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Background: Non-Enterococcus faecium, non-E. faecalis (NFF) enterococci are a heterogeneous group of clinically pathogenic enterococci that include species with intrinsic low-level vancomycin resistance. Patients with cancer are at increased risk for bacteremia with NFF enterococci, but their clinical and molecular epidemiology have not been extensively described. Methods: We conducted a retrospective review of all patients (n = 70) with NFF bacteremia from 2016 to 2022 at a major cancer center. The main outcomes assessed were 30-day mortality, microbiological failure (positive blood cultures for ≥4 days), and recurrence of bacteremia (positive blood culture <14 days after clearance). Whole-genome sequencing was performed on all available NFF (n = 65). Results: Patients with hematological malignancies made up 56% of the cohort (77% had leukemia). The majority of solid malignancies (87%) were gastrointestinal in origin. The majority of infections (83%) originated from an intra-abdominal source. The most common NFF species were E. gallinarum (50%) and E. casseliflavus (30%). Most (61%) patients received combination therapy. Bacteremia recurred in 4.3% of patients, there was a 30-day mortality of 23%, and 4.3% had microbiological failure. E. gallinarum and E. casseliflavus isolates were genetically diverse with no spatiotemporal clustering to suggest a single strain. Frequencies of ampicillin resistance (4.3%) and daptomycin resistance (1.9%) were low. Patients with hematologic malignancy had infections with NFF enterococci that harbored more resistance genes than patients with solid malignancy (P = .005). Conclusions: NFF bacteremia is caused by a heterogeneous population of isolates and is associated with significant mortality. Hematological malignancy is an important risk factor for infection with NFF resistant to multiple antibiotics.
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Daptomycin (DAP) is often used as a first-line therapy to treat vancomycin-resistant Enterococcus faecium infections, but emergence of DAP non-susceptibility threatens the effectiveness of this antibiotic. Moreover, current methods to determine DAP minimum inhibitory concentrations (MICs) have poor reproducibility and accuracy. In enterococci, DAP resistance is mediated by the LiaFSR cell membrane stress response system, and deletion of liaR encoding the response regulator results in hypersusceptibility to DAP and antimicrobial peptides. The main genes regulated by LiaR are a cluster of three genes, designated liaXYZ. In Enterococcus faecalis, LiaX is surface-exposed with a C-terminus that functions as a negative regulator of cell membrane remodeling and an N-terminal domain that is released to the extracellular medium where it binds DAP. Thus, in E. faecalis, LiaX functions as a sentinel molecule recognizing DAP and controlling the cell membrane response, but less is known about LiaX in E. faecium. Here, we found that liaX is essential in E. faecium with an activated LiaFSR system. Unlike E. faecalis, E. faecium LiaX is not detected in the extracellular milieu and does not appear to alter phospholipid architecture. We further postulated that LiaX could be used as a surrogate marker for cell envelope activation and non-susceptibility to DAP. For this purpose, we developed and optimized a LiaX enzyme-linked immunosorbent assay (ELISA). We then assessed 86 clinical E. faecium bloodstream isolates for DAP MICs and used whole genome sequencing to assess for substitutions in LiaX. All DAP-resistant clinical strains of E. faecium exhibited elevated LiaX levels. Strikingly, 73% of DAP-susceptible isolates by standard MIC determination also had elevated LiaX ELISAs compared to a well-characterized DAP-susceptible strain. Phylogenetic analyses of predicted amino acid substitutions showed 12 different variants of LiaX without a specific association with DAP MIC or LiaX ELISA values. Our findings also suggest that many E. faecium isolates that test DAP susceptible by standard MIC determination are likely to have an activated cell stress response that may predispose to DAP failure. As LiaX appears to be essential for the cell envelope response to DAP, its detection could prove useful to improve the accuracy of susceptibility testing by anticipating therapeutic failure.
