Emerging resistant bacteria strains in bloodstream infections of acute leukaemia patients: results of a prospective study by the Rete Ematologica Lombarda (Rel)

An Emergent Change in Epidemiologic and Microbiological Characteristics of Bloodstream Infections in Adults With Febrile Neutropenia Resulting From Chemotherapy for Acute Leukemia and Lymphoma at Reference Centers in Chile, Ecuador, and Peru

Background

Febrile neutropenia is a life-threatening condition commonly observed in patients with hematologic malignancies. The aim of this article is to provide updated knowledge about bloodstream infections in febrile neutropenia episodes within the Andean region of Latin America.

Method

This retrospective study was based in 6 hospitals in Chile, Ecuador, and Peru and included adult patients with acute leukemia or lymphoma and febrile neutropenia between January 2019 and December 2020.

Results

Of the 416 febrile neutropenia episodes, 38.7% had a bloodstream infection, 86% of which were caused by gram-negative rods, with Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa being the most frequently identified bacteria. K pneumoniae isolates were more frequently resistant than E coli to cefotaxime (65% vs 39.6%), piperacillin-tazobactam (56.7% vs 27.1%), and imipenem (35% vs 2.1%) and were more frequently multidrug resistant (61.7% vs 12.5%). Among P aeruginosa, 26.7% were resistant to ceftazidime, piperacillin-tazobactam, and imipenem, and 23.3% were multidrug resistant. Overall 30-day mortality was 19.8%, being higher with vs without a bloodstream infection (26.7% vs 15.3%, P = .005). Fever duration was also significantly longer, as well as periods of neutropenia and length of hospital stay for patients with bloodstream infection. Additionally, the 30-day mortality rate was higher for episodes with inappropriate vs appropriate empirical antibiotic therapy (41.2% vs 26.6%, P = .139).

Conclusions

Considering the high rates of bacteria-resistant infection and 30-day mortality, it is imperative to establish strategies that reduce the frequency of bloodstream infections, increasing early identification of patients at higher risks of multidrug bacteria resistance, and updating existing empirical antibiotic recommendations.

Antimicrobial Stewardship on Patients with Neutropenia: A Narrative Review Commissioned by Microorganisms

The emergence of antibiotic resistance poses a global health threat. High-risk patients such as those with neutropenia are particularly vulnerable to opportunistic infections, sepsis, and multidrug-resistant infections, and clinical outcomes remain the primary concern. Antimicrobial stewardship (AMS) programs should mainly focus on optimizing antibiotic use, decreasing adverse effects, and improving patient outcomes. There is a limited number of published studies assessing the impact of AMS programs on patients with neutropenia, where early appropriate antibiotic choice can be the difference between life and death. This narrative review updates the current advances in strategies of AMS for bacterial infections among high-risk patients with neutropenia. Diagnosis, drug, dose, duration, and de-escalation (5D) are the core variables among AMS strategies. Altered volumes of distribution can make standard dose regimens inadequate, and developing skills towards a personalized approach represents a major advance in therapy. Intensivists should partner antibiotic stewardship programs to improve patient care. Assembling multidisciplinary teams with trained and dedicated professionals for AMS is a priority.

Clinical outcomes of antimicrobial resistance in cancer patients: a systematic review of multivariable models

BACKGROUND

Infections are major causes of disease in cancer patients and pose a major obstacle to the success of cancer care. The global rise of antimicrobial resistance threatens to make these obstacles even greater and hinder continuing progress in cancer care. To prevent and handle such infections, better models of clinical outcomes building on current knowledge are needed. This internally funded systematic review (PROSPERO registration: CRD42021282769) aimed to review multivariable models of resistant infections/colonisations and corresponding mortality, what risk factors have been investigated, and with what methodological approaches.

METHODS

We employed two broad searches of antimicrobial resistance in cancer patients, using terms associated with antimicrobial resistance, in MEDLINE and Embase through Ovid, in addition to Cinahl through EBSCOhost and Web of Science Core Collection. Primary, observational studies in English from January 2015 to November 2021 on human cancer patients that explicitly modelled infection/colonisation or mortality associated with antimicrobial resistance in a multivariable model were included. We extracted data on the study populations and their malignancies, risk factors, microbial aetiology, and methods for variable selection, and assessed the risk of bias using the NHLBI Study Quality Assessment Tools.

