A population-based investigation of invasive vancomycin-resistant Enterococcus infection in metropolitan Atlanta, Georgia, and predictors of mortality

Does Vancomycin Resistance Increase Mortality? Clinical Outcomes and Predictive Factors for Mortality in Patients with Enterococcus faecium Infections

The prevalence of enterococcal infection, especially E. faecium, is increasing, and the issue of the impact of vancomycin resistance on clinical outcomes is controversial. This study aimed to investigate the clinical outcomes of infection caused by E. faecium and determine the risk factors associated with mortality. This retrospective study was performed at the Phramongkutklao Hospital during the period from 2014 to 2018. One hundred and forty-five patients with E. faecium infections were enrolled. The 30-day and 90-day mortality rates of patients infected with vancomycin resistant (VR)-E. faecium vs. vancomycin susceptible (VS)-E. faecium were 57.7% vs. 38.7% and 69.2% vs. 47.1%, respectively. The median length of hospitalization was significantly longer in patients with VR-E. faecium infection. In logistic regression analysis, VR-E. faecium, Sequential Organ Failure Assessment (SOFA) scores, and bone and joint infections were significant risk factors associated with both 30-day and 90-day mortality. Moreover, Cox proportional hazards model showed that VR-E. faecium infection (HR 1.91; 95%CI 1.09–3.37), SOFA scores of 6–9 points (HR 2.69; 95%CI 1.15–6.29), SOFA scores ≥ 10 points (HR 3.71; 95%CI 1.70–8.13), and bone and joint infections (HR 0.08; 95%CI 0.01–0.62) were significant risk factors for mortality. In conclusion, the present study confirmed the impact of VR-E. faecium infection on mortality and hospitalization duration. Thus, the appropriate antibiotic regimen for VR-E. faecium infection, especially for severely ill patients, is an effective strategy for improving treatment outcomes.

Vancomycin-resistant enterococci infection and predisposing factors for infection and mortality in patients with acute leukaemia and febrile neutropenia

BACKGROUND

Vancomycin-resistant enterococcus (VRE) is an infectious agent that can increase morbidity and mortality, especially in patients with neutropenia in haematology departments. We analysed VRE infections and mortality rates among VRE colonized patients with acute leukaemia, defined predisposing risk factors for infection and mortality, and investigated the influence of daptomycin or linezolid treatment on mortality.

PATIENTS-METHODS

We included 200 VRE colonized adult acute leukaemia patients with febrile neutropenia between January 2010 and January 2016. Data were collected from electronic files.

RESULTS

There were 179 patients in the colonized group, and 21 patients in the infected group. Enterococcus faecium (van A) was isolated from all patients. The infection rate was 10.5 %, and the types of infections noted were as follows: bloodstream (n = 14; 66.7 %), skin and soft tissue (n = 3; 14.3 %), urinary (n = 2; 9.5 %), and others (9.5 %). In the multivariate logistic regression analysis, exposure to invasive procedures, coinfection status, and >15 days of VRE positivity were independent risk factors for VRE infections. In hospital mortality rates were 57.1 % in the infected group, and 9.5 % in the colonized group (p < 0.001). Older age, female gender, absolute neutropenia, and coinfection status were statistically significant predictor of survival.

CONCLUSION

Vancomycin-resistant enterococcus infections are associated with high morbidity and mortality in haematology patients with neutropenia. Clinicians should be aware of predisposing risk factors for VRE infection to avoid unfavourable outcomes. We believe that larger studies are necessary regarding the influence of treatment with daptomycin and linezolid.

Vancomycin-Resistant Enterococci (VRE) in Nigeria: The First Systematic Review and Meta-Analysis

