P < 0.001), whereas Klebsiella pneumoniae-BSI increased (P = 0.01). Carbapenem nonsusceptibility rates in K. pneumoniae isolates increased from 0.0% to 76.5% (P < 0.001). BSI caused by K. pneumoniae (adjusted odds ratio 2.17; 95% confidence interval 1.12-4.21) was associated with higher 28-d all-cause mortality compared to that caused by CoNS (adjusted odds ratio 0.86; 95% confidence interval 0.48-1.55).

CONCLUSION

The pathogenic spectrum of BSI-causing bacteria in patients with HMs gradually shifted from Gram-positive to Gram-negative, especially from CoNS to K. pneumoniae. Considering that K. pneumoniae-BSI had a significantly higher 28-d mortality rate than CoNS-BSI, this evolving trend could adversely impact the clinical outcomes of patients with HMs.

Pathogenic spectrum and drug resistance of bloodstream infection in patients with acute myeloid leukaemia: a single centre retrospective study

Background

Bloodstream infection (BSI) represent a prevalent complication in haematological malignancies (HMs). Typically, Patients with BSI usually undergo empirical treatment pending pathogen identification. The timely and effective management of BSIs significantly influences patient prognosis. However, pathogen distribution in BSIs exhibits regional variation. In this study, we investigated the clinical characteristics, pathogen spectrum, drug resistance, risk factors of short-term prognosis and long-term prognostic factors of acute myeloid leukemia (AML) patients with BSI at Zhejiang Provincal People's Hospital.

Methods

From 2019 to 2021, a total of 56 AML patients with BSI were treated in the Department of Haematology at Zhejiang Province People's Hospital. Data regarding pathogen spectrum and drug resistance were collected for analysis. The patients were stratified into non-survivor cohort and survivor cohort within 30 days after BSI, and the predictors of 30-days mortality were identified through both univariate and multivariate Logistic regression analyses. Furthermore, Kaplan-Meier survival analysis and Cox regression analysis were employed to ascertain the risk factors associated with poor prognosis in AML patients complicated by BSI.

Results

A total of 70 strains of pathogenic bacteria were isolated from 56 AML patients with BSI. Gram-negative bacteria constituted the predominant pathogens (71.4%), with Klebsiella pneumoniae being the most prevalent (22.9%). Gram-positive bacteria and fungi accounted for 22.9% and 5.7%, respectively. Univariate and multivariate analyses revealed significant differences in total protein, albumin levels, and the presence of septic shock between the non-survivor cohort and the survior cohort 30 days post-BSI. COX regression analysis showed that agranulocytosis duration exceeding 20 days (HR:3.854; 95% CI: 1.451-10.242) and septic shock (HR:3.788; 95% CI: 1.729-8.299) were independent risk factors for poor prognosis in AML patients complicated by BSI. Notably, the mortality rate within 30 days after Stenotrophomonas maltophilia infection was up to 71.4%.

Conclusions

In this study, Gram-negative bacteria, predominantly Klebsiella pneumoniae, constituted the primary pathogens among AML patients with BSIs. Serum albumin levels and the presence of septic shock emerged as independent risk factors for mortality within 30 days among AML patients with BSI. In terms of long-term prognosis, extended agranulocytosis duration exceeding 20 days and septic shock were associated with elevated mortality rates in AML patients with BSI. Additionally, in our centre, Stenotrophomonas maltophilia infection was found to be associated with a poor prognosis. Early intervention for Stenotrophomonas maltophilia infection in our centre could potentially improve patient outcomes.

Ciprofloxacin prophylaxis during haematopoietic cell transplantation: a role for use in patients with germ cell tumours?

Introduction. Fluoroquinolone prophylaxis during haematopoietic cell transplantation (HCT) can lead to antimicrobial resistance (AMR). Identifying the groups of patients that have the highest likelihood of benefiting from prophylactic antimicrobials is important for antimicrobial stewardship (AMS).Hypothesis. We aimed to identify groups of HCT recipients that have the highest likelihood of benefiting from prophylactic fluroquinolones.Methods. All admissions for HCT in a tertiary centre between January 2020 and December 2022 (N = 400) were retrospectively studied. Allogeneic HCT (allo-HCT) recipients had prophylaxis with ciprofloxacin during the chemotherapy-induced neutropenia, while autologous HCT (auto-HCT) recipients did not. Bacteraemias were recorded when non-contaminant bacterial pathogens were isolated in blood cultures.Results. Allo-HCT was performed for 43.3 % (173/400) of patients and auto-HCT was performed for 56.7 % (227/400). A bacteraemia was documented in 28.3 % (113/400) of cases. Allo-HCT recipients were more likely to have a Gram-positive bacteraemia (20.8%, 36/173, vs 10.1%, 23/227, P = 0.03), while a difference was not observed for Gram-negative bacteraemias (18.5%, 32/173 vs 18.1%, 41/227, P = 0.91). Among auto-HCT recipients not receiving ciprofloxacin prophylaxis, patients with germ cell tumours had the highest probability (P for trend 0.09) of recording any bacteraemia (43.5%, 10/23) followed by patients with lymphomas (32.5%, 13/40), other auto-HCT indications (22.2%, 2/9), multiple myeloma (22.1%, 29/131) and multiple sclerosis (12.5%, 3/24). The higher number of bacteraemias in patients with germ cell tumours was primarily driven by Gram-negative pathogens.Conclusions. Ciprofloxacin prophylaxis was associated with a reduced incidence of Gram-negative bacteraemias in allo-HCT recipients. Auto-HCT recipients due to germ cell tumours, not receiving ciprofloxacin prophylaxis, recorded the highest incidence of bacteraemias and represent a possible target group for this intervention.

Do oral conditions influence the incidence of bloodstream infection after hematopoietic stem cell transplantation? A retrospective study in Japan

PURPOSE

This study aimed to evaluate the incidence of bloodstream infection (BSI) among patients undergoing hematopoietic stem cell transplantation (HSCT) for teeth indicated for extraction.

METHODS

Patients who underwent HSCT at Toranomon Hospital (Tokyo, Japan) between January 2017 and December 2019 were retrospectively evaluated. The incidence of BSI among patients with teeth indicated for extraction who did not undergo extraction (oral high-risk group) and patients who did not have this risk (oral low-risk group) was compared.

RESULTS

Among the 191 consecutive patients included in this study, 119 patients were classified as undergoing high-risk transplantation. BSI after HSCT was observed in 32 out of 60 (53.3%) patients and 56 out of 131 (42.7%) patients in the oral low-risk and oral high-risk groups, respectively (p = 0.173). Multivariable analyses revealed that the presence of > 3 teeth as intraoral sources of infection and age over 50 years were determinants of BSI originating from the oral cavity after engraftment (odds ratio [OR], 9.11; 95% confidential interval [CI] 2.27-36.61]; p = 0.002; OR, 3.22; CI [1.47-7.08], p = 0.004, respectively).

CONCLUSION

In patients undergoing HSCT, the presence of less than three intraoral sources of infection did not affect the incidence of BSI after HSCT.

Clinical Analysis of Bacterial Infection Characteristics in Lymphoma Patients with High-dose Chemotherapy Combined with Autologous Hematopoietic Stem Cell Transplantation-A Single-Centered Retrospective Study

BACKGROUND

High-dose chemotherapy combined with autologous hematopoietic stem cell transplantation (HDT/AHSCT) is used to treat lymphoma. Although AHSCT has made considerable strides and become safer, HDT-AHSCT infection continues to be a leading cause of morbidity and mortality associated with transplantation.

OBJECTIVE

To characterise pathogenic bacterial infections in HDT/AHSCT-treated lymphoma patients. The prevalence of pathogenic microorganisms and the timing of foci after transplantation, along with bloodstream infection (BSI) risk factors, can help determine the need for empirical antibiotics after AHSCT.

METHODS

We retrospectively analyzed 133 lymphoma patients treated by HDT/AHSCT from April 2017 to October 2021 at Peking University International Hospital, Beijing, China. We analyzed their clinical characteristics, microbiological distribution characteristics, and BSI risk factors in detail.