Assuntos
Membrana Celular , Daptomicina , Enterococcus faecium , Infecções por Bactérias Gram-Positivas , Humanos , Antibacterianos/uso terapêutico , Biomarcadores/metabolismo , Daptomicina/farmacologia , Daptomicina/uso terapêutico , Farmacorresistência Bacteriana/genética , Enterococcus faecalis , Infecções por Bactérias Gram-Positivas/tratamento farmacológico , Infecções por Bactérias Gram-Positivas/metabolismo , Testes de Sensibilidade Microbiana , Filogenia , Reprodutibilidade dos TestesRESUMO
Daptomycin (DAP) is often used as a first line therapy to treat vancomycin-resistant Enterococcus faecium (VR Efm ) infections but emergence of DAP non-susceptibility threatens the effectiveness of this antibiotic. Moreover, current methods to determine DAP MICs have poor reproducibility and accuracy. In enterococci, DAP resistance is mediated by the LiaFSR cell membrane stress response system and deletion of liaR encoding the response regulator results in hypersusceptibility to DAP and antimicrobial peptides. The main genes regulated by LiaR are a cluster of three genes, designated liaXYZ . In Enterococcus faecalis , LiaX is surface exposed with a C-terminus that functions as a negative regulator of cell membrane remodeling and an N-terminal domain that is released to the extracellular medium where it binds DAP. Thus, in E. faecalis , LiaX functions as a sentinel molecule recognizing DAP and controlling the cell membrane response, but less is known about LiaX in E. faecium . Here, we found that liaX is essential in E. faecium ( Efm ) with an activated LiaFSR system. Unlike E. faecalis , Efm LiaX is not detected in the extracellular milieu and does not appear to alter phospholipid architecture. We further postulated that LiaX could be used as a surrogate marker for cell envelope activation and non-susceptibility to DAP. For this purpose, we developed and optimized a LiaX ELISA. We then assessed 86 clinical E. faecium BSI isolates for DAP MICs and used whole genome sequencing to assess for substitutions in LiaX. All DAP-R clinical strains of E. faecium exhibited elevated LiaX levels. Strikingly, 73% of DAP-S isolates by standard MIC determination had elevated LiaX ELISAs above the established cut-off. Phylogenetic analyses of predicted amino acid substitutions showed 12 different variants of LiaX without a specific association with DAP MIC or LiaX ELISA values. Our findings also suggest that many Efm isolates that test DAP susceptible by standard MIC determination are likely to have an activated cell stress response that may predispose to DAP failure. As LiaX appears to be essential for the cell envelope response to DAP, its detection could prove useful to improve the accuracy of susceptibility testing by anticipating therapeutic failure.
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Failure to maintain segregation of oral and gut microbial communities has been linked to several diseases. We sought to characterize oral-fecal microbiome community coalescence, ectopic extension of oral bacteria, clinical variables contributing to this phenomenon, and associated infectious consequences by analyzing the 16S rRNA V4 sequences of longitudinal fecal (n=551) and oral (n=737) samples from 97 patients with acute myeloid leukemia (AML) receiving induction chemotherapy (IC). Clustering observed in permutation based multivariate analysis of variance (PERMANOVA) of Bray-Curtis dissimilarity and PCoA plot of UniFrac distances between intra-patient longitudinal oral-stool sample pairs suggested potential oral-stool microbial community coalescence. Bray-Curtis dissimilarities and UniFrac distances were used to create an objective definition of microbial community coalescence. We determined that only 23 of the 92 patients exhibited oral-stool community coalescence. This was validated through a linear mixed model which determined that patients who experienced coalescence had an increased proportion of shared to unique OTUs between their oral-stool sample pairs over time compared to non-coalesced patients. Evaluation of longitudinal microbial characteristics revealed that patients who experienced coalescence had increased stool abundance of Streptococcus and Stenotrophomonas compared to non-coalesced patients. When treated as a time-varying covariate, each additional day of linezolid (HR 1.15, 95% CI 1.06 - 1.24, P <0.001), meropenem (HR 1.13, 95% CI 1.05 - 1.21, P = 0.001), metronidazole (HR 1.13, 95% CI 1.05 - 1.21, P = 0.001), and cefepime (HR 1.10, 95% CI 1.01 - 1.18, P = 0.021) increased the hazard of oral-stool microbial community coalescence. Levofloxacin receipt was associated with a lower risk of microbiome community coalescence (HR 0.75, 95% CI 0.61 - 0.93, P = 0.009). By the time of neutrophil recovery, the relative abundance of Bacteroidia (P<0.001), Fusobacteria (P=0.012), and Clostridia (P=0.013) in the stool were significantly lower in patients with oral-gut community coalescence. Exhibiting oral-stool community coalescence was associated with the occurrence of infections prior to neutrophil recovery (P=0.002), as well as infections during the 90 days post neutrophil recovery (P=0.027). This work elucidates specific antimicrobial effects on microbial ecology and furthers the understanding of oral/intestinal microbial biogeography and its implications for adverse clinical outcomes.