Vancomycin-Resistant Enterococci (VRE) are on the rise worldwide. Here, we report the first prevalence of VRE in Nigeria using systematic review and meta-analysis. International databases MedLib, PubMed, International Scientific Indexing (ISI), Web of Science, Scopus, Google Scholar, and African journals online (AJOL) were searched. Information was extracted by two independent reviewers, and results were reviewed by the third. Two reviewers independently assessed the study quality using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist. OpenMeta analyst was used. The random effect was used, and publication bias was assessed using a funnel plot. Between-study heterogeneity was assessed, and the sources were analysed using the leave-one-out meta-analysis, subgroup analysis, and meta-regression. Nineteen studies met the eligibility criteria and were added to the final meta-analysis, and the study period was from 2009–2018. Of the 2552 isolates tested, 349 were VRE, and E. faecalis was reported the most. The pooled prevalence of VRE in Nigeria was estimated at 25.3% (95% CI; 19.8–30.8%; I² = 96.26%; p < 0.001). Between-study variability was high (t² = 0.011; heterogeneity I² = 96.26% with heterogeneity chi-square (Q) = 480.667, degrees of freedom (df) = 18, and p = 0.001). The funnel plot showed no publication bias, and the leave-one-out forest plot did not affect the pooled prevalence. The South-East region had a moderate heterogeneity though not significant (I² = 51.15%, p = 0.129). Meta-regression showed that all the variables listed contributed to the heterogeneity except for the animal isolate source (p = 0.188) and studies that were done in 2013 (p = 0.219). Adherence to proper and accurate antimicrobial usage, comprehensive testing, and continuous surveillance of VRE are required.

Infectious Diseases Consultation Is Associated With Decreased Mortality in Enterococcal Bloodstream Infections

Background

Enterococcus species frequently cause health care-associated bacteremia, with high attributable mortality. The benefit of consultation with infectious disease (ID) specialists has been previously illustrated with Staphylococcus aureus bacteremia. Whether ID consultation (IDC) improves mortality in enterococcal bacteremia is unknown.

Methods

This is a retrospective cohort single-center study from January 1, 2015, to June 30, 2016, that included all patients >18 years of age admitted with a first episode of Enterococcus bacteremia. Patients were excluded if death or transfer to palliative care occurred within 2 days of positive blood culture.

Results

Two hundred five patients were included in the study, of whom 64% received IDC. Participants who received IDC were more likely to undergo repeat cultures to ensure clearance (99% vs 74%; P < .001), echocardiography (79% vs 45%; P < .001), surgical intervention (20% vs 7%; P = 0.01), and have appropriate antibiotic duration (90% vs 46%; P < .001). Thirty-day mortality was significantly higher in the no-IDC group (27 % vs 12 %; P < .007). In multivariate analysis, 30-day in-hospital mortality was associated with both E. faecium bacteremia (adjusted odds ratio [aOR], 2.39; 95% confidence interval [CI], 1.09-5.23) and IDC (aOR, 0.35; 95% CI, 0.16-0.76).

Conclusions

Patients who received IDC for Enterococcus bacteremia had significantly lower 30-day mortality. Further prospective studies are necessary to determine if these outcomes can be validated in other institutions for patients who receive IDC with Enterococcus bacteremia.

Prevalence of Vancomycin resistant enterococci (VRE) in Ethiopia: a systematic review and meta-analysis

Background

The emergence of Vancomycin resistant enterococci (VRE) poses a major public health problem since it was first reported. Although the rising rates of VRE infections are being reported elsewhere in the worldwide; there is limited national pooled data in Ethiopia. Therefore, this study was aimed to estimate the pooled prevalence of VRE and antimicrobial resistance profiles of enterococci in Ethiopia.

Methods

Literature search was done at PubMed, EMBASE, Google scholar, African Journals online (AJOL) and Addis Ababa University repository following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Both published and unpublished studies reporting the prevalence of VRE until June 30, 2019 were included. Data were extracted using Microsoft Excel and copied to Comprehensive Meta-analysis (CMA 2.0) for analysis. Pooled estimate of VRE was computed using the random effects model and the 95% CIs. The level of heterogeneity was assessed using Cochran’s Q and I² tests. Publication bias was checked by visual inspection of funnel plots and Begg’s and/or Egger’s test.

Results

Twenty studies fulfilled the eligibility criteria and found with relevant data. A total of 831 enterococci and 71 VRE isolates were included in the analysis. The pooled prevalence of VRE was 14.8% (95% CI; 8.7–24.3; I² = 74.05%; P <  0.001). Compared to vancomycin resistance, enterococci had higher rate of resistance to Penicillin (60.7%), Amoxicillin (56.5%), Doxycycline (55.1%) and Tetracycline (53.7%). Relatively low rate of resistance was found for Daptomycin and Linezolid with a pooled estimate of 3.2% (95% CI, 0.5–19.7%) and 9.9% (95% CI, 2.8–29.0%); respectively. The overall pooled multidrug resistance (MDR) rate of enterococci was 60.0% (95% CI, 42.9–75.0%).

Conclusion

The prevalence of VRE and drug resistant enterococci are on the rise in Ethiopia. Enterococcal isolates showed resistance to one or more of the commonly prescribed drugs in different or the same drug lines. Multidrug resistant (MDR) enterococci were also found. Although the rates were low, the emergence of resistance to Daptomycin and Linezolid is an alarm for searching new ways for the treatment and control of VRE infections. Adherence to antimicrobial stewardship, comprehensive testing and ongoing monitoring of VRE infections in the health care settings are required.

Multi-drug resistant organism infections in a medical ICU: Association to clinical features and impact upon outcome

OBJECTIVE

To define clinical features associated with Intensive Care Unit (ICU) infections caused by multi-drug resistant organisms (MDRO) and their impact on patient outcome.

DESIGN

A single-center, retrospective case-control study was carried out between January 2010 and May 2010.

SETTING

A medical ICU (MICU) in the United States.

PATIENTS

The study included a total of 127 MDRO-positive patients and 186 MDRO-negative patients.

INTERVENTIONS

No interventions were carried out.

RESULTS

Out of a total of 313 patients, MDROs were present in 127 (41.7%). Based on the multivariate analysis, only infection as a cause of admission [OR 3.3 (1.9-5.8)]), total days of ventilation [OR 1.07 (1.01-1.12)], total days in hospital [OR 1.04 (1.01-1.07)], immunosuppression [OR 2.04 (1.2-3.5)], a history of hyperlipidemia [OR 2.2 (1.2-3.8)], surgical history [OR 1.82 (1.05-3.14)] and age [OR 1.02 (1.00-1.04)] were identified as clinical factors independently associated to MDROs, while the Caucasian race was negatively associated to MDROs. The distribution of days on ventilation, days in hospital and days of antibiotic treatment prior to infection differed between the MDRO-positive and MDRO-negative groups. The MDRO-positive patients showed a greater median number of days in hospital and days of antibiotic treatment before infection, with a greater median number of days in hospital, days of antibiotic treatment and days of ventilation after infection, compared to the MDRO-negative patients. The mortality rate was not significantly different between the two groups. Appropriate empirical antibiotic therapy was prescribed in 82% of the MDRO-positive cases - such treatment being started within 24h after onset of the infection in 68.5% of the cases.

CONCLUSION

Defining clinical factors associated with MDRO infections and administering timely and appropriate empirical antibiotic therapy may help reduce the mortality associated with these infections. In our hospital we did not withhold broad spectrum drugs as empirical therapy in patients with clinical features associated to MDRO infection. Our rate of appropriate empirical therapy was therefore high, which could explain the absence of excessive mortality in patients infected with MDROs.

Incidence and Outcomes Associated With Infections Caused by Vancomycin-Resistant Enterococci in the United States: Systematic Literature Review and Meta-Analysis

BACKGROUND

Information about the health and economic impact of infections caused by vancomycin-resistant enterococci (VRE) can inform investments in infection prevention and development of novel therapeutics.

OBJECTIVE

To systematically review the incidence of VRE infection in the United States and the clinical and economic outcomes.

METHODS

We searched various databases for US studies published from January 1, 2000, through June 8, 2015, that evaluated incidence, mortality, length of stay, discharge to a long-term care facility, readmission, recurrence, or costs attributable to VRE infections. We included multicenter studies that evaluated incidence and single-center and multicenter studies that evaluated outcomes. We kept studies that did not have a denominator or uninfected controls only if they assessed postinfection length of stay, costs, or recurrence. We performed meta-analysis to pool the mortality data.

RESULTS

Five studies provided incidence data and 13 studies evaluated outcomes or costs. The incidence of VRE infections increased in Atlanta and Detroit but did not increase in national samples. Compared with uninfected controls, VRE infection was associated with increased mortality (pooled odds ratio, 2.55), longer length of stay (3-4.6 days longer or 1.4 times longer), increased risk of discharge to a long-term care facility (2.8- to 6.5-fold) or readmission (2.9-fold), and higher costs ($9,949 higher or 1.6-fold more).

CONCLUSIONS

VRE infection is associated with large attributable burdens, including excess mortality, prolonged in-hospital stay, and increased treatment costs. Multicenter studies that use suitable controls and adjust for time at risk or confounders are needed to estimate the burden of VRE infections.

Infect Control Hosp Epidemiol. 2017;38:203–215

Risk factors for ambulatory urinary tract infections caused by high-MIC fluoroquinolone-susceptible Escherichia coli in women: results from a large case-control study

OBJECTIVES

The prevalence of high-MIC fluoroquinolone-susceptible Escherichia coli (FQSEC) has been increasing. These isolates are one step closer to full fluoroquinolone (FQ) resistance and may lead to delayed response to FQ therapy. Our study aimed to investigate the epidemiology of high-MIC FQSEC in ambulatory urinary tract infections (UTIs).