RESULTS

In order, intestinal infection (56 cases), BSI (17 cases), pulmonary (12 cases), upper respiratory tract (5 cases), and perianal (4 cases) were the most common locations of infection after HDT/AHSCT. The infection sites yielded 92 putative pathogenic pathogens, with bacteria predominating (61.96%), fungi (28.26%), viruses (5.43%), and mycoplasma (4.35%). Gram-negative bacteria (GNB) strains outnumbered gram-positive bacteria (GPB) strains (73.68%). Two strains of Escherichia coli produced extended-spectrum β-lactamase (ESBL) and one strain of carbapenem-resistant enterobacteriaceae (CRE). Methicillin-resistant Staphylococcus epidermidis (MRSE) had one strain. BSI was caused by Escherichia coli (82.35%), Intestinal mucositis (23.52%), and catheter-associated infections (11.76%). Age, CD34, pretreatment regimen, antibiotic regimen, and past chemotherapeutic agent lung damage were BSI risk variables in univariate analysis. CD34 and past chemotherapeutic drug lung damage were the primary causes of BSI after HDT/AHSCT for lymphoma.

CONCLUSION

High-dose chemotherapy combined with autologous hematopoietic stem cell transplantation (HDT/AHSCT) is used to treat lymphoma. Although AHSCT has made considerable strides and become safer, HDT-AHSCT infection continues to be a leading cause of morbidity and mortality associated with transplantation.

Prevalence of Pseudomonas aeruginosa and its antibiotic resistance in patients who have received Hematopoietic Stem-Cell Transplantation; A globally Systematic Review

Gram-negative bacteria are infectious and life-threatening agents after hematopoietic stem cell transplantation (HSCT). So, this study aimed to investigate the prevalence of Pseudomonas aeruginosa and its antibiotic resistance in patients who have received Hematopoietic Stem-Cell Transplantation through a systematic review. The systematic search was done with key words; Pseudomonas aeruginosa, hematopoietic stem cell transplantation from 2000 to the end of July 2023 in Google Scholar and PubMed/Medline, Scopus, and Web of Science. Twelve studies were able to include our study. Quality assessment of studies was done by Appraisal tool for Cross-Sectional Studies. The most of the included studies were conducted as allo-HSCT. Infections such as respiratory infection, urinary infection and bacteremia have occurred. The rate of prevalence with P. aeruginosa has varied between 3 and 100%. The average age of the participants was between 1 and 74 years. The rate of prevalence of P. aeruginosa resistant to several drugs has been reported to be variable, ranging from 20 to 100%. The highest antibiotic resistance was reported against cefotetan (100%), and the lowest was related to tobramycin (1.8%) followed by amikacin, levofloxacin and ciprofloxacin with the prevalence of 16.6%. Our findings showed a high prevalence and antibiotic resistance rate of P. aeruginosa in Hematopoietic stem cell transplantation. Therefore, more serious health measures should be taken in patients after transplantation.

A Primed Neutrophil Subset Predicts the Risk of Bloodstream Infections in Allogeneic Hematopoietic Stem-Cell Transplant Patients: A Prospective Study

BACKGROUND

Bloodstream infections (BSIs) are the most common infectious complication in patients who receive allogeneic hematopoietic stem-cell transplants (allo-HSCTs). Polymorphonuclear neutrophils (PMNs) are quantified to monitor the susceptibility to BSIs; however, their degree of activation is not. We previously identified a population of primed PMNs (pPMNs) with distinct markers of activation representing approximately 10% of PMNs in circulation. In this study, we investigate whether susceptibility to BSIs is related to the proportion of pPMNs rather than strictly PMN counts.

METHODS

In this prospective observational study, we used flow cytometry to assess pPMNs in blood and oral rinse samples collected from patients receiving an allo-HSCT over the course of their treatment. We used the proportion of pPMNs in the blood on day 5 post-transplant to categorize patients into a high- or a low-pPMN group (>10% or <10% pPMNs). These groups were then used as a predictor of BSIs.

RESULTS

A total of 76 patients were enrolled in the study with 36 in the high-pPMN group and 40 in the low-pPMN group. Patients in the low-pPMN group had lower expression of PMN activation and recruitment markers and displayed a delay in PMN repopulation of the oral cavity after the transplant. These patients were more susceptible to BSIs compared with patients in the high-pPMN group with an odds ratio of 6.5 (95% confidence interval, 2.110-25.07; P = .002).

CONCLUSIONS

In patients who receive an allo-HSCT, having <10% pPMNs early in the post-transplant phase can be an independent predictor of BSI in allo-HSCT patients.

High Rate of Inappropriate Antibiotics in Patients with Hematologic Malignancies and Pseudomonas aeruginosa Bacteremia following International Guideline Recommendations

Optimal coverage of Pseudomonas aeruginosa is challenging in febrile neutropenic patients due to a progressive increase in antibiotic resistance worldwide. We aimed to detail current rates of resistance to antibiotics recommended by international guidelines for P. aeruginosa isolated from bloodstream infections (BSI) in patients with hematologic malignancies. Secondarily, we aimed to describe how many patients received inappropriate empirical antibiotic treatment (IEAT) and its impact on mortality. We conducted a retrospective, multicenter cohort study of the last 20 BSI episodes caused by P. aeruginosa in patients with hematologic malignancies from across 14 university hospitals in Spain. Of the 280 patients with hematologic malignancies and BSI caused by P. aeruginosa, 101 (36%) had strains resistant to at least one of the β-lactam antibiotics recommended in international guidelines, namely, cefepime, piperacillin-tazobactam, and meropenem. Additionally, 21.1% and 11.4% of the strains met criteria for MDR and XDR P. aeruginosa, respectively. Even if international guidelines were followed in most cases, 47 (16.8%) patients received IEAT and 66 (23.6%) received inappropriate β-lactam empirical antibiotic treatment. Thirty-day mortality was 27.1%. In the multivariate analysis, pulmonary source (OR 2.22, 95% CI 1.14 to 4.34) and IEAT (OR 2.67, 95% CI 1.37 to 5.23) were factors independently associated with increased mortality. We concluded that P. aeruginosa-causing BSI in patients with hematologic malignancies is commonly resistant to antibiotics recommended in international guidelines, which is associated with frequent IEAT and higher mortality. New therapeutic strategies are needed. IMPORTANCE Bloodstream infection (BSI) caused by P. aeruginosa is related with an elevated morbidity and mortality in neutropenic patients. For this reason, optimal antipseudomonal coverage has been the basis of all historical recommendations in the empirical treatment of febrile neutropenia. However, in recent years the emergence of multiple types of antibiotic resistances has posed a challenge in treating infections caused by this microorganism. In our study we postulated that P. aeruginosa-causing BSI in patients with hematologic malignancies is commonly resistant to antibiotics recommended in international guidelines. This observation is associated with frequent IEAT and increased mortality. Consequently, there is a need for a new therapeutic strategy.

Clinical application value of metagenomic second-generation sequencing technology in hematologic diseases with and without transplantation

Introduction

Hematological patients are at risk of infections. It is unknown whether the pathogenic microbial spectrum differs between HSCT and non-HSCT patients, and whether metagenomic next-generation sequencing (mNGS) of peripheral blood can be used as a substitute test specimen such as alveolar lavage.

Methods

A retrospective study was conducted to evaluate the clinical application value of mNGS in hematological patients with and without HSCT.

