Colonization, bloodstream infection, and mortality caused by vancomycin-resistant enterococcus early after allogeneic hematopoietic stem cell transplant

Prior colonization is associated with increased risk of antibiotic-resistant Gram-negative bacteremia in cancer patients

We hypothesized that prior colonization with antibiotic-resistant Gram-negative bacteria is associated with increased risk of subsequent antibiotic-resistant Gram-negative bacteremia among cancer patients. We performed a matched case-control study. Cases were cancer patients with a blood culture positive for antibiotic-resistant Gram-negative bacteria. Controls were cancer patients with a blood culture not positive for antibiotic-resistant Gram-negative bacteria. Prior colonization was defined as any antibiotic-resistant Gram-negative bacteria in surveillance or non-sterile-site cultures obtained 2-365 days before the bacteremia. Thirty-two (37%) of 86 cases and 27 (8%) of 323 matched controls were previously colonized by any antibiotic-resistant Gram-negative bacteria. Prior colonization was strongly associated with antibiotic-resistant Gram-negative bacteremia (odds ratio [OR] 7.2, 95% confidence interval [CI] 3.5-14.7) after controlling for recent treatment with piperacillin-tazobactam (OR 2.5, 95% CI 1.3-4.8). In these patients with suspected bacteremia, prior cultures may predict increased risk of antibiotic-resistant Gram-negative bacteremia.

Comparative cost-effectiveness of alternative empiric antimicrobial treatment options for suspected enterococcal bacteremia

OBJECTIVES

Enterococcus species are the fourth leading cause of bacteremia. Resistance rates are rising and delays in appropriate initial antimicrobial therapy have been associated with increased mortality. Empiric treatment of patients with suspected enterococcal bacteremia varies and significant cost differences exist between alternatives. The objective of this study was to determine the cost-effectiveness of various empiric treatments for patients with suspected enterococcal bacteremia.

METHODS

A decision-analytic model was constructed from the hospital perspective to assess the cost-effectiveness of alternative empiric treatment options for enterococcal bacteremia, including antimicrobials active against vancomycin-resistant enterococcus (VRE). The model was populated from available literature sources and included resistance patterns, associated mortality with early versus delayed effective treatment, and the cost of treatment. Univariate sensitivity analyses tested the robustness of the model to determine the degree to which model uncertainties influenced outcomes. We also undertook a probabilistic sensitivity analysis varying parameters in 10,000 Monte Carlo simulations.

MAIN RESULTS

The incremental cost-effectiveness ratio was $791 and $749/quality-adjusted-life-year utilizing empiric daptomycin and linezolid, respectively. The model also predicted an incremental cost/life saved of $11,703 by utilizing empiric daptomycin and $11,084 with linezolid utilization. Ampicillin was dominated (i.e., less effective and associated with increased costs) by both VRE-active agents and vancomycin. A probabilistic Monte Carlo sensitivity analysis showed that an agent with VRE activity had a 100% chance of being cost-effective at traditionally used willingness-to-pay thresholds. The decision-analytic model was sensitive to variations in E. faecium mortality and short-term postdischarge survival rates.

CONCLUSION

Results of our model showed that empiric utilization of an antimicrobial with activity against VRE may be a cost-effective option for the treatment of suspected enterococcal bacteremia when compared with vancomycin or β-lactam therapy.

Targeted therapy against multi-resistant bacteria in leukemic and hematopoietic stem cell transplant recipients: guidelines of the 4th European Conference on Infections in Leukemia (ECIL-4, 2011)

The detection of multi-resistant bacterial pathogens, particularly those to carbapenemases, in leukemic and stem cell transplant patients forces the use of old or non-conventional agents as the only remaining treatment options. These include colistin/polymyxin B, tigecycline, fosfomycin and various anti-gram-positive agents. Data on the use of these agents in leukemic patients are scanty, with only linezolid subjected to formal trials. The Expert Group of the 4(th) European Conference on Infections in Leukemia has developed guidelines for their use in these patient populations. Targeted therapy should be based on (i) in vitro susceptibility data, (ii) knowledge of the best treatment option against the particular species or phenotype of bacteria, (iii) pharmacokinetic/pharmacodynamic data, and (iv) careful assessment of the risk-benefit balance. For infections due to resistant Gram-negative bacteria, these agents should be preferably used in combination with other agents that remain active in vitro, because of suboptimal efficacy (e.g., tigecycline) and the risk of emergent resistance (e.g., fosfomycin). The paucity of new antibacterial drugs in the near future should lead us to limit the use of these drugs to situations where no alternative exists.

[Vancomycin-resistant enterococci (VRE). Recent results and trends in development of antibiotic resistance]

Enterococci (mainly E. faecalis, E. faecium) are important nosocomial pathogens predominantly affecting older and/or immunocompromised patients. The bacteria possess a broad spectrum of intrinsic and acquired antibiotic resistance properties. Among these, the transferrable glycopeptide resistance of the vanA and vanB genotypes in vancomycin-resistant enterococci (VRE; reservoir: E. faecium) as well as resistance to last resort antibiotics (e.g. linezolid and tigecycline) are of special concern. Enterococci (including VRE) are easily transferred in hospitals; however, colonizations are far more frequent than infections. Resistance frequencies for vancomycin in clinical E. faecium isolates have remained at a relatively constant level of 8-15% (but with local or regional variations) in recent years whereas frequencies for teicoplanin resistance have shown a slight decrease. Glycopeptide resistance trends correlate with a spread of hospital-associated E. faecium strains carrying the vanA and, with rising frequency in recent years, the vanB gene cluster, the latter being associated with teicoplanin susceptibility. This increased occurrence of vanB-positive E. faecium strains may be caused by an increased use of antibiotics selecting enterococci and VRE as well as due to methodological reasons (e.g. reduced EUCAST MIC-breakpoints for glycopeptides; increased use and sensitive performance of chromogenic VRE agars, increased use of molecular diagnostic assays).

Vancomycin-resistant enterococci infection: not just for the transplanted

Vancomycin-resistant enterococcal (VRE) blood stream infections (BSIs) pose significant hazards to patients with hematologic malignancy. We compared and examined VRE BSI rates, patient characteristics and clinical outcomes for two cohorts of patients: those who did and did not undergo hematopoietic cell transplant (HCT). In this single institution study, we retrospectively analyzed records of consecutive patients from 1998 through 2011. Over this 14-year period, VRE was identified in 14% of all BSIs in patients with HCT with a cumulative rate of 1.9% (48/2581 BSIs/patients). VRE was identified in 10% of all BSIs in non-HCT patients with a cumulative rate of 1.1% (35/3154 BSIs/patients). Transplant patients who developed VRE BSI tended to be younger, hospitalized more frequently, were exposed to vancomycin therapy frequently, and were more likely to have had a central venous catheter removed. VRE remains a significant cause of morbidity and mortality, as 22 deaths were directly or indirectly attributed to this infection. Both HCT and non-HCT patients are susceptible to VRE infection and are equally at risk for adverse outcomes related to VRE BSI.

Impact of vancomycin resistance on mortality in neutropenic patients with enterococcal bloodstream infection: a retrospective study

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI) is generally associated with the delayed administration of adequate antibiotics. The identification of risk factors and outcomes of VRE BSI is necessary for establishing strategies for managing neutropenic fever in patients with hematological malignancies.

METHODS

We retrospectively analysed consecutive cases of enterococcal BSI in patients with neutropenia after chemotherapy or stem cell transplantation between July 2009 and December 2011 at a single center.

RESULTS

During the 30-month period, among 1,587 neutropenic patients, the incidence rate of enterococcal BSI was 1.76 cases per 1,000 person-days. Of the 91 enterococcal BSIs, there were 24 cases of VRE. VRE BSI was associated with E. faecium infection (P < .001), prolonged hospitalization (P = .025) and delayed administration (≥ 48 hours after the febrile episode) of adequate antibiotics (P = .002). The attributable mortality was 17% and 9% for VRE and vancomycin-susceptible Enterococcus (VSE), respectively (P = .447). The 30-day crude mortality was 27% and 23% for VRE and VSE, respectively (OR 1.38, 95% CI 0.53-3.59; P = .059). Only SAPS-II was an independent predictive factor for death (adjusted OR 1.12, 95% CI 1.08-1.17; P < .001).

CONCLUSIONS

In conclusion, vancomycin resistance showed some trend towards increasing 30-day mortality, but is not statistically significant despite the delayed use of adequate antibiotics (≥48 hours). Only underlying severity of medical condition predicts poor outcome in a relatively homogeneous group of neutropenic patients.

Worldwide challenges of multidrug-resistant bacteria in patients with hematologic malignancies

SUMMARY The emergence of infections due to multidrug-resistant (MDR) bacteria poses a major public health threat to all patients, but patients with hematologic malignancies are especially at risk. A common thread across all classes of bacteria is that increased reliance on and usage of broad-spectrum antibacterial agents, combined with the intrinsic ability of bacteria to develop and transmit resistance-conferring mutations, has led to the widespread dissemination of MDR organisms. In this article, we summarize the most worrisome MDR bacteria, assess their clinical impact on patients with hematologic malignancies and outline measures that are required to mitigate this impact.

Life-threatening infection in transplant recipients

Modern post-transplant care pathways commonly encompass periods of critical care support. Infectious events account for many of these interactions making critical care physicians integral members of multidisciplinary transplant teams. Despite continuing advances in clinical care and infection prophylaxis, the morbidity and mortality attributable to infection post-transplant remains considerable. Emerging entities constantly add to the breadth of potential opportunistic pathogens. Individualized risk assessments, rapid and thorough diagnostic evaluation, and prompt initiation of appropriate antimicrobial therapies are essential. The approach to managing transplant recipients with infection in critical care is discussed and common and emerging opportunistic pathogens are reviewed.

Trends and significance of VRE colonization in the ICU: a meta-analysis of published studies

Background

The burden and significance of vancomycin-resistant enterococci (VRE) colonization in the ICU is not clearly understood.

Methods

We searched PubMed and EMBASE up to May 2013 for studies reporting the prevalence of VRE upon admission to the ICU and performed a meta-analysis to assess rates and trends of VRE colonization. We calculated the prevalence of VRE on admission and the acquisition (colonization and/or infection) rates to estimate time trends and the impact of colonization on ensuing VRE infections.

Findings

Across 37 studies (62,959 patients at risk), the estimated prevalence of VRE on admission to the ICU was 8.8% (7.1-10.6). Estimates were more consistent when cultures were obtained within 24 hours from admission. The VRE acquisition rate was 8.8% (95% CI 6.9-11.0) across 26 evaluable studies (35,364 patients at risk). Across US studies, VRE acquisition rate was 10.2% (95% CI 7.7-13.0) and demonstrated significant decline in annual trends. We used the US estimate of colonization on admission [12.3% (10.5-14.3)] to evaluate the impact of VRE colonization on admission in overall VRE prevalence. We demonstrated that VRE colonization on admission is a major determinant of the overall VRE burden in the ICU. Importantly, among colonized patients (including admitted and/or acquired cases) the VRE infection rates vary widely from 0-45% (with the risk of VRE bacteremia being reported from 0-16%) and <2% among those without a proven colonization.

Conclusion

In summary, up to 10.6% of patients admitted in the ICU are colonized with VRE on admission and a similar percentage will acquire VRE during their ICU stay. Importantly, colonization on admission is a major determinant of VRE dynamics in the ICU and the risk of VRE-related infections is close related to colonization.

Evaluation of risk factors for vancomycin-resistant Enterococcus bacteremia among previously colonized hematopoietic stem cell transplant patients

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) recipients colonized with vancomycin-resistant Enterococcus (VRE) may have an increased risk of developing VRE bacteremia. Identification of risk factors for the development of subsequent VRE bacteremia among colonized HSCT recipients is necessary to predict which patients may benefit the most from receiving anti-VRE antibiotic therapy as part of an initial antimicrobial regimen when gram-positive bacteremia is suspected.

METHODS

This study was a retrospective chart review conducted from May 2008 to May 2011. Adult HSCT patients admitted to the hospital found to have positive VRE surveillance cultures were included. A multivariate analysis was completed to identify risk factors for the development of VRE bacteremia in the study population.

RESULTS

Of 152 patients, 19 (13%) patients developed subsequent VRE bacteremia. Risk factors identified for patients with current VRE colonization for VRE bacteremia were the utilization of vancomycin subsequent to VRE surveillance culture positivity (P = 0.017), prolonged duration of neutropenia (P = 0.001), immunosuppression (P < 0.001), and timing of first VRE surveillance screen positivity at week 1 (P = 0.005). A history of VRE colonization on a prior admission was not an independent risk factor for bacteremia in HSCT patients (P = 1.0). HSCT patients with VRE bacteremia had a 30-day all-cause inpatient mortality rate of 29% (P = 0.001).

CONCLUSION

HSCT patients receiving immunosuppressive therapy, who have been exposed to vancomycin subsequent to surveillance culture positivity, have had prolonged neutropenia of >30 days, or first surveillance culture positive at week 1 of admission are potential candidates for early implementation of anti-VRE therapy when a gram-positive bacteremia is suspected.

The intestinal microbiota and susceptibility to infection in immunocompromised patients

PURPOSE OF REVIEW

Many infections of immunocompromised patients originate from the gastrointestinal tract. The pathogenesis of these infections often begins with alteration of the intestinal microbiota. Understanding the microbiota and how it can either cause or prevent infection is vital for the development of more effective prevention and treatment of these infections. This article reviews and discusses recent work providing insight into the intestinal microbiota of these at-risk immunocompromised patients.

RECENT FINDINGS

Studies continue to support the premise that commensal bacteria, largely anaerobic, serve to maintain microbial stability and colonization resistance by preventing overgrowth or domination with more pathogenic bacteria, through interactions within the microbial community and with the host. In patients with immune suppression due to high-dose chemotherapy or hematopoietic stem cell transplantation, disruption of the microbiota through antibiotics as well as impairment of host immunity gives rise to perturbations favoring intestinal domination by pathogenic species, leading to increased bacterial translocation and susceptibility to systemic infection.

SUMMARY

An understanding of the intestinal microbiota and the impact of antibiotics will help to guide our treatment of these gut-originating infections.

Systematic review and meta-analysis of linezolid and daptomycin for treatment of vancomycin-resistant enterococcal bloodstream infections

Bloodstream infections due to vancomycin-resistant enterococci (VRE-BSI) result in substantial patient mortality and cost. Daptomycin and linezolid are commonly prescribed for VRE-BSI, but there are no clinical trials to determine optimal antibiotic selection. We conducted a systematic review for investigations that compared daptomycin and linezolid for VRE-BSI. We searched Medline from 1966 through 2012 for comparisons of linezolid and daptomycin for VRE-BSI. We included searches of EMBASE, clinicaltrials.gov, and national meetings. Data were extracted using a standardized instrument. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using a fixed-effects model. Our search yielded 4,243 publications, of which 482 contained data on VRE treatment. Most studies (452/482) did not present data on BSI or did not provide information on linezolid or daptomycin. Among the remaining 30 studies, 9 offered comparative data between the two agents. None were randomized clinical trials. There was no difference in microbiologic (n = 5 studies, 517 patients; OR, 1.0; 95% CI, 0.4 to 1.7; P = 0.95) and clinical (n = 3 studies, 357 patients; OR, 1.2; 95% CI, 0.7 to 2.0; P = 0.7) cures between the two antibiotics. There was a trend toward increased survival with linezolid compared to daptomycin treatment (n = 9 studies, 1,074 patients; OR, 1.3; 95% CI, 1.1 to 1.8; I(2) = 0 [where I(2) is a measure of inconsistency]), but this did not reach statistical significance (P = 0.054). There are limited data to inform clinicians on optimal antibiotic selection for VRE-BSI. Available studies are limited by small sample size, lack of patient-level data, and inconsistent outcome definitions. Additional research, including randomized clinical trials, is needed before conclusions can be drawn about treatment options for VRE therapy.

Treatment considerations in vancomycin-resistant enterococcal bacteremia: daptomycin or linezolid? A review

BACKGROUND

Vancomycin resistant enterococcal bloodstream infections are an important cause of morbidity and mortality in hospitalized patients.

AIM OF THE REVIEW

A search of the literature was undertaken to determine the optimal antimicrobial therapy for the management of vancomycin resistant enterococcal bloodstream infections.

METHOD

MEDLINE, EMBASE, and the Cochrane Library (unrestricted to time or language) were searched for studies of vancomycin resistant enterococcal bloodstream infections in adults reporting outcomes of direct comparisons of linezolid versus daptomycin on November 26, 2012. Studies of basic science, reviews, commentaries, pharmacologic, epidemiologic, or pediatric studies, and those studies examining conditions other than enterococcal bacteremia, a single antimicrobial agent or other antimicrobials were excluded.

RESULTS

226 studies were screened for eligibility and yielded eight studies evaluating a total of 807 patients. Inter-rater agreement was 100 %. Qualitative evaluation of the studies was performed using the Newcastle-Ottawa scale. No randomized controlled trials were identified. All studies were retrospective cohorts and non-randomized. 458 (57 %) patients treated with linezolid and 349 (43 %) with daptomycin were analyzed. Variable comorbidities and severity of illness were described in the included studies and reported here for comparison.

CONCLUSION

The optimal treatment of vancomycin resistant enterococcal bloodstream infections is yet to be determined. Well-designed prospective studies are needed to lend more convincing evidence regarding choice of antimicrobial therapy for this important multidrug resistant organism.

Recent changes in bacteremia in patients with cancer: a systematic review of epidemiology and antibiotic resistance

Bacteremia remains a major cause of life-threatening complication in patients with cancer. Significant changes in the spectrum of microorganisms isolated from blood culture have been reported in cancer patients over the past years. The aim of our systematic review was to inventory the recent trends in epidemiology and antibiotic resistance of microorganisms causing bacteremia in cancer patients. Data for this review was identified by searches of Medline, Scopus and Cochrane Library for indexed articles and abstracts published in English since 2008. The principal search terms were: "antimicrobial resistance", "bacteremia", "bacterial epidemiology", "bloodstream infection", "cancer patients", "carbapenem resistance", "Escherichia coli resistance", "extended-spectrum β-lactamase producing E. coli", "febrile neutropenia", "fluoroquinolone resistance", "neutropenic cancer patient", "vancomycin-resistant Enterococcus", and "multidrug resistance". Boolean operators (NOT, AND, OR) were also used in succession to narrow and widen the search. Altogether, 27 articles were selected to be analyzed in the review. We found that Gram-negative bacteria were the most frequent pathogen isolated, particularly in studies with minimal use of antibiotic prophylaxis. Another important trend is the extensive emergence of antimicrobial-resistant strains associated with increased risk of morbidity, mortality and cost. This increasing incidence of antibiotic resistance has been reported in Gram-negative bacteria as well as in Gram-positive bacteria. This exhaustive review, reporting the recent findings in epidemiology and antibiotic resistance of bacteremia in cancer patients, highlights the necessity of local continuous surveillance of bacteremia and stringent enforcement of antibiotic stewardship programs in cancer patients.