PATIENTS AND METHODS

A case-control study was conducted at outpatient services within the University of Pennsylvania Health System, Philadelphia. All female subjects with non-recurrent UTI caused by FQSEC (levofloxacin MIC < 4 mg/L) were enrolled. Cases were subjects with high-MIC FQSEC UTI (levofloxacin MIC >0.12 but < 4 mg/L) and controls were subjects with low-MIC FQSEC UTI (levofloxacin MIC ≤0.12 mg/L). Data on microbiology results and baseline characteristics were extracted from electronic medical records.

RESULTS

During the 3 year study period (May 2008-April 2011), 11 287 episodes of E. coli bacteriuria were identified. The prevalence of FQSEC, FQ-intermediate susceptible E. coli and FQ-resistant E. coli was 75.0%, 0.4% and 24.6%, respectively. A total of 2001 female subjects with FQSEC UTI were enrolled into our study (165 cases and 1836 controls). Independent risk factors for high-MIC FQ susceptibility included Asian race (OR = 2.92; 95% CI = 1.29-6.58; P = 0.02), underlying renal disease (OR = 2.18; 95% CI = 1.15-4.14; P = 0.02) and previous nitrofurantoin exposure (OR = 8.86; 95% CI = 1.95-40.29; P = 0.005).

CONCLUSIONS

Asian race, underlying renal disease and previous exposure to nitrofurantoin were identified as independent risk factors for high-MIC FQSEC. There may be some factors that are more common in Asians, which may result in the selection of high-MIC FQSEC. Further studies are necessary to explore these findings.

Assessing outcomes of adult oncology patients treated with linezolid versus daptomycin for bacteremia due to vancomycin-resistant Enterococcus

Background

The incidence and severity of vancomycin-resistant Enterococcus blood stream infections continue to rise and is a significant burden in the healthcare setting. Literature thus far is minimal regarding treatment outcomes in patients with malignancy and vancomycin-resistant Enterococcus bacteremia. Appropriate antibiotic selection is vital to treatment success due to high rates of resistance, limited antimicrobials and mortality in this patient population. We conducted this study to determine whether treatment outcomes differed between cancer patients treated with linezolid and those treated with daptomycin for vancomycin-resistant Enterococcus bacteremia.

Methods

This single-center, retrospective study included adult patients hospitalized on the oncology service with documented vancomycin-resistant Enterococcus faecium or Enterococcus faecalis bacteremia who received at least 48 h of either linezolid or daptomycin as primary treatment.

Results

A total of 65 patients were included in the analysis. Thirty-two patients received daptomycin as primary treatment, and 33 patients received linezolid as primary treatment. Twenty-six (76.5%) patients in the linezolid cohort versus 22 (71%) patients in the daptomycin cohort achieved microbiological cure ( p = 0.6141). Median length of stay in days (30 vs. 42, p = 0.0714) and mortality (7/32 (20.6%) vs. 8/33 (25.8%), p = 0.6180) were also similar between the linezolid and daptomycin treated patients, respectively.

Conclusion

No differences in microbiological cure, length of stay or mortality were identified between the groups. This study suggests that linezolid and daptomycin are each reasonable options for treating vancomycin-resistant Enterococcus bacteremia in oncology patients. Further prospective, randomized controlled trials are needed to assess the optimal treatment for vancomycin-resistant Enterococcus bacteremia in this patient population.

Vancomycin resistance has no influence on outcomes of enterococcal bacteriuria

BACKGROUND

Infections with vancomycin-resistant enterococci (VRE) are a growing concern in hospitals. The impact of vancomycin resistance in enterococcal urinary tract infection is not well-defined.

AIM

To describe the epidemiology of enterococcal bacteriuria in a hospital and compare the clinical picture and patient outcomes depending on vancomycin resistance.

METHODS

This was a 6-month prospective cohort study of hospital patients who were admitted with or who developed enterococcal bacteriuria in a 1250-bed tertiary care hospital. We examined clinical presentation, diagnostic work-up, management, and outcomes.

