2004 Lowbury Lecture: the Western Australian experience with vancomycin-resistant enterococci – from disaster to ongoing control

Contact tracing for vancomycin-resistant Enterococcus faecium (VRE): evaluation of the Dutch policy of quintuple screening cultures

Detection of vancomycin-resistant Enterococcus faecium (VRE) is hampered by low sensitivity of rectal swab cultures. This study aimed to define the number of screening cultures needed to increase sensitivity to detect VRE transmission, and to determine time from presumed exposure to detectable colonization. In a tertiary care setting, we retrospectively analyzed data from 9 VRE outbreaks. As a proxy or estimation for time to detectable colonization, the time between first positive culture of the presumed index patient and that of their contacts was determined. Only 64% of secondary cases were positive in the first out of five cultures. By using the first three out of five rectal swabs, 89% (95%CI: 78-95%) of all secondary cases would have been identified. The median number of days between the positive culture of the index patient and the first positive culture of secondary cases was 9 days. Eleven percent of secondary cases would have been missed if only three rectal samples would have been obtained. Furthermore, our results show that one or more rectal swabs taken around day 9 after presumed exposure should at least be included in the screening approach. In our setting, obtaining a fourth and a fifth rectal swab showed a relevant additional value compared to only one to three swabs. Our findings are useful for determining the most effective VRE contact tracing approach to prevent transmission.

Silica nanoparticles with encapsulated DNA (SPED) to trace the spread of pathogens in healthcare

Background

To establish effective infection control protocols, understanding pathogen transmission pathways is essential. Non-infectious surrogate tracers may safely explore these pathways and challenge pre-existing assumptions. We used silica nanoparticles with encapsulated DNA (SPED) for the first time in a real-life hospital setting to investigate potential transmission routes of vancomycin-resistant enterococci in the context of a prolonged outbreak.

Methods

The two study experiments took place in the 900-bed University Hospital Zurich, Switzerland. A three-run ‘Patient experiment’ investigated pathogen transmission via toilet seats in a two-patient room with shared bathroom. First, various predetermined body and fomite sites in a two-bed patient room were probed at baseline. Then, after the first patient was contaminated with SPED at the subgluteal region, both patients sequentially performed a toilet routine. All sites were consequently swabbed again for SPED contamination. Eight hours later, further spread was tested at predefined sites in the patient room and throughout the ward. A two-run ‘Mobile device experiment’ explored the potential transmission by mobile phones and stethoscopes in a quasi-realistic setting. All SPED contamination statuses and levels were determined by real-time qPCR.

Results

Over all three runs, the ‘Patient experiment’ yielded SPED in 59 of 73 (80.8%) predefined body and environmental sites. Specifically, positivity rates were 100% on subgluteal skin, toilet seats, tap handles, and entertainment devices, the initially contaminated patients’ hands; 83.3% on patient phones and bed controls; 80% on intravenous pumps; 75% on toilet flush plates and door handles, and 0% on the initially not contaminated patients’ hands. SPED spread as far as doctor’s keyboards (66.6%), staff mobile phones (33.3%) and nurses’ keyboards (33.3%) after eight hours. The ‘Mobile device experiment’ resulted in 16 of 22 (72.7%) positive follow-up samples, and transmission to the second patient occurred in one of the two runs.

Conclusions

For the first time SPED were used to investigate potential transmission pathways in a real hospital setting. The results suggest that, in the absence of targeted cleaning, toilet seats and mobile devices may result in widespread transmission of pathogens departing from one contaminated patient skin region.

Economic impact of an outbreak of carbapenemase producing-Enterobacteriaceae in a surgical intensive care unit

BACKGROUND

A 15-month outbreak of carbapenemase-producing Enterobacterales (CPE) occurred in the surgical intensive care unit (SICU) of our institution. We aimed to estimate the financial impact of this outbreak from the perspective of the French public health insurance system.

