Etiology, clinical course and outcome of healthcare-associated bloodstream infections in patients with hematological malignancies: a retrospective study of 350 patients in a Finnish tertiary care hospital

Clinical Predictors of Bacteremia Outcome After Initial Empirical Antimicrobial Therapy in Patients with Hematological Malignancies: A Retrospective Analysis

Objective

We performed a retrospective analysis to investigate the clinical predictors of bacteremia outcome involving Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) after initial empirical antimicrobial therapy among hematological malignancy cases.

Methods

This retrospective study was conducted between April 2018 and April 2023. All bloodstream infections (BSIs) caused by E. coli and K. pneumoniae in hospitalized hematological malignancy (HM) patients were identified. Data on patient demographics, clinical characteristics, empirical antimicrobial treatment, outcomes and the antimicrobial susceptibility were collected from medical records. Multivariate analyses were utilized to assess the risk factors for all-cause mortality within 28 days and carbapenem resistance. Optimal cutoffs for continuous predictive variables were evaluated by receiver operating characteristic (ROC) curve analysis.

Results

Among 61 individuals diagnosed with bacteremia, 39 cases were caused by E. coli bacteremia, while the remaining 22 were identified as K. pneumoniae bacteremia. Out of these, there were 10 cases of carbapenem-resistant Enterobacteriaceae (CRE) and 12 cases resulted in all-cause mortality within 28 days. Analysis indicated that Pitt score was an independent risk factor for mortality and a cut-off of 2.5 was a reliable predictor with 83.3% sensitivity and 85.7% specificity, respectively. Impaired mental status and elevated body temperature exceeding 38.6°C as well as a procalcitonin (PCT) level over 8.24 ng/mL on the third day (d3) after antimicrobial treatment were identified as independent risk factors for predicting carbapenem resistance.

Conclusion

We found that Pitt score with a cut-off of 2.5 was a reliable predictor for mortality within 28 days in HM bacteremia cases. Impaired mental status and elevated temperature exceeding 38.6°C as well as a procalcitonin (PCT) level over 8.24 ng/mL on d3 after antimicrobial treatment were identified as predictive risk factors to carbapenem resistance.

Bloodstream gram-negative bacterial infections in adult patients with leukemia: A retrospective review of medical records in a tertiary care hospital in Western Saudi Arabia

BACKGROUND

Patients with neutropenic cancers are at high risk of acquiring infections, especially if on chemotherapy. Gram-negative bacterial infections are associated with high mortality. This study aimed to assess clinical characteristics, outcomes, and epidemiology of gram-negative bacterial (GNB) bloodstream infections (BSI) in adult patients with leukemia.

METHODS

This single-center, retrospective study included 102 adult patients diagnosed with leukemia between 2017 and 2019. The patients' demographics, infection diagnosis, leukemia diagnosis, comorbidities, and infection outcomes were collected from electronic medical records.

RESULTS

The most common GNB were Klebsiella pneumoniae (33.3 %), Pseudomonas aeruginosa (23.5 %), and Escherichia coli (17.6 %). Additionally, 36.7 % of infections were multidrug resistant. The most common comorbidities were cardiovascular diseases (36.7 %), diabetes mellitus (33.3 %), and liver diseases (24.1 %). GNB-infected patients had a higher mortality than noninfected patients (35.3 % and 11.8 %, respectively, p = 0.005). In a multivariable analysis, patients with acute myeloid leukemia and acute lymphoid leukemia were significantly more likely to acquire GNB BSI (p = 0.01), while patients with chronic myelogenous leukemia and chronic lymphocytic leukemia had a lower likelihood of developing GNB BSI. In addition, low hemoglobin level was an independent risk factor of GNB BSI (p = 0.001). Chemotherapeutic agents showed an association with increased risk of GNB BSI.

CONCLUSIONS

Patients with acute leukemia and low hemoglobin levels have increased risk of GNB BSI, which was associated with increased mortality. Prospective studies are needed to further assess the effect of co-morbidities and chemotherapy medications on the occurrence of GNB BSI according to the type of leukemia.

Microbiology and prognostic prediction model of bloodstream infection in patients with hematological malignancies

Background

In recent years, with the continuous development of treatments for hematological malignancies (HMs), the remission and survival rates of patients with HMs have been significantly improved. However, because of severe immunosuppression and long-term recurrent neutropenia during treatment, the incidence and mortality of bloodstream infection (BSI) were all high in patients with HMs. Therefore, we analyzed pathogens' distribution and drug-resistance patterns and developed a nomogram for predicting 30-day mortality in patients with BSIs among HMs.

Methods

In this retrospective study, 362 patients with positive blood cultures in HMs were included from June 2015 to June 2020 at West China Hospital of Sichuan University. They were randomly divided into the training cohort (n = 253) and the validation cohort (n = 109) by 7:3. A nomogram for predicting 30-day mortality after BSIs in patients with HMs was established based on the results of univariate and multivariate logistic regression. C-index, calibration plots, and decision curve analysis were used to evaluate the nomogram.

Results

Among 362 patients with BSIs in HMs, the most common HM was acute myeloid leukemia (48.1%), and the most common pathogen of BSI was gram-negative bacteria (70.4%). The final nomogram included the septic shock, relapsed/refractory HM, albumin <30g/l, platelets <30×10⁹/l before BSI, and inappropriate empiric antibiotic treatment. In the training and validation cohorts, the C-indexes (0.870 and 0.825) and the calibration plots indicated that the nomogram had a good performance. The decision curves in both cohorts showed that the nomogram model for predicting 30-day mortality after BSI was more beneficial than all patients with BSIs or none with BSIs.

Conclusion

In our study, gram-negative bacterial BSIs were predominant in patients with HMs. We developed and validated a nomogram with good predictive ability to help clinicians evaluate the prognosis of patients.

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.

Coagulase negative Staphylococcus bacteremia in hematopoietic stem cell transplant recipients: Clinical features and molecular characterization

The purpose of our study was to investigate the epidemiology of coagulase negative staphylococci (CoNS) responsible for bacteremia in hematopoietic stem cell transplant (HSCT) recipients and to determine the prevalence and the genetic background of methicillin resistance. The prevalence of CoNS bacteremia was 7.4% (54/728), higher in allograft (10.7%) than in autograft (4.7%) recipients. A sepsis or a septic shock were observed in 9% of cases. No deaths were attributable to CoNS bacteremia. The methicillin resistance rate was 81%. All MR-CoNS, harbored mecA gene and 90% were typeable with SCCmec typing using PCR amplification. The SCCmec type IV was the most frequent (44%). Clonal dissemination of MR- Staphylococcus epidermidis strains was limited. Our study showed a low prevalence and favorable outcome of CoNS bacteremia in HSCT recipients with limited clonal diffusion. However, they were associated with a significant rate of severe infections and a high rate of methicillin resistance, mediated by SCCmec IV element in most cases.

Epidemiology, Risk Factors, and Clinical Outcomes of Bloodstream Infection due to Extended-Spectrum Beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae in Hematologic Malignancy: A Retrospective Study from Central South China

Objective: To determine the epidemiology, risk factors, and prognosis of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections (BSIs) among hematology malignancy (HM) patients in China. Method: From January 2010 to June 2018, we retrospectively collected and analyzed the 449 HM patients with E. coli or K. pneumoniae BSIs from three leading hospitals in Hunan Province, China. Results: Two hundred four (45.4%) patients harbored ESBL-producing bacteremia. The proportion of ESBL-producing bacteremia increased significantly with the growth of the year, with a ratio of 34.47% in 2010-2014 to 54.7% in 2015-2018. Comparing with non-ESBL groups in HM patients, central venous catheter (odds ratio [OR] 1.717, p = 0.009), previous antibiotic exposure (OR 1.559, p = 0.035), and E. coli (OR 2.561, p ≤ 0.001) among ESBL groups were independent risk factors. No significant differences in 30-day mortality were tested in patients with BSI caused by ESBL-producing or non-ESBL-producing E. coli and K. pneumoniae (17.1% vs. 16.7%; p = 0. 893). The proportion of carbapenem used within 72 hours after the onset of bacteremia in two groups was high, which was routinely used as "last-resort drugs" in Gram-negative bacterial infections. Risk factors associated with 30-day mortality in HM patients with E. coli or K. pneumoniae bacteremia were myelodysplastic syndrome, incomplete remission of the disease, Multinational Association of Supportive Care in Cancer score <21, Pitt bacteremia score ≥4, Charlson comorbidity score >3, catheter insertion, use of vasopressors, and inappropriate antibiotics within 72 hours of BSI onset. Conclusions: The results of this study may provide some references for the whole process management of HM patients with BSIs.