FINDINGS

We included 254 patients with enterococcal bacteriuria; 160 (63%) were female and median age was 65 years (range: 17-96). A total of 116 (46%) bacteriurias were hospital-acquired and 145 (57%) catheter-associated. Most patients presented with asymptomatic bacteriuria (ASB) (119; 47%) or pyelonephritis (64; 25%); 51 (20%) had unclassifiable bacteriuria and 20 (8%) had cystitis. Secondary bloodstream infection was detected in 8 (3%) patients. Seventy of 119 (59%) with ASB received antibiotics (mostly vancomycin). There were 74 (29%) VRE bacteriurias. VRE and vancomycin-susceptible enterococci (VSE) produced similar rates of pyelonephritis [19 (25%) vs 45 (25%); P = 0.2], cystitis, and ASB. Outcomes such as ICU transfer [10 (14%) VRE vs 17 (9%) VSE; P = 0.3], hospital length of stay (6.8 vs 5.0 days; P = 0.08), and mortality [10 (14%) vs 13 (7%); P = 0.1] did not vary with vancomycin susceptibility.

CONCLUSIONS

Vancomycin resistance did not affect the clinical presentation nor did it impact patient outcomes in this cohort of inpatients with enterococcal bacteriuria. Almost half of our cohort had enterococcal ASB; more than 50% of these asymptomatic patients received unnecessary antibiotics. Antimicrobial stewardship efforts should address overtreatment of enterococcal bacteriurias.

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.

Enterococcal bacteraemia: factors influencing mortality, length of stay and costs of hospitalization

Enterococci are a major cause of nosocomial bacteraemia. The impacts of vanB vancomycin resistance and antibiotic therapy on outcomes in enterococcal bacteraemia are unclear. Factors that affect length of stay (LOS) and costs of managing patients with enterococcal bacteraemia are also unknown. This study aimed to identify factors associated with mortality, LOS and hospitalization costs in patients with enterococcal bacteraemia and the impact of vancomycin resistance and antibiotic therapy on these outcomes. Data from 116 patients with vancomycin-resistant Enterococci (VRE), matched 1:1 with patients with vancomycin-susceptible Enterococcus (VSE), from two Australian hospitals were reviewed for clinical and economic outcomes. Univariable and multivariable logistic and quantile regression analyses identified factors associated with mortality, LOS and costs. Intensive care unit admission (OR, 8.57; 95% CI, 3.99-18.38), a higher burden of co-morbidities (OR, 4.55; 95% CI, 1.83-11.33) and longer time to appropriate antibiotics (OR, 1.02; 95% CI, 1.01-1.03) were significantly associated with mortality in enterococcal bacteraemia. VanB vancomycin resistance increased LOS (4.89 days; 95% CI, 0.56-11.52) and hospitalization costs (AU$ 28 872; 95% CI, 734-70 667), after adjustment for confounders. Notably, linezolid definitive therapy was associated with lower mortality (OR, 0.13; 95% CI, 0.03-0.58) in vanB VRE bacteraemia patients. In patients with VSE bacteraemia, time to appropriate antibiotics independently influenced mortality, LOS and hospitalization costs, and underlying co-morbidities were associated with mortality. The study findings highlight the importance of preventing VRE bacteraemia and the significance of time to appropriate antibiotics in the management of enterococcal bacteraemia.

Risk factors for fluoroquinolone resistance in Gram-negative bacilli causing healthcare-acquired urinary tract infections

The prevalence of urinary tract infections caused by fluoroquinolone-resistant Gram-negative bacilli (FQ-resistant GNB-UTIs) has been increasing. Previous studies that explored risk factors for FQ resistance have focused only on UTIs caused by Escherichia coli and/or failed to distinguish colonisation from infection. We conducted a case-control study at two medical centres within the University of Pennsylvania Health System to identify risk factors for FQ resistance among healthcare-acquired GNB-UTIs. Subjects with positive urine cultures for GNB and who met Centers for Disease Control and Prevention criteria for healthcare-acquired UTI were eligible. Cases were subjects with FQ-resistant GNB-UTI and controls were subjects with FQ-susceptible GNB-UTI matched to cases by month of isolation and species of infecting organism. In total, 251 cases and 263 controls were included from 1 January 2003 to 31 March 2005. Independent risk factors (adjusted odds ratio; 95% confidence interval) for FQ resistance included male sex (2.03; 1.21-3.39; P=0.007), African-American race (1.80; 1.10-2.94; P=0.020), chronic respiratory disease (2.58; 1.18-5.62; P=0.017), residence in a long term care facility (4.41; 1.79-10.88; P=0.001), hospitalisation within the past two weeks (2.19; 1.31-3.64; P=0.003), hospitalisation under a medical service (2.72; 1.63-4.54; P<0.001), recent FQ exposure (15.73; 6.15-40.26; P<0.001), recent cotrimoxazole exposure (2.49; 1.07-5.79; P=0.033), and recent metronidazole exposure (2.89; 1.48-5.65; P=0.002).