RESULTS

Two searches yielded a total of 27,151 unique records, of which 144 studies were included after screening and reading. Of the outcomes studied, mortality was the most common (68/144, 47%). Forty-five per cent (65/144) of the studies focused on haemato-oncological patients, and 27% (39/144) studied several bacteria or fungi. Studies included a median of 200 patients and 46 events. One-hundred-and-three (72%) studies used a p-value-based variable selection. Studies included a median of seven variables in the final (and largest) model, which yielded a median of 7 events per variable. An in-depth example of vancomycin-resistant enterococci was reported.

CONCLUSIONS

We found the current research to be heterogeneous in the approaches to studying this topic. Methodological choices resulting in very diverse models made it difficult or even impossible to draw statistical inferences and summarise what risk factors were of clinical relevance. The development and adherence to more standardised protocols that build on existing literature are urgent.

Evaluation of a Shotgun Metagenomics Approach for Detection of ESBL- and/or Carbapenemase-Producing Enterobacterales in Culture Negative Patients Recovered from Acute Leukemia

Patients diagnosed with acute leukemia (AL) have a weakened immune system. Infections acquired by these patients are cause for concern and especially worrisome when Gram-negative multidrug-resistant (MDR) bacteria are involved, as they are difficult to treat, especially in the case of ESBL- and/or carbapenemase-producing Enterobacterales. Culture-based approaches have been relied on over the past decades as the method of choice for the early detection of gut colonization by MDR Gram-negative bacteria. However, various studies have indicated its limited sensitivity, underlining the need for new screening procedures in onco-hematological patients. Here, we evaluated a shotgun metagenomics approach to detect ESBL- and/or carbapenemase-producing Enterobacterales in the gut of 28 patients who had recovered from AL, which were previously colonized by these bacteria but cured at the time of sampling, as judged by culture-based methods. No ESBL or carbapenemase determinants were detected among the many resistance genes found by the metagenomics approach, supporting that patients were truly decolonized, with considerable consequences for their future clinical management. Due to the relatively low number of patients available for the present investigation, further studies should be conducted to support the utility and applicability of metagenomics for the routine screening of MDR bacteria in onco-hematological patients.

The potential utility of fecal (or intestinal) microbiota transplantation in controlling infectious diseases

The intestinal microbiota is recognized to play a role in the defense against infection, but conversely also acts as a reservoir for potentially pathogenic organisms. Disruption to the microbiome can increase the risk of invasive infection from these organisms; therefore, strategies to restore the composition of the gut microbiota are a potential strategy of key interest to mitigate this risk. Fecal (or Intestinal) Microbiota Transplantation (FMT/IMT), is the administration of minimally manipulated screened healthy donor stool to an affected recipient, and remains the major 'whole microbiome' therapeutic approach at present. Driven by the marked success of using FMT in the treatment of recurrent Clostridioides difficile infection, the potential use of FMT in treating other infectious diseases is an area of active research. In this review, we discuss key examples of this treatment based on recent findings relating to the interplay between microbiota and infection, and potential further exploitations of FMT/IMT.

Bloodstream Infections in Patients with Hematologic Diseases: Causative Organisms and Factors Associated with Resistance

Background

Materials and Methods

Results

Conclusion

How to adapt an intestinal microbiota transplantation programme to reduce the risk of invasive multidrug-resistant infection

BACKGROUND

Vulnerable patients with intestinal colonization of multidrug-resistant organisms (MDROs) are recognized to be at increased risk of invasive MDRO-driven infection. Intestinal microbiota transplantation (IMT, also called faecal microbiota transplant) is the transfer of healthy screened donor stool to an affected recipient, and recent interest has focused on its impact on the reduction of invasive MDRO infection.

OBJECTIVES

To describe how to establish a clinical IMT pathway for patients at risk of MDRO invasive infection, with special considerations for optimizing administration and assessment of endpoints.

SOURCES

Expert guidelines and peer-reviewed clinical studies are encompassed and discussed.

CONTENT

IMT is offered to patients with MDROs detected on rectal or stool screening and either at risk of MDRO invasive infection due to altered immune status or those with recurrent MDRO-mediated invasive disease and considered at risk of further disease. Donor screening should include pathogens with theoretical or demonstrated risk of transmission (including MDROs themselves and SARS-CoV-2) and take into consideration the relative immunosuppressed state of potential recipients. Delivery of IMT is timed for when the patient is free from active infection, but no additional antibiotics are indicated. If administered when future immunosuppression is to take place, IMT is aligned at least 2 weeks beforehand to ensure sufficient time for engraftment. Patients are followed up in terms of adverse effects from IMT and clinicians are advised to discuss with the IMT multidisciplinary team on choice of antibiotics if needed to take into consideration the impact upon the intestinal microbiome. Prevention of invasive disease is the primary measure of success, rather than using intestinal decolonization as a binary outcome. Repeat IMT is considered case by case.