Results

Viruses were prevalent pathogens in both non-HSCT (44%) and HSCT (45%) patients, chiefly human cytomegalovirus and Epstein-Barr virus. In non-HSCT patients, Gram-negative bacilli accounted for 33% (predominantly Klebsiella pneumonia), and Gram-positive cocci accounted for 7% (predominantly Enterococcus faecium) of pathogens. However, in HSCT patients, Gram-negative bacilli accounted for 13% (predominantly Stenotrophomonas maltophilia), and Gram-positive cocci accounted for 24% (predominantly Streptococcus pneumonia) of pathogens. Mucor was the most common fungu s in two groups. The positive rate of pathogens by mNGS was 85.82%, higher than conventional detection (20.47%, P < 0.05). Mixed infection accounted for 67.00%, among which the mixed infection of bacteria and virus (25.99%) was the most common. 78 cases had pulmonary infection, the positive rate of traditional laboratory tests was 42.31% (33/78), and of mNGS in peripheral blood was 73.08% (57/78), showing a statistical difference (P = 0.000). The non-HSCT patients had a higher frequency of Klebsiella pneumonia (OR=0.777, 95% CI, 0.697-0.866, P = 0.01) and Torque teno virus (OR=0.883, 95% CI, 0.820-0.950, P = 0.031) infections than HSCT patients, while the rates of Streptococcus pneumonia (OR=12.828, 95% CI, 1.378-119.367, P = 0.016), Candida pseudosmooth (OR=1.100, 95% CI, 0.987-1.225, P = 0.016), human betaherpesvirus 6B (OR=6.345, 95% CI, 1.105-36.437, P = 0.039) and human polyomavirus 1 (OR=1.100, 95% CI, 0.987-1.225, P = 0.016) infections were lower. Leishmania could be detected by mNGS.

Conclusion

mNGS of peripheral blood can be used as a substitute test method for hematological patients with pulmonary infection, the detection rate of mixed infections by mNGS was high, and mNGS has high clinical recognition rate and sensitivity in pathogen detection, and provides a basis for guiding the anti-infective treatment in hematological diseases with symptoms such as fever.

Molecular Evolutionary Analyses of the Pseudomonas-Derived Cephalosporinase Gene

Despite the increasing evidence of the clinical impact of Pseudomonas-derived cephalosporinase (PDC) sequence polymorphisms, the molecular evolution of its encoding gene, blaPDC, remains elusive. To elucidate this, we performed a comprehensive evolutionary analysis of blaPDC. A Bayesian Markov Chain Monte Carlo phylogenetic tree revealed that a common ancestor of blaPDC diverged approximately 4660 years ago, leading to the formation of eight clonal variants (clusters A-H). The phylogenetic distances within clusters A to G were short, whereas those within cluster H were relatively long. Two positive selection sites and many negative selection sites were estimated. Two PDC active sites overlapped with negative selection sites. In docking simulation models based on samples selected from clusters A and H, piperacillin was bound to the serine and the threonine residues of the PDC active sites, with the same binding mode for both models. These results suggest that, in P. aeruginosa, blaPDC is highly conserved, and PDC exhibits similar antibiotic resistance functionality regardless of its genotype.

Clinical impact and early prediction of carbapenem-resistant Pseudomonas aeruginosa bacteraemia in allogeneic hematopoietic stem cell transplantation recipients

OBJECTIVE

Although antipseudomonal agents are administered in high-risk patients, no reports have focused on the risk of carbapenem-resistant (CR) Pseudomonas aeruginosa bacteraemia in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients.

METHODS

We retrospectively studied a cohort of adult allo-HSCT recipients with P. aeruginosa bacteraemia, focusing on a comparison between carbapenem-sensitive (CS) and CR P. aeruginosa after initiating conditioning chemotherapy at our institute between January 2005 and December 2020. The incidence, all-cause 30-d mortality of P. aeruginosa bacteraemia, and risk factors for carbapenem resistance among patients with P. aeruginosa bacteraemia in allo-HSCT recipients were evaluated.

RESULTS

Forty-eight patients with P. aeruginosa bacteraemia were included, with an incidence of 3.84/100 recipients (CS = 1.92 vs. CR = 1.92). The all-cause 30-d mortality was significantly higher in CR P. aeruginosa bacteraemia (CS = 4.2% vs. CR = 39.1%; P = 0.003). The factor significantly associated with CR P. aeruginosa bacteraemia was carbapenem use for at least 3 d within 30 d before the onset of bacteraemia (odds ratio = 8.92; 95% confidence interval: 1.35-58.90). Inappropriate antimicrobial selection was significantly more frequent in CR P. aeruginosa bacteraemia (CS = 0% vs. CR = 29.2%; P ˂ 0.009).

CONCLUSION

Empirical combination therapy with reference to antimicrobial susceptibility profiles in each institution should be considered when CR P. aeruginosa bacteraemia is suspected in allo-HSCT recipients based on the risk of carbapenem exposure.

Oral and post-transplantation infectious status in patients with hematopoietic stem cell transplants: A prospective observational study

OBJECTIVE

Infectious status may be life threatening in hematopoietic stem cell transplant (HSCT) recipients. The aim of this study was to evaluate the effect of oral status on infectious conditions during the neutropenic phase after HSCT.

STUDY DESIGN

Seventy patients with various hematologic malignancies were involved. Before HSCT, oral and periodontal examination, including the number of teeth and decayed, missing, and filled teeth index (DMFT); visible plaque (%); bleeding on probing (BOP [%]); clinical attachment level; and probing depth (PD) values were collected. Daily blood cultures were collected and analyzed in terms of infection-related parameters, including febrile neutropenia (FN), bacteremia, and C-reactive protein (CRP) during the neutropenic phase of HSCT.

RESULTS

Forty-two patients (60%) received autologous and 28 (40%) allogeneic HSCT. In both groups, patients without FN after HSCT had significantly lower DMFT index scores and fewer sites with PD ≥4 mm (P < .05). However, bacteremia, FN, and CRP were similar in patients with periodontitis compared with non-periodontitis patients (P > .05).

CONCLUSIONS

The results suggest that periodontal status may not significantly impact the infection-related parameters in patients treated for HSCT. However, DMFT and the prevalence of sites with PD ≥4 mm may be involved in febrile neutropenia.

Infection prevention practices among EBMT hematopoietic cell transplant centers: the EBMT Infectious Disease Working Party survey

We aimed to describe the current status of infection prevention practices among EBMT centers. Questionnaires were distributed to all 553 EBMT transplant centers to capture clinical practices regarding antimicrobial prophylaxis, protective measures, isolation procedures and growth-factor support of patients undergoing hematopoietic cell transplantation. Responses from 127 centers in 32 countries were obtained. Most centers housed patients in single rooms (autologous-82%; allogeneic-98%), with high-efficiency particulate air (HEPA)-filters (autologous-73%; allogeneic-100%) and positive pressure (autologous-61%; allogeneic-88%). Pre-engraftment G-CSF was utilized by 77 and 31% of centers after autologous and allogeneic transplantation, respectively (P < 0.00001). Antibacterial prophylaxis was provided by 57 and 69% (P = 0.086) of centers and antifungal prophylaxis by 65 and 84% (P = 0.0008) of centers, to patients undergoing autologous and allogeneic transplantation, respectively. Yet, 16 and 3% of centers provided neither antibacterial nor antifungal prophylaxis to patients undergoing autologous and allogeneic transplantation, respectively. Considerable variation existed between centers and across countries in antimicrobial prophylaxis practices, medications employed and duration of preventive therapy. There were considerable discordances between guidelines and daily practices. JACIE accredited and non-accredited centers did not differ significantly in their antimicrobial prophylaxis practices. Whether these differences between transplant centers translated into differences in infectious morbidity, mortality and financial costs, warrants further research.

Increased incidence rates of positive blood cultures shortly after chemotherapy compared to radiotherapy among individuals treated for solid malignant tumours

BACKGROUND

Cancer treatments suppress immune function and are associated with increased risk of infections, but the overall burden of serious infectious diseases in treated patients has not been clearly elucidated.

METHODS

All patients treated for solid malignant tumours with radiotherapy (RT) and/or standard first-line chemotherapy (C) at the Department of Oncology at Rigshospitalet between 01/1/2010 and 31/12/2016 were included. Patients were followed from treatment initiation until the first of new cancer treatment, 1 year after treatment initiation, end of follow-up or death. Incidence rates (IR) of positive blood culture (PBC) per 1000 person-years follow-up (PYFU) were calculated.

FINDINGS

12,433 individuals were included, 3582 (29%), 6349 (51%), and 2502 (20%) treated with RT, C, or both RT & C, respectively, contributing 8182 PYFU. 429 (3%) individuals experienced 502 unique episodes of PBC, incidence rate (95% CI) 52.43 (47.7, 57.6) per 1000 PYFU. The 30-day mortality rate after PBC was 24% independent of treatment modality. Adjusted incidence rate ratios in the first 3 months (95% CI) after PBC significantly varied by treatment: 2.89 (1.83, 4.55) and 2.52 (1.53, 4.14) for C and RT & C compared to RT. Escherichia coli (n = 127, 25%) was the top microorganism identified.

INTERPRETATION

PBCs are not common, but when they occur, mortality is high.

Bloodstream Infections in Hematologic Malignancy Patients with Fever and Neutropenia: Are Empirical Antibiotic Therapies in the United States Still Effective?

Background

Rising antimicrobial resistance rates may impact the efficacy of empirical antibiotic treatment for febrile neutropenia in high-risk cancer patients. Lacking contemporary data about the epidemiology, antibiotic resistance patterns, and clinical outcomes from bloodstream infections (BSI) in U.S. cancer patients, it is unclear if current guidelines remain relevant.

Methods

In a cross-sectional study, fourteen U.S. cancer centers prospectively identified BSIs in high-risk FN patients, including those receiving chemotherapy for hematologic malignancies or hematopoietic stem cell transplantation.

Results

Among 389 organsims causing BSI in 343 patients, there was an equal distribution of Gram-negative (GN) and Gram-positive (GP) bacteria, with variability across centers. Cefepime and piperacillin-tazobactam were the most commonly prescribed empirical antibiotics for FN, at 62% and 23% respectively; a GP-directed agent was empirically included in nearly half of all FN episodes within the first 24 hours. Susceptibility to fluoroquinolones, cefepime, piperacillin-tazobactam, and carbapenems was 49%, 84%, 88% and 96% respectively among GN isolates. Critical illness (CrI), defined as a new requirement for mechanical ventilation, vasopressor or death within 30 days, occurred in 15% and did not correlate with fluoroquinolone prophylaxis, organism type, initial antibiotics or adequacy of coverage. Only severity of illness at presentation, signified by a Pitt bacteremia score &gt; 2, predicted for critical illness within 30 days. Mortality was 4% by day 7 and 10% overall.

Conclusion

In accordance with U.S. guidelines, cefepime or piperacillin-tazobactam remain effective agents or empirical treatment for high risk cancer patients with FN who are stable at presentation, maintaining high GN pathogen susceptibility and yielding excellent outcomes.

Characteristics and Outcomes of Bloodstream Infections in a Tertiary-Care Pediatric Hematology-Oncology Unit: A 10-Year Study

Bloodstream infections (BSIs) after chemotherapy or hematopoietic stem cell transplantation (HSCT) are a leading cause of morbidity and mortality. Data on 154 BSIs that occurred in 111 onco-hematological patients (57 hematological malignancies, 28 solid tumors, and 26 non-malignant hematological diseases) were retrospectively collected and analyzed. Monomicrobial Gram-positive (GP), Gram-negative (GN), and fungal BSIs accounted for 50% (77/154), 38.3% (59/144), and 3.2% (5/154) of all episodes. Polymicrobial infections were 7.8% (12/154), while mixed bacterial-fungal infections were 0.6% (1/154). The most frequent GN isolates were Escherichia coli (46.9%), followed by Pseudomonas aeruginosa (21.9%), Klebsiella species (18.8%), and Enterobacter species (6.3%). Overall, 18.8% (12/64) of GN organisms were multidrug-resistant (seven Escherichia coli, three Klebsiella pneumoniae, and two Enterobacter cloacae), whereas GP resistance to glycopeptides was observed in 1% (1/97). Initial empirical antibiotic therapy was deemed inappropriate in 12.3% of BSIs (19/154). The 30-day mortality was 7.1% (11/154), while the bacteremia-attributable mortality was 3.9% (6/154). In multivariate analysis, septic shock was significantly associated with 30-day mortality (p = 0.0001). Attentive analysis of epidemiology and continuous microbiological surveillance are essential for the appropriate treatment of bacterial infections in pediatric onco-hematological patients.

Levofloxacin Versus Ciprofloxacin-Based Prophylaxis during the Pre-Engraftment Phase in Allogeneic Hematopoietic Stem Cell Transplant Pediatric Recipients: A Single-Center Retrospective Matched Analysis

Infectious complications are the most common and significant cause of mortality and morbidity after allogeneic hematopoietic stem cell transplantation (HSCT). Antibacterial prophylaxis in pediatric cancer patients is a controversial issue. Our study compared the outcomes of levofloxacin versus ciprofloxacin prophylaxis in allogeneic HSCT pediatric recipients treated for hematological malignancies. A total of 120 patients received levofloxacin prophylaxis, and 60 patients received ciprofloxacin prophylaxis. Baseline characteristics such as age, gender, primary diagnosis, type of conditioning, donor type, stem cell source, and supportive care of the patients were similar, and duration of antibiotics prophylaxis was similar. Both prophylaxis regimens demonstrated the same efficacy on the risk of febrile neutropenia and severe complications such as sepsis, the same rate of overall mortality, hospital readmission, and length of hospital stay. Levofloxacin prophylaxis was associated with significantly lower cumulative antibiotic exposure. The median of Gram-positive infection-related antibiotic days was 10 days in the levofloxacin group versus 25 days in the ciprofloxacin group (p < 0.0001). The median of Gram-negative infection-related antibiotics was 10 days in the levofloxacin group compared with 20 days in the ciprofloxacin group (p < 0.0001). The number of days with body temperature ≥38 °C was significantly less in the levofloxacin group (p < 0.001).

Bloodstream Infections and Outcomes Following Allogeneic Hematopoietic Cell Transplantation: A Single-Center Study

This study investigated the single-center incidence and risk factors for bloodstream infections (BSIs) in 651 adults who underwent allogeneic hematopoietic cell transplantation (alloHCT) between 2015 and 2019 and explored the impact of these BSIs on post-transplantation outcomes. Antibiotic prophylaxis with ciprofloxacin was given during the aplastic phase. Overall, the median patient age was 57 years, 79.7% of patients received an alternative donor graft, and 68.7% received post-transplantation cyclophosphamide (PTCy) as part of their graft-versus-host disease (GVHD) prophylaxis. Of the 651 patients, 358 (55.0%) had at least 1 episode of BSI, and the overall mortality rate secondary to this complication was 7.5% (12.6% among those diagnosed with at least 1 episode of BSI). BSI was more often diagnosed during the first 30 days (58.7%), and gram-positive bacteria were the most prevalent microorganisms isolated during the entire post-transplantation follow-up (62%). A high Disease Risk Index (hazard ratio [HR], 1.47; P < .029) and receipt of PTCy-based GVHD prophylaxis (HR, 3.33; P < .001) were identified as risk factors for BSI. Additionally, univariate analysis showed that patients diagnosed with a BSI during post-transplantation follow-up had worse overall survival (HR, 2.48; P < .001) and higher nonrelapse mortality (HR, 2.68; P < .001) than those without BSI. In conclusion, alloHCT recipients with a BSI had a higher risk of mortality compared with those who did not develop BSI. The inclusion of PTCy as part of GVHD prophylaxis was identified as an independent risk factor for BSI during early post-transplantation follow-up. Single-center analyses focused on reporting the incidence and risk factors for BSI highlight the need for active implementation of preemptive strategies to decrease BSI incidence in the alloHCT setting. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Severe acute graft-versus-host disease increases the incidence of blood stream infection and mortality after allogeneic hematopoietic cell transplantation: Japanese transplant registry study

This study aimed to clarify the risk factors and prognosis associated with blood stream infection (BSI) in allogeneic hematopoietic cell transplantation (allo-HCT), and the relationship between BSI and acute graft-versus-host disease (aGVHD). This retrospective analysis included 11,098 patients in the Japanese national transplant registry. A total of 2172 patients developed BSI after allo-HCT, with 2332 identified pathogens. The cumulative incidences of BSI were 15.5% at 30 days and 20.9% at 100 days after allo-HCT. In a multivariate analysis, severe (grade III-IV) aGVHD was associated with a higher risk of BSI (vs. grade 0-I aGVHD: hazard ratio [HR] 3.34 [95% confidence interval (CI), 2.85-3.92; P < 0.001]). In a multivariate analysis, severe aGVHD before BSI was associated with a higher risk of overall mortality after BSI (vs. grade 0-I aGVHD: HR 2.61 [95% CI 2.18-3.11; P < 0.001]). In addition, BSI (vs. no-BSI: HR 1.20 [95% CI, 1.12-1.29; P < 0.001]) and severe aGVHD (vs. grade 0-I aGVHD: HR 1.97 [95% CI, 1.83-2.12; P < 0.001]) were independent risk factors for overall mortality after allo-HCT. In the setting of allo-HCT, severe aGVHD was associated with increases in both BSI incidence and post-BSI overall mortality. Furthermore, BSI was an independent risk factor for overall mortality.

