Comparison of Enterococcus faecium Bacteremic Isolates from Hematologic and Non-hematologic Patients: Differences in Antimicrobial Resistance and Molecular Characteristics

Impact of an antimicrobial stewardship programme on antibiotic utilization and resistance burden in patients with acute leukaemia: an 11-year longitudinal cohort study using interrupted time-series analysis

BACKGROUND

Antimicrobial resistance (AMR), driven by inappropriate and overuse of antibiotics, poses a significant threat, especially to patients with acute leukaemia.

OBJECTIVES

To evaluate the impact of antimicrobial stewardship programmes (ASPs) on antibiotic use and analyse temporal changes in bloodstream infections (BSI) caused by AMR organisms.

METHODS

We performed a retrospective, interventional, longitudinal cohort study spanning an 11-year period. ASPs included optimizing antibiotic use, enhancing tracking and reporting systems and delineating leadership and accountability. A segmented regression model of interrupted time series was used to evaluate the trend of antibiotic consumption and BSI with AMR organisms after the interventions.

RESULTS

A total of 3296 BSI episodes with 454 419 days of therapy (DOT) from 7754 patients were obtained. ASPs were significantly associated with an immediate reduction [-70.03 DOT/1000 patient-days (PD), P = 0.036] and a decreasing trend (-11.65 DOT/1000 PD per quarter, P < 0.001) in overall antibiotic use. The increasing incidence of BSI with AMR before ASP intervention was notably curbed and revealed a decreasing trend (slope change: -0.06 BSI/1000 PD per quarter, P = 0.002). The decreasing trend was more significant for Enterobacterales: ciprofloxacin-resistant and ESBL-producing isolates showed a slope change of -0.06 BSI/1000 PD and -0.08 BSI/1000 PD per quarter, respectively (all P < 0.05). However, Pseudomonas aeruginosa BSI increased.

CONCLUSIONS

Multidimensional ASPs effectively reduced both the immediate and trends in overall antibiotic usage even in patients with acute leukaemia. Additionally, there was a notable decrease in the incidence of BSI caused by AMR organisms, particularly among Enterobacterales.

Characteristics of Enterococcus species bloodstream infections among adults with and without onco-hematological malignancies: Experiences from the national center of Hungary

Introduction

Over the past decade, enterococcal bloodstream infection (BSI) shows increasing incidence globally among the elderly and in patients with comorbidities. In this study, we aimed to assess microbiological and clinical characteristics and long-term outcomes of BSIs caused by Enterococcus spp. in adult patients with and without active onco-hematological malignancies hospitalized at a national referral institute.

Methods

A prospective analysis of consecutive enterococcal BSI cases was conducted in the National Institute of Hematology and Infectious Diseases (Budapest, Hungary) between December 2019 and April 2022. We compared characteristics and outcomes at 30-days and 1 year after diagnosis among patients with and without onco-hematological malignancies.

Results

In total, 141 patients were included (median age 68 ± 21 years, female sex 36.9%), 37% (52/141) had active onco-hematological malignancies. The distribution of species was as follows: 50.4% Enterococcus faecalis, 46.1% Enterococcus faecium, 1.4% Enterococcus avium and Enterococcus gallinarum, and 0.7% Enterococcus raffinosus. No statistically significant differences in all-cause mortality rates were observed between patient subgroups at 30 days (32.7 vs. 28.1%; P = 0.57) and 1 year (75.0 vs. 60.7%; P = 0.09).

Conclusion

Enterococcal bloodstream infections yielded a relevant burden of morbidity, but with no statistical difference in long-term outcomes of adult patients with and without active onco-hematological malignancies.

Epidemiological profiles and pathogenicity of Vancomycin-resistant Enterococcus faecium clinical isolates in Taiwan

The emerging Vancomycin-resistant Enterococcus faecium (VRE-fm) is an opportunistic pathogen causing nosocomial infections. The identification of VRE-fm is important for successful prevention and control in healthcare settings. VRE-fm clinical isolates obtained from regional hospitals in northern Taiwan were characterized for antimicrobial susceptibility, virulence genes and biofilm production. Most isolates exhibited multi-drug resistance and carried the virulence genes, esp and hyl. While all isolates produce biofilms, those isolates that carried esp exhibited greater biofilm production. Isolates with different virulence gene carriages were examined for pathogenicity by using a nematode model, Caenorhabditis elegans, for determining microbial-host interactions. The survival assay showed that C. elegans was susceptible to Linezolid-resistant VRE-fm isolates with hyl. Combining the molecular epidemiological profiles regarding pathogenesis in C. elegans can serve as a guide for physicians in limiting opportunistic infections caused by VRE-fm.