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.

Observational study of the epidemiology and outcomes of vancomycin-resistant Enterococcus bacteraemia treated with newer antimicrobial agents

Vancomycin-resistant Enterococcus bloodstream infections (VRE-BSI) are a growing problem with few clinical trials to guide therapy. We conducted a retrospective study of management and predictors of mortality for VRE-BSI at a tertiary-care centre from January 2005 to August 2008. Univariate and multivariable analyses examined the relationship of patient characteristics and antibiotic therapy with 30-day all-cause mortality. Rates of VRE-BSI increased from 0·06 to 0·17 infections/1000 patient-days (P=0·03). For 235 patients, 30-day mortality was 34·9%. Patients were primarily treated with linezolid (44·2%) or daptomycin (36·5%). Factors associated with mortality were haemodialysis [odds ratio (OR) 3·2, 95% confidence interval (CI) 1·6-6·3, P=0·007], mechanical ventilation (OR 3·7, 95% CI 1·3-10·4, P=0·01), and malnutrition (OR 2·0, 95% CI 1·0-4·0, P=0·046). Use of linezolid, but not daptomycin (P=0·052) showed a trend towards an association with survival. In conclusion, VRE-BSI is a growing problem, associated with significant 30-day mortality. Multiple factors were associated with poor outcomes at our hospital.

Dissemination of an Enterococcus Inc18-Like vanA plasmid associated with vancomycin-resistant Staphylococcus aureus

Of the 9 vancomycin-resistant Staphylococcus aureus (VRSA) cases reported to date in the literature, 7 occurred in Michigan. In 5 of the 7 Michigan VRSA cases, an Inc18-like vanA plasmid was identified in the VRSA isolate and/or an associated vancomycin-resistant Enterococcus (VRE) isolate from the same patient. This plasmid may play a critical role in the emergence of VRSA. We studied the geographical distribution of the plasmid by testing 1,641 VRE isolates from three separate collections by PCR for plasmid-specific genes traA, repR, and vanA. Isolates from one collection (phase 2) were recovered from surveillance cultures collected in 17 hospitals in 13 states. All VRE isolates from 2 Michigan institutions (n = 386) and between 60 and 70 VRE isolates (n = 883) from the other hospitals were tested. Fifteen VRE isolates (3.9%) from Michigan were positive for an Inc18-like vanA plasmid (9 E. faecalis [12.5%], 3 E. faecium [1.0%], 2 E. avium, and 1 E. raffinosus). Six VRE isolates (0.6%) from outside Michigan were positive (3 E. faecalis [2.7%] and 3 E. faecium [0.4%]). Of all E. faecalis isolates tested, 6.0% were positive for the plasmid, compared to 0.6% for E. faecium and 3.0% for other spp. Fourteen of the 15 plasmid-positive isolates from Michigan had the same Tn1546 insertion site location as the VRSA-associated Inc18-like plasmid, whereas 5 of 6 plasmid-positive isolates from outside Michigan differed in this characteristic. Most plasmid-positive E. faecalis isolates demonstrated diverse patterns by PFGE, with the exception of three pairs with indistinguishable patterns, suggesting that the plasmid is mobile in nature. Although VRE isolates with the VRSA-associated Inc18-like vanA plasmid were more common in Michigan, they remain rare. Periodic surveillance of VRE isolates for the plasmid may be useful in predicting the occurrence of VRSA.

Streptococcal Infections

The streptococci are a large heterogeneous group of gram-positive spherically shaped bacteria widely distributed in nature. They include some of the most important agents of human disease as well as members of the normal human flora. Some streptococci have been associated mainly with disease in animals, while others have been domesticated and used for the culture of buttermilk, yogurt, and certain cheeses. Those known to cause human disease comprise two broad categories: First are the pyogenic streptococci, including the familiar β-hemolytic streptococci and the pneumococcus. These organisms are not generally part of the normal flora but cause acute, often severe, infections in normal hosts. Second are the more diverse enteric and oral streptococci, which are nearly always part of the normal flora and which are more frequently associated with opportunistic infections.