Long-term carriage of vancomycin-resistant enterococci in patients discharged from hospitals: a 12-year retrospective cohort study

Therapeutics for Vancomycin-Resistant Enterococcal Bloodstream Infections

Vancomycin-resistant enterococci (VRE) are common causes of bloodstream infections (BSIs) with high morbidity and mortality rates. They are pathogens of global concern with a limited treatment pipeline. Significant challenges exist in the management of VRE BSI, including drug dosing, the emergence of resistance, and the optimal treatment for persistent bacteremia and infective endocarditis. Therapeutic drug monitoring (TDM) for antimicrobial therapy is evolving for VRE-active agents; however, there are significant gaps in the literature for predicting antimicrobial efficacy for VRE BSIs. To date, TDM has the greatest evidence for predicting drug toxicity for the three main VRE-active antimicrobial agents daptomycin, linezolid, and teicoplanin. This article presents an overview of the treatment options for VRE BSIs, the role of antimicrobial dose optimization through TDM in supporting clinical infection management, and challenges and perspectives for the future.

Carriage of vancomycin-resistant Enterococcus faecium in infants following an outbreak in the neonatal intensive care unit: time to clearance of carriage and use of molecular methods to detect colonization

Among 46 infants colonized with vancomycin-resistant Enterococcus faecium during an outbreak in a neonatal intensive care unit, the estimated time until half had achieved clearance was 217 days. All 40 infants who completed follow-up cleared carriage by 1 year. No predictors of prolonged carriage (> 6 months) were identified.

Predictors of Vancomycin-Resistant Enterococcus spp. Intestinal Carriage among High-Risk Patients in University Hospitals in Serbia

The predictors of intestinal carriage of vancomycin-resistant Enterococcus spp. (VRE) among high-risk patients in the counties of the Southeast Europe Region are insufficiently investigated, yet they could be of key importance in infection control. The aim of the study was to identify risk factors associated with fecal VRE colonization among high-risk inpatients in university hospitals in Serbia. The study comprised 268 inpatients from three university hospitals. Data on patient demographics and clinical characteristics, length of hospital stay, therapy, and procedures were obtained from medical records. Chi-squared tests and univariate and multivariate logistic regressions were performed. Compared to the hemodialysis departments, stay in the geriatric departments, ICUs, and haemato-oncology departments increased the risk for VRE colonization 7.6, 5.4, and 5.5 times, respectively. Compared to inpatients who were hospitalized 48 h before stool sampling for VRE isolation, inpatients hospitalized 3–7, 8–15, and longer than 16 days before sampling had 5.0-, 4.7-, and 6.6-fold higher risk for VRE colonization, respectively. The use of cephalosporins and fluoroquinolones increased the risk for VRE colonization by 2.2 and 1.9 times, respectively. The age ≥ 65 years increased the risk for VRE colonization 2.3 times. In comparison to the University Clