Vancomycin-resistant Enterococcus faecium bacteremia: risk factors for infection

Antibacterial and antiyeast compounds from marine-derived bacteria

Two new (2 and 3) and a known (1) antimicrobial compounds were isolated from EtOAc extracts of two marine bacterial strains cultured in modified Bennett’s broth medium. The structures of these compounds were determined based on the analysis of nuclear magnetic resonance (NMR), high resolution mass spectroscopy (HRMS), literature data review and considering biogenesis. All the compounds (1–3) demonstrated in vitro antimicrobial activities against selected pathogenic strains.

Vancomycin-resistant Enterococcus faecium Bacteremia in a tertiary care hospital: epidemiology, antimicrobial susceptibility, and outcome

Vancomycin-resistant Enterococcus faecium (VREF) has emerged as a relevant multidrug-resistant pathogen and potentially lethal etiology of health care associated infections worldwide. The objective of this retrospective cohort study was to assess factors associated with mortality in patients with VREF bacteremia in a major tertiary referral hospital in Southern Brazil. All documented cases of bacteremia identified between May 2010 and July 2012 were evaluated. Cox regression was performed to determine whether the characteristics related to the host or antimicrobial treatment were associated with the all-cause 30-day mortality. In total, 35 patients with documented VREF bacteremia were identified during the study period. The median APACHE-II score of the study population was 26 (interquartile range: 10). The overall 30-day mortality was 65.7%. All VREF isolates were sensitive to linezolid, daptomycin, and quinupristin-dalfopristin. Linezolid was the only antimicrobial agent with in vitro activity against VREF that was administered to the cohort. After multivariate analysis, linezolid treatment (HR, 0.08; 95% CI, 0.02–0.27) and presence of acute kidney injury at the onset of bacteremia (HR, 4.01; 95% CI, 1.62–9.94) were independently associated with mortality. Presentation with acute kidney injury and lack of treatment with an effective antibiotic poses risk for mortality in patients with VREF bacteremia.

Algorithm for pre-emptive glycopeptide treatment in patients with haematologic malignancies and an Enterococcus faecium bloodstream infection

Introduction

Nowadays Enterococcus faecium has become one of the most emerging and challenging nosocomial pathogens. The aim of this study was to determine risk factors in haematology patients who are at risk of an Enterococcus faecium bloodstream infection (BSI) and should be considered for pre-emptive glycopeptide treatment. With these identified risk factors a prediction model can be developed for clinical use.

Methods

Retrospectively clinical and microbiological data in 33 patients with an E. faecium BSI were compared to 66 control patients during a 5-year period at the haematology ward. Multivariate logistic regression was used to explore the independent risk factors and a prediction model was developed to determine the risk of an E. faecium BSI.

Results

E. faecium BSIs were found to be associated with high mortality rates. Independent risk factors for E. faecium BSI were colonization with E. faecium 30 days prior to blood culture (OR 5.71; CI 1.7-18.7), combination of neutropenia and abdominal focus (4.37; 1.4-13.4), age > 58 years (4.01; 1.3-12.5), hospital stay prior to blood culture > 14 days (3.55; 0.98-12.9) and CRP (C-reactive protein) level >125 mg/L (4.37; 1.1-10.2).

Conclusion

Using data from this study, risk stratification for the development of an E. faecium BSI in patients with haematological malignancies is possible. Pre-emptive treatment should be considered in those patients who are at high risk. Using a prediction model as designed in this study, antibiotic stewardship in terms of prudent use of glycopeptides can be improved and might be helpful in controlling further spread of VRE (vancomycin resistant enterococci).

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.

Identification of vancomycin-resistant enterococci clones and inter-hospital spread during an outbreak in Taiwan

BACKGROUND

In 2003, nosocomial infections caused by vancomycin-resistant enterococci (VRE) occurred rarely in Taiwan. Between 2003 and 2010, however, the average prevalence of vancomycin resistance among enterococci spp. increased from 2% to 16% in community hospitals and from 3% to 21% in medical centers of Taiwan. We used molecular methods to investigate the epidemiology of VRE in a tertiary teaching hospital in Taiwan.

METHODS

Between February 2009 and February 2011, rectal samples and infection site specimens were collected from all inpatients in the nephrology ward after patient consent was obtained. VRE strain types were determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

A total of 59 vanA gene-containing VRE isolates (1 per patient) were obtained; 24 originated from rectal sample surveillance of patients who exhibited no symptoms (22 Enterococcus faecium and 2 Enterococcus faecalis), and 35 had developed infections over 3 days after admission (32 E. faecium, 2 E. faecalis, and 1 Enterococcus durans). The 59 VRE isolates demonstrated vancomycin minimum inhibitory concentrations (MICs) of ≥256 μg/m. The MIC range for linezolid, tigecycline, and daptomycin was 0.25-1.5 μg/mL, 0.032-0.25 and 1-4 μg/mL, respectively. For 56 isolates, the MIC for teicoplanin was >8 μg/mL. The predominant types in the nephrology ward were MLST types 414, 78, and18 as well as PFGE types A, C, and D.

CONCLUSION

VREs are endemic in nephrology wards. MLST 414 is the most predominant strain. The increase VRE prevalence is due to cross-transmission of VRE clones ST 414,78,18 by undetected VRE carriers. Because similar VRE STs had been reported in a different hospital of Taiwan, this finding may indicate inter-hospital VRE spread in Taiwan. Active surveillance and effective infection control policies are important controlling the spread of VRE in high risk hospital zones. All endemic VRE strains are resistant to teicoplanin but are sensitive to daptomycin, linezolid, and tigecycline.