METHODS

The characteristics of the colonised/infected CPE patients and outbreak management according to French national guidelines were prospectively collected. Loss of productivity was assessed in terms of the reduction in total number of admissions (TNA) and discharges and in ICU length of stay (LoS). The additional financial burden associated with this outbreak was estimated by the accounting department of the hospital, including the impact of the extended LoS and restricted admissions.

RESULTS

Sixteen CPE patients (19 stays) were hospitalised in the SICU (10/2016-01/2018). The median ICU LoS for the CPE cases was 17 [8-36] days versus 6.5 and 6.1 days in 2016 and 2017, respectively, for the whole SICU population. The total number of lost bed days during the outbreak was 452. The TNA dropped dramatically in 2017 (decrease of 20.6%). The estimated costs were 768,386 EUR for bed days lost; 297,176 EUR and 63,675 EUR for the extended LoS for the CPE cases and the patients on contact precautions, respectively; 34,045 EUR for staff reinforcements; 85,764 EUR for bacteriological screening tests; and 42,857 EUR for antimicrobial treatment. The total financial burden of the outbreak was 1,291,903 EUR.

CONCLUSION

Management of a CPE outbreak in the SICU is associated with a huge financial burden for the unit and for the institution.

Enterococcus faecium: from microbiological insights to practical recommendations for infection control and diagnostics

Early in its evolution, Enterococcus faecium acquired traits that allowed it to become a successful nosocomial pathogen. E. faecium inherent tenacity to build resistance to antibiotics and environmental stressors that allows the species to thrive in hospital environments. The continual wide use of antibiotics in medicine has been an important driver in the evolution of E. faecium becoming a highly proficient hospital pathogen.For successful prevention and reduction of nosocomial infections with vancomycin resistant E. faecium (VREfm), it is essential to focus on reducing VREfm carriage and spread. The aim of this review is to incorporate microbiological insights of E. faecium into practical infection control recommendations, to reduce the spread of hospital-acquired VREfm (carriage and infections). The spread of VREfm can be controlled by intensified cleaning procedures, antibiotic stewardship, rapid screening of VREfm carriage focused on high-risk populations, and identification of transmission routes through accurate detection and typing methods in outbreak situations. Further, for successful management of E. faecium, continual innovation in the fields of diagnostics, treatment, and eradication is necessary.

Elucidating vancomycin-resistant Enterococcus faecium outbreaks: the role of clonal spread and movement of mobile genetic elements

Background

Vancomycin-resistant Enterococcus faecium (VREfm) has emerged as a nosocomial pathogen worldwide. The dissemination of VREfm is due to both clonal spread and spread of mobile genetic elements (MGEs) such as transposons.

Objectives

We aimed to combine vanB-carrying transposon data with core-genome MLST (cgMLST) typing and epidemiological data to understand the pathways of transmission in nosocomial outbreaks.

Methods

Retrospectively, 36 VREfm isolates obtained from 34 patients from seven VREfm outbreak investigations in 2014 were analysed. Isolates were sequenced on a MiSeq and a MinION instrument. De novo assembly was performed in CLC Genomics Workbench and the hybrid assemblies were obtained through Unicycler v0.4.1. Ridom SeqSphere+ was used to extract MLST and cgMLST data. Detailed analysis of each transposon and their integration points was performed using the Artemis Comparison Tool (ACT) and multiple blast analyses.

Results

Four different vanB transposons were found among the isolates. cgMLST divided ST80 isolates into three cluster types (CTs); CT16, CT104 and CT106. ST117 isolates were divided into CT24, CT103 and CT105. Within VREfm isolates belonging to CT103, two different vanB transposons were found. In contrast, VREfm isolates belonging to CT104 and CT106 harboured an identical vanB transposon.

Conclusions

cgMLST provides a high discriminatory power for the epidemiological analysis of VREfm. However, additional transposon analysis is needed to detect horizontal gene transfer. Combining these two methods allows investigation of both clonal spread as well as the spread of MGEs. This leads to new insights and thereby better understanding of the complex transmission routes in VREfm outbreaks.