Evaluation and Management of Bacterial and Fungal Infections Occurring in Patients with a Hematological Malignancy: A 2011 Update

Patients with a hematological malignancy are a heterogeneous patient population who are afflicted with diseases that range from rapidly fatal acute leukemia to indolent lymphoma or chronic leukemia. Treatment options for these patients range from observation to hematopoietic stem cell transplantation (HSCT), but all patients are more susceptible to infection. The problem of infection is dynamic with continued shifts in pathogenic organisms and microbial susceptibilities, new treatment regimens that further diminish immune function, and patients receiving treatment who are now older and frailer. The classic patterns of immunodeficiency for patients with a hematological malignancy include: periods of profound neutropenia, increased iatrogenic risks (i.e., central vascular catheters), and cellular immune suppression that affects HSCT recipients, patients with lymphoid malignancies, and those receiving treatment with corticosteroids or agents like alemtuzumab [1–4]. Recent advances in antimicrobial drug development, new technology, clinical trial results, and further clinical experience have enhanced the database on which to make infection prophylaxis and treatment decisions. However, the practicing clinician must remember that the majority of basic infection management principles for patients who are neutropenic remain unchanged.

Using antimicrobial adjuvant therapy in cancer treatment: a review

Recent clinical and pre-clinical data demonstrate that adjuvant antimicrobial therapy is beneficial in cancer treatment. There could be several reasons for this effect, which include treating cancer associated bacteria and viruses, prophylaxis of post-chemotherapy infections due to immunosuppression, and antiproliferative effect of certain antimicrobials. Targeting cancer associated viruses and bacteria with antimicrobial agents is currently used for gastric, cervical, hematopoietic, liver and brain cancer. However this treatment is effective only in combination with conventional therapies. Antimicrobials can also have a direct antiproliferative and cytotoxic effect, and can cause apoptosis. Moreover, some antimicrobials are known to be helpful in overcoming side effects of drugs commonly used in cancer treatment. Chemotherapy related bacteremia and neutropenia can be overcome by the appropriately timed use of antimicrobials. This review summarizes the data on the effects of antivirals and antibiotics on cancer treatment and describes their mechanisms.

T cell-depleted stem cell transplantation for adults with high-risk acute lymphoblastic leukemia: long-term survival for patients in first complete remission with a decreased risk of graft-versus-host disease

Consolidation with allogeneic hematopoietic stem cell transplantation (allo-HSCT) provides a survival benefit to patients with acute lymphoblastic leukemia (ALL). We have previously reported comparable survival and relapse rates after T cell-depleted (TCD) allo-HSCT compared with unmodified transplantations for acute myelogenous leukemia, myelodysplastic syndrome, and non-Hodgkin lymphoma with significantly decreased graft-versus-host disease (GVHD). We performed a 56-patient retrospective study to evaluate TCD allo-HSCT for the treatment of ALL after myeloablative total body irradiation-based therapy. The 2-year and 5-year overall survival rates for patients with ALL after TCD allo-HSCT were 0.39 (95% confidence interval [CI], 0.26-0.52) and 0.32 (95% CI, 0.19-0.44), respectively, and the 2-year and 5-year disease-free survival rates were 0.38 (95% CI, 0.25-0.50) and 0.32 (95% CI, 0.20-0.44). There was a trend toward improved survival of patients who underwent TCD allo-HSCT in first complete remission compared with those who did so in other remission states. The cumulative incidence of grade II-IV acute GVHD at 1 year was 0.20 (95% CI, 0.10-0.31), and no patients developed grade IV acute GVHD. The cumulative incidence of chronic GVHD in 41 evaluable patients at 2 and 5 years was 0.15 (95% CI, 0.04-0.26), and that of extensive chronic GVHD at 2 and 5 years was 0.05 (95% CI, 0-11.6). We demonstrate OS and DFS rates that compare favorably to unmodified allo-HSCT with lower rates of GVHD.

Performance characteristics of the Cepheid Xpert vanA assay for rapid identification of patients at high risk for carriage of vancomycin-resistant Enterococci

We compared the performance characteristics of culture and the Cepheid Xpert vanA assay for routine surveillance of vancomycin-resistant enterococci (VRE) from rectal swabs in patients at high risk for VRE carriage. The Cepheid Xpert vanA assay had a limit of detection of 100 CFU/ml and correctly detected 101 well-characterized clinical VRE isolates with no cross-reactivity in 27 non-VRE and related culture isolates. The clinical sensitivity, specificity, positive predictive value, and negative predictive value of the Xpert vanA PCR assay were 100%, 96.9%, 91.3%, and 100%, respectively, when tested on 300 consecutively collected rectal swabs. This assay provides excellent predictive values for prompt identification of VRE-colonized patients in hospitals with relatively high rates of VRE carriage.

Intestinal domination and the risk of bacteremia in patients undergoing allogeneic hematopoietic stem cell transplantation

BACKGROUND

Bacteremia is a frequent complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). It is unclear whether changes in the intestinal microbiota during allo-HSCT contribute to the development of bacteremia. We examined the microbiota of patients undergoing allo-HSCT, and correlated microbial shifts with the risk of bacteremia.

METHODS

Fecal specimens were collected longitudinally from 94 patients undergoing allo-HSCT, from before transplant until 35 days after transplant. The intestinal microbiota was characterized by 454 pyrosequencing of the V1-V3 region of bacterial 16S ribosomal RNA genes. Microbial diversity was estimated by grouping sequences into operational taxonomic units and calculating the Shannon diversity index. Phylogenetic classification was obtained using the Ribosomal Database Project classifier. Associations of the microbiota with clinical predictors and outcomes were evaluated.

RESULTS

During allo-HSCT, patients developed reduced diversity, with marked shifts in bacterial populations inhabiting the gut. Intestinal domination, defined as occupation of at least 30% of the microbiota by a single predominating bacterial taxon, occurred frequently. Commonly encountered dominating organisms included Enterococcus, Streptococcus, and various Proteobacteria. Enterococcal domination was increased 3-fold by metronidazole administration, whereas domination by Proteobacteria was reduced 10-fold by fluoroquinolone administration. As a predictor of outcomes, enterococcal domination increased the risk of Vancomycin-resistant Enterococcus bacteremia 9-fold, and proteobacterial domination increased the risk of gram-negative rod bacteremia 5-fold.