Reduced acquisition and overgrowth of vancomycin-resistant enterococci and Candida species in patients treated with fidaxomicin versus vancomycin for Clostridium difficile infection

Fidaxomicin causes less disruption of anaerobic microbiota during treatment of Clostridium difficile infection (CDI) than vancomycin and has activity against many vancomycin-resistant enterococci (VRE). In conjunction with a multicenter randomized trial of fidaxomicin versus vancomycin for CDI treatment, we tested the hypothesis that fidaxomicin promotes VRE and Candida species colonization less than vancomycin. Stool was cultured for VRE and Candida species before and after therapy. For patients with negative pretreatment cultures, the incidence of VRE and Candida species acquisition was compared. For those with preexisting VRE, the change in concentration during treatment was compared. The susceptibility of VRE isolates to fidaxomicin was assessed. Of 301 patients, 247 (82%) had negative VRE cultures and 252 (84%) had negative Candida species cultures before treatment. In comparison with vancomycin-treated patients, fidaxomicin-treated patients had reduced acquisition of VRE (7% vs 31%, respectively; P < .001) and Candida species (19% vs 29%, respectively; P = .03). For patients with preexisting VRE, the mean concentration decreased significantly in the fidaxomicin group (5.9 vs 3.8 log₁₀ VRE/g stool; P = .01) but not the vancomycin group (5.3 vs 4.2 log₁₀ VRE/g stool; P = .20). Most VRE isolates recovered after fidaxomicin treatment had elevated fidaxomicin minimum inhibitory concentrations (MICs; MIC₉₀, 256 µg/mL), and subpopulations of VRE with elevated fidaxomicin MICs were common before therapy. Fidaxomicin was less likely than vancomycin to promote acquisition of VRE and Candida species during CDI treatment. However, selection of preexisting subpopulations of VRE with elevated fidaxomicin MICs was common during fidaxomicin therapy.

Clinical Trials Registration. NCT00314951.

Dynamics of ampicillin-resistant Enterococcus faecium clones colonizing hospitalized patients: data from a prospective observational study

Background

Little is known about the dynamics of colonizing Enterococcus faecium clones during hospitalization, invasive infection and after discharge.

Methods

In a prospective observational study we compared intestinal E. faecium colonization in three patient cohorts: 1) Patients from the Hematology Unit at the University Hospital Basel (UHBS), Switzerland, were investigated by weekly rectal swabs (RS) during hospitalization (group 1a, n = 33) and monthly after discharge (group 1b, n = 21). 2) Patients from the Intensive Care Unit (ICU) at the University Medical Center Utrecht, the Netherlands (group 2, n = 25) were swabbed weekly. 3) Patients with invasive E. faecium infection at UHBS were swabbed at the time of infection (group 3, n = 22). From each RS five colonies with typical E. faecium morphology were picked. Species identification was confirmed by PCR and ampicillin-resistant E. faecium (ARE) isolates were typed using Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). The Simpson's Index of Diversity (SID) was calculated.

Results

Out of 558 ARE isolates from 354 RS, MT159 was the most prevalent clone (54%, 100%, 52% and 83% of ARE in groups 1a, 1b, 2 and 3, respectively). Among hematological inpatients 13 (40%) had ARE. During hospitalization, the SID of MLVA-typed ARE decreased from 0.745 [95%CI 0.657-0.833] in week 1 to 0.513 [95%CI 0.388-0.637] in week 3. After discharge the only detected ARE was MT159 in 3 patients. In the ICU (group 2) almost all patients (84%) were colonized with ARE. The SID increased significantly from 0.373 [95%CI 0.175-0.572] at week 1 to a maximum of 0.808 [95%CI 0.768-0.849] at week 3 due to acquisition of multiple ARE clones. All 16 patients with invasive ARE were colonized with the same MLVA clone (p < 0.001).

Conclusions

In hospitalized high-risk patients MT159 is the most frequent colonizer and cause of invasive E. faecium infections. During hospitalization, ASE are quickly replaced by ARE. Diversity of ARE increases on units with possible cross-transmission such as ICUs. After hospitalization ARE are lost with the exception of MT159. In invasive infections, the invasive clone is the predominant gut colonizer.

New aspirations: the debate on aspiration pneumonia treatment guidelines

Aspiration pneumonia occurs most commonly in patients with a predisposition to aspiration (eg, those with neurological bulbar dysfunction). There is limited evidence regarding the involvement of anaerobes in most cases of aspiration pneumonia. Most patients respond to treatment for aspiration pneumonia without specific anti-anaerobic therapy such as metronidazole. Metronidazole has adverse side effects, and widespread use where not indicated can promote carriage of multiresistant intestinal flora such as vancomycin-resistant enterococci. Use of metronidazole may be appropriate in patients with aspiration pneumonia and evidence of a lung abscess, necrotising pneumonia, putrid sputum or severe periodontal disease.