Recommendations for the successful control of a large outbreak of vancomycin-resistant Enterococcus faecium in a non-endemic hospital setting

BACKGROUND

A large outbreak of three epidemic vancomycin-resistant Enterococcus faecium (VRE) clones affected the study hospital for almost two years.

AIM

To describe the strategy to successfully control this outbreak and eradicate VRE from the study hospital.

METHODS

Infection control interventions started after detection of VRE in three patients. Hospital-wide surveillance was started after ongoing transmission despite isolation precautions, cleaning and contact tracing. Hygiene education and discipline were enhanced. Despite these interventions, additional measures were required to control the outbreak, such as ward disinfection with hydrogen peroxide vapour and the introduction of a VRE quarantine ward. Ultimately, ciprofloxacin prophylaxis for haematological patients on chemotherapy was abandoned.

FINDINGS

Over a 22-month period, 242 VRE carriers were identified. Of these, 128 (53%) patients were detected by hospital-wide surveillance alone. Three epidemic clones were detected: ST494-vanA (N = 160), ST78-vanA (N = 23) and ST117-vanB (N = 32). In total, 5614 possible contacts were identified. VRE transmission occurred on 13 out of 23 wards. VRE was cultured from clinical specimens in 22 patients (seven with bacteraemia). Since January 2014, no further transmission of these VRE clones has been observed.

CONCLUSION

Infection control measures according to international guidelines were insufficient to expose the outbreak to its full extent and control it. Its full extent only became apparent after sustained hospital-wide screening. Successful control of this hospital-wide VRE outbreak was feasible, but required great effort. Final containment and eradication of the epidemic clones was achieved by environmental decontamination with hydrogen peroxide vapour, strict isolation precautions, a VRE quarantine ward and antimicrobial stewardship.

Efficient national surveillance for health-care-associated infections

Background

Detecting novel healthcare-associated infections (HCAI) as early as possible is an important public health priority. However, there is currently no evidence base to guide the design of efficient and reliable surveillance systems. Here we address this issue in the context of a novel pathogen spreading primarily between hospitals through the movement of patients.

Methods

Using a mathematical modelling approach we compare the current surveillance system for a HCAI that spreads primarily between hospitals due to patient movements as it is implemented in Scotland with a gold standard to determine if the current system is maximally efficient or whether it would be beneficial to alter the number and choice of hospitals in which to concentrate surveillance effort.

Results

We validated our model by demonstrating that it accurately predicts the risk of meticillin-resistant Staphylococcus aureus bacteraemia cases in Scotland.

Using the 29 (out of 182) sentinel hospitals that currently contribute most of the national surveillance effort results in an average detection time of 117 days. A reduction in detection time to 87 days is possible by optimal selection of 29 hospitals. Alternatively, the same detection time (117 days) can be achieved using just 22 optimally selected hospitals. Increasing the number of sentinel hospitals to 38 (teaching and general hospitals) reduces detection time by 43 days; however decreasing the number to seven sentinel hospitals (teaching hospitals) increases detection time substantially to 268 days.

Conclusions

Our results show that the current surveillance system as it is used in Scotland is not optimal in detecting novel pathogens when compared to a gold standard. However, efficiency gains are possible by better choice of sentinel hospitals, or by increasing the number of hospitals involved in surveillance. Similar studies could be used elsewhere to inform the design and implementation of efficient national, hospital-based surveillance systems that achieve rapid detection of novel HCAIs for minimal effort.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2172-9) contains supplementary material, which is available to authorized users.

French recommendations for the prevention of 'emerging extensively drug-resistant bacteria' (eXDR) cross-transmission