Risk Factors for Mortality in Hematopoietic Stem Cell Transplantation Recipients with Bloodstream Infection: Points To Be Addressed by Future Guidelines

In recent years, important epidemiologic changes have been described in hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infection (BSI), with increases in gram-negative bacilli and multidrug resistant (MDR) gram-negative bacilli. These changes have been linked to a worrisome increase in mortality. We aimed to define the risk factors for mortality of HSCT patients experiencing BSI. All episodes of BSI in patients with HSCT between 2008 and 2017 were prospectively collected. Multivariate analyses were performed. A total of 402 BSI episodes were documented in 293 patients who had undergone HSCT (75.4% allogenic, 32.3% autologous, 19.3% second HSCT). The median time from HSCT to BSI was 62 days (interquartile range, 9 to 182 days). Gram-positive cocci accounted for 56.7% of the episodes; gram-negative bacilli, for 42%. The most common microorganisms were coagulase-negative staphylococci (30.6%) and Pseudomonas aeruginosa (15.9%). MDR gram-negative bacilli caused 11.9% of all episodes. Clinical characteristics, source of BSI, etiology, and outcomes changed depending on time since HSCT. Globally, 26.6% of episodes were treated with inappropriate empiric antibiotic therapy, more frequently in BSI episodes caused by P. aeruginosa, MDR P. aeruginosa, and MDR gram-negative bacilli. The 30-day mortality was 19.2%. Independent risk factors for mortality were BSI occurring ≥30 days after HSCT (odds ratio [OR], 11.21; 95% confidence interval [CI], 4.63 to 27.19), shock (OR, 7.10; 95% CI, 2.98 to 16.94), BSI caused by MDR P. aeruginosa (OR, 4.45; 95% CI, 1.12 to 17.72), and inappropriate empiric antibiotic therapy for gram-negative bacilli or Candida spp. (OR, 3.73; 95% CI, 1.27 to 10.89). HSCT recipients experiencing BSI have high mortality related to host and procedure factors, causative microorganism, and empiric antibiotic therapy. Strategies to identify HSCT recipients at risk of MDR P. aeruginosa and reducing inappropriate empiric antibiotic therapy are paramount to reduce mortality.

Carbapenem-Resistant Enterobacteriaceae-Implications for Treating Acute Leukemias, a Subgroup of Hematological Malignancies

Acute leukemias (AL) are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. Patients with AL are highly susceptible to infectious diseases due to the disease itself, factors attributed to treatment, and specific individual risk factors. Enterobacteriaceae presence (e.g., Klebsiella pneumonia and Escherichia coli) is a frequent cause of bloodstream infections in AL patients. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging health problem worldwide; however, the incidence of CRE varies greatly between different regions. Carbapenem resistance in Enterobacteriaceae is caused by different mechanisms, and CRE may display various resistance profiles. Bacterial co-expression of genes conferring resistance to both broad-spectrum β-lactam antibiotics (including carbapenems) and other classes of antibiotics may give rise to multidrug-resistant organisms (MDROs). The spread of CRE represents a major treatment challenge for clinicians due to lack of randomized clinical trials (RCTs), a limited number of antibiotics available, and the side-effects associated with them. Most research concerning CRE infections in AL patients are limited to case reports and retrospective reviews. Current research recommends treatment with older antibiotics, such as polymyxins, fosfomycin, older aminoglycosides, and in some cases carbapenems. To prevent the spread of resistant microbes, it is of pivotal interest to implement antibiotic stewardship to reduce broad-spectrum antibiotic treatment, but without giving too narrow a treatment to neutropenic infected patients.

[Potential of ultrasound in allogeneic stem cell transplantation and transplant-related complications]

Allogeneic hematopoietic stem cell transplantation (HCT) is a complex therapeutic procedure causing significant morbidity and mortality, including the gastrointestinal tract. Early diagnosis and treatment of HCT-associated complications are, therefore, of utmost importance to improve overall HCT outcome. Sonography can be a powerful diagnostic tool and is easily accessible at the bedside of HCT patients. In the hands of a sonography-experienced physician, it allows for instant diagnosis and can also rule out several important transplant-associated complications. Here we review available evidence on the diagnostic and clinical value of ultrasound prior, during and after HCT.

The impact of graft cell source on bloodstream infection in the first 100 days after allogeneic hematopoietic cell transplantation

Bloodstream infection (BSI) is a major infectious complication after allogeneic hematopoietic cell transplantation (HCT). To clarify the impact of graft cell source on the incidence of BSI after transplantation, we retrospectively examined 782 adult patients receiving their first allogeneic HCT: 122 recipients of related peripheral blood stem cells or bone marrow, 215 recipients of unrelated bone marrow, and 445 recipients of unrelated umbilical cord blood (U-CB). The cumulative incidence of BSI was 42.5% at 100 days after transplantation (95% confidence interval, 39.0-46.0). Gram-positive cocci were present in 64.2% of detected isolates. Among the pre-transplant factors including age, performance status, primary disease, disease status, graft cell source, sex and ABO blood type matching, and the intensity of conditioning regimen, U-CB use was identified as the most significant risk factor for BSI by multivariate analysis (hazard ratio, 1.76; 95% confidence interval, 1.40-2.22; p < 0.00001). Among the U-CB recipients, those who are not in remission at the time of transplantation were at the greatest risk of BSI (hazard ratio, 1.69; 95% confidence interval, 1.14-2.50; p < 0.01). The study makes it clear that graft cell source has an impact on BSI development after allogeneic HCT.

Inappropriate Empirical Antibiotic Treatment in High-risk Neutropenic Patients With Bacteremia in the Era of Multidrug Resistance

BACKGROUND

We aimed to describe the current rates of inappropriate empirical antibiotic treatment (IEAT) in oncohematological patients with febrile neutropenia (FN) and its impact on mortality.

METHODS

This was a multicenter prospective study of all episodes of bloodstream infection (BSI) in high-risk FN patients (2006-2017). Episodes receiving IEAT were compared with episodes receiving appropriate empirical therapy. Adherence to Infectious Diseases Society of America (IDSA) recommendations was evaluated. Multivariate analysis was performed to identify independent risk factors for mortality in Pseudomonas aeruginosa episodes.

RESULTS

Of 1615 episodes, including Escherichia coli (24%), coagulase-negative staphylococci (21%), and P. aeruginosa (16%), 394 (24%) received IEAT despite IDSA recommendations being followed in 87% of cases. Patients with multidrug-resistant gram-negative bacilli (MDR-GNB), accounting for 221 (14%) of all isolates, were more likely to receive IEAT (39% vs 7%, P < .001). Overall mortality was higher in patients with GNB BSI who received IEAT (36% vs 24%, P = .004); when considering individual microorganisms, only patients with infection caused by P. aeruginosa experienced a significant increase in mortality when receiving IEAT (48% vs 31%, P = .027). Independent risk factors for mortality in PA BSI (odds ratio [95% confidence interval] were IEAT (2.41 [1.19-4.91]), shock at onset (4.62 [2.49-8.56]), and pneumonia (3.01 [1.55-5.83]).

CONCLUSIONS

IEAT is frequent in high-risk patients with FN and BSI, despite high adherence to guidelines. This inappropriate treatment primarily impacts patients with P. aeruginosa-related BSI mortality and in turn is the only modifiable factor to improve outcomes.

Oral microorganisms and bloodstream infection in allogeneic hematopoietic stem cell transplantation

OBJECTIVES

We aimed to compare oral and pathogenic microorganisms in bloodstream infections (BSIs) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). We also investigated the relationship between BSIs and oral mucositis to identify the ratio of BSIs caused by oral microorganisms and the pathogenic microorganisms involved.