Association of Procalcitonin with the Patient’s Infection Characteristics and Prognosis after Hematopoietic Stem Cell Transplantation

Objective

To study whether procalcitonin (PCT) is an important indicator of infection with or without agranulocytosis and to reveal whether PCT can distinguish between infected sites and affect prognosis after hematopoietic stem cell transplantation (HSCT).

Method

In the present study, 682 patients with HSCT were enrolled, and their clinical characteristics were noted. Their blood culture and inflammatory and biochemical indicators were studied. The patients were divided into respective groups according to the degree of agranulocytosis, type of bacterial infection, infected sites, and prognosis.

Results

The PCT, CRP, and D-dimer levels were significantly improved in patients with positive blood culture results compared to the case for those with negative blood culture results. The PCT level was the highest in the gram-negative group. The levels of PCT and D-dimer were significantly elevated in patients with infection and agranulocytosis after HSCT compared to those in the nonagranulocytosis cohort. Interestingly, no significant difference in the PCT level was observed among any of the eight foci. Lower PCT levels were associated with higher survival in patients with infection after HSCT.

Conclusion

Among patients that underwent HSCT, PCT levels were significantly elevated in those with infection and agranulocytosis, with the levels being specifically high in the gram-negative group. Moreover, lower PCT levels were associated with higher survival in patients with infection after HSCT.

Comparative characteristics of sequence types, genotypes and virulence of multidrug-resistant E. faecium isolated from various hosts in eastern Poland. Spread of clonal complex 17 in humans and animals

The aim of the study was to carry out a comparative analysis of the occurrence of sequence types, genotypes, and virulence genes of multidrug-resistant E. faecium isolated from humans, domestic animals, and wildlife from eastern Poland. The genetic correlation of strains was determined using multilocus sequence typing, and the method of Amplification of DNA fragments Surrounding Rare Restriction Sites. The presence of 49 different STs (including 12 not reported previously) was shown. All human isolates, 56% of E. faecium isolated from poultry and 40% isolated from wildlife, belonged to the hospital-adapted CC17. E. faecium CC17 were characterized by statistically higher resistance to aminoglycosides and penicillin, the presence of the aac(6')-Ie-aph(2")-Ia and hyl gene and mutations in gyrA and parC, compared to other strains (p > 0.05). E. faecium were classified into 73 genotypes grouped into clusters including isolates from the same host species. The present study showed that the virulence, resistance, and genotype profiles of E. faecium were correlated with the individual host but not with the sequence type. The occurrence of E. faecium CC17 in both humans and animals proves the large circulation of the complex among various hosts.

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

Background

Materials and Methods

Results

Conclusion

Heterologous Expression and Application of Multicopper Oxidases from Enterococcus spp. for Degradation of Biogenic Amines

BACKGROUND

Biogenic amines are harmful to human health at a certain extent. As a kind of biogenic amine oxidase, multicopper oxidase can be used to degrade them. Currently, the literature about enzyme from Enterococcus spp. are limited, and recombinant multicopper oxidase might be an effective way to degrade biogenic amines.

OBJECTIVE

(i) Select and identify strains that can degrade biogenic amines, (ii) overexpress enzyme from Enterococcus spp., (iii) measure gene expression and probe amine-degradation differences among strains (native, E. coli DH5α, and L. delbruckii), and (iv) examine the biochemical properties of recombinant multicopper oxidase, (v) apply the recombinant enzyme into smoked horsemeat sausage.

METHODS

Reverse transcription PCR and high-performance liquid chromatography were performed to examine gene expression and amine degradation rate.

RESULTS

The results demonstrated that target enzymes were successfully overexpressed, accompanied by increased amine-degrading activity (P <0.05). Gene from E. faecalis M5B was expressed in L. delbrueckii resulted in degradation rates for phenylethylamine, putrescine, histamine and tyramine of 54%, 52%, 70% and 40%, respectively, significantly higher than achieved by other recombinant strains.