Controlling the spread of multi- or extensively drug-resistant bacteria (MDR or XDR) includes a dual strategy for reducing antibiotic prescriptions and preventing their spread from patient carriers. Standard precautions are applicable to all health professionals caring for any patients; additional barrier precautions (isolation) are recommended for patients carrying transmissible infectious diseases or MDR bacteria in sporadic or epidemic situations. Moreover, additional precautions may be required for populations at particular risk of infection or colonization by emerging XDR (eXDR), defined in our country as carbapenemase-producing Enterobacteriaceae and vancomycin-resistant enterococci. Our ability to detect and identify eXDR carriers early and ensure their follow-up, through effective communication between all those involved, is a significant challenge for controlling their spread. Thus, the French High Committee for Public Health has updated and standardized all French existing recommendations concerning the prevention of the cross-transmission of these bacteria, and these recommendations are summarized in this review. The recommendations are based on scientific and operational knowledge up to 2013. Different preventive strategies are recommended for patients found to be carrying eXDR and those who are considered to be at risk of having eXDR because of a history of contact. The local context, the experience of the infection control team, the different times at which detection of eXDR takes place (during admission, hospitalization, etc.) and the epidemiological situation (sporadic cases, clusters, outbreaks, widespread epidemic) must be included in risk assessments that in turn inform the control measures that should be applied in each clinical circumstance.

Moving toward Elimination of Healthcare-Associated Infections: A Call to Action

Jointly, the Association for Professionals in Infection Control and Epidemiology (APIC), the Society for Healthcare Epidemiology of America (SHEA), the Infectious Diseases Society of America (IDSA), the Association of State and Territorial Health Officials (ASTHO), the Council of State and Territorial Epidemiologists (CSTE), Pediatric Infectious Diseases Society (PIDS), and the Centers for Disease Control and Prevention (CDC) propose a call to action to move toward the elimination of healthcare-associated infections (HAIs) by adapting the concept and plans used for the elimination of other diseases, including infections. Elimination, as defined for other infectious diseases, is the maximal reduction of “the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent reestablishment of transmission are required.” (p24) This definition has been useful for elimination efforts directed toward polio, tuberculosis, and syphilis and can be readily adapted to HAIs. Sustained elimination of HAIs can be based on this public health model of constant action and vigilance. Elimination will require the implementation of evidence-based practices, the alignment of financial incentives, the closing of knowledge gaps, and the acquisition of information to assess progress and to enable response to emerging threats. These efforts must be under-pinned by substantial research investments, the development of novel prevention tools, improved organizational and personal accountabilities, strong collaboration among a broad coalition of public and private stakeholders, and a clear national will to succeed in this arena.

Efficient surveillance for healthcare-associated infections spreading between hospitals

Early detection of new or novel variants of nosocomial pathogens is a public health priority. We show that, for healthcare-associated infections that spread between hospitals as a result of patient movements, it is possible to design an effective surveillance system based on a relatively small number of sentinel hospitals. We apply recently developed mathematical models to patient admission data from the national healthcare systems of England and The Netherlands. Relatively short detection times are achieved once 10-20% hospitals are recruited as sentinels and only modest reductions are seen as more hospitals are recruited thereafter. Using a heuristic optimization approach to sentinel selection, the same expected time to detection can be achieved by recruiting approximately half as many hospitals. Our study provides a robust evidence base to underpin the design of an efficient sentinel hospital surveillance system for novel nosocomial pathogens, delivering early detection times for reduced expenditure and effort.

Evaluation of iNtRON VRE vanA/vanB real-time PCR for follow-up surveillance of VRE-infected or colonized patients

The iNtRON vancomycin-resistant enterococci (VRE) vanA/vanB real-time PCR assay was directly applied to stool surveillance (direct-PCR). direct-PCR was compared to 2 culture-based methods using Enterococcosel broth (enrichment-culture) and ChromID VRE media. The positive broth of the enrichment-culture was submitted to phenotypic confirmation of subcultured colonies and genotyping by Seeplex VRE PCR. From September 2011 to May 2012, 208 stool specimens from 188 patients previously positive for VRE were enrolled. Enrichment-culture and direct-PCR detected 178 and 158 positives, respectively. Among 129 specimens cultured with ChromID, direct-PCR and ChromID yielded 105 and 104 positives, respectively. Compared to the enrichment-culture, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of direct-PCR and ChromID were 86.0%, 83.3%, 96.8%, 50.0%, and 89.5%, 86.7%, 98.1%, 52.0%, respectively. Considering the excellent PPV and low NPV, direct-PCR would be useful to monitor VRE-colonized or infected patients on the day, but enrichment-culture is required for direct-PCR-negative specimens.