MATERIALS AND METHODS

We collected data on BSIs in 96 patients who underwent allo-HSCT in our institute between April 2009 and December 2019, including BSI pathogens isolated from blood cultures (BBSIs) and microorganisms isolated from washing the oral cavity with sterile distilled water. Oral microorganisms obtained at the onset of BSI (OBSIs) and during allo-HSCT (OSCTs) were defined as isolates collected during the week of blood culturing. Study entry was limited to samples collected up to 1 month after allo-HSCT without BSI. When the BBSI and OBSI were the same, we considered the oral microorganism to have caused the BSI.

RESULTS

The incidence rate of BSIs was 27%, and the predominant microorganism was coagulase-negative Staphylococci. Normal bacterial flora were decreased to 15.8% in OBSIs and 25.5% in OSCTs. The distribution of microorganisms without normal bacterial flora showed significant difference between BBSIs and OSCTs (p < 0.05). Oral mucositis was found in 72.9%, and BSI caused by oral microorganisms occurred in 46.2% of BSIs in allo-HSCT patients.

CONCLUSION

The distribution of microorganisms obtained from blood in patients with BSI during allo-HSCT was found to be similar to that of microorganisms from oral cultures.

CLINICAL RELEVANCE

Oral microorganism monitoring may be able to predict BSI during allo-HSCT.

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

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.

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.

Antibody response to vaccination after haematopoietic cell transplantation in children using a reduced dose schedule-A retrospective cohort study

Children receiving HCT loose protective immunity to vaccines received pre-HCT. Therefore, revaccination post-HCT is of major importance. In Denmark, a vaccination schedule with fewer doses post-HCT has been used, including two doses for diphtheria, tetanus, polio, measles, mumps, and rubella, and one dose only for Haemophilus influenzae type B. The background for this was the presumption that post-HCT immunization constituted booster vaccination of donor immunity. Our objective was to evaluate the proportion of children protected after the scheduled vaccination programme. A nationwide retrospective cohort study of all children who have received an HCT in Denmark during 1994-2012. Antibody levels were analysed in blood samples drawn before and after vaccination, and the probability of achieving protection after the scheduled immunization programme was estimated. A total of 198 children were included. The protection post-immunization was as follows: diphtheria 75.3%, tetanus 89.1%, polio 97.7%, and Haemophilus influenzae type B 94.8%. For diphtheria and tetanus, the probability of achieving protection increased to 93.8% and 97.3%, respectively, after a third dose. For measles, mumps, and rubella, the probability of achieving protection was 89.4%, 80.9%, and 94.2%, respectively. In conclusion, our findings support a more extensive vaccination schedule including three doses for diphtheria and tetanus which are in line with current international guidelines.

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

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

Infections after Allogenic Transplant with Post-Transplant Cyclophosphamide: Impact of Donor HLA Matching

Incidence and outcome of infections after allogeneic hematopoietic stem cell transplantation (HSCT) with post-transplant cyclophosphamide (PT-Cy) as graft-versus-host disease (GVHD) prophylaxis are largely unknown. Study aims were to estimate the incidence of pre-engraftment bloodstream infections (PE-BSIs) and viral infections (VIs; cytomegalovirus [CMV], adenovirus [ADV], human herpes virus 6 [HHV6], and BK-polyomavirus hemorrhagic-cystitis [BKPyV-HC]), their predictive factors, and infection-related mortality (IRM) after HSCT with PT-Cy. We analyzed 235 patients: 62%, 21%, and 17% received haploidentical (haplo), matched-unrelated donor (MUD), and matched-related donor, respectively. Overall, 72 patients had 77 PE-BSI episodes at a median time of 13 days after HSCT: cumulative incidence function (CIF) at 28 days was 32%, without differences among donor types (P = .988). By multivariate analysis, CIF of PE-BSI was higher in patients with severe neutropenia before HSCT (adjusted hazard ratio [AHR] = 2.90) and in multidrug-resistant Gram-negative bacteria rectal carriers (AHR = 2.68). IRM at 30 days was 5%, without differences by donor type (P = .106). Overall, 208 patients experienced ≥1 VIs (first occurrence among CMV, HHV6, ADV, BKPyV-HC) at a median time of 20 days after HSCT: CIF at 90 days was 91%, significantly higher in MUD and haplo (P = .0089). By multivariate analysis, also acute GVHD grade ≥2 (AHR = 1.32) and host/donor CMV-serology mismatch (positive/positive versus negative/negative: AHR = 2.95, positive/negative versus negative/negative: AHR = 2.41, negative/positive versus negative/negative: AHR = 2.35) affected VIs occurrence. IRM at 180 days was 8%, without differences among donor types (P = .106). In conclusion, study results did not show a significant impact of donor type on PE-BSI incidence; conversely, MUD and haploidentical transplants retained a higher occurrence of VIs in the early phase after HSCT.

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.

Proposal of a clinical score to stratify the risk of multidrug-resistant gram-negative rods bacteremia in cancer patients

Introduction

Multidrug-resistant gram-negative rods (MDR GNR) represent a growing threat for patients with cancer. Our objective was to determine the characteristics of and risk factors for MDR GNR bacteremia in patients with cancer and to develop a clinical score to predict MDR GNR bacteremia.

Material and Methods

Multicenter prospective study analyzing initial episodes of MDR GNR bacteremia. Risk factors were evaluated using a multiple logistic regression (forward-stepwise selection) analysis including variables with a p < 0.10 in univariate analysis.

Results

394 episodes of GNR bacteremia were included, with 168 (42.6 %) being MDR GNR. Five variables were identified as independent risk factors: recent antibiotic use (OR = 2.8, 95 % CI 1.7–4.6, p = 0.001), recent intensive care unit admission (OR = 2.9, 95 % CI 1.1–7.8, p = 0.027), hospitalization ≥ 7 days prior to the episode of bacteremia (OR = 3.5, 95 % CI 2–6.2, p = 0.005), severe mucositis (OR = 5.3, 95 % CI 1.8–15.6, p = 0.002), and recent or previous colonization/infection with MDR GNR (OR = 2.3, 95 % CI 1.2–4.3, p = 0.028). Using a cut-off value of two points, the score had a sensitivity of 66.07 % (95 % CI 58.4–73.2 %), a specificity of 77.8 % (95 % CI 71.4–82.7 %), a positive predictive value of 68 % (95 % CI 61.9–73.4 %), and a negative predictive value of 75.9 % (95 % CI 71.6–79.7 %). The overall performance of the score was satisfactory (AUROC 0.78; 95 % CI 0.73-0.82). In the cases with one or none of the risk factors identified, the negative likelihood ratio was 0.18 and the post-test probability of having MDR GNR was 11.68 %.

Conclusions

With the growing incidence of MDR GNR as etiologic agents of bacteremia in cancer patients, the development of this score could be a potential tool for clinicians.

Systems-level analysis of NalD mutation, a recurrent driver of rapid drug resistance in acute Pseudomonas aeruginosa infection

Pseudomonas aeruginosa, a main cause of human infection, can gain resistance to the antibiotic aztreonam through a mutation in NalD, a transcriptional repressor of cellular efflux. Here we combine computational analysis of clinical isolates, transcriptomics, metabolic modeling and experimental validation to find a strong association between NalD mutations and resistance to aztreonam-as well as resistance to other antibiotics-across P. aeruginosa isolated from different patients. A detailed analysis of one patient's timeline shows how this mutation can emerge in vivo and drive rapid evolution of resistance while the patient received cancer treatment, a bone marrow transplantation, and antibiotics up to the point of causing the patient's death. Transcriptomics analysis confirmed the primary mechanism of NalD action-a loss-of-function mutation that caused constitutive overexpression of the MexAB-OprM efflux system-which lead to aztreonam resistance but, surprisingly, had no fitness cost in the absence of the antibiotic. We constrained a genome-scale metabolic model using the transcriptomics data to investigate changes beyond the primary mechanism of resistance, including adaptations in major metabolic pathways and membrane transport concurrent with aztreonam resistance, which may explain the lack of a fitness cost. We propose that metabolic adaptations may allow resistance mutations to endure in the absence of antibiotics and could be targeted by future therapies against antibiotic resistant pathogens.