IMPLICATIONS

Future research areas should include randomized studies that consider clinical outcomes and cost-effectiveness, and better understanding of mechanisms to identify markers of treatment success and functional microbiome components that could be used therapeutically.

Healthcare-associated blood stream infections in hematological patients in Finland during the years 2006-2016

OBJECTIVES

The aim was to identify the clinical characteristics, outcome, and antimicrobial susceptibility of healthcare-associated bloodstream infections (BSIs) in hematological patients.

METHODS

This retrospectively collected laboratory-based surveillance data include 3404 healthcare-associated BSIs in 2296 patients with a hematological malignancy in hospitals participating in the Finnish Hospital Infection Program from January 1, 2006, to December 31, 2016.

RESULTS

The most common underlying diseases were acute myelogenous leukemia (35%) and non-Hodgkin lymphoma (22%). Gram-positive organisms accounted for 60%-46% and gram-negative organisms for 24%-36% of BSIs in 2006-2016. The most common causative organism was coagulase-negative staphylococci (CoNS) (n = 731). The 7- and 28-day case fatality rates were 5.2% and 11.4%, respectively, and was highest in BSIs caused by Candida species (10.8% and 30.8%). The median age of patients increased from 59 years in 2006-2008 to 62 years in 2015-2016 (P < .01). Five percent of S aureus isolates were resistant to methicillin and five percent of Pseudomonas aeruginosa isolates were multidrug-resistant. Four percent of Klebsiella and seven percent of E coli isolates were resistant to ceftazidime.

CONCLUSIONS

The proportion of gram-positive bacteria decreased and gram-negative bacteria increased over time. The case fatality rate was low and the median age of patients increased during the study.

Clinical outcomes and prognostic factors in bloodstream infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae among patients with malignancy: a meta-analysis

Background

The colonization of Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) in bloodstream infections (BSIs) has been increased dramatically worldwide, and it was associated with worse clinical outcomes in patients with malignancy. We performed the meta-analysis to investigate the prognosis and risk factors in BSIs caused by ESBL-PE in oncological patients.

Methods

PubMed, EMBASE, and Cochrane Library were searched for related studies. All-cause mortality was considered as the primary outcome. Subgroup analyses, meta-regression analyses, and sensitivity analysis were used to investigate heterogeneity and reliability in results.

Results

6,729 patients from 25 studies were eligible. Six studies enrolled oncological patients with BSIs caused by ESBL-PE only, while 19 studies both enrolled ESBL-PE and non-ESBL-PE infections. The results showed that BSIs caused by ESBL-PE in patients with malignancy was associated with higher mortality than non-ESBL-PE infections (RR = 2.21, 95% CI: 1.60–3.06, P < 0.001), with a significant between-study heterogeneity (I² =78.3%, P < 0.001). Subgroup analyses showed that children (RR = 2.80, 95% CI: 2.29–3.43, P < 0.001) and hematological malignancy (RR = 3.20, 95% CI: 2.54–4.03, P < 0.001) were associated with a higher mortality. Severe sepsis/ septic shock, pneumonia, and ICU admission were the most common predictors of mortality.

Conclusions

Our study identified that BSIs caused by ESBL-PE in patients with malignancy were associated with worse clinical outcomes compared with non-ESBL-PE infections. Furthermore, children and hematological malignancy were associated with higher mortality. Severe sepsis/ septic shock, pneumonia, and ICU admission were the most common predictors of mortality.