CONCLUSIONS

During allo-HSCT, the diversity and stability of the intestinal flora are disrupted, resulting in domination by bacteria associated with subsequent bacteremia. Assessment of fecal microbiota identifies patients at highest risk for bloodstream infection during allo-HCST.

Enterococcal bacteremia is associated with increased risk of mortality in recipients of allogeneic hematopoietic stem cell transplantation

BACKGROUND

Enterococci are an important cause of healthcare-associated infections. We retrospectively analyzed risk factors and outcome of vancomycin-resistant enterococci (VRE) and vancomycin-sensitive enterococci (VSE) infections.

METHODS

Seven hundred fifty-two patients who received hematopoietic stem cell transplants from 2004 through 2008 at the University of Minnesota were included.

RESULTS

Ninety-three patients had enterococcal bloodstream infection (BSI) during the first year after transplant. Vancomycin resistance was observed in 66% and 31% of isolates in adults and children, respectively. Cumulative incidence of VRE and VSE bacteremia was 6.6% (95% confidence interval [CI], 4.8%-8.4%) and 5.7% (95% CI, 4.0%-7.4%), respectively. Colonization with VRE before or after transplant was a risk factor for VRE bacteremia (odds ratio [OR], 3.3 [95% CI, 1.3-8.3] and 7.0 [95% CI, 4.0-14.8], respectively). Delay in engraftment increased the incidence of VRE bacteremia from 4.5% (95% CI, 2.9-6.6) if engrafted before day 21 and to 15% (95% CI, 3.2%-38%) if engrafted between days 36 and 42. In adults, mortality 30 days after infection was 38% for both VRE (95% CI, 25%-54%) and VSE cases (95% CI, 21%-62%). The hazard ratio for all-cause mortality up to 1 year after transplant was 4.2 (95% CI, 3.1-6.9) and 2.7 (95% CI, 1.4-5.1) for patients with VRE and VSE BSIs, respectively, compared to patients without enterococcal BSI. In pediatric patients, mortality 30 days after VRE and VSE bacteremia was 20% (95% CI, 5.4%-59%) and 4.5% (95% CI, .6%-28%), respectively.

CONCLUSION

High rates of vancomycin resistance and association of enterococcal infections with significant mortality warrant further efforts to optimize prevention and management of these infections.

Serious infection risk and immune recovery after double-unit cord blood transplantation without antithymocyte globulin

Factors contributing to infection risk after cord blood transplantation (CBT) include the use of anti-thymocyte globulin (ATG), prolonged neutropenia, and failure to transfer immunity. In the present study, we investigated the potential of double-unit CBT without ATG to reduce the risk of infection and evaluated the nature of serious infections in the first year after CBT using this approach. Seventy-two predominantly adult patients underwent CBT for hematologic malignancies; of these, 52 patients received myeloablative conditioning, and 20 received nonmyeloablative conditioning. The peak incidences of bacterial infections (32%), fungal infections (14%), and bacterial/fungal pneumonias (10%) occurred in the first 30 days posttransplantation. Three such infections contributed to early mortality. The peak incidence of viral infections was 31-60 days posttransplantation, affecting 30% of patients. Cytomegalovirus (CMV) was the most common viral infection. CMV infections occurring before day 120 (n = 23) had no relationship with graft-versus-host disease (GVHD), whereas CMV infections occurring after day 120 (n = 5), along with all cases of Epstein-Barr virus viremia (n = 5) and adenoviral enteritis (n = 2), occurred exclusively in the context of GVHD therapy or corticosteroid use for another indication. Viral infections had the highest lethality: 2 were a direct cause of death, and 3 contributed to death. Patients exhibited steady immune recovery, achieving a median CD3(+)4(+) T cell count >200 cells/μL by day 120 post-CBT, and no infection-related deaths occurred after day 120. Our results suggest that double-unit CBT without ATG is associated with prompt T cell recovery, and, unlike in CBT incorporating ATG, infection is rarely a primary cause of death. However, CBT without ATG is associated with a significant risk of GVHD, and serious infections remain a challenge, especially in the setting of GVHD. New strategies are needed to further reduce infectious complications after CBT; these will require earlier neutrophil recovery and more effective prevention of GVHD, ideally without the profound T cell depletion associated with ATG therapy.

Molecular epidemiology and risk factors for colonization by vancomycin-resistant Enterococcus in patients with hematologic malignancies

OBJECTIVE

To study the molecular epidemiology of vancomycin-resistant Enterococcus (VRE) colonization and to identify modifiable risk factors among patients with hematologic malignancies.

SETTING

A hematology-oncology unit with high prevalence of VRE colonization.

PARTICIPANTS

Patients with hematologic malignancies and hematopoietic stem cell transplantation recipients admitted to the hospital.

METHODS

Patients underwent weekly surveillance by means of perianal swabs for VRE colonization and, if colonized, were placed in contact isolation. We studied the molecular epidemiology in fecal and blood isolates by pulsed-field gel electrophoresis over a 1-year period. We performed a retrospective case-control study over a 3-year period. Cases were defined as patients colonized by VRE, and controls were defined as patients negative for VRE colonization. Case patients and control patients were matched by admitting service and length of observation time.

RESULTS

Molecular genotyping demonstrated the primarily polyclonal nature of VRE isolates. Colonization occurred at a median of 14 days. Colonized patients were characterized by longer hospital admissions. Previous use of ceftazidime was associated with VRE colonization (P < .001), while use of intravenous vancomycin and antibiotics with anaerobic activity did not emerge as a risk factor. There was no association with neutropenia or presence of colonic mucosal disruption, and severity of illness was similar in both groups.

CONCLUSION

Molecular studies showed that in the majority of VRE-colonized patients the strains were unique, arguing that VRE acquisition was sporadic rather than resulting from a common source of transmission. Patient-specific factors, including prior antibiotic exposure, rather than breaches in infection control likely predict for risk of fecal VRE colonization.

Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the infectious diseases society of america

This document updates and expands the initial Infectious Diseases Society of America (IDSA) Fever and Neutropenia Guideline that was published in 1997 and first updated in 2002. It is intended as a guide for the use of antimicrobial agents in managing patients with cancer who experience chemotherapy-induced fever and neutropenia. Recent advances in antimicrobial drug development and technology, clinical trial results, and extensive clinical experience have informed the approaches and recommendations herein. Because the previous iteration of this guideline in 2002, we have a developed a clearer definition of which populations of patients with cancer may benefit most from antibiotic, antifungal, and antiviral prophylaxis. Furthermore, categorizing neutropenic patients as being at high risk or low risk for infection according to presenting signs and symptoms, underlying cancer, type of therapy, and medical comorbidities has become essential to the treatment algorithm. Risk stratification is a recommended starting point for managing patients with fever and neutropenia. In addition, earlier detection of invasive fungal infections has led to debate regarding optimal use of empirical or preemptive antifungal therapy, although algorithms are still evolving. What has not changed is the indication for immediate empirical antibiotic therapy. It remains true that all patients who present with fever and neutropenia should be treated swiftly and broadly with antibiotics to treat both gram-positive and gram-negative pathogens. Finally, we note that all Panel members are from institutions in the United States or Canada; thus, these guidelines were developed in the context of North American practices. Some recommendations may not be as applicable outside of North America, in areas where differences in available antibiotics, in the predominant pathogens, and/or in health care-associated economic conditions exist. Regardless of venue, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection.

Comparison of outcomes from daptomycin or linezolid treatment for vancomycin-resistant enterococcal bloodstream infection: A retrospective, multicenter, cohort study

BACKGROUND

The optimal treatment for bloodstream infections (BSIs) with vancomycin-resistant enterococci (VRE) is unknown.

OBJECTIVE

This study examined outcomes in patients treated with daptomycin or linezolid for VRE BSI.

METHODS

A retrospective, multicenter, cohort study was performed via chart review. Hospitalized patients treated for VRE BSI with daptomycin or linezolid from September 1, 2003, to June 30, 2007, were identified via pharmacy and microbiology reports at each institution. Patients aged <18 years or with polymicrobial bacteremia were excluded from analysis. Linezolid and daptomycin were included because the participating institutions used either of the 2 agents as first-line treatment for VRE BSI. Univariate and multivariate analyses were performed to determine the effect of drug selection on mortality and duration of BSI. Duration of BSI was defined as the amount of time from the draw date of the first positive blood culture to the draw date of the first finalized negative blood culture. Adverse events were not assessed.

RESULTS

One-hundred one patients from 3 participating US hospitals experiencing VRE BSI were identified. Sixty-seven patients were treated with daptomycin and 34 with linezolid. Baseline characteristics appeared comparable between the daptomycin- and linezolidtreated groups, with the exception of shock (P = 0.049), prior vancomycin treatment (P = 0.002), and prior linezolid treatment (P < 0.001), all of which occurred significantly more often in daptomycin-treated patients. Inpatient mortality occurred in 31 daptomycin- and 10 linezolid-treated patients (46.3% vs 29.4%; P = NS). Linear regression found that shock (P = 0.015), infective endocarditis (P = 0.021), and concurrent rifampin or gentamicin treatment (P = 0.01) were associated with prolonged duration of positive cultures. Logistic regression revealed that shock (odds ratio [OR] = 14.24; P = 0.008), infection with Enterococcus faecium (OR = 53.10; P = 0.024), previous linezolid treatment (OR = 6.63; P = 0.031), concurrent rifampin or gentamicin treatment (OR = 6.48; P = 0.046), and a nonline source of infection (OR = 6.67; P = 0.019) were associated with increased mortality.

CONCLUSIONS

In this retrospective cohort analysis, there were no significant differences in mortality of VRE BSI between patients receiving daptomycin or linezolid. Underlying comorbidities appeared to best predict outcome; however, given the retrospective nature of this study, larger, prospective, randomized, comparative studies are needed to control for potential biases and determine definitive outcome differences between these 2 antimicrobials.

Executive Summary: Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer: 2010 Update by the Infectious Diseases Society of America

This document updates and expands the initial Infectious Diseases Society of America (IDSA) Fever and Neutropenia Guideline that was published in 1997 and first updated in 2002. It is intended as a guide for the use of antimicrobial agents in managing patients with cancer who experience chemotherapy-induced fever and neutropenia.

Recent advances in antimicrobial drug development and technology, clinical trial results, and extensive clinical experience have informed the approaches and recommendations herein. Because the previous iteration of this guideline in 2002, we have a developed a clearer definition of which populations of patients with cancer may benefit most from antibiotic, antifungal, and antiviral prophylaxis. Furthermore, categorizing neutropenic patients as being at high risk or low risk for infection according to presenting signs and symptoms, underlying cancer, type of therapy, and medical comorbidities has become essential to the treatment algorithm. Risk stratification is a recommended starting point for managing patients with fever and neutropenia. In addition, earlier detection of invasive fungal infections has led to debate regarding optimal use of empirical or preemptive antifungal therapy, although algorithms are still evolving.

What has not changed is the indication for immediate empirical antibiotic therapy. It remains true that all patients who present with fever and neutropenia should be treated swiftly and broadly with antibiotics to treat both gram-positive and gram-negative pathogens.

Finally, we note that all Panel members are from institutions in the United States or Canada; thus, these guidelines were developed in the context of North American practices. Some recommendations may not be as applicable outside of North America, in areas where differences in available antibiotics, in the predominant pathogens, and/or in health care–associated economic conditions exist. Regardless of venue, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection.

Outcomes of therapy: vancomycin-resistant enterococcal bacteremia in hematology and bone marrow transplant patients

PURPOSE

The purpose of this study was to evaluate the risk factors associated with the treatment failure and 30-day mortality in hematology and bone marrow transplant patients treated with daptomycin or linezolid for vancomycin-resistant enterococci (VRE) bacteremia. The safety and tolerability of therapy was also assessed.

METHODS

This single-center, retrospective study included adult patients admitted to the hematology or bone marrow transplant service with documented vancomycin-resistant Enterococcus faecium or Enterococcus faecalis bacteremia and received at least 48 h of either linezolid or daptomycin as primary treatment. Clinical and microbiologic outcomes were assessed at day 7, 14, and 30 of hospital stay.

RESULTS

A total of 72 patients were included in the analysis. Forty-three patients received daptomycin as primary treatment and 29 received linezolid as primary treatment. Overall success rate at day 7 was 81.9%, day 14 success rate was 79.2%, and day 30 success rate was 76.4% for all patients. Forty-one patients (57.0%) had high-grade bacteremia defined as greater than one positive blood culture for VRE. The mortality rate was significantly higher if high-grade bacteremia was present (34.1% vs. 7.0%; p = 0.009).