Bacterial spectrum and antimicrobial susceptibility pattern of bloodstream infections in children with febrile neutropenia: experience of single center in southeast of Turkey

Empirical antimicrobial therapy is usually started in febrile neutropenic patients without having culture results. The aim of this study was to help determine the policies of empirical antibiotic usage in febrile neutropenic children by detecting the antimicrobial susceptibility profile in this group of patients. In this study 811 blood cultures taken from neutropenic children hospitalized at the Department of Oncology of Gaziantep Children Hospital November 2007 and February 2010 were retrospectively evaluated. Blood cultures were routinely collected in aerobic and anaerobic media and incubated using the BACTEC system. Identification and antimicrobial susceptibility testing of the isolates to antimicrobial agents was performed using the Vitek2(®) system according to the recommendations of the Clinical and Laboratory Standards Institute. Of 811 isolates analyzed, 128 (56.4%) were gram positive cocci, 43 (18.9%) were gram negative bacilli and fungi accounted for 56 (24.7%). The main isolated Gram-positive bacteria from blood were coagulase-negative staphylococcus (56.7%), followed by methicillin-resistant Staphylococcus aureus (14.1%). S. aureus and Streptococcus spp. were all susceptible to linezolid, vancomycin and teicoplanin. S aureus was still susceptible to few other antimicrobial agents such as tetracycline (82.4%), chloramphenicol (55.6%). Seven E. faecium, 7 E. fecalis and 1 E. hirae was isolated from blood cultures. Vancomycin resistance was detected in 6 out of 15 (40%) Enterococcus spp. isolates. Among gram-negative bacteria E. coli (30.2%) was followed by Klebsiella pneumoniae (20.9%) and Proteus spp. (18.6%). Imipenem (89.2%), meropenem (86.6%), chloramphenicol (88.9%), amicasin (82.4%) and fosfomycin (81.3%) showed highest susceptibility in vitro activity against all Gram-negative isolates. To know the antimicrobial susceptibility profile of the pathogens frequently isolated from febrile neutropenic children and to consider this profile before starting an empirical antibiotic therapy would help the clinics which have any role in the treatment of these patients to determine the empirical antibiotic usage policies.

Multi-drug-resistant gram-negative bacterial infection in surgical patients hospitalized in the ICU: a cohort study

We sought to identify risk factors for postoperative infections, caused by multi-drug-resistant gram-negative bacteria (MDR-GNB) in surgical patients. This was a retrospective cohort study among patients hospitalized in the intensive care unit (ICU) for more than 5 days, following general surgical operations. Comparison of patients who developed infection caused by MDR-GNB with the remainder of the cohort showed that every minute of operative time, use of special treatments during hospitalization (antineoplastic, immunosuppressive or immunomodulating therapies), every day of metronidazole, and every day of carbapenems use, increased patients' odds to acquire an infection caused by MDR-GNB by 0.7%, 8.9 times, 9%, and 9%, respectively [OR (95% CI): 1.007 (1.003-1.011), p = 0.001; 8.9 (1.8-17.3), p = 0.004; 1.09 (1.04-1.18), p = 0.039; 1.09 (1.01-1.18), p = 0.023, respectively]. The above were adjusted in the multivariable analysis for the confounder of time distribution of infections caused by MDR-GNB. Finally, the secondary comparison, with patients that did not develop any infection, showed that patients who had received antibiotics, within 3 months prior to admission, had 3.8 times higher odds to acquire an infection caused by MDR-GNB [OR (95% CI): 3.8 (1.07-13.2), p = 0.002]. This study depicts certain, potentially modifiable, risk factors for postoperative infections in patients hospitalized in the ICU for more than 5 days.

Treatment of resistant enterococcal urinary tract infections

Enterococcus spp have emerged as important pathogens in urinary tract infection (UTI), especially in hospitalized patients. Resistance to multiple antibiotics, including vancomycin, has become common, particularly in infections involving Enterococcus faecium. The management of UTIs caused by Enterococcus spp has become challenging given the presence of underlying comorbidities in these patients and the limited therapeutic options available to treat multidrug-resistant (MDR) Enterococcus. Routine therapy for asymptomatic bacteriuria with MDR-Enterococcus is not recommended. Removal of indwelling urinary catheters should be considered. Appropriate antibiotic therapy selection should be guided by urine culture and susceptibility results. Data are limited on the treatment of UTIs caused by MDR-Enterococcus. Potential oral agents active against MDR-Enterococcus that may be considered for acute uncomplicated UTI include nitrofurantoin, fosfomycin, and fluoroquinolones. Potential parenteral agents for the treatment of pyelonephritis and complicated UTIs caused by MDR-Enterococcus include daptomycin, linezolid, and quinipristin-dalfopristin. Aminoglycosides or rifampin may be considered as adjunctive therapy in serious infections.

Choice of antibiotics in late neonatal sepsis in the extremely low birth weight infant

OBJECTIVE

To review the choice of antibiotics in treating suspected late neonatal sepsis in infants weighing 1000 g or less in a neonatal intensive care unit.

METHODS

Retrospective review of medical records.

RESULTS

Ninety-six infants weighing 1000 g or less were admitted to the neonatal intensive care unit during the study period. Sixty-two infants survived beyond four days of life and had at least one sepsis workup done to exclude late neonatal infection. Of the 62 study patients, 42 (68%) were started on ampicillin and netilmicin (A/N) and 20 (32%) were started on vancomycin and ceftizoxime (V/C) as the antibiotics of choice, pending culture results. Of the patients started on A/N, 17 of 42 had a positive blood culture compared with 11 of 20 on V/C (40% versus 55%, P=0.40). The mean (+/-SD) birth weight of infants started on A/N was 793+/-133 g compared with a mean of 728+/-153 g in the group that received V/C (P=0.09). Seven patients died in the A/N group compared with three in the V/C group (16.7% versus 15%, P=0.84). In addition to the sepsis episode studied, before they were discharged from hospital, 21 of 42 (50%) infants in the A/N group had further workups for suspected sepsis, compared with 16 of 20 (80%) (P=0.048) infants initially given V/C.

CONCLUSIONS

Ampicillin and netilmicin is a safe antibiotic combination for neonates suspected of late sepsis. This, in turn, may be important in reducing vancomycin overuse and the potential for bacterial resistance to this antimicrobial agent.

Risk factors for prolonged carriage of vancomycin-resistant Enterococcus faecium among patients in intensive care units: a case-control study

OBJECTIVES

The aim of this study was to identify the risk factors for prolonged carriage of vancomycin-resistant Enterococcus faecium (VREF) in intensive care units (ICUs).

METHODS

A retrospective case-control study was performed in the ICUs of a university hospital in Korea from September 2006 to July 2009. VREF carriage was identified through weekly active surveillance rectal cultures. Clinical characteristics and the risk factors for VREF acquisition were compared between cases with prolonged VREF carriage (≥ 5 weeks, n = 58) and controls with shorter VREF carriage (<3 weeks, n = 36) in a multivariate logistic regression model. The effect of vancomycin consumption on vancomycin-resistant enterococci (VRE) colonization pressure was investigated using time-series analysis with an autoregressive error model.

RESULTS

Out of a total of 6327 rectal swab cultures examined, 1915 (30.3%) specimens from 266 patients were positive for VREF. The weekly VRE colonization pressure ranged from 0.77% to 42.42%. Vancomycin use after VREF acquisition significantly increased VREF carriage (adjusted odds ratio = 4.09; 95% confidence interval = 1.32-12.65). The case group had higher in-hospital mortality than the control group [21 (36.2%) versus 4 (11.1%), P = 0.007]. Increment of VRE colonization pressure was significantly associated with vancomycin consumption of 1week before (i.e. time t - 1) (P = 0.0028) and moderately associated with that of the corresponding week (i.e. time t) (P = 0.0595).

CONCLUSIONS

Vancomycin use in patients with VREF colonization might prolong the duration of carriage. Restriction of vancomycin use should be strengthened in these patients through infection control measures.

Appropriateness is critical

Inappropriate empirical antibiotic therapy for severe infections in the intensive care unit is a modifiable prognostic factor that has a great effect on patient outcome and health care resources. Inappropriate treatment is usually associated with microorganisms resistant to the common antibiotics, which must be empirically targeted when risk factors are present. Previous antibiotic exposure, prolonged length of hospital stay, admission category, local susceptibilities, colonization pressure, and the presence of invasive devices increase the likelihood of infection by resistant pathogens. Consideration of issues beyond in vitro susceptibility, such as antibiotic physicochemistry, tissue penetration, and pharmacokinetic/pharmacodynamic-driven dosing, is mandatory for the optimization of antibiotic use.

Implications for vancomycin-resistant Enterococcus colonization associated with Clostridium difficile infections

BACKGROUND

Vancomycin-resistant Enterococcus (VRE) colonization of the gastrointestinal tract shares similar risk factors with Clostridium difficile infection. We sought to elucidate the prevalence and risk factors of VRE colonization associated with C difficile infection.

METHODS

All adult inpatients with C difficile infection from July 2006 to October 2006 were prospectively evaluated. All C difficile toxin-positive stool samples were screened for detection of VRE. Risk factors for VRE colonization were compared in patients with C difficile infection with and without VRE colonization.

RESULTS

Of the 158 cases of C difficile infection evaluated, 88 (55.7%) involved VRE colonization. Independent risk factors for VRE colonization were admission from long-term care facilities (P = .013), dementia (P = .017), and hospitalization in the previous 2 months (P = .014). No statistically significant difference between C difficile infection cases with and without VRE colonization in terms of previous receipt (within 1 month) of antibiotics, including metronidazole and vancomycin, was found on multivariate analysis. C difficile infection cases with VRE colonization had a higher prevalence of coinfection with methicillin-resistant Staphylococcus aureus (P = .002) and Acinetobacter spp (P = .006).

CONCLUSION

VRE colonization was associated with >50% of C difficile infection cases and with a higher rate of coinfection with multidrug-resistant pathogens. Given the high rate of C difficile infection associated with VRE colonization, active surveillance of VRE in patients with C difficile infection is reasonable in high-risk settings.

Risk of postdischarge infection with vancomycin-resistant enterococcus after initial infection or colonization

Postdischarge risks of vancomycin-resistant Enterococcus (VRE) infection among carriers are unknown. We conducted a retrospective cohort study of 199 patients newly detected as VRE carriers. Fifteen patients (8%) developed 27 VRE infections in the 18 months after detection. Among 10 postdischarge infections, 2 involved bacteremia and 3 resulted in readmission.