The Value of Adding Surveillance Cultures to Fluoroquinolone Prophylaxis in the Management of Multiresistant Gram Negative Bacterial Infections in Acute Myeloid Leukemia

Multidrug resistant Gram-Negative Bacterial Infections (MR-GNBI) are an increasing cause of mortality in acute myeloid leukemia (AML), compromising the success of antineoplastic therapy. We prospectively explored a novel strategy, including mandatory fluoroquinolone prophylaxis, weekly surveillance cultures (SC) and targeted antimicrobial therapy for febrile neutropenia, aimed to reduce infectious mortality due to MR-GNBI. Over 146 cycles of chemotherapy, cumulative incidence of colonization was 50%. Half of the colonizations occurred in the consolidation phase of treatment. Application of this strategy led to a significant reduction in the incidence of GNB and carbapenemase-producing Klebisella pneumoniae (cpKp) species, resulting in a reduction of infectious mortality (HR 0.35 [95%, CI 0.13–0.96], p = 0.042). In multivariate analysis, fluroquinolone prophylaxis in addition to SC was associated with improved survival (OR 0.55 [95% CI 0.38–0.79], p = 0.001). Targeted therapy for colonized patients did not overcome the risk of death once cpKp or XDR Pseudomonas aeruginosa infections were developed. Mortality rate after transplant was similar between colonized and not colonized patients. However only 9% of transplanted patients were colonized by cpkp. In conclusion, colonization is a common phenomenon, not limited to the induction phase. This strategy reduces infectious mortality by lowering the global incidence of GN infections and the spread of resistant species.

Fecal microbiota transplantation before or after allogeneic hematopoietic transplantation in patients with hematologic malignancies carrying multidrug-resistance bacteria

Fecal microbiota transplantation is an effective treatment in recurrent Clostridium difficile infection. Promising results to eradicate multidrug-resistant bacteria have also been reported with this procedure, but there are safety concerns in immunocompromised patients. We report results in ten adult patients colonized with multidrug-resistant bacteria, undergoing fecal microbiota transplantation before (n=4) or after (n=6) allogeneic hematopoietic stem cell transplantation for hematologic malignancies. were obtained from healthy related or unrelated donors. Fecal material was delivered either by enema or via nasogastric tube. Patients were colonized or had infections from either carbapenemase-producing bacteria (n=8) or vancomycin-resistant enterococci (n=2). Median age at fecal microbiota transplantation was 48 (range, 16-64) years. Three patients needed a second transplant from the same donor due to initial failure of the procedure. With a median follow up of 13 (range, 4-40) months, decolonization was achieved in seven of ten patients. In all patients, fecal micro-biota transplantation was safe: one patient presented with constipation during the first five days after FMT and two patients had grade I diarrhea. One case of gut grade III acute graft-versus-host disease occurred after fecal microbiota transplantation. In patients carrying or infected by multidrug-resistant bacteria, fecal microbiota transplantation is an effective and safe decolonization strategy, even in those with hematologic malignancies undergoing hematopoietic stem cell transplantation.

A New Scoring System to Predict Blood Stream Infections in Patients with Complicated Intra-Abdominal Infections: Experience from a Tertiary Referral Hospital in China

BACKGROUND

This purpose of this study was to investigate the effects of blood stream infections (BSIs) on the prognosis of patients with complicated intra-abdominal infections (IAIs) and to make predictions based on patients' characteristics on admission.

PATIENTS AND METHODS

One hundred eighty-seven patients with complicated IAI in 2014 and 2015 were included in our retrospective analysis, except for those diagnosed with central line-associated blood stream infections (CLABSIs). Patients with BSIs were compared with patients without BSIs. Multivariable logistic regression was applied to identify factors associated with BSIs and also the subtypes of BSIs. The predictive score systems were established further.

RESULTS

Seventy-four patients (39.6%) with complicated IAIs developed BSIs after admission. Four factors evaluated on admission were associated independently with BSIs including alanine aminotransferase (ALT) ≥66 U/L (two scores), insensitivity to initial empirical antibiotic agents (IIEA; three scores), Sepsis-Related Organ Failure Assessment (SOFA) score of two or more (three scores), and generalized peritonitis (four scores). A total score of five or more was regarded as the critical value in the combined test to predict BSIs, with a sensitivity of 0.78 and a specificity of 0.73. Blood stream infections were further divided as secondary BSIs and non-secondary BSIs. The risk factors of secondary BSIs included IIEA (three scores), SOFA score of two or more (five scores), and generalized peritonitis (eight scores), where a total score of nine or more was regarded as the critical value in the combined test, with a sensitivity of 0.68 and a specificity of 0.87, whereas the risk factors of non-secondary BSIs included IIEA (three scores), SOFA score of two or more (three scores) and procalcitonin (PCT) ≥0.43 mcg/L (three scores), where a total score of six or more was regarded as the critical value in the combined test, with a sensitivity of 0.75 and a specificity of 0.70. Moreover, BSIs were linked with the worse clinical outcomes in organ functions, hospitalization costs, and mortality.

