Comparison of Mortality Associated with Vancomycin-Resistant and Vancomycin-Susceptible Enterococcal Bloodstream Infections: A Meta-analysis

Emergence of daptomycin-resistant VRE: experience of a single institution

Recent surveillance from US hospitals shows that more than 99.5% of vancomycin-resistant enterococci (VRE) isolates remain susceptible to daptomycin. This report describes emergence of daptomycin-resistant VRE at a major cancer center. The percentage of patients with daptomycin-resistant VRE bacteremia increased from 3.4% in 2007 to 15.2% in 2009 ([Formula: see text]). Without susceptibility data, empiric daptomycin therapy for VRE infections should be used with caution.

Are you survey ready? Online evaluation of a multidrug-resistant organisms educational program in a behavioral health hospital

PURPOSE

The Joint Commission established a new safety goal mandating staff education in evidence-based infection prevention due to multidrug-resistant organisms (MDROs). This pilot study assessed the effectiveness of the MDRO educational module in our behavioral health hospital.

DESIGN AND METHODS

An online survey was administered to a convenience sample (N= 44) consisting of employees hired within the previous 8 months.

FINDINGS

Results identified knowledge gaps between and among disciplines that guided subsequent improvements to our MDRO educational module.

PRACTICE IMPLICATIONS

Online surveys are an effective way to evaluate knowledge gaps and may be useful in other educational activities within nursing.

Vancomycin-resistant enterococcal bacteraemia and daptomycin: are higher doses necessary?

BACKGROUND

The MIC corresponding to daptomycin susceptibility for vancomycin-resistant enterococci (VRE) is ≤ 4 mg/L. Based on the concentration-dependent killing properties of daptomycin, there may be concern about achieving adequate concentrations when the MIC approaches the upper end of the susceptible range (3-4 mg/L). Higher doses of daptomycin may be needed to treat VRE isolates with higher MICs.

METHODS

We conducted a single-centre retrospective chart review of adult cases with VRE bacteraemia who received daptomycin as initial therapy. The primary outcome was time to microbiological cure (TMC) between standard doses (≤ 6 mg/kg) and high doses (> 6 mg/kg) of daptomycin and whether TMC differed based on MICs. The secondary outcome evaluated the daptomycin MIC distribution and assessed whether recent exposure to vancomycin was associated with higher daptomycin MICs.

RESULTS

Forty-six cases were included in the primary analysis and 60.9% of patients were neutropenic. The two dose groups differed in the baseline characteristics of age, body mass index, blood culture source and catheter removal. Median TMC was 2 days for both dose groups. There was no significant difference in TMC between MIC subgroups of ≤ 2 mg/L versus >2 and ≤ 4 mg/L. For the secondary analysis 227 VRE isolates were evaluated and 62% had daptomycin MICs of 3-4 mg/L. Each daptomycin MIC group had a similar incidence of prior vancomycin exposure.

CONCLUSIONS

Based on this retrospective review we did not observe a difference in TMC based on daptomycin dose and MIC; however, there were various limitations to this study, and the study was not powered to detect a difference in TMC. Also, prior vancomycin exposure did not appear to influence daptomycin MICs. The frequency of daptomycin MICs of 3-4 mg/L reported in this study is higher than those reported in the literature.

Increased risk of vancomycin-resistant enterococcus (VRE) infection among patients hospitalized for inflammatory bowel disease in the United States

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) infection has become an increasingly common hospital-acquired infection in U.S. hospitals. Patients with inflammatory bowel disease (IBD) frequently require hospitalization and therefore may be at increased risk of nosocomial infections.

METHODS

We used the Nationwide Inpatient Sample (NIS) to identify admissions for IBD (n = 116,842) between 1998 and 2004. We compared the prevalence of VRE in this group to that of non-IBD gastrointestinal (GI) inpatients and general inpatients and assessed for associations between VRE and hospital mortality, length of stay, and total charges.

RESULTS

The crude VRE prevalence was 2.1/10,000 in hospitalized IBD patients, 1.3/10,000 in non-IBD GI patients, and 0.9/10,000 in general inpatients. After adjustment for confounders, IBD inpatients were at increased risk of VRE compared to the non-IBD GI (adjusted odds ratio [aOR] 1.65; 95% confidence interval [CI]: 1.03-2.64) and general inpatient (aOR 2.37; 95% CI: 1.31-4.27) groups. Among IBD patients, there was a higher prevalence of VRE infection in those who had surgery (4.4/10,000 versus 1.7/10,000; P < 0.04) and total parenteral nutrition (6.9/10,000 versus 1.8/10,000; P < 0.003). VRE infection was not associated with an increase in mortality (0% versus 0.7%, P = 0.8); however, it was associated with 3-fold higher total hospital charges ($63,517 versus $21,918 USD; P < 0.0001) and increased average length of stay in hospital (16.1 versus 6.1 days; P < 0.0001).

CONCLUSIONS

Hospitalized IBD patients have increased susceptibility to VRE that is associated with increased economic burden. This study reinforces the importance of measures to prevent nosocomial infection, particularly in the vulnerable IBD population.

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.

Serodiversity of opsonic antibodies against Enterococcus faecalis--glycans of the cell wall revisited

In a typing system based on opsonic antibodies against carbohydrate antigens of the cell envelope, 60% of Enterococcus faecalis strains can be assigned to one of four serotypes (CPS-A to CPS-D). The structural basis for enterococcal serotypes, however, is still incompletely understood. Here we demonstrate that antibodies raised against lipoteichoic acid (LTA) from a CPS-A strain are opsonic to both CPS-A and CPS-B strains. LTA-specific antibodies also bind to LTA of CPS-C and CPS-D strains, but fail to opsonize them. From CPS-C and CPS-D strains resistant to opsonization by anti-LTA, we purified a novel diheteroglycan with a repeating unit of →6)-β-Galf-(1→3)- β-D-Glcp-(1→ with O-acetylation in position 5 and lactic acid substitution at position 3 of the Galf residue. The purified diheteroglycan, but not LTA absorbed opsonic antibodies from whole cell antiserum against E. faecalis type 2 (a CPS-C strain) and type 5 (CPS-D). Rabbit antiserum raised against purified diheteroglycan opsonized CPS-C and CPS-D strains and passive protection with diheteroglycan-specific antiserum reduced bacterial counts by 1.4-3.4 logs in mice infected with E. faecalis strains of the CPS-C and CPS-D serotype. Diheteroglycan-specific opsonic antibodies were absorbed by whole bacterial cells of E. faecalis FA2-2 (CPS-C) but not by its isogenic acapsular cpsI-mutant and on native PAGE purified diheteroglycan co-migrated with the gene product of the cps-locus, suggesting that it is synthesized by this locus. In summary, two polysaccharide antigens, LTA and a novel diheteroglycan, are targets of opsonic antibodies against typeable E. faecalis strains. These cell-wall associated polymers are promising candidates for active and passive vaccination and add to our armamentarium to fight this important nosocomial pathogen.

High burden of antimicrobial resistance in Asia

Antimicrobial resistance is associated with high mortality rates and high medical costs. Marked variations in the resistance profiles of bacterial and fungal pathogens as well as the quality of public hygiene have had a considerable impact on the effectiveness of antimicrobial agents in Asian countries. In Asia, one of the epicentres of antimicrobial drug resistance, there is an alarming number of antibiotic-resistant species, including penicillin- and erythromycin-resistant Streptococcus pneumoniae, ampicillin-resistant Haemophilus influenzae, multidrug-resistant (MDR) Acinetobacter baumannii, extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (particularly mediated by CTX-M-9, CTX-M-14 and CTX-M-15), New Delhi metallo-β-lactamase 1 (NDM-1)-producing Enterobacteriaceae, MDR Salmonella enterica serotypes Choleraesuis and Typhi, carbapenem-resistant A. baumannii (OXA-58 and OXA-23 carbapenemases) and azole-resistant Candida glabrata. A few clones of MDR A. baumannii and hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) have been widely disseminated in hospital settings in Asia, and K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae strains have been widely distributed in China. In addition, the emergence of extensively drug-resistant Mycobacterium tuberculosis (XDR-TB) has illustrated the need for regular monitoring of resistance profiles of clinical isolates as well as the deliberative use of fluoroquinolones. Continuous surveillance of resistance data from clinical isolates as well as implementation of strict infection control policies in healthcare settings are required to mitigate the progression of antimicrobial resistance.

Hospital epidemiology and infection control in acute-care settings

Health care-associated infections (HAIs) have become more common as medical care has grown more complex and patients have become more complicated. HAIs are associated with significant morbidity, mortality, and cost. Growing rates of HAIs alongside evidence suggesting that active surveillance and infection control practices can prevent HAIs led to the development of hospital epidemiology and infection control programs. The role for infection control programs has grown and continues to grow as rates of antimicrobial resistance rise and HAIs lead to increasing risks to patients and expanding health care costs. In this review, we summarize the history of the development of hospital epidemiology and infection control, common HAIs and the pathogens causing them, and the structure and role of a hospital epidemiology and infection control program.

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.

Importance and Impact of Antimicrobial Stewardship

The landscape of health care is rapidly changing. With health care reform on the horizon, institutions are examining many practices to determine the best way to provide optimal care while minimizing economic burden. Antimicrobial stewardship is one method many institutions are implementing to achieve this balance. Antimicrobial stewardship encompasses a wide range of services aimed at improving patient outcomes and minimizing the untoward effects of antimicrobial agents including side effects as well as induction of resistance. These programs have been shown to decrease both the development of resistance as well as expenditures on antimicrobial agents. Recently, computerized decision support software has been implemented at many institutions. This technology has greatly improved the productivity of antimicrobial stewardship programs. Combining available technology with expert knowledge in infectious diseases is necessary to ensure the continued efficacy of current antimicrobial agents.

Improving efficiency in active surveillance for methicillin-resistant Staphylococcus aureus or vancomycin-resistant Enterococcus at hospital admission

OBJECTIVE

Mandatory active surveillance culturing of all patients admitted to Veterans Affairs (VA) hospitals carries substantial economic costs. Clinical prediction rules have been used elsewhere to identify patients at high risk of colonization with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE). We aimed to derive and evaluate the clinical efficacy of prediction rules for MRSA and VRE colonization in a VA hospital. Design and setting.  Prospective cohort of adult inpatients admitted to the medical and surgical wards of a 119-bed tertiary care VA hospital.

METHODS

Within 48 hours after admission, patients gave consent, completed a 44-item risk factor questionnaire, and provided nasal culture samples for MRSA testing. A subset provided perirectal culture samples for VRE testing.

RESULTS

Of 598 patients enrolled from August 30, 2007, through October 30, 2009, 585 provided nares samples and 239 provided perirectal samples. The prevalence of MRSA was 10.4% (61 of 585) (15.0% in patients with and 5.6% in patients without electronic medical record (EMR)-documented antibiotic use during the past year; P < .01). The prevalence of VRE was 6.3% (15 of 239) (11.3% in patients with and 0.9% in patients without EMR-documented antibiotic use; P < .01). The use of EMR-documented antibiotic use during the past year as the predictive rule for screening identified 242.8 (84%) of 290.6 subsequent days of exposure to MRSA and 60.0 (98%) of 61.0 subsequent days of exposure to VRE, respectively. EMR documentation of antibiotic use during the past year identified 301 (51%) of 585 patients as high-risk patients for whom additional testing with active surveillance culturing would be appropriate.

CONCLUSIONS

EMR documentation of antibiotic use during the year prior to admission identifies most MRSA and nearly all VRE transmission risk with surveillance culture sampling of only 51% of patients. This approach has substantial cost savings compared with the practice of universal active surveillance.

Lysozyme activates Enterococcus faecium to induce necrotic cell death in macrophages

Enterococci are commensal organisms in the alimentary tract. However, they can cause a variety of life-threatening infections, especially in nosocomial settings. We hypothesized that induction of cell death might enable these facultative pathogenic bacteria to evade the innate immune response and to cause infections of their host. We demonstrate that E. faecium when exposed to lysozyme induces cell death in macrophages in vitro and in vivo. Flow cytometric analyses of J774A.1 macrophages infected with E. faecium revealed loss of cell membrane integrity indicated by uptake of propidium iodide and decrease of the inner mitochondrial transmembrane potential DeltaPsi(m). Inhibition of caspases, treatment of macrophages with cytochalasin D, or rifampicin did not prevent cells from dying, suggesting cell death mechanisms that are independent of caspase activation, bacterial uptake, and intracellular bacterial replication. Characteristics of necrotic cell death were demonstrated by both lack of procaspase 3 activation and cell shrinkage, electron microscopy, and release of lactate dehydrogenase. Pretreatment of E. faecium with lysozyme and subsequently with broad spectrum protease considerably reduced cell death, suggesting that a bacterial surface protein is causative for cell death induction. Moreover, in a mouse peritonitis model we demonstrated that E. faecium induces cell death of peritoneal macrophages in vivo. Altogether, our results show that enterococci, under specific conditions such as exposure to lysozyme, induce necrotic cell death in macrophages, which might contribute to disseminated infections by these facultative pathogenic bacteria.