CONCLUSIONS

This study suggests that linezolid and daptomycin are both reasonable options for treating VRE bacteremia in hematology and bone marrow transplant patients; however, patients with high-grade VRE bacteremia may be at increased risk for treatment failure.

Vancomycin-resistant Enterococcus domination of intestinal microbiota is enabled by antibiotic treatment in mice and precedes bloodstream invasion in humans

Bloodstream infection by highly antibiotic-resistant bacteria, such as vancomycin-resistant Enterococcus (VRE), is a growing clinical problem that increasingly defies medical intervention. Identifying patients at high risk for bacterial sepsis remains an important clinical challenge. Recent studies have shown that antibiotics can alter microbial diversity in the intestine. Here, we characterized these effects using 16s rDNA pyrosequencing and demonstrated that antibiotic treatment of mice enabled exogenously administered VRE to efficiently and nearly completely displace the normal microbiota of the small and large intestine. In the clinical setting, we found that intestinal domination by VRE preceded bloodstream infection in patients undergoing allogeneic hematopoietic stem cell transplantation. Our results demonstrate that antibiotics perturb the normal commensal microbiota and set the stage for intestinal domination by bacteria associated with hospital-acquired infections. Thus, high-throughput DNA sequencing of the intestinal microbiota could identify patients at high risk of developing bacterial sepsis.

Characterization of bacterial infections in allogeneic hematopoietic stem cell transplant recipients who received prophylactic levofloxacin with either penicillin or doxycycline

OBJECTIVE

To describe the effect of a combination prophylactic regimen of levofloxacin, a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class, with either penicillin or doxycycline on the changing epidemiology of bacterial infections and antimicrobial resistance patterns of isolated organisms in the allogeneic hematopoietic stem cell transplant (HSCT) patient population.

PATIENTS AND METHODS

We conducted a single-center, retrospective cohort study of all allogeneic HSCT recipients from January 1, 2003, through August 31, 2008, who received prophylactic levofloxacin in combination with penicillin (or with doxycycline in penicillin-allergic patients) from allogeneic stem cell infusion until neutrophil engraftment.

RESULTS

Of the 258 patients who underwent allogeneic HSCT during the study period, 231 received levofloxacin prophylaxis, 76 (33%) of whom developed an infection within 3 months after transplant. Over time, the ratio of gram-positive to gram-negative (GN) infections decreased from 2.11 in 2004, the first year that GN organisms were isolated, to 1.11 in 2008 (P=.20). Emergence of fluoroquinolone-resistant GN bacteria was observed (P=.02), whereas resistance to extended-spectrum beta-lactams did not change over time. Combined vancomycin-resistant enterococci colonization and infection rates increased during the study period (P=.04). Clostridium difficile colitis was uncommon.

CONCLUSION

Levofloxacin with penicillin or doxycycline prophylaxis may contribute to the emergence of resistant GN infections in allogeneic HSCT recipients over time. Our findings provide additional support for the current standard of practice of administering empiric monotherapy with an antipseudomonal beta-lactam if these patients develop fever or are suspected to have an infection.

A potential role for daptomycin in enterococcal infections: what is the evidence?

Nosocomial infections caused by enterococci present a challenge for clinicians because treatment options are often limited due to the widespread occurrence of strains resistant to multiple antibiotics, including vancomycin. Daptomycin is a first-in-class cyclic lipopeptide that has proven efficacy for the treatment of Gram-positive infections. Although methicillin-resistant Staphylococcus aureus has been the most prominent target in the clinical development of daptomycin, this agent has demonstrated potent bactericidal activity in enterococcal infection models and has been used for the treatment of enterococcal infections in humans. In recent years, large-scale susceptibility studies have shown that daptomycin is active against >98% of enterococci tested, irrespective of their susceptibility to other antibacterial agents. This lack of cross-resistance reflects the fact that daptomycin has a mode of action distinct from those of other antibiotics, including glycopeptides. While there are limited data available from randomized controlled trials, extensive clinical experience with daptomycin in enterococcal infections (including bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and urinary tract infections) has been reported. This growing body of evidence provides useful insights regarding the efficacy of daptomycin against enterococci in clinical settings.

The changing epidemiology of vancomycin-resistant Enterococcus (VRE) bacteremia in allogeneic hematopoietic stem cell transplant (HSCT) recipients

The impact of the rising prevalence of vancomycin-resistant Enterococcus (VRE) prior to hematopoietic stem cell transplantation (HSCT) and changes in transplant techniques on risk of VREB (VRE bacteremia) early after HSCT is not known. This is a retrospective study of 247 adult patients who underwent allogeneic HSCT in the years 2008 and 2009 at the Memorial Sloan-Kettering Cancer Center. Sixty-eight of 247 (27.5%) patients were VRE colonized on pretransplant screening. VRE was the leading cause of bacteremia in the first 30 days after HSCT; 23 of 43 (53.5%) patients with positive blood cultures had VRE. Only 13 (57%) of the 23 patients with early VREB were colonized with VRE on pre-HSCT screening cultures. Mortality was directly attributable to VRE infection in 9% of patients with early VREB. VRE is emerging as the most common cause of preengraftment bacteremia in patients undergoing allogeneic HSCT, and is associated with substantial mortality. Pre-HSCT screening for VRE with stool cultures will not identify all patients who are at risk for VREB. The use of alternate agents with activity against Gram-positive bacteria for fever and neutropenia early after HSCT should be evaluated further in prospective studies.

Outcomes of invasive infection due to vancomycin-resistant Enterococcus faecium during a recent outbreak

BACKGROUND

Earlier reports have shown a high mortality of invasive infection due to vancomycin-resistant Enterococcus faecium (VREF). Most of these studies have been conducted in US hospitals prior to the advent of newer VREF-active antimicrobials, and the reported poor outcomes have been explained by the limited choices for effective antimicrobial therapy.

PATIENTS AND METHODS

A total of 25 cases of invasive VREF infection were seen during an outbreak in a tertiary care hospital. Patient characteristics and outcomes were evaluated by a structured retrospective chart review and descriptive analysis.

RESULTS

Severe underlying diseases such as leukemia not in remission (86%) were highly prevalent among patients with invasive VREF infection. Fifty-two percent of underlying diseases and/or comorbidities were considered according to the McCabe classification as rapidly fatal. Most patients had received high-dose cytotoxic chemotherapy, and many were neutropenic at the onset of VREF infection. Concomitant infection due to other organisms was found in 48% of the patients. All patients had received extensive antibiotic treatment prior to the onset of VREF infection. Resistance to linezolid was observed in four cases. Overall survival at day 30 was 48%. Four deaths were considered to be directly related to VREF infection.