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Microbioma Gastrointestinal , Leucemia Mieloide Aguda , Microbiota , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Fezes/microbiologia , Humanos , Leucemia Mieloide Aguda/complicações , Leucemia Mieloide Aguda/tratamento farmacológico , RNA Ribossômico 16S/genéticaRESUMO
BACKGROUND: Vancomycin-resistant enterococci (VRE) are major therapeutic challenges. Prospective contemporary data characterizing the clinical and molecular epidemiology of VRE bloodstream infections (BSIs) are lacking. METHODS: The Vancomycin-Resistant Enterococcal BSI Outcomes Study (VENOUS I) is a prospective observational cohort of adult patients with enterococcal BSI in 11 US hospitals. We included patients with Enterococcus faecalis or Enterococcus faecium BSI with ≥1 follow-up blood culture(s) within 7 days and availability of isolate(s) for further characterization. The primary study outcome was in-hospital mortality. Secondary outcomes were mortality at days 4, 7, 10, 12, and 15 after index blood culture. A desirability of outcome ranking was constructed to assess the association of vancomycin resistance with outcomes. All index isolates were subjected to whole genome sequencing. RESULTS: Forty-two of 232 (18%) patients died in hospital and 39 (17%) exhibited microbiological failure (lack of clearance in the first 4 days). Neutropenia (hazard ratio [HR], 3.13), microbiological failure (HR, 2.4), VRE BSI (HR, 2.13), use of urinary catheter (HR, 1.85), and Pitt BSI score ≥2 (HR, 1.83) were significant predictors of in-hospital mortality. Microbiological failure was the strongest predictor of in-hospital mortality in patients with E faecium bacteremia (HR, 5.03). The impact of vancomycin resistance on mortality in our cohort changed throughout the course of hospitalization. Enterococcus faecalis sequence type 6 was a predominant multidrug-resistant lineage, whereas a heterogeneous genomic population of E faecium was identified. CONCLUSIONS: Failure of early eradication of VRE from the bloodstream is a major factor associated with poor outcomes.
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BACKGROUND: Stenotrophomonas maltophilia is increasingly common in patients with acute myeloid leukemia (AML). Little is known about factors that drive S. maltophilia infection. We evaluated the microbiome and cumulative antibiotic use as predictors of S. maltophilia infection in AML patients receiving remission induction chemotherapy (RIC). METHODS: Subanalysis of a prospective, observational cohort of patients with AML receiving RIC between September 2013 and August 2015 was performed. Fecal and oral microbiome samples collected from initiation of RIC until neutrophil recovery were assessed for the relative abundance of Stenotrophomonas via 16S rRNA gene quantitation. The primary outcome, microbiologically proven S. maltophilia infection, was analyzed using a time-varying Cox proportional hazards model. RESULTS: Of 90 included patients, 8 (9%) developed S. maltophilia infection (pneumonia, n = 6; skin-soft tissue, n = 2); 4/8 (50%) patients were bacteremic; and 7/8 (88%) patients with S. maltophilia infection had detectable levels of Stenotrophomonas vs 22/82 (27%) without infection (P < .01). An oral Stenotrophomonas relative abundance of 36% predicted infection (sensitivity, 96%; specificity, 93%). No association of S. maltophilia infection with fecal relative abundance was found. Cumulative meropenem exposure was associated with increased infection risk (hazard ratio, 1.17; 95% confidence interval, 1.01-1.35; P = .03). CONCLUSIONS: Here, we identify the oral microbiome as a potential source for S. maltophilia infection and highlight cumulative carbapenem use as a risk factor for S. maltophilia in leukemia patients. These data suggest that real-time monitoring of the oral cavity might identify patients at risk for S. maltophilia infection.