CONCLUSION

In this work, gene expression levels were higher in recombinant M5B than recombinant M2B, regardless of host. E. coli is more stable to express multicopper oxidase. Besides, the amine-degrading ability was markedly increased in the two recombinant strains. After prolonged incubation, the recombinant enzyme could degrade three amines, and it displayed high alkali resistance and thermostability.

In vitro activity of ampicillin and ceftriaxone against ampicillin-susceptible Enterococcus faecium

OBJECTIVES

To assess activity of the combination of ceftriaxone and ampicillin against clinical isolates of ampicillin-susceptible Enterococcus faecium.

METHODS

Ampicillin-susceptible E. faecium (n = 29) and Enterococcus faecalis (n = 10) collected from locations in the USA and France were used for this analysis. Susceptibility testing was performed by gradient diffusion strip (GDS) and broth microdilution (BMD). Synergy with the combination of ceftriaxone and ampicillin was assessed in all isolates using GDS crossing and double disc diffusion methods. Selected isolates (nine E. faecium and three E. faecalis) were assessed for synergy in time-kill studies using ampicillin alone and in combination with ceftriaxone.

RESULTS

In isolates of E. faecium, the median (range) ampicillin MIC by BMD was 0.5 (0.25-4) mg/L and by GDS it was 2 (1-8)  mg/L. In E. faecalis, the median (range) ampicillin MIC by BMD was 0.5 (0.5-1) mg/L and by GDS it was 2 (0.75-3) mg/L. A total of 24/29 (82.8%) isolates of E. faecium displayed synergy by GDS and 22/29 (75.9%) by double disc diffusion. Seven of 10 (70%) isolates of E. faecalis displayed synergy by GDS and 4/10 (40%) by double disc diffusion. Time-kill studies found synergy in 3/9 (33.3%) E. faecium and 3/3 (100%) E. faecalis.

CONCLUSIONS

In contrast to the demonstrated synergy in time-kill models of ceftriaxone and ampicillin for E. faecalis, this combination does not appear to provide uniform synergy in E. faecium. Antagonism was not observed. Clinical correlation is necessary and caution should be used when considering ampicillin and ceftriaxone for the treatment of infections caused by ampicillin-susceptible E. faecium.

Serum procalcitonin as an independent diagnostic markers of bacteremia in febrile patients with hematologic malignancies

Background

Serum procalcitonin (PCT) and C-reactive protein (CRP) are biomarkers of infection. In patients with hematologic disorders with or without hematopoietic stem cell transplantation (HSCT), it is difficult to distinguish bloodstream infections from aseptic causes of febrile episodes. The objective of this study was to investigate diagnostic values of PCT and CRP in predicting systemic bacterial infection in patients with hematologic malignancies.

Methods

Clinical and laboratory data of 614 febrile episode cases from 511 patients were analyzed. Febrile episodes were classified into four groups: (1) culture-positive bacterial infection by Gram-positive cocci (GPC), (2) culture-positive bacterial infection by Gram-negative bacilli (GNB), (3) fungal infection, and (4) viral infection or a noninfectious etiology.

Results

Of 614 febrile cases, systemic bacterial infections were confirmed in 99 (16.1%) febrile episodes, including 38 (6.2%) GPC and 61 (9.9%) GNB infections. PCT levels were significantly higher in GNB infectious episodes than those in febrile episodes caused by fungal infection (0.58 ng/mL (95% CI: 0.26–1.61) vs. 0.22 ng/mL (0.16–0.38), P = 0.047). Bacterial infectious episodes showed higher PCT and CRP levels than non-bacterial events (PCT: 0.49 (0.26–0.93) ng/mL vs. 0.20 (0.18–0.22) ng/mL, P < 0.001; CRP: 76.6 (50.5–92.8) mg/L vs. 58.0 (51.1–66.5) mg/L, P = 0.036). For non-neutropenic febrile episodes, both PCT and CRP discriminated bacteremia from non-bacteremia. However, in neutropenic febrile episodes, PCT only distinguished bacteremia from non-bacteremia. In non-neutropenic episode, both PCT and CRP showed good diagnostic accuracy (AUC: 0.757 vs. 0.763). In febrile neutropenia, only PCT discriminated bacteremia from non-bacterial infection (AUC: 0.624) whereas CRP could not detect bacteremia (AUC: 0.500, 95% CI: 0.439–0.561, P > 0.05).

Conclusions

In this single-center observational study, PCT was more valuable than CRP for discriminating between bacteremia and non-bacteremia independent of neutropenia or HSCT.