Antimicrobial Stewardship in Hematological Patients at the intensive care unit: a global cross-sectional survey from the Nine-i Investigators Network

A global cross-sectional survey was performed to gather data on the current treatment of infections caused by multidrug-resistant (MDR) bacteria among hematological patients admitted to ICUs worldwide. The survey was performed in April 2019 using an electronic platform (SurveyMonkey®) being distributed among 83 physicians and completed by 48 (57.8%) responders. ESBL Enterobacteriaceae, carbapenem-resistant K. pneumoniae and carbapenem-resistant P. aeruginosa were the main concerns. Previous MDR infection (34% of responders), MDR colonization (20%) and previous antibiotic exposure within the last 3 months (20.5%) were considered the most relevant risk factors of bloodstream infection (BSI) due to MDR bacteria. In 48.8% of the ICUs, there was no antimicrobial stewardship (AMS) team focused on hematological patients. Updates on local epidemiology of MDR pathogens were provided in 98% of the centers, using phone or verbal communications (56.1% and 53.7%, respectively). In presence of febrile neutropenia, initial therapy consisted of anti-Gram-negative plus anti-Gram-positive antibiotics for 41% of participants. Antibiotic de-escalation and/or discontinuation of therapy were considered as a promising strategy for the prevention of MDR development (32.4%). Factors associated with antibiotic de-escalation were clinical improvement (43.6%) and neutrophil count recovery (12.8%). Infectious Disease consultation and AMS interventions were not determining factors for de-escalation decisions (more than 50% of responders). Infection control and educational programs were valued as necessary measures for implementation by ICU practitioners. These findings should guide future efforts on collaborative team working, improving compliance with adequate treatment protocols, implementing antimicrobial stewardship programs in critically ill hematological patients, and educational activities.

Etiology, drug sensitivity profiles and clinical outcome of bloodstream infections: A retrospective study of 784 pediatric patients with hematological and neoplastic diseases

Bloodstream infections (BSI) represent one of the most serious complications in patients in the hematology-oncology unit. In this study, the prevalence, distribution, drug sensitivity profiles, and clinical outcome of BSI were analyzed in pediatric patients with hematological malignancies. Patients admitted to the pediatric hematology-oncology unit at Shenzhen Children's Hospital (Shenzen, China) between January 2016 and December 2017 were enrolled. Their medical records, including gender, age, primary diseases, and microbiology results of all clinical specimens, were reviewed. The incidence of BSI, microbiology characteristics, and effectiveness of antimicrobial therapy were analyzed. A total of 125 BSI cases in 108 patients (mean age, 5.5 years) were recorded, of which 69 (55.2%) were nosocomial BSI cases. The overall rate of BSI was 18.8% in the hematology-oncology unit, of which 75 (75.2%) episodes were neutropenic patients. Patients with nosocomial BSIs and the neutropenic group were older (p#.02, p#.03). HSCTs and AML were more often observed in nosocomial BSIs, while solid tumors were more found in nonnosocomial and non-neutropenic BSIs. BSIs were dominated by Gram-negative pathogens (49.6%) in the hematology-oncology unit compared with Gram-positive pathogens (39.2%). The most common pathogens were coagulase-negative Staphylococcus (24.2%) followed by Klebsiella pneumonia (15.2%), Escherichia coli (12.5%), viridans streptococci (8.2%), and Candida species (7.8%). The antibiotic therapy success rate in patients was 93.5%. Based on our center's experience, Gram-negative pathogens were commonly observed among pediatric hematology-oncology patients with BSI. Coagulase-negative Staphylococcus and K. pneumoniae predominated and antibiotic therapy was effective in these patients.

Gram-negative Bacteremia in Children With Hematologic Malignancies and Following Hematopoietic Stem Cell Transplantation: Epidemiology, Resistance, and Outcome

Gram-negative rod (GNR) infections adversely affect the outcome of patients with malignancies and following hematopoietic stem cell transplantation (HSCT). This retrospective observational study aimed to describe the epidemiology, outcome, and resistance patterns of GNR bacteremia in children with hematologic malignancies (HM) and after HSCT during the period spanning from 2010 to 2014 in a tertiary children's hospital. A total of 270 children were included in the analysis; 65 (24%) developed 85 episodes of GNR bacteremia; the rate was 36/122 (29.5%) in post-HSCT and 29/178 (16.3%) in HM patients (P<0.05). Overall, 10% of the GNRs were carbapenem resistant. In multivariate analysis, prolonged neutropenia (≥7 d; odds ratio: 19.5, 95% confidence interval: 2.6-148.4) and total hospitalization for a duration of >30 days in the last 3 months (odds ratio: 17.5, 95% confidence interval: 1.4-224.4) were associated with carbapenem-resistant GNR bacteremia. Thirty-day mortality following GNR bacteremia was 0% in HM and 7/52 episodes (13.5%) in HSCT patients (P<0.05). Carbapenem-resistant versus carbapenem-sensitive bacteremia was associated with longer duration of bacteremia (mean: 3.8 vs. 1.7 d), higher risk for intensive care unit hospitalization (44.4% vs. 10.1%), and higher mortality rate (33% vs. 5.8%) (P<0.05). To summarize, GNR bacteremia was frequent, especially in post-HSCT children. Carbapenem resistance adversely affects patients' outcome, increasing morbidity and mortality. Empirical antibiotic therapy must be adjusted to the local resistance patterns.

Contribution of specific pathogens to bloodstream infection mortality in neutropenic patients with hematologic malignancies: Results from a multicentric surveillance cohort study

Bloodstream infection (BSI) remains a serious complication in patients with hematologic malignancies and neutropenia. The risk factors for mortality after BSI and the contributions of BSI pathogens to mortality remain incompletely understood. We evaluated first BSI among adult neutropenic patients undergoing high-dose chemotherapy for hematologic malignancies in the setting of (a) an early disease stage of autologous (auto-HSCT) or allogeneic (allo-HSCT) hematopoietic stem cell transplantation or (b) for acute leukemia. Risk factors for intensive care admission and all-cause mortality were analyzed by multivariable logistic regression 7 and 30 days after onset of the first BSI in the first neutropenic episode. Between 2002 and 2015, 9080 patients met the study inclusion criteria, and 1424 (16%) developed BSIs, most of them during the first week of neutropenia. Mortality during neutropenia within 7 days and 30 days after BSI onset was 2.5% and 5.1%, respectively, and differed considerably between BSI pathogens. Both 7-day and 30-day mortalities were highest for Pseudomonas aeruginosa BSI (16.7% and 26.7%, respectively) and lowest for BSI due to coagulase-negative Staphylococcus spp. (CoNS) and Streptococcus spp. BSI pathogens were independently associated with 7-day mortality included P aeruginosa, Klebsiella spp., Enterobacter spp., Serratia spp., and enterococci. Only gram-negative BSI and candidemia were associated with admission to intensive care within 7 days after BSI onset. BSI caused by P aeruginosa continues to carry a particularly poor prognosis in neutropenic patients. The unexpected association between enterococcal BSI and increased mortality needs further study.

Changing epidemiology of bloodstream infection in a 25-years hematopoietic stem cell transplant program: current challenges and pitfalls on empiric antibiotic treatment impacting outcomes

We aimed to describe epidemiology changes in bloodstream infections (BSI) episodes in hematopoietic stem cell transplant (HSCT) recipients throughout a 25-year period (1993-2017), comparing five-year time spans, and we evaluate their impact on inappropriate empirical antibiotic treatment (IEAT) and mortality. During the study period, 1164 BSI episodes were documented in patients undergoing HSCT (71.6% allogenic and 29% autologous). A significant decrease in gram-positive cocci (GPC) and increase in gram-negative bacilli (GNB) were observed (p < 0.001). Among GP, coagulase-negative staphylococci (CoNS) significantly decreased whereas rising E. faecium BSI was documented. Among GNB, E. coli, Pseudomonas aeruginosa and K. pneumoniae rates increased. Multidrug-resistant (MDR) GNB, especially ESBL-E. coli and MDR-P. aeruginosa, emerged in 2008 and has gradually increased. IEAT against MDR-P. aeruginosa, but not in other MDR-GNB, augmented throughout the study period. Overall, 30-day and related mortality rates were 12.7% and 7.7% respectively, both increasing over time (p < 0.001 and p = 0.025). In GNB, 30-day and related mortality were 18.5% and 12.8%, respectively, increasing over time (p < 0.001 and p = 0.004). To conclude, important BSI epidemiological changes were described in a 25-year period. Concerning increase in IEAT for P. aeruginosa infections and rising 30-day mortality rate were documented.