CONCLUSION

Invasive VREF infection during this outbreak was confined to patients with severe underlying comorbidity. The mortality of VREF infection remained high, despite treatment with newer VREF-active antibiotics such as linezolid and quinupristin-dalfopristin.

Incidence of vancomycin-resistant enterococci (VRE) infection in high-risk febrile neutropenic patients colonized with VRE

PURPOSE

This study seeks to determine the incidence of vancomycin-resistant enterococci (VRE) infection in high-risk neutropenic fever patients colonized with VRE and to determine patient characteristics associated with VRE infection.

METHODS

We conducted a retrospective, single-center, unmatched case-control study. Fifty-three VRE-colonized, high-risk patients with neutropenic fever were identified between January 2006 and February 2009. The two most common diagnoses/conditions included acute myeloid leukemia and hematopoietic stem cell transplantation. Data collected included days of neutropenia, days of fever, demographic data, culture results, and antimicrobial therapy.

RESULTS

Twenty of the 53 patients (38%) with VRE colonization developed a VRE infection. The most common VRE infections were bacteremias (26%). The presence of neutropenia lasting longer than 7 days was associated with the development of VRE infection in this high-risk population colonized with VRE. The timeframe to develop VRE infection varied from 1 day to 2 weeks.

CONCLUSION

For patients colonized with VRE, approximately 38% of high-risk neutropenic patients developed a VRE infection. This is the first study to specifically evaluate the incidence of VRE infections in febrile neutropenic patients colonized with VRE. Future research into the use and efficacy of empiric VRE coverage is needed.

Neutropenic fever syndromes in patients undergoing cytotoxic therapy for acute leukemia and myelodysplastic syndromes

Fever represents the major surrogate of infection in neutropenic cancer patients. A number of neutropenic fever syndromes have been recognized, the causes and significance of which will vary depending upon the clinical context. First neutropenic fever syndromes are typically of bacterial origin, the character of which may be influenced by whether antibacterial chemoprophylaxis has been administered. Persistent neutropenic fevers are documented during the empirical systemic antibacterial therapy for the first neutropenic fever, the cause of which is likely outside the spectrum of activity of the initial therapy. Recrudescent neutropenic fevers, defined by the appearance of a new fever after defervescence of the first fever, are often a function of invasive fungal infection or gram-positive infections outside the spectrum of the initial empirical antibacterial regimen. The myeloid reconstitution syndrome occurs in parallel with neutrophil recovery from aplasia and may not necessarily represent new infection. Recognition of these patterns can help the clinician make better clinical judgments and management plans.

Linezolid for patients with neutropenia: are bacteriostatic agents appropriate?

A long-held doctrine is that bactericidal antibiotics are required for infections in neutropenic patients. We evaluated the available published evidence regarding the role of linezolid, a bacteriostatic antibiotic, in neutropenic patients with Gram-positive infection. We retrieved two prospective comparative studies (one of them a double-blind, randomized, controlled trial), a prospective cohort study, two retrospective studies and eight case reports that focused on the use of linezolid for Gram-positive bacterial infections in neutropenic patients. Linezolid was administered to 438 neutropenic patients, mainly on a compassionate-use basis, as other antibiotics failed to cure the infection or were associated with significant adverse events. The clinical cure rate ranged between 57 and 87.3% in the intention-to-treat population of the prospective studies. In total, 56 out of 438 (12.7%) neutropenic patients that received linezolid died during therapy. In the only randomized controlled trial that compared linezolid with vancomycin in the treatment of Gram-positive infections in neutropenic patients, mortality was 5.6 versus 7.6%, respectively (p = 0.4). In conclusion, the available evidence suggests that linezolid may be successful in a significant proportion of neutropenic patients with infection, despite the fact that it is a bacteriostatic agent. Such data seem to justify further studies regarding the role of linezolid in this patient population.

Daptomycin for the treatment of enterococcal bacteraemia: results from the Cubicin Outcomes Registry and Experience (CORE)

Enterococcal infections are a common cause of nosocomial bloodstream infections. Vancomycin resistance and the emergence of linezolid resistance necessitate alternative therapies. Studies in vitro as well as animal and case studies suggest that daptomycin may be effective in enterococcal infections. Patients with positive blood cultures for enterococci in the Cubicin((R)) Outcomes Registry and Experience (CORE) 2005-2006 were identified. Patients with endocarditis, intracardiac foreign body infections or non-speciated enterococci were excluded. Outcome was assessed using protocol-defined criteria. Of 159 patients included in the efficacy population, Enterococcus faecium and Enterococcus faecalis were isolated in 120 (75.5%) and 39 (24.5%) patients, respectively. Vancomycin resistance was detected in 91% and 23% of patients with E. faecium and E. faecalis infections, respectively. Prior to daptomycin, 94/159 (59.1%) and 35/159 (22.0%) patients had received vancomycin and linezolid, respectively. Daptomycin was first-line therapy in 27/159 cases (17%). Success was observed in 139/159 patients (87%) and in 104/120 (87%) and 35/39 (90%) patients with E. faecium and E. faecalis infections, respectively. Among the safety population (n=211), 20 (9.5%) experienced 28 adverse events possibly related to daptomycin, 8 of which were considered serious. Daptomycin may be a useful agent for treating enterococcal bacteraemia caused by E. faecium or E. faecalis. Further studies are warranted.

Bloodstream infections in haematology: risks and new challenges for prevention

Bloodstream infections are an important cause of morbidity and mortality in the haematology population, and may contribute to delayed administration of chemotherapy, increased length of hospitalisation, and increased healthcare expenditure. For gram-positive, gram-negative, anaerobic and fungal infections, specific risk factors are recognised. Unique host and environmental factors contributing to pathogenesis are acknowledged in this population. Trends in spectrum and antimicrobial susceptibility of pathogens are examined, and potential contributing factors are discussed. These include the widespread use of empiric antimicrobial therapy, increasingly intensive chemotherapeutic regimens, frequent use of central venous catheters, and local infection control practices. In addition, the risks and benefits of prophylaxis, and spectrum of endemic flora are identified as relevant factors within individual centres. Finally, challenges are presented regarding prevention, early detection, surveillance and prophylaxis. To reduce the rate and impact of bloodstream infections multifaceted and customised strategies are required within individual haematology units.