The Clinical Link between Human Intestinal Microbiota and Systemic Cancer Therapy

Clinical interest in the human intestinal microbiota has increased considerably. However, an overview of clinical studies investigating the link between the human intestinal microbiota and systemic cancer therapy is lacking. This systematic review summarizes all clinical studies describing the association between baseline intestinal microbiota and systemic cancer therapy outcome as well as therapy-related changes in intestinal microbiota composition. A systematic literature search was performed and provided 23 articles. There were strong indications for a close association between the intestinal microbiota and outcome of immunotherapy. Furthermore, the development of chemotherapy-induced infectious complications seemed to be associated with the baseline microbiota profile. Both chemotherapy and immunotherapy induced drastic changes in gut microbiota composition with possible consequences for treatment efficacy. Evidence in the field of hormonal therapy was very limited. Large heterogeneity concerning study design, study population, and methods used for analysis limited comparability and generalization of results. For the future, longitudinal studies investigating the predictive ability of baseline intestinal microbiota concerning treatment outcome and complications as well as the potential use of microbiota-modulating strategies in cancer patients are required. More knowledge in this field is likely to be of clinical benefit since modulation of the microbiota might support cancer therapy in the future.

Association between antimicrobial resistance among Enterobacteriaceae and burden of environmental bacteria in hospital acquired infections: analysis of clinical studies and national reports

Background

WHO has named three groups of gram-negative bacteria “our critical antimicrobial resistance-related problems globally”. It is thus a priority to unveil any important covariation of variables behind this three-headed epidemic, which has gained alarming proportions in Low Income Countries, and spreads rapidly. Environmental bacteria including Acinetobacter spp. are common nosocomial pathogens in institutions that have high rates of antimicrobial resistance among other groups of gram-negative bacteria.

Methods

Based on two different data sources, we calculated the correlation coefficient (Pearson's r) between pathogenic burden of Acinetobacter spp. and antimicrobial resistance among Enterobacteriaceae in European and African nosocomial cohorts.

Clinical reports

Database search for studies on nosocomial sepsis in Europe and Africa was followed by a PRISMA-guided selection process.

National reports

Data from Point prevalence survey of healthcare-associated infections published by European Centre for Disease Prevention and Control were used to study the correlation between prevalence of Acinetobacter spp. and antimicrobial resistance among K. pneumoniae in blood culture isolates.

Findings

The two approaches both revealed a strong association between prevalence of Acinetobacter spp. and rates of resistance against 3. generation cephalosporins among Enterobacteriaceae. In the study of clinical reports (13 selected studies included), r was 0.96 (0.80–0.99) when calculated by proportions on log scale. Based on national reports, r was 0.80 (0.56–0.92) for the correlation between resistance rates of K. pneumoniae and proportion of Acinetobacter spp.

Interpretation

The critical antimicrobial resistance-related epidemics that concern enteric and environmental gram-negative bacteria are not independent epidemics; they have a common promoting factor, or they are mutually supportive. Further, accumulation of antimicrobial resistance in nosocomial settings depends on the therapeutic environment. Burden of Acinetobacter spp. as defined here is a candidate measure for this dependence.

[Clinical and bacteriological analysis of lymphoid tissue neoplasms patients with bacteria bloodstream infections]

Objective: To investigate the clinical status of lymphoid tissue neoplasms patients with bacteria bloodstream infections, bacteriology and drug susceptibility results, and provide the basis for rational clinical anti-infection option. Methods: A retrospectively analysis of clinical data and bacterial susceptibility test results of patients with bacteria bloodstream infections from September 2010 to December 2014 was conducted. Results: A total of 134 cases including 107 patients with bloodstream infections were enrolled. 84 cases were male, 50 cases were female, the median age was 31 (12-71) years old. 112 cases were agranulocytosis, and 106 cases were severe agranulocytosis (ANC<0.1×10(9)/L) . 27 cases underwent hematopoietic stem cell transplantation, 100 cases received chemotherapy[33 cases with VD (I) CP±L (vincristine+daunorubicin/idarubicin + cyclophosphamide + prednison±asparaginasum) induction chemotherapy, 41 cases with intensive chemotherapy of Hyper-CVAD/MA or MA (mitoxantrone+cytarabine) , 26 cases with other chemotherapy regimens], and 7 cases were infected without chemotherapy. 10 patients discharged from hospital owing to treatment abandoning, 120 cases were cured through anti-infective therapy, 2 patients died of bacteria bloodstream infections, 1 patient died of sudden cardiac, and 1 patient died of GVHD after allogenic hematopoietic stem cell transplantation. A total of 144 strains were isolated, including 108 strains (75.0%) of Gram-negative bacteria and 36 strains (25.0%) of Gram-positive cocci. The susceptibility of Gram-negative bacteria to the carbapenems was 98.00%, and the adjustment treatment rate of carbapenems was 3.0%. The susceptibility of Gram-negative bacteria to the other antibiotics was 60.30%, and the adjustment treatment rate was 90.5%. The susceptibility of Grampositive cocci to the carbapenems was 49.3%, and to glycopeptides and linezolid was 100.0%. Comparing all patients'empirical use of antimicrobial agents with the drugs susceptibility results of blood cultures, 80.1% of the patients'initial drug selection was sensitive. Conclusion: The lymphoid neoplasms patients experienced bacteria bloodstream infections most often after receiving the chemotherapy regimens of treating acute lymphoblastic leukemia. The majority type of bacteria was Gram-negative bacteria. Drug susceptibility test showed that susceptibility of Gram-negative bacteria to the carbapenems was the highest, and the treatment adjustment rate was obviously lower. The susceptibility of Gram-positive cocci to glycopeptides and linezolid was high, and which could be applied to the patients with Gram-positive cocci sepsis on basis of susceptibility results in general.