Risk factors for multidrug-resistant organisms among deceased organ donors

Donor infection or colonization with a multidrug-resistant organism (MDRO) affects organ utilization and recipient antibiotic management. Approaches to identifying donors at risk of carrying MDROs are unknown. We sought to determine the risk factors for MDROs among transplant donors. A multicenter retrospective cohort study was conducted at four transplant centers between 2015 and 2016. All deceased donors who donated at least one organ were included. Cultures obtained during the donor's terminal hospitalization and organ procurement were evaluated. The primary outcome was isolation of an MDRO on culture. Multivariable Cox regression was used to determine risk factors associated with time to donor MDRO. Of 440 total donors, 64 (15%) donors grew an MDRO on culture. Predictors of an MDRO on donor culture included hepatitis C viremia (hazard ratio [HR] 4.09, 95% confidence interval [CI] 1.71-9.78, P = .002), need for dialysis (HR 4.59, 95% CI 1.09-19.21, P = .037), prior hematopoietic cell transplant (HR 7.57, 95% CI 1.03-55.75, P = .047), and exposure to antibiotics with a narrow gram-negative spectrum (HR 1.13, 95% CI 1.00-1.27, P = .045). This is the first study to determine risk factors for MDROs among deceased donors and will be important for risk stratifying potential donors and informing transplant recipient prophylaxis.

Allogeneic hematopoietic stem cell transplantation from unrelated donors is associated with higher infection rates in children with acute lymphoblastic leukemia-A prospective international multicenter trial on behalf of the BFM-SG and the EBMT-PDWP

Severe infections (SI) significantly impact on non‐relapse mortality after hematopoietic stem cell transplantation (HSCT). We assessed 432 children and adolescents with acute lymphoblastic leukemia (ALL) after total body irradiation based myeloablative HSCT within the multicenter ALL‐BFM‐SCT 2003 trial for SI grade 3 or higher according to common terminology criteria for adverse events. A total 172 patients experienced at least one SI. Transplantation from matched unrelated donors (MUD) was associated with any type of SI in the pre‐engraftment period (hazard ratio [HR]: 2.57; P < .001), and with any SI between day +30 and + 100 (HR: 2.91; P = .011). Bacterial (HR: 2.24; P = .041) and fungal infections (HR: 4.06; P = .057) occurred more often in the pre‐engraftment phase and viral infections more often before day +30 (HR: 2.66; P = .007) or between day +30 and + 100 (HR: 3.89; P = .002) after HSCT from MUD as compared to matched sibling donors. Chronic GvHD was an independent risk factor for any type of SI after day +100 (HR: 2.57; P < .002). We conclude that allogeneic HSCT from MUD in children and adolescents with pediatric ALL is associated with higher infection rates, which seems attributable to an intensified GvHD prophylaxis including serotherapy and methotrexate.

Incidence and Outcomes of Bacterial Bloodstream Infections during Acute Graft-versus-Host Disease Involving the Gastrointestinal Tract after Hematopoietic Cell Transplantation

Despite the association of acute graft-versus-host disease (aGVHD) and bacterial bloodstream infections (BSIs) in hematopoietic cell transplant (HCT) recipients, relatively little is known about BSIs, specifically during gastrointestinal (GI) tract aGVHD (aGHVD-GI). The purpose of this study was to evaluate the incidence, risk factors, and mortality of BSIs complicating aGVHD-GI. This was a retrospective review of adult HCT recipients with grades I to IV aGVHD-GI between January 2009 and October 2017 at Oregon Health and Sciences University. BSIs occurring within 30 days of onset of aGVHD-GI were included. BSIs were categorized as "clinical" or "surveillance" based on chart review. A subgroup analysis of patients with grade IV aGVHD-GI examined potential BSI risk factors and cumulative survival at 30 and 45 days after onset of aGVHD-GI. Included were 229 patients. There were 45 unique BSIs in 39 patients (17%): 31 clinical (68.9%) and 14 surveillance (32.1%). The median time from aGVHD-GI onset to BSI was 18.5 days. BSIs were significantly more common during grade IV aGVHD-GI compared with grades I, II, or III. Fifty-two organisms were isolated during BSIs: 23 (44.2%) gram-positive and 29 (55.8%) gram-negative. Sixteen BSIs (36%) occurred during antibiotic exposure, and those were more likely to be caused by multidrug-resistant organisms. Prior BSI occurring between the time of HCT and onset of aGVHD-GI and receipt of etanercept for steroid-refractory aGVHD-GI were independently associated with BSI. Eight patients, all with grade IV aGVHD, representing 30.8% of patients with BSI in this subgroup, experienced infection-associated mortality. Cumulative survival at days 30 and 45 after onset of grade IV aGVHD-GI was similar among patients with and without BSI. BSI is a common complication of grade IV aGVHD-GI, resulting in significant infection-associated mortality. Interventions targeting those at highest risk may be warranted.

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.

Infections in Allogeneic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has become a widely used modality of therapy for a variety of malignant and nonmalignant diseases. Despite advances in pharmacotherapy and transplantation techniques, infection remains one of the most severe and frequently encountered complications of allo-HSCT.

This chapter will address the risk factors for development of infection following allo-HSCT, including those related to the host, the conditioning regimen, and the graft, as well as the timing of opportunistic infections after allo-HSCT. The most common bacterial, viral, fungal, and parasitic infections, as well as issues surrounding their diagnostics and treatment, will be discussed. Finally, this chapter will address vaccination and other preventative strategies to be utilized when caring for patients undergoing allo-HSCT.

Current time-to-positivity of blood cultures in febrile neutropenia: a tool to be used in stewardship de-escalation strategies

OBJECTIVES

We aimed to describe the current time-to-positivity (TTP) of blood cultures in individuals with onco-haematological diseases with febrile neutropenia. We assessed the probability of having a multidrug-resistant Gram-negative bacilli (MDR-GNB) bloodstream infection (BSI) 24 h after cultures were taken, to use this information for antibiotic de-escalation strategies.

METHODS

BSI episodes were prospectively collected (2003-2017). When a patient experienced more than one BSI, only one episode was randomly chosen. Time elapsed from the beginning of incubation to a positive reading was observed; TTP was recorded when the first bottle had a positive result.

RESULTS

Of the 850 patient-unique episodes, 323 (38%) occurred in acute leukaemia, 185 (21.8%) in non-Hodgkin's lymphoma and 144 (16.9%) in solid neoplasms. Coagulase-negative staphylococci (225; 26.5%), Escherichia coli (207; 26.1%), Pseudomonas aeruginosa (136; 16%), Enterococcus spp. (81; 9.5%) and Klebsiella pneumoniae (67; 7.9%), were the most frequent microorganisms isolated. MDR-GNB were documented in 126 (14.8%) episodes. Median TTP was 12 h (interquartile range 9-16.5 h). Within the first 24 h, 92.1% of blood cultures were positive (783/850). No MDR-GNB was positive over 24 h. Of the 67 (7.9%) episodes with a TTP ≥24 h, 25 (37.3%) occurred in patients who were already receiving active antibiotics against the isolated pathogen. Most common isolations with TTP ≥24 h were coagulase-negative staphylococci, candidaemia and a group of anaerobic GNB.

CONCLUSIONS

Currently, the vast majority of BSI in individuals with onco-haematological diseases with febrile neutropenia have a TTP <24 h, including all episodes caused by MDR-GNB. Our results support reassessing empiric antibiotic treatment in neutropenic patients at 24 h, to apply antibiotic stewardship de-escalation strategies.