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).

Eradication of an outbreak of vancomycin-resistant Enterococcus (VRE): the cost of a failure in the systematic screening

Background

Vancomycin-resistant enterococci (VRE) are still a concern in hospital units tending to seriously ill patients. However, the cost-effectiveness of active surveillance program to identify asymptomatically VRE colonized patient remains debatable. This work aims at evaluating the cost of a failure in the active surveillance of VRE that had resulted in an outbreak in a French University Hospital.

Findings

A VRE outbreak was triggered by a failure in the systematic VRE screening in a medico-surgical ward specialised in liver transplantation as a patient was not tested for VRE. This failure was likely caused by the reduction of healthcare resource. The outbreak involved 13 patients. Colonized patients were grouped in a dedicated part of the infectious diseases unit and tended by a dedicated staff. Transmission was halted within two months after discovery of the index case.

The direct cost of the outbreak was assessed as the cost of staffing, disposable materials, hygiene procedures, and surveillance cultures.

The loss of income from spare isolation beds was computed by difference with the same period in the preceding year. Payments were drawn from the hospital database. The direct cost of the outbreak (2008 Euros) was €60 524 and the loss of income reached €110 915.

Conclusions

Despite this failure, the rapid eradication of the VRE outbreak was a consequence of the rapid isolation of colonized patient. Yet, eradicating even a limited outbreak requires substantial efforts and resources. This underlines that special attention has to be paid to strictly adhere to active surveillance program.

Infection prevention in a connected world: the case for a regional approach

Results from microbiological and epidemiological investigations, as well as mathematical modelling, show that the transmission dynamics of nosocomial pathogens, especially of multiple antibiotic-resistant bacteria, is not exclusively amenable to single-hospital infection prevention measures. Crucially, their extent of spread depends on the structure of an underlying "healthcare network", as determined by inter-institutional referrals of patients. The current trend towards centralized healthcare systems favours the spread of hospital-associated pathogens, and must be addressed by coordinated regional or national approaches to infection prevention in order to maintain patient safety. Here we review recent advances that support this hypothesis, and propose a "next-generation" network-approach to hospital infection prevention and control.

[Performance evaluation of BD GeneOhm MRSA PCR assay for detection of nasal colonization of methicillin-resistant Staphylococcus aureus at endemic intensive care units]

BACKGROUND

The BD GeneOhm MRSA PCR assay (Becton Dickinson, USA) is a qualitative real-time PCR test for rapid detection of nasal colonization of methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the performance of BD GeneOhm MRSA PCR assay versus MRSASelect (Bio-Rad, France) and broth enrichment cultures for detection of MRSA from nasal swabs.

METHODS

From August 2008 to January 2009, 295 nasal swabs were taken from patients in intensive care units and transported to the laboratory with BD CultureSwab Liquid Stuart Single Swab (Becton Dickinson, USA). The swabs were inoculated onto MRSASelect first and then suspended into GeneOhm sample buffer: 100 microL of the suspension was inoculated into 6.5% NaCl-tryptic soy broth (Becton Dickinson, USA), which was subcultured on MRSASelect after overnight incubation (TSBS). Performances of GeneOhm MRSA and MRSASelect were compared to TSBS.

RESULTS

With GeneOhm MRSA, 125 swabs (44.6%) were positive for MRSA, 13 (4.4%) were unresolved, and 2 were not determined. With MRSASelect and TSBS 86 (29.4%) and 106 swabs (36.2%), respectively, were positive. The sensitivity, specificity, and positive and negative predictive value of GeneOhm MRSA were 85.8%, 77.5%, and 72.8% and 93.5%, respectively, and corresponding values for MRSASelect were 78.3%, 94.8%, and 96.5% and 88.9%. Of the 33 patients whose 34 specimens were found false positive in GeneOhm MRSA, 23 patients were MRSA-positive either previously or subsequently to this study. All of the 10 patients with false-negative specimens in GeneOhm MRSA PCR assay were previously MRSA or methicilln-resistant coagulase negative staphylococci (MRCNS)-positive and were treated for MRSA, but they became MRSA-positive after 1 to 4 negative surveillance cultures.