Characterization of vancomycin-resistant Enterococcus faecium isolated from swine in three Michigan counties

Vancomycin-resistant enterococci are a major cause of nosocomial infections but are rarely found in humans in the community and have not been identified in food animals in the United States. We evaluated a total of 360 fecal specimens from humans and their animals being raised for exhibit at three county fairs in Michigan. Fecal samples from 158 humans, 55 swine, 50 cattle, 25 horses, 57 sheep, 14 goats, and 1 llama were obtained and plated onto Enterococcosel agar containing 16 μg/ml of vancomycin. Vancomycin-resistant Enterococcus faecium (VREF) was isolated from six pigs but not from humans or any animal other than pigs. All six VREF isolates had a MIC to vancomycin of ≥256 μg/ml and contained the vanA gene. Pulsed-field gel electrophoresis (PFGE) patterns of the six VREF isolates were ≥80% similar. Multilocus sequence typing (MLST) revealed sequence type 5 (ST5) (n = 2), ST6 (n = 3), and ST185 (n = 1), which are E. faecium sequence types belonging to clonal complex 5 (CC5). These findings show the dissemination of VREF strains among pigs in three Michigan counties. This is the first report of VRE found in food animals in the United States.

Risk factors for vancomycin-resistant enteroccocci colonization in infants in neonatal intensive care unit

We aimed to evaluate the risk factors for VRE colonization in neonatal intensive care units. In December 2007, we identified a neonate with VRE infection (urinary tract infection and we performed blood and stool cultures for VRE until the last colonized patient was discharged from our clinic. All the neonates hospitalized in NICU during December 2007 to January 2008. Active surveillance cultures for VRE fecal carriage was carried out in neonatal intensive care unit. Resistance to vancomycin was detected by the E-test method. Epidemiological data was recorded for all patients included in the study and was used for the risk factors. Totally 54 infants in NICU were screened for VRE colonization. Totally 11 infants (20%) were colonized with vancomycin-resistant enterococci. The average duration of all antimicrobial therapy was significantly longer in colonized patients. The infants who were hospitalized for more than 10 days were found to be significantly more colonized with VRE when compared to the infants with shorter hospital stay (p<0.05). There were no statistically significant differences between VRE colonized and non-colonized infants in respect to sex, to third generation cephalosporin usage, glycopeptide usage, presence of prematurity, presence of mechanical ventilation(p> 0.05). The premature infants and the mature infants were under risk of VRE colonization. Longer duration of hospitalization and antimicrobial usage were the prominent risk factors. Since infants in neonatal intensive care units were under risk of infections, periodic active surveillance cultures should be combined with logical antimicrobial therapy.

Low prevalence of VRE gastrointestinal colonization of hospitalized patients in Manitoba tertiary care and community hospitals

OBJECTIVE

To determine the prevalence of vancomycin-resistant enterococci (VRE) bowel colonization in hospitalized patients in Manitoba who had stool specimens collected for Clostridium difficile toxin and/or culture testing.

DESIGN

Two tertiary care and five community hospitals in Winnipeg and three rural Manitoba community hospitals participated in this study. From January 1 to December 31, 1997 stool specimens, one per patient, submitted to hospital microbiology laboratories for C difficile toxin and/or culture testing were screened for VRE on colistin-nalidixic acid-vancomycin (6 microg/mL) (CNAV) agar plates. The study was divided into six, eight-week intervals. Stool specimens received in the first two weeks of each eight week interval were screened for VRE.

MAIN RESULTS

A total of 1408 stool specimens were submitted over the 48-week study period. Sixty-seven (4.8%) patients with VRE colonization of their lower gastrointestinal tract were identified. Three of the 67 (4.5%) VRE isolates were Enterococcus faecium, with the remaining 64 (95.5%) were Enterococcus gallinarum. The three vancomycin-resistant E faecium -VREF- (from two different Winnipeg hospitals) demonstrated the vanA genotype, and were resistant to vancomycin, teicoplanin and ampicillin. All three VREF isolates also demonstrated high level resistance to both gentamicin and streptomycin but were susceptible to quinuprisitin/dalfopristin and LY333328.

CONCLUSION

VRE colonization in hospitalized patients in Manitoba is infrequent and most commonly due to E gallinarum. The prevalence of VREF colonization in the patients studied was 0.2% (three of 1408).

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.

Novel anti-infective compounds from marine bacteria

As a result of the continuous evolution of microbial pathogens towards antibiotic-resistance, there have been demands for the development of new and effective antimicrobial compounds. Since the 1960s, the scientific literature has accumulated many publications about novel pharmaceutical compounds produced by a diverse range of marine bacteria. Indeed, marine micro-organisms continue to be a productive and successful focus for natural products research, with many newly isolated compounds possessing potentially valuable pharmacological activities. In this regard, the marine environment will undoubtedly prove to be an increasingly important source of novel antimicrobial metabolites, and selective or targeted approaches are already enabling the recovery of a significant number of antibiotic-producing micro-organisms. The aim of this review is to consider advances made in the discovery of new secondary metabolites derived from marine bacteria, and in particular those effective against the so called "superbugs", including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), which are largely responsible for the increase in numbers of hospital acquired, i.e., nosocomial, infections.