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Infecções por Bactérias Gram-Negativas , Leucemia Mieloide Aguda , Microbiota , Stenotrophomonas maltophilia , Carbapenêmicos/uso terapêutico , Infecções por Bactérias Gram-Negativas/epidemiologia , Humanos , Leucemia Mieloide Aguda/complicações , Leucemia Mieloide Aguda/tratamento farmacológico , Estudos Prospectivos , RNA Ribossômico 16S/genéticaRESUMO
BACKGROUND: Accumulating evidence suggests that the intestinal microbiome may dramatically affect the outcomes of hematopoietic stem cell transplant (HSCT) recipients. Providing 16S ribosomal RNA based microbiome characterization in a clinically actionable time frame is currently problematic. Thus, determination of microbial metabolites as surrogates for microbiome composition could offer practical biomarkers. METHODS: Longitudinal fecal specimens (n = 451) were collected from 44 patients before HSCT through 100 days after transplantation, as well as 1-time samples from healthy volunteers (n = 18) as controls. Microbiota composition was determined using 16S ribosomal RNA V4 sequencing. Fecal indole and butyrate levels were determined using liquid chromatography tandem mass spectrometry. RESULTS: Among HSCT recipients, both fecal indole and butyrate levels correlated with the Shannon diversity index at baseline (P = .02 and P = .002, respectively) and directly after transplantation (P = .006 and P < .001, respectively). Samples with high butyrate levels were enriched for Clostridiales, whereas samples containing high indole were also enriched for Bacteroidales. A lower Shannon diversity index at the time of engraftment was associated with increased incidence of acute intestinal graft-vs-host disease (iGVHD) (P = .02) and transplant-related deaths (P = .03). Although fecal metabolites were not associated with acute iGVHD or overall survival, patients contracting bloodstream infections within 30 days after transplantation had significantly lower levels of fecal butyrate (P = .03). CONCLUSIONS: Longitudinal analysis of fecal microbiome and metabolites after HSCT identified butyrate and indole as potential surrogate markers for microbial diversity and specific taxa. Further studies are needed to ascertain whether fecal metabolites can be used as biomarkers of acute iGVHD or bacteremia after HSCT.
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The aim of the study was to assess the association inflammation with symptom burden in patients with acute myeloid leukemia (AML), assessed before and during remission induction chemotherapy (IC). Patients with AML (nâ¯=â¯95) were followed from baseline (before IC) to the third week of IC for severity of self-reported somatic symptoms (assessed with the MD Anderson Symptom Inventory) and plasma levels of 13 inflammation-related biomarkers (nâ¯=â¯64). A composite symptom burden severity score was computed as the average score of the six most severe somatic symptoms i.e., fatigue, disturbed sleep, drowsiness, dry mouth, lack of appetite, and pain. Results from cross-sectional analyses showed that inflammation was weakly associated with symptom burden before IC (multiple regression model, explained varianceâ¯=â¯10%) but this association grew stronger during IC (week 3 explained varianceâ¯=â¯35%). About half of the sample showed a change over time in symptom severity. These changes were not reflected in similar changes over time in inflammatory markers, suggesting that it is the absolute concentration of a given inflammatory marker at a given time point rather than its relative change over time that is of importance. In conclusion, inflammation was strongly associated with symptom burden only during IC, possibly because expression of cytokines only then becomes relevant for regulation of symptom burden. While the current study does not allow for determination of causality, the results suggest that AML patients might benefit from anti-inflammatory interventions during treatment to alleviate somatic symptom experience.