CONCLUSIONS

GeneOhm MRSA PCR assay showed a relatively high negative predictive value. However, its low specificity and frequent occurrence of unresolved results would be problematic in the endemic areas with a high prevalence of MRSA.

Functional genomics of Enterococcus faecalis: multiple novel genetic determinants for biofilm formation in the core genome

The ability of Enterococcus faecalis to form robust biofilms on host tissues and on abiotic surfaces such as catheters likely plays a major role in the pathogenesis of opportunistic antibiotic-resistant E. faecalis infections and in the transfer of antibiotic resistance genes. We have carried out a comprehensive analysis of genetic determinants of biofilm formation in the core genome of E. faecalis. Here we describe 68 genetic loci predicted to be involved in biofilm formation that were identified by recombinase in vivo expression technology (RIVET); most of these genes have not been studied previously. Differential expression of a number of these determinants during biofilm growth was confirmed by quantitative reverse transcription-PCR, and genetic complementation studies verified a role in biofilm formation for several candidate genes. Of particular interest was genetic locus EF1809, predicted to encode a regulatory protein of the GntR family. We isolated 14 independent nonsibling clones containing the putative promoter region for this gene in the RIVET screen; EF1809 also showed the largest increase in expression during biofilm growth of any of the genes tested. Since an in-frame deletion of EF1809 resulted in a severe biofilm defect that could be complemented by the cloned wild-type gene, we have designated EF1809 ebrA (enterococcal biofilm regulator). Most of the novel genetic loci identified in our studies are highly conserved in gram-positive bacterial pathogens and may thus constitute a pool of uncharacterized genes involved in biofilm formation that may be useful targets for drug discovery.

Changes in bacterial isolates from burn wounds and their antibiograms: a 20-year study (1986-2005)

BACKGROUND

Our aim is to elucidate shifts in the bacterial spectrum colonising burn wounds and corresponding antibiotic susceptibilities during a 20-year study period.

METHODS

Microbiological results from burn patients collected between 1986 and 2005 were analysed retrospectively.

RESULTS

Staphylococcus aureus was isolated most frequently (20.8%), followed by Escherichia coli (13.9%), Pseudomonas aeruginosa (11.8%), coagulase-negative staphylococci (CNS) (10.9%), Enterococcus sp. (9.7%), Enterobacter cloacae (5.6%), Klebsiella pneumoniae (5%), Acinetobacter sp. (3.2%), Proteus mirabilis (2%) and Stenotrophomonas maltophilia (1.4%). Susceptibility of S. aureus to broad-spectrum substances such as ciprofloxacin or penicillinase-stable penicillins has waned, others such as cotrimoxazole or netilmicin remained effective. Not a single resistance against vancomycin was recorded. Increases in methicillin-resistant S. aureus (MRSA) were pronounced (3% in 1986-1997 (the first of the three study periods) to 16% in 1998-2001 and 13% in 2002-2005). Results for methicillin-resistant CNS (MRCNS) show an even greater increase. P. aeruginosa has shown increasing susceptibility against netilmicin (1986-1989: 84%, 2002-2005: 95%). Susceptibility of P. aeruginosa to ceftazidime has decreased markedly. S. maltophilia has shown clinically relevant susceptibility mainly against ciprofloxacin. Acinetobacter sp. have shown little susceptibility to most antibiotics. Imipenem or meropenem have been very reliable reserve antibiotics throughout the study period for the fermenting Enterobacteriaceae (E. coli, K. pneumoniae, E. cloacae and P. mirabilis), with susceptibilities of or near 100%.

CONCLUSION

In-depth knowledge of the bacteria causing infectious complications and of their antibiotic susceptibilities is a prerequisite for treating burn patients. Our study shows shifts in the microbial spectrum and their antibiogram, which mandate frequent reassessments.