Token economy to improve adherence to activities of daily living

BACKGROUND

Participation in key activities of daily living (ADL), including daily bathing, physical activity, and oral hygiene, can decrease the risk of bloodstream infections, oral complications, and deconditioning in pediatric patients undergoing hematopoietic stem cell transplant (HSCT). However, many patients fail to perform ADL during their inpatient stay. To improve inpatient adherence to ADL, we tested a token economy to engage patients, families, and the clinical team in improving adherence to these important health behaviors during this critical time.

METHODS

We used a controlled before-after study design to test our hypothesis. All patients were prescribed three ADL. We used an "all or none" measurement for each component of the ADL 1-2-3 initiative to measure adherence. HSCT patients with poor ADL adherence (<20%) were eligible to receive the intervention, which consisted of rewarding patients through an ADL via a token economy.

RESULTS

Twenty-one patients participated in the study. ADL adherence for the 14 days prior to intervention in study subjects (n = 294 inpatient days) averaged 0.51 ADL per day (95% CI 0.45-0.57). In the 14 days postinitiation of the token economy intervention (n = 294 inpatient days), the average adherence was 2.5 ADL per day (95% CI 2.4-2.5; P = <0.001).

DISCUSSION

Positive reinforcement through a token economy system is associated with improved adherence to ADL in hospitalized pediatric patients who demonstrated poor ADL adherence at baseline. We believe this intervention can positively impact adherence to targeted health behaviors with the ability to correlate with improved health outcomes.

The outcome and timing of death of 17,767 nosocomial bloodstream infections in acute care hospitals in Finland during 1999-2014

Few studies covering all patient groups and specialties are available regarding the outcome of nosocomial bloodstream infections (BSI). We analyzed the role of patient characteristics and causative pathogens of nosocomial BSIs reported by the hospitals participating in national surveillance in Finland during 1999-2014, in terms of outcome, with particular interest in those leading to death within 2 days (i.e. early death). National nosocomial BSI surveillance was laboratory-based and hospital-wide. Data on nosocomial BSIs was collected by infection control nurses, and dates of death were obtained from the national population registry with linkage to national identity codes. A total of 17,767 nosocomial BSIs were identified; 557 BSIs (3%) were fatal within 2 days and 1150 (6%) within 1 week. The 1-month case fatality was 14% (2460 BSIs), and 23% of the deaths occurred within 2 days and 47% within 1 week. The patients who died early were older than those who survived > 28 days, and their BSIs were more often related to intensive care. Gram-positive bacteria caused over half of the BSIs of patients who survived, whereas gram-negative bacteria, especially Pseudomonas aeruginosa, caused more often BSIs of patients who died early, and fungi BSIs of patients who died within 1 week. A significant portion of patients with nosocomial BSIs died early, which underlines the importance of rapid recognition of BSI. Hospital-wide surveillance data of causative pathogens can be utilized when composing recommendations for empiric antimicrobial treatment in collaboration with clinicians, as well as when promoting infection prevention.

Global prevalence of carbapenem resistance in neutropenic patients and association with mortality and carbapenem use: systematic review and meta-analysis

Background

Carbapenem-resistant Gram-negative bacteria are recognized as a cause of difficult-to-treat infections associated with high mortality.

Objectives

To perform a systematic review of currently available data on distribution, characteristics and outcome associated with carbapenem-resistant bloodstream infections in adult neutropenic patients.

Methods

Included studies were identified through Medline, Embase and Cochrane databases between January 1995 and April 2016. Random effect meta-analysis was used to quantify the association between carbapenem resistance and mortality and between carbapenem exposure and resistance.