Risk Factors and Outcomes for Vancomycin-Resistant Enterococcus Bloodstream Infection in Children

Background and objective. Enterococcal bloodstream infections (BSIs) cause morbidity and mortality in children. This study aims to describe the epidemiological characteristics of enterococcal BSI, to determine the risk factors for vancomycin-resistant Enterococcus (VRE) BSI, and to compare outcomes of VRE BSI and vancomycin-susceptible Enterococcus (VSE) BSI in this population. Methods. A retrospective cohort study at a 418-bed tertiary care children's hospital in Philadelphia, Pennsylvania, examined the epidemiological characteristics of children hospitalized with enterococcal BSI during the period from 2001 through 2006. A nested case-control study compared patients with VRE BSI with control patients with VSE BSI. Analysis included regression modeling to identify independent risk factors for VRE BSI. Results. We identified 339 patients with enterococcal BSI during the study period, including 39 patients with VRE infection. Fifty-three patients (16%) died before hospital discharge. Risk factors for VRE included long-term receipt of mechanical ventilation (adjusted odds ratio [OR], 5.40 [95% confidence interval {CI}, 1.28-6.48]), receipt of immunosuppressive medications during the preceding 30 days (adjusted OR, 2.88 [95% CI, 1.40-20.78]), use of vancomycin during the 2 weeks before onset of bacteremia (adjusted OR per day of vancomycin use, 1.25 [95% CI, 1.14-1.38]), and older age (adjusted OR, 1.08 [95% CI, 1.03-1.14]). VRE BSI was not associated with an increased length of stay after onset of bacteremia (0.77 days [95% CI, 0.55-1.07 days]). Mortality was higher for VRE BSI, but the difference was not statistically significant (adjusted OR, 1.94 [95% CI, 0.78-4.8]). Conclusion. Most enterococcal BSI in children was caused by VSE. Risk factors for VRE BSI included receipt of vancomycin, long-term receipt of mechanical ventilation, immunosuppression, and older age. Differences in length of stay and mortality were not detected.

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.

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.

Attributable costs of enterococcal bloodstream infections in a nonsurgical hospital cohort

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) bloodstream infections (BSIs) are associated with increased morbidity and mortality.

OBJECTIVE

To determine the hospital costs and length of stay attributable to VRE BSI and vancomycin-sensitive Enterococcus (VSE) BSI and the independent effect of vancomycin resistance on hospital costs.

METHODS

A retrospective cohort study was conducted of 21,154 nonsurgical patients admitted to an academic medical center during the period from 2002 through 2003. Using administrative data, attributable hospital costs (adjusted for inflation to 2007 US dollars) and length of stay were estimated with multivariate generalized least-squares (GLS) models and propensity score-matched pairs.

RESULTS

The cohort included 94 patients with VRE BSI and 182 patients with VSE BSI. After adjustment for demographics, comorbidities, procedures, nonenterococcal BSI, and early mortality, the costs attributable to VRE BSI were $4,479 (95% confidence interval [CI], $3,500-$5,732) in the standard GLS model and $4,036 (95% CI, $3,170-$5,140) in the propensity score-weighted GLS model, and the costs attributable to VSE BSI were $2,250 (95% CI, $1,758-$2,880) in the standard GLS model and $2,023 (95% CI, $1,588-$2,575) in the propensity score-weighted GLS model. The median values of the difference in costs between matched pairs were $9,949 (95% CI, $1,579-$24,693) for VRE BSI and $5,282 (95% CI, $2,042-$8,043) for VSE BSI. The costs attributable to vancomycin resistance were $1,713 (95% CI, $1,338-$2,192) in the standard GLS model and $1,546 (95% CI, $1,214-$1,968) in the propensity score-weighted GLS model. Depending on the statistical method used, attributable length of stay estimates ranged from 2.2 to 3.5 days for patients with VRE BSI and from 1.1 to 2.2 days for patients with VSE BSI.

CONCLUSIONS

VRE BSI and VSE BSI were independently associated with increased hospital costs and increased length of stay. Vancomycin resistance was associated with increased costs.

Bacteremia in the elderly

Bacteremia is an increasingly significant health problem among the elderly. Older adults may present with atypical manifestations of bacteremia. In addition, there are age-related differences in etiologic agents and corresponding resistance patterns. Important factors to consider when prescribing antibiotics for older adults with bacteremia include the severity and source of infection, antimicrobial susceptibility of the organism and renal function. The association between increasing age and poor outcomes in patients with bacteremia is well established. Despite the current paucity of data, the understanding of the natural history of bacteremia in the elderly should not be limited to mortality but should also focus on functional status, cognitive function and the eventual need for long-term care. Appropriate management of bacteremia in the elderly requires timely administration of broad-spectrum antibiotics in addition to managing key geriatric issues. Further studies are required to assess the impact of using broader outcomes other than mortality when addressing bacteremia in the elderly.

Clinical characteristics and outcomes of patients with vancomycin-susceptible Enterococcus faecalis and Enterococcus faecium bacteraemia--a five-year retrospective review

The purpose of this study was to assess the epidemiology and outcomes of enterococcal bacteraemia. A retrospective review of demographic, microbiological and clinical data in patients 16 years of age and over with Enterococcus faecalis or E. faecium bacteraemia at Auckland City Hospital, New Zealand, from June 2002 to May 2007 was carried out. A total of 212 patients fulfilled the inclusion criteria, with 205 being included in the analysis. E. faecalis accounted for 86% (176/205) and E. faecium 14% (29/205) of the patients. Amoxycillin resistance occurred in 69% (20/29) of E. faecium isolates. High-level gentamicin resistance was present in 38% (65/171) of E. faecalis isolates and 25% (7/28) of E. faecium isolates (P = NS). No vancomycin-resistant enterococci were isolated. Healthcare association was present in 73% (149/205) of patients. Co-morbidities were present in 86% (176/205) of patients. The 7-day mortality was 13% (27/205) and the 30-day mortality 25% (52/205). On multivariate analysis, the 7-day mortality was statistically significantly associated with cirrhosis and shorter intravenous amoxycillin therapy. The 30-day mortality was statistically significantly associated with cirrhosis, malignancy, E. faecium bacteraemia and not receiving active antimicrobial therapy. No statistically significant association between high-level gentamicin resistance and mortality was demonstrated on multivariate analysis. Enterococcal bacteraemia occurs in a co-morbid, healthcare-exposed population. Associated mortality is high, and is associated with severe underlying disease, E. faecium bacteraemia and treatment factors.

Therapeutic options for infections due to vancomycin-resistant enterococci

BACKGROUND

Vancomycin-resistant enterococci (VRE) are an important cause of nosocomial infection occurring in critical care or immunocompromised patients.

OBJECTIVES

To provide updated information about therapeutic options for VRE infection.

METHODS

MEDLINE, EMBASE, and the Cochrane Library were searched to identify in vitro susceptibility data of VRE isolates, randomized and non-randomized controlled trials, case series, and cohort studies of VRE therapy published before 31 July 2008.

RESULTS/CONCLUSION

The updated in vitro susceptibility data for VRE show high resistance to ampicillin and aminoglycosides. Quinupristin-dalfopristin is limited by its lack of activity against vancomycin-resistant Enterococcus faealis and its musculoskeletal side effects. Emerging linezolid resistance has been reported to cause hospital spread and may be related to prolonged linezolid use. Quinupristin-dalfopristin resistance is usually linked to agricultural use of streptogramin. Nitrofurantoin and fosfomycin are alternatives in uncomplicated VRE urinary tract infection. Daptomycin and tigecycline have shown excellent potential for treating VRE infection.

Antibiotic usage and risk of colonization and infection with antibiotic-resistant bacteria: a hospital population-based study

Accurate assessment of risk factors for nosocomial acquisition of colonization by antibiotic-resistant bacteria (ARB) is often confounded by scarce data on antibiotic use. A 12-month, nested, multicenter cohort study was conducted. Target ARB were methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA). Nares and rectal swabs were obtained before and after starting antibiotics. Pulsed-field gel electrophoresis was done to define genetic relatedness of the strains. Primary outcomes were (i) the mean time, in days, for acquisition of target ARB colonization in patients previously not colonized; (ii) the rate of acquisition per 1,000 antibiotic-days according to different classes of antibiotics; (iii) the rate of infection caused by the same bacteria as those previously isolated in screening samples; and (iv) the risk factors for ARB acquisition. In total, 6,245 swabs from 864 inpatients were processed. The rate of acquisition was 3%, 2%, and 1% for MRSA, VRE, and CR-PA, respectively. The rate of acquisition of ARB per 1,000 antibiotic-days was 14 for carbapenems, 9 for glycopeptides, and 6 for broad-spectrum cephalosporins and quinolones. The highest rates of acquisition were observed for carbapenems in dialyzed and diabetic patients. Four risk factors were independently associated with acquisition of target ARB: use of carbapenems, age of >70 years, hospitalization for >16 days, and human immunodeficiency virus infection. During the 30-day follow-up, 4 among 42 patients newly colonized by ARB (9%) suffered from an infection due to the same bacteria as those isolated in a previous screening sample. Colonizing and infecting strains from single patients were genotypically identical. Identifying ARB colonization early during antibiotic therapy could target a high-risk hospitalized population that may benefit from intervention to decrease the risk of subsequent nosocomial infections.

Enterococcal bacteraemia: Epidemiological, microbiological, clinical and prognostic characteristics, and the impact of high level gentamicin resistance

Enterococci are increasingly common nosocomial pathogens that can cause serious infections and often acquire antibiotic resistance. This study focused on the epidemiological, microbiological and clinical characteristics of enterococcal bacteraemia with special attention to the impact of high level gentamicin resistance (HLGR) on prognosis. 117 cases of enterococcal bacteraemia constituted 8% of all bacteraemic episodes during the y 2002. The most common source of infection was the urinary tract, more than half of the episodes were polymicrobial and the vast majority of cases was healthcare-associated. 50 of 117 isolates (43%) were resistant to gentamicin. Infection-related mortality (22 of 117, 19%) was associated with 2 independent variables in multivariate analysis: severity-of-illness score (OR=39.6, p<0.00001) and HLGR (OR=6.4, p=0.006). It was concluded that HLGR adversely affects the outcome of bacteraemic enterococcal infection.

Antibiotic considerations in the treatment of multidrug-resistant (MDR) pathogens: a case-based review

The recent rise in antimicrobial resistance among health-care associated pathogens is a growing public health concern. According to the National Nosocomial Infections Surveillance System, rates of methicillin-resistant Staphylococcus aureus (MRSA) in intensive care units have nearly doubled over the last decade. Of equal importance, gram-negative agents such as Pseudomonas aeruginosa, Acinetobacter baumannii, and extended-spectrum beta lactamase-producing Enterobacteriaceae demonstrate increasing resistance to third-generation cephalosporins, fluoroquinolones, and, in some cases, carbapenems. As a consequence, hospitalists may find themselves utilizing new antibiotics in the treatment of bacterial infections. This case-based review will highlight 8 antibiotics that have emerging clinical indications in treating these multidrug-resistant (MDR) pathogens.

Bacterial contamination of health care workers' white coats

BACKGROUND

Patient-to-patient transmission of nosocomial pathogens has been linked to transient colonization of health care workers, and studies have suggested that contamination of health care workers' clothing, including white coats, may be a vector for this transmission.

METHODS

We performed a cross-sectional study involving attendees of medical and surgical grand rounds at a large teaching hospital to investigate the prevalence of contamination of white coats with important nosocomial pathogens, such as methicillin-sensitive Stapylococcus aureus, methicillin-resistant S aureus (MRSA), and vancomycin-resistant enterococci (VRE). Each participant completed a brief survey and cultured his or her white coat using a moistened culture swab on lapels, pockets, and cuffs.

RESULTS

Among the 149 grand rounds attendees' white coats, 34 (23%) were contaminated with S aureus, of which 6 (18%) were MRSA. None of the coats was contaminated with VRE. S aureus contamination was more prevalent in residents, those working in inpatient settings, and those who saw an inpatient that day.

CONCLUSION

This study suggests that a large proportion of health care workers' white coats may be contaminated with S aureus, including MRSA. White coats may be an important vector for patient-to-patient transmission of S aureus.

Blood stream infections in allogeneic hematopoietic stem cell transplant recipients: reemergence of Gram-negative rods and increasing antibiotic resistance

Blood stream infections (BSI) are a well-known cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) patients. The aim of this study was to analyze etiology and microbial resistance of BSI in patients undergoing allogeneic HSCT in a single center over a 4-year period (2004-2007). There were 168 episodes of BSI in 132 patients (median 10 days after HSCT) and 182 pathogens were isolated. Gram-positive bacteria (GPB) accounted for 57% of 182 isolates. Gram-negative rods (GNR) for 37% and fungi for 6%. All patients received routine fluoroquinolone prophylaxis. There was a significant decrease in GPB/GNR ratio over time, from 2.4 in 2004 to 1 in 2007 (P = .043). Among GPB, staphylococci decreased from 37 of 68 (64%) in 2004-2005 to 8 of 35 (23%) in 2006-2007 (P < .002). The Enterococcus faecalis/E. faecium ratio decreased from 4.5 in 2004 to 0.33 in 2007 (P = .006), whereas the total number of enterococcal strains per year did not change. The incidence of Escherichia coli among GNR increased from 3 of 15 (20%) in 2004 to 13 of 21 (62%) in 2007 (P = .003). Fluoroquinolone-resistance was common, both among GPB and GNR (81% and 74%, respectively). Mortality rate at 7 days after BSI was 11% (19 of 168), reaching 39% for Pseudomonas aeruginosa BSI (7 of 18). BSI remains a frequent and potentially life-threatening complication of allogeneic HSCT, the causative organism influencing 7- and 30-day mortality rate. BSI etiology may change rapidly, requiring implementation of new empirical-therapy schemes.