Predictors and outcome associated with an Enterococcus positive isolate during intensive care unit admission

This study reports the incidence, risk factors and mortality associated with a positive Enterococcus spp. isolate during admission to two tertiary intensive care units participating in an antibiotic cycling study. Incidence was low, with only 4.2% of admissions (36/852) at Royal Brisbane and Women's Hospital and 2.8% (31/1104) at Westmead Hospital developing a positive Enterococcus spp. isolate (P=0.087). A positive enterococcal isolate, while not an independent predictor of mortality (odds ratio [OR]=1.6, 95% confidence interval [CI] 0.80 to 3.2, P=0.18), may be a marker of the underlying severity of illness with higher unadjusted in-hospital mortality (26% or 17/66 vs 14% or 250/1855, P=0.007). Independent risk factors for a positive isolate were use of meropenem/imipenem (OR=5.7, 95% CI 2.4 to 14, P <0.001) and cefepime (OR=2.5, 95% CI 1.2 to 5.3, P=0.017) within 48 hours of intensive care unit admission, the presence of a nasogastric tube (OR=4.1, 95% CI 1.3 to 14, P=0.018), renal replacement therapy (OR=2.2, 95% CI 1.0 to 4.7, P=0.046), operative intervention (OR=1.8, 95% CI 1.0 to 3.2, P=0.035) and age (OR=1.2, 95% CI 1.1 to 1.5, P=0.009). None of these factors, except for the need for renal replacement therapy (OR=6.2, 95% CI 1.4 to 27, P=0.015), was associated with increased mortality. Enterococci-directed empiric therapy in the treatment of sepsis remains of unproven value, although this negative finding must be evaluated against other higher powered studies.

Epidemiology and control of an outbreak of vancomycin-resistant enterococci in the intensive care units

PURPOSE

This study was aimed to describe a vancomycin-resistant enterococci (VRE) outbreak across three intensive care units (ICUs) of a Korean hospital from September 2006 to January 2007 and the subsequent control strategies.

MATERIALS AND METHODS

We simultaneously implemented multifaceted interventions to control the outbreak, including establishing a VRE cohort ward, active rectal surveillance cultures, daily extensive cleaning of environmental surfaces and environmental cultures, antibiotic restriction, and education of hospital staff. We measured weekly VRE prevalence and rectal acquisition rates and characterized the VRE isolates by polymerase chain reaction (PCR) of the vanA gene and Sma1-pulsed-field gel electrophoresis (PFGE).

RESULTS

During the outbreak, a total of 50 patients infected with VRE were identified by clinical and surveillance cultures, and 46 had vancomycin-resistant Enterococcus faecium (VREF). PFGE analysis of VREF isolates from initial two months disclosed 6 types and clusters of two major types. The outbreak was terminated 5 months after implementation of the interventions: The weekly prevalence rate decreased from 9.1/100 patients-day in September 2006 to 0.6/100 by the end of January 2007, and the rectal acquisition rates also dropped from 6.9/100 to 0/100 patients-day.

CONCLUSION

Our study suggests that an aggressive multifaceted control strategy is a rapid, effective approach for controlling a VRE outbreak.

[Interventions implemented to control an outbreak of vancomycin-resistant enterococci in a university hospital]

At the end of 2004, a Vancomycin-resistant enterococci (VRE) outbreak occurred in the university hospital of Nancy. Interventions were simultaneous implemented in this hospital (promotion of hand washing, gathering of VRE carriers in the same part of units) and the outbreak seemed to be controlled before the end of 2005. But one year later, the number of discovered new colonisations increased again. Then, promotion of exclusive hand disinfection with alcohol-based hand-rub solutions and cohorting of VRE carriers in a dedicate ward were the only two effective interventions to control the outbreak. At the beginning of the year 2007, before being controlled, this outbreak expanded to several other healthcare centres in Lorraine. A specific regional team was set up in July 2007. A programme to eradicate VRE was elaborated based on national guidelines modified and adapted regarding particularities of each situation. These new guidelines were published on an internet site. A list of all healthcare centres accommodating patients colonized with VRE is established weekly and diffused to all hospitals in Lorraine which then could optimise readmission conditions of potential VRE carriers or contact patients. Between 2004 and 2008, more than 900 patients were found colonized with VRE in Lorraine. Finally, the application of all the measures previously described, seemed to be efficient to control the ERV outbreak in Lorraine.

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.

Incidence and risk factors of infection caused by vancomycin-resistant enterococcus colonization in neurosurgical intensive care unit patients

OBJECTIVE

This study was aimed to identify the incidence and risk factors of vancomycin-resistant enterococcus (VRE) colonization in neurosurgical practice of field, with particular attention to intensive care unit (ICU).

METHODS

This retrospective study was carried out on the Neurosurgical ICU (NICU), during the period from January. 2005 to December. 2007, in 414 consecutive patients who had been admitted to the NICU. Demographics and known risk factors were retrieved and assessed by statistical methods.

RESULTS

A total of 52 patients had VRE colonization among 414 patients enrolled, with an overall prevalence rate of 6.1%. E. faecium was the most frequently isolated pathogen, and 92.3% of all VRE were isolated from urine specimen. Active infection was noticed only in 2 patients with bacteremia and meningitis. Relative antibiotic agents were third-generation cephalosporin in 40%, and vancomycin in 23%, and multiple antibiotic usages were also identified in 13% of all cases. Multivariate analyses showed Glasgow coma scale (GCS) score less than 8, placement of Foley catheter longer than 2 weeks, ICU stay over 2 weeks and presence of nearby VRE-positive patients had a significantly independent association with VRE infection.

CONCLUSION

When managing the high-risk patients being prone to be infected VRE in the NICU, extreme caution should be paid upon. Because prevention and outbreak control is of ultimate importance, clinicians should be alert the possibility of impending colonization and infection by all means available. The most crucial interventions are careful hand washing, strict glove handling, meticulous and active screening, and complete segregation.