CONCLUSIONS

Our new scoring methods may have potential advantages on the early prediction and recognition of BSIs in patients with complicated IAIs.

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.

Bloodstream infections with gram-negative organisms and the impact of multidrug resistance in patients with hematological malignancies

Infections and especially blood stream infections (BSI) with gram-negative bacteria (GNB) represent a major threat for patients with hematological diseases undergoing chemotherapy and mainly contribute to morbidity and mortality. In this retrospective single-center study, we analyzed the impact of BSI with different gram-negative multidrug-resistant bacteria (MDRGN) compared to BSI with antibiotic susceptible gram-negative bacteria. Data of 109 patients with hematological malignancies and GNB BSI were analyzed with overall survival (OS) 30 days after BSI being the primary endpoint. BSI with non-fermentative gram-negative bacteria were found in 26.6% of all patients and 73.4% suffered from a BSI with an Enterobacteriaceae. Thirty-two of 109 patients suffered from BSI with MDRGN. Characteristics of MDRGN and non-MDRGN BSI patients did not differ besides the fact that significantly more patients received an immunosuppressive therapy in the MDRGN BSI group. OS (30 days after BSI) of patients with MDRGN BSI was significantly lower (85.6 vs. 55.9%; p < 0.001) compared to patients with non-MDRGN BSI. Patients with MDRGN BSI with non-fermentative pathogens had a worse OS after 30 days compared to MDRGN BSI with Enterobacteriaceae and the same holds true for non-MDRGN BSI. In multivariate analysis of MDRGN BSI, non-fermenters and ICU admission were independently associated with increased 30-day mortality. Our data demonstrate the negative impact of non-fermentative gram-negative pathogens causing BSI compared to Enterobacteriaceae in hematological patients and thereby underlining the heterogeneity of gram-negative BSI.

Acute myeloid leukemia and the infectious diseases consultant

Infectious complications following treatment of acute myeloid leukemia (AML) are important causes of morbidity and mortality. The spectrum and complexity of these infections is reflected by the severe net state of immunosuppression of AML patients, that is dynamic and continuously changing, the polypharmacy, including the widespread use of anti-infectives and the complex epidemiology of severe and frequently resistant pathogens afflicting these patients. Infectious diseases (ID) consultants having a critical mass of expertise and intimate knowledge of the intricacies of leukemia care, add considerable value in improving outcomes of patients with AML who develop infections. Furthermore, pharmaco-economic considerations such as length of stay, choice of cost-effective anti-infective program, infection control and antibiotic stewardship strategies create a delicate interplay of the ID consultant and the ecosystem of care of AML patients. This is an increasingly recognized area of cross collaboration and a productive direction for future collaborative practice models and research.

Bloodstream infections in acute myeloid leukemia patients treated according to the Finnish Leukemia Group AML-2003 protocol - a prospective nationwide study

BACKGROUND

Infections greatly influence the outcome of acute myeloid leukemia (AML) patients receiving intensive treatment. The aim of this study was to establish the incidence, microbial etiology, risk factors and prognosis of bloodstream infections (BSIs) in patients with AML and compare the results with the previous treatment protocol (AML-92).

METHODS

Registery data were gathered prospectively from 357 patients aged 16-65 years recruited on the AML-2003 treatment protocol between November 2003 and November 2011 during different treatment cycles.

RESULTS

Blood culture data were available on 977 treatment episodes, in which there were 503 BSIs (51%). The overall incidence rate (IR) for BSIs (per 1000 hospital days) was 16.7. Twenty patients (5.6%) died due to an infection and 16 of them (80%) had a BSI. The most commonly detected microbes (polymicrobial episodes included) in blood cultures were coagulase-negative staphylococci (CoNS, 24.7%), viridans group streptococci (VGS, 19.1%), enterococci (13.9%) and Enterobacteriacae group (25.9%). The etiology of BSIs varied greatly from treatment cycle to cycle.

CONCLUSIONS

Enterococcal BSIs have increased compared to our previous treatment protocol, and they represent significant pathogens in blood cultures. Infection-related mortality has decreased despite the increase in the IR of BSIs. Enterococci seem to be an increasingly prominent pathogen underlying BSIs in the AML patients, especially during induction therapy (20%).