Results

A total of 30 studies from 21 countries were included. Overall carbapenem resistance varied from 2% to 53% (median 9%) among studies. Infections due to carbapenem-resistant Pseudomonas spp . were reported in 18 (60%) studies showing high median resistance rates (44% of all carbapenem-resistant Gram-negatives and 19% of Pseudomonas isolates). Resistance of Enterobacteriaceae was less commonly reported and bloodstream infections due to carbapenem-resistant Klebsiella spp. were mainly documented from endemic areas (Greece, Italy, Israel). Carbapenem resistance in Acinetobacter spp. was reported in 9 (30%) studies (median resistance 58% of Acinetobacter isolates). Mortality rates ranged from 33% to 71% (median 50%) in patients with carbapenem-resistant infections. Carbapenem resistance appeared to correlate with mortality (OR 4.89, 95% CI 3.30-7.26) and previous exposure to carbapenems (OR 4.63, 95% CI 3.08-6.96).

Conclusions

Carbapenem resistance represents a threat to neutropenic patients. In this group, resistance is likely promoted by previous carbapenem use and leads to high mortality rates. The knowledge of resistance patterns is crucial and can direct clinicians in the use of alternatives to carbapenem-based regimens.

Analysis of distribution and antibiotic resistance of pathogens isolated from the paediatric population in Shenmu Hospital from 2011-2015

Objective

This study aimed to investigate the epidemiology and changes in antibacterial susceptibility of children in Shenmu City, northern Shaanxi, and provide a basis for rational drug use.

Methods

The distribution and drug resistance pattern of pathogenic bacteria isolated from children were retrospectively analysed.

Results

A total of 573 strains of pathogens were cultivated. A total of 201 (35.07%) strains of Gram-positive cocci and 183 (31.93%) strains of Gram-negative cocci were detected. A total of 189 (32.98%) strains of fungi were detected. The resistance rate of Staphylococcus to penicillin was 100% and that to erythromycin was 90.69%. There were varying degrees of resistance to other drugs, but no single strain had vancomycin resistance. Gram-negative bacilli were generally resistant to ampicillin, but had low resistance to the combined preparation of enzyme inhibitors, quinolones, and aminoglycosides, and were highly sensitive to imipenem and meropenem.

Conclusion

Gram-negative bacilli are the main pathogens of bacterial infection in the paediatric ward. Strengthening clinical monitoring of bacterial distribution in paediatric clinical isolates and understanding changes in drug resistance are important for guiding the rational use of antibiotics. These measures could also prevent emergence and spreading of resistant strains.

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%).

Pretreatment gut microbiome predicts chemotherapy-related bloodstream infection

Background

Bacteremia, or bloodstream infection (BSI), is a leading cause of death among patients with certain types of cancer. A previous study reported that intestinal domination, defined as occupation of at least 30 % of the microbiota by a single bacterial taxon, is associated with BSI in patients undergoing allo-HSCT. However, the impact of the intestinal microbiome before treatment initiation on the risk of subsequent BSI remains unclear. Our objective was to characterize the fecal microbiome collected before treatment to identify microbes that predict the risk of BSI.

Methods

We sampled 28 patients with non-Hodgkin lymphoma undergoing allogeneic hematopoietic stem cell transplantation (HSCT) prior to administration of chemotherapy and characterized 16S ribosomal RNA genes using high-throughput DNA sequencing. We quantified bacterial taxa and used techniques from machine learning to identify microbial biomarkers that predicted subsequent BSI.

Results

We found that patients who developed subsequent BSI exhibited decreased overall diversity and decreased abundance of taxa including Barnesiellaceae, Coriobacteriaceae, Faecalibacterium, Christensenella, Dehalobacterium, Desulfovibrio, and Sutterella. Using machine-learning methods, we developed a BSI risk index capable of predicting BSI incidence with a sensitivity of 90 % at a specificity of 90 % based only on the pretreatment fecal microbiome.

Conclusions

These results suggest that the gut microbiota can identify high-risk patients before HSCT and that manipulation of the gut microbiota for prevention of BSI in high-risk patients may be a useful direction for future research. This approach may inspire the development of similar microbiome-based diagnostic and prognostic models in other diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-016-0301-4) contains supplementary material, which is available to authorized users.

Epigenetics: A primer for clinicians

With recent advances in cellular biology, we now appreciate that modifications to DNA and histones can have a profound impact on transcription and function, even in the absence of changes to DNA sequence. These modifications, now commonly referred to as "epigenetic" alterations, have changed how we understand cell behavior, reprogramming and differentiation and have provided significant insight into the mechanisms underlying carcinogenesis. Epigenetic alterations, to this point, are largely identified by changes in DNA methylation and hydroxymethylation as well as methylation, acetylation, and phosphorylation of histone tails. These modifications enable significant flexibility in gene expression, rather than just turning genes "ON" or "OFF." Herein we describe the epigenetic landscape in the regulation of gene expression with a particular focus on interrogating DNA methylation in myeloid malignancy.