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.

The risk of developing a vancomycin-resistant Enterococcus bloodstream infection for colonized patients

EPIDEMIOLOGY

Between 2 to 4 million patients each year develop health care-acquired infections in the United States. Infection resulting from vancomycin-resistant Enterococcus (VRE) is now the second to third most common cause of nosocomial infections in the United States. VRE is most often transmitted by the contaminated hands, clothing, and equipment of health care workers. Patients with VRE bloodstream infections (BSIs) have increased rates of recurrent BSI (16.9% vs 3.7%, respectively, P < .0001), increased crude case fatality rates (relative risk [RR], 2.57; 95% confidence interval [CI]: 2.27-2.91), increased mortality because of bacteremia (RR, 1.79; 95% CI: 1.28-2.50), and increased hospital costs of $27,000 per episode of BSI (P = .04) compared with those with vancomycin-susceptible BSI. Additionally, transfer of the gene responsible for vancomycin resistance to S aureus has been demonstrated in vitro, and reports of clinical infections because of vancomycin-resistant Staphylococcus aureus have been reported from many areas of the world, including the United States. Risk factors for VRE colonization and infection include prolonged length of hospital stay, use of broad-spectrum antibiotics, having an indwelling invasive device, and close proximity to another VRE-colonized or -infected patient; however, risk factors for developing VRE BSI among colonized patients have not been fully described.

INFECTION CONTROL

Infection control measures for VRE include antibiotic-usage control, reducing contamination of the environment with proper cleaning and disinfection, and reducing contamination of health care workers by use of contact precautions. Health care-acquired BSIs can also be effectively controlled by closely following central venous line prevention guidelines and complying with the central venous line bundle. Control and prevention of VRE colonization and thus infection would be expected to reduce morbidity, reduce health care costs, and save lives.

Impact of antimicrobial resistance on the treatment and outcome of patients with sepsis

Antimicrobial therapy is one of the main stones of sepsis therapy. A recent study of septic shock patients showed that each hour of delay in antimicrobial administration during the ensuing 6 h after the onset of hypotension was associated with a decrease in survival rates. However, many questions regarding the impact of infection caused by antimicrobial-resistant pathogens on the mortality of patients with sepsis still need to be clarified. There is a lack of fair studies in the literature. Most studies have had inadequate sample size, inadequate adjustment for predictors of adverse outcomes, and inadequate definition of appropriate antibiotic therapy. Despite the fact that appropriate therapy is essential to treat sepsis, it seems that severity of underlying diseases and comorbidities are more important than resistance, although the studies were not well designed to examine the real impact of resistance on outcome. Finally, new technologies such as microarray that can identify different microorganisms, genes of resistance, and virulence in a few hours might have a great impact on the treatment of sepsis due to antimicrobial-resistant pathogens in the future.

Peptide nucleic acid fluorescent in situ hybridization for hospital-acquired enterococcal bacteremia: delivering earlier effective antimicrobial therapy

Hospital-acquired vancomycin-resistant enterococcal bacteremia has been associated with increased hospital costs, length of stay, and mortality. The peptide nucleic acid fluorescent in situ hybridization (PNA FISH) test for Enterococcus faecalis and other enterococci (EFOE) is a multicolor probe that differentiates E. faecalis from other enterococcal species within 3 h directly from blood cultures demonstrating gram-positive cocci in pairs and chains (GPCPC). A quasiexperimental study was performed over two consecutive years beginning in 2005 that identified GPCPC by conventional microbiological methods, and in 2006 PNA FISH was added with a treatment algorithm developed by the antimicrobial team (AMT). The primary outcome assessed was the time from blood culture draw to the implementation of effective antimicrobial therapy before and after PNA FISH. The severity of illness, patient location, and empirical antimicrobial therapy were measured. A total of 224 patients with hospital-acquired enterococcal bacteremia were evaluated, with 129 in the preintervention period and 95 in the PNA FISH period. PNA FISH identified E. faecalis 3 days earlier than conventional cultures (1.1 versus 4.1 days; P < 0.001). PNA FISH identified Enterococcus faecium a median 2.3 days earlier (1.1 versus 3.4 days; P < 0.001) and was associated with statistically significant reductions in the time to initiating effective therapy (1.3 versus 3.1 days; P < 0.001) and decreased 30-day mortality (26% versus 45%; P = 0.04). The EFOE PNA FISH test in conjunction with an AMT treatment algorithm resulted in earlier initiation of appropriate empirical antimicrobial therapy for patients with hospital-acquired E. faecium bacteremia.

Nosocomial outbreak of Enteroccocus gallinarum: untaming of rare species of enterococci

An unusual increase in infections caused by vancomycin-resistant Enterococcus gallinarum (VREG) was identified in May 2004, in a Colombian tertiary care teaching hospital. A case-control study was subsequently designed to identify risk factors associated with the development of infections due to these organisms. All VREG isolates were subjected to antimicrobial susceptibility testing, vancomycin resistance gene detection and pulsed-field gel electrophoresis (PFGE) typing. Additionally, the presence of genes associated with an acquired pathogenicity island of E. faecalis and a hyl-like gene of E. faecium was assessed by hybridisation assays. Eleven cases of VREG were identified between May through June 2004. VREG was isolated from blood (N=4), surgical secretions (N=4), paranasal sinus secretion (N=1), lung abscess (N=1) and urine (N=1). Infections with VREG were associated with mucositis, hospitalisation in the haematology ward and surgical unit, length of hospital stay prior to culture and invasive procedures within 30 days prior to the culture. Logistic regression found that female sex and hospitalisation in the surgical unit were independent factors for VREG infection. All isolates were identified as E. gallinarum, harboured the vanC1 gene and exhibited indistinguishable restriction patterns by PFGE. Virulence-associated genes were not detected. This is the first documented hospital-wide outbreak of VREG and highlights the fact that uncommon species of enterococci are capable of nosocomial dissemination.

Antimicrobial resistance: international control strategies, with a focus on limited-resource settings

Microorganisms resistant to multiple anti-infective agents have increased worldwide. These organisms threaten both optimal care of patients with infection as well as the viability of current healthcare systems. In addition, antimicrobials are valuable resources that enhance both prevention and treatment of infections. As resistance diminishes this resource, it is a societal goal to minimise resistance and therefore to reduce forces that produce resistance. This review considers strategies for minimising resistance that are needed at several different levels of responsibility, ranging from the patient care provider to international agencies. It then describes responses that might be appropriate according to the resources available for control, focusing on limited-resource settings. Antimicrobial resistance represents an international concern. Response to this problem demands concerted efforts from multiple sectors both in developed and developing countries, as well as the strengthening of multinational/international partnerships and regulations. Both medical and public health agencies should be in the forefront of these efforts.

A functional collagen adhesin gene, acm, in clinical isolates of Enterococcus faecium correlates with the recent success of this emerging nosocomial pathogen

Enterococcus faecium recently evolved from a generally avirulent commensal into a multidrug-resistant health care-associated pathogen causing difficult-to-treat infections, but little is known about the factors responsible for this change. We previously showed that some E. faecium strains express a cell wall-anchored collagen adhesin, Acm. Here we analyzed 90 E. faecium isolates (99% acm(+)) and found that the Acm protein was detected predominantly in clinically derived isolates, while the acm gene was present as a transposon-interrupted pseudogene in 12 of 47 isolates of nonclinical origin. A highly significant association between clinical (versus fecal or food) origin and collagen adherence (P Collapse

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MESH Headings

• Adhesins, Bacterial/genetics
• Adhesins, Bacterial/metabolism
• Animals
• Antibodies, Bacterial/blood
• Bacterial Adhesion
• Bacterial Typing Techniques
• Cattle
• Chickens
• Cluster Analysis
• Collagen/metabolism
• Cross Infection/microbiology
• DNA Fingerprinting
• DNA Transposable Elements
• DNA, Bacterial/genetics
• Electrophoresis, Gel, Pulsed-Field
• Endocarditis, Bacterial/immunology
• Enterococcus faecium/classification
• Enterococcus faecium/genetics
• Enterococcus faecium/isolation & purification
• Enterococcus faecium/pathogenicity
• Feces/microbiology
• Food Microbiology
• Genes, Bacterial
• Genotype
• Gram-Positive Bacterial Infections/microbiology
• Humans
• Pseudogenes
• Sequence Analysis, DNA
• Swine
• Turkeys

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Grants

• R01 AI067861 NIAID NIH HHS
• UL1 RR024148 NCRR NIH HHS
• R01 AI 67861 NIAID NIH HHS

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Affiliation(s)

Sreedhar R Nallapareddy Department of Internal Medicine, Division of Infectious Diseases, Center for the Study of Emerging and Re-Emerging Pathogens, University of Texas Medical School, Houston, Texas 77030, USA
Kavindra V Singh
Pablo C Okhuysen
Barbara E Murray

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