Virulence determinants in vancomycin-resistant Enterococcus faecium vanB: clonal distribution, prevalence and significance of esp and hyl in Australian patients with haematological disorders

European studies have suggested that the esp gene and other virulence factors have roles in vancomycin-resistant Enterococcus faecium (VREfm) infections. The aim of this study was to examine the relationship between the spectrum of clinical disease and putative virulence factors in vanB VREfm isolates. A multiplex polymerase chain reaction was used to amplify potential virulence genes (asa1, gel E, cylA, esp and hyl) in VREfm isolates obtained from an Australian population of haematology patients. Clonality was assessed by pulsed-field gel electrophoresis (PFGE) and automated ribotyping. Infection, requirement for intensive care unit (ICU) admission and all-cause 30-day mortality were used as clinical indicators of organism virulence. Forty-one VREfm vanB isolates (41 patients; 14 infected and 27 colonised only) were analysed. Thirty-five of these isolates were typed by PFGE, 31 of which were represented by three clusters. The esp gene was identified in 22 of 27 (81.5%) screening and 11 of 14 (78.6%) infection-associated isolates. One isolate was hyl gene positive, and no isolate contained asa1, gel E or cylA genes. VREfm infection was independently associated with host factors (underlying diagnosis of acute myeloid leukaemia, age <or=60 years) but not with presence of the esp gene. ICU admission was negatively associated with presence of the esp gene (OR: 0.05; 95% CI: 0.01-0.61; P=0.02). There was no association between 30-day mortality and host factors or the presence of the esp gene. When compared to European and US reports, a high esp gene prevalence and low hyl gene prevalence was observed in polyclonal VRE isolates obtained from this immunocompromised population.

Prevention and management of infections associated with burns in the combat casualty

Burns complicate 5% to 10% of combat associated injuries with infections being the leading cause of mortality. Given the long term complications and rehabilitation needs after initial recovery from the acute burns, these patients are often cared for in dedicated burn units such as the Department of Defense referral burn center at the United States Army Institute of Surgical Research in San Antonio, TX. This review highlights the evidence-based recommendations using military and civilian data to provide the most comprehensive, up-to-date management strategies for burned casualties. Areas of emphasis include antimicrobial prophylaxis, debridement of devitalized tissue, topical antimicrobial therapy, and optimal time to wound coverage.

Vancomycin-resistant enterococci outbreak, Germany, and calculation of outbreak start

On the basis of a large outbreak of vancomycin-resistant Enterococcus faecium in a German university hospital, we estimated costs (≈1 million Euros) that could have been avoided by early detection of the imminent outbreak. For this purpose, we demonstrate an easy-to-use statistical method.

Discrimination between epidemic and non-epidemic glycopeptide-resistant E. faecium in a post-outbreak situation

Vancomycin-resistant enterococci (VRE) have been isolated in increasing numbers. Hospital-adapted VRE exhibit relatively high pathogenicity by expressing factors like enterococcal surface protein (Esp), which facilitates epidemic spread. By contrast, 'community-acquired' VRE show low pathogenicity and non-epidemic features. In 2004 and 2005 an extended outbreak of VRE occurred at a university hospital in Southwestern Germany and an infection control programme was implemented to confine the outbreak. Pulsed-field gel electrophoresis (PFGE), esp PCR, multiple-locus variable number of tandem repeat analysis (MLVA), purK1 typing and multiple-locus sequence typing (MLST) were performed on representative VRE isolates. Twenty-six non-epidemic and two epidemic VRE types (MLST203, MLST280) were identified by PFGE. Seven of the non-outbreak VRE types were esp gene negative, whereas 19 non-outbreak and both epidemic VRE types were esp positive. Eight MLVA types were identified. MLVA type 1 included five PFGE types and MLVA type 159 included 16 PFGE types. Currently there is no efficient method available to identify non-epidemic VRE and avoid unnecessary isolation of patients. More than 50% non-epidemic clones were esp positive; nevertheless, esp PCR appears to be the most promising approach to identify non-epidemic VRE.