Rapid curbing of a vancomycin-resistant Enterococcus faecium outbreak in a nephrology department

BACKGROUND AND OBJECTIVES

Vancomycin-resistant enterococci (VRE) are recovered with increasing frequency among patients with chronic renal failure, making VRE a major concern in nephrology departments, especially for patients who are treated by hemodialysis. We report herein the successful aggressive management of a VRE outbreak in a nephrology department.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

An Enterococcus faecium vanB strain was isolated from a peritoneal dialysis solution from an inpatient. Immediately, infection control measures were enforced and active screening was performed for all contact patients. Carriers were isolated, and patients were divided into three cohorts: Positive, contact, and noncontact patients. We then performed a case-control study to understand risk factors for VRE carriage comparing VRE carriers with contact patients who were negative for VRE.

RESULTS

A total of 14 VRE-positive and 125 VRE-negative contact patients were identified. VRE-positive patients were more likely to receive hemodialysis and have longer hospital stays in nephrology. VRE-positive patients more often had a central venous catheter for a longer period of time and received more antibiotics than VRE-negative patients. Treatment with large-spectrum beta-lactams and number of days in the nephrology ward were significantly associated with a higher risk for VRE carriage by using multivariate analysis.

CONCLUSIONS

These findings suggest that case mix, longer hospital stays, and antibiotic use are major risk factors for VRE acquisition. In addition, it demonstrates that strict enforcement of isolation precautions and cohorting associated with active screening are successful to curb the transmission of VRE in renal units despite continuous colonization pressure.

Global resistance trends and the potential impact on empirical therapy

Globally, antibiotic resistance continues to be an increasing problem. The emergence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and extended spectrum beta-lactamase-producing Enterobacteriaceae has seriously reduced the number of empirical agents suitable for selected indications. Increasing Gram-negative resistance has also negatively impacted the physician's alternatives when choosing adequate initial therapy; increased reliance on the carbapenem class as empirical agents has led to the emergence of multidrug resistance in non-enteric Gram-negative bacilli. There is a critical need for new, broad-spectrum alternatives to the currently available broad-spectrum agents.

Skin and environmental contamination with vancomycin-resistant Enterococci in patients receiving oral metronidazole or oral vancomycin treatment for Clostridium difficile-associated disease

BACKGROUND

Oral metronidazole has been recommended for treatment of mild-to-moderate Clostridium difficile-associated disease (CDAD), in part because of concern that use of vancomycin may be more likely to promote colonization and transmission of vancomycin-resistant enterococci (VRE). The objective of our study was to compare the frequency of skin and environmental VRE contamination associated with metronidazole treatment for CDAD with such frequency associated with vancomycin treatment for CDAD.

DESIGN

Prospective, observational study. This study was performed at the Cleveland Veterans Affairs Medical Center (Cleveland, OH). For patients with CDAD who had concurrent VRE colonization, stool, skin, and environmental samples were cultured for VRE before, during, and up to 3 weeks after therapy with metronidazole or vancomycin. The proportions of skin and environmental contamination were compared before and after resolution of diarrhea and during treatment with metronidazole or vancomycin.

RESULTS

Of the 34 patients, 17 were treated with vancomycin and 17 were treated with metronidazole. The proportion of environmental cultures that were positive for VRE was significantly higher during resolution of diarrhea than it was after resolution of diarrhea (38% vs 28%; P=.025), whereas the proportion of skin cultures positive was not different during and after resolution of diarrhea (78% vs 71%; P=.60). There were no differences between patients who received metronidazole and patients who received vancomycin in the proportions of skin culture results (73% vs 77%; P=.80) or environmental culture results (37% vs 32%; P=.359) that were positive for VRE. Eleven patients (32%) had chronic fecal incontinence, and 28 (82%) had incontinence at least once during their CDAD episode.

CONCLUSIONS

In VRE-colonized patients with CDAD who experienced frequent fecal incontinence, skin and environmental VRE contamination was common during and after resolution of diarrhea. The frequency of VRE contamination was similar between patients treated with metronidazole and patients treated with vancomycin.

Matching criteria in case-control studies in the field of antimicrobial resistance

OBJECTIVE

We evaluated the available evidence from case-control studies in the field of antimicrobial resistance to identify the degree that matching was performed and the criteria used to do so.

METHODS

We performed a systematic search of the PubMed database (articles archived by 08/2006) to identify relevant studies. Studies that used the individual matching technique were further analyzed.

RESULTS

115 case-control studies with a focus on antimicrobial resistance were identified: 28 regarding Acinetobacter baumannii, 25 regarding Pseudomonas aeruginosa, and 62 for other bacteria. Individual matching was performed in 32 (27.8%) out of the 115 studies. Age was the most frequently used matching criterion in 22 of 32 (69%) evaluated matched case-control studies, while sex was used in 11 (34%), presence of underlying illness in 8 (25%), site of infection in 5 (16%), and area of residence in 4 studies (12.5%). Other criteria were used in less than 10% of the studies. Analysis of data for matched pairs was performed in 18 of 32 (56.3%) studies that used a matched case-control design.

DISCUSSION

The available evidence from the analyzed data from case-control studies in the field of antimicrobial resistance shows that individual matching is employed only in a proportion of such studies and only for a few characteristics, when it was used. Also, analysis for matched pairs was not used by almost a half of the relevant studies.

Both oral metronidazole and oral vancomycin promote persistent overgrowth of vancomycin-resistant enterococci during treatment of Clostridium difficile-associated disease

For treatment of mild to moderate Clostridium difficile-associated disease (CDAD), oral metronidazole has been recommended as the preferred agent, in part due to concern that vancomycin may be more likely to promote colonization by vancomycin-resistant enterococci (VRE). We performed a prospective observational study to examine the effects of oral metronidazole or vancomycin treatment of CDAD on acquisition and concentration of VRE stool colonization. Before, during, and after 90 courses of CDAD therapy, stool samples were cultured for VRE, and the concentrations were quantified. Eighty-seven subjects (97%) had received antibiotics within the past month. For 56 treatment courses in which preexisting VRE colonization was present, metronidazole (n = 37 courses) and vancomycin (n = 19 courses), each promoted persistent VRE overgrowth during therapy, and the concentration decreased significantly in both groups by approximately 2 weeks after completion of treatment (P <0.049). For 34 treatment courses in which baseline cultures were negative for VRE, new detection of VRE stool colonization occurred during 3 (14%) of the 22 courses of metronidazole and 1 (8%) of the 12 courses of vancomycin (P = 1.0). These results demonstrate that both oral metronidazole and oral vancomycin promote the overgrowth of VRE during treatment of CDAD. New CDAD treatments are needed that are less likely to disrupt the intestinal microflora and promote overgrowth of healthcare-associated pathogens.

Enterococcal endocarditis associated with crescentic glomerulonephritis

Glomerulonephritis secondary to infective endocarditis (IE) is an uncommon diagnosis and is usually associated with cardiac valvular infection by blood-culture-positive bacteria. We report a case of necrotizing glomerulonephritis associated with culture-positive endocarditis caused by Enterococcus faecalis. The patient presented with renal abnormalities and was further investigated by renal biopsy. He had immune complex-mediated necrotizing and crescentic glomerulonephritis with mesengial and capillary deposition of immunoglobulin M (Ig M), Ig G, and complement 3 (C3). He was treated with antibiotics, including ampicillin and gentamicin. In addition, steroid and cyclophosphamide were administered. The patient died of renal failure 48 days after hospital admission. In conclusion, glomerulonephritis caused by Enterococcus faecalis endocarditis is an immune-complex-mediated disease characterized by necrotizing and crescentic glomerular lesions that can be fatal despite aggressive antimicrobial and immunosuppressive therapy.

Hospital-acquired Clostridium difficile-associated disease in the intensive care unit setting: epidemiology, clinical course and outcome

Background

Clostridium difficile-associated disease (CDAD) is a serious nosocomial infection, however few studies have assessed CDAD outcome in the intensive care unit (ICU). We evaluated the epidemiology, clinical course and outcome of hospital-acquired CDAD in the critical care setting.

Methods

We performed a historical cohort study on 58 adults with a positive C. difficile cytotoxin assay result occurring in intensive care units.

Results

Sixty-two percent of patients had concurrent infections, 50% of which were bloodstream infections. The most frequently prescribed antimicrobials prior to CDAD were anti-anaerobic agents (60.3%). Septic shock occurred in 32.8% of CDAD patients. The in-hospital mortality was 27.6%. Univariate analysis revealed that SOFA score, at least one organ failure and age were predictors of mortality. Charlson score ≥3, gender, concurrent infection, and number of days with diarrhea before a positive C. difficile toxin assay were not significant predictors of mortality on univariate analysis. Independent predictors for death were SOFA score at infection onset (per 1-point increment, OR 1.40; CI95 1.13–1.75) and age (per 1-year increment, OR 1.10; CI95 1.02–1.19).

Conclusion

In ICU patients with CDAD, advanced age and increased severity of illness at the onset of infection, as measured by the SOFA score, are independent predictors of death.

Management of severe bacterial infections

Defining the severity of an infection can play a central role for a correct therapeutic choice, avoiding inadequate antimicrobial treatments. Severe bacterial infections are, in fact, characterized by high morbidity and mortality rates so that the appropriateness of therapy can have a profound clinical impact. Indeed, initial inappropriate empirical therapies, and the further need to modify them, substantially increase the mortality risk. Several strategies have been suggested to improve the clinical outcome of patients affected by severe bacterial infections, such as the use of guidelines, use of antibiotics in combination, de-escalation therapy, cycling therapy and the use of infectious disease specialist consultation. A closer collaboration between the medical staff in the wards and infectious disease specialists can possibly bridge the gap between different strategies and individual needs of the patient, thereby improving the decision-making process.

Tratamiento de infecciones por Enterococcus resistente a vancomicina con linezolid en un hospital pediátrico

OBJECTIVE

To describe the use of linezolid in vancomycin-resistant Enterococcus infections in a paediatric hospital.

METHOD

Retrospective, observational study of hospitalised patients at the "Juan P. Garrahan" paediatric hospital receiving linezolid for the treatment of vancomycin-resistant Enterococcus, during the period between January 2002 and July 2004.

RESULTS

During 18 months, linezolid was prescribed 17 times for a total of 15 seriously ill patients. The median age was 7 years old (range: 1 month-15 years) and the median length of the treatment was 15 days, with an average hospital stay of 74 days. Infection with vancomycin-resistant Enterococcus was microbiologically documented in 11 (73.3%) patients; they all responded to treatment with linezolid with the exception of two, who died while receiving treatment. The most frequently reported adverse reactions were of a haematological nature (55.5%).

CONCLUSIONS

Linezolid was effective and moderately well tolerated for the treatment of vancomycin-resistant Enterococcus in children with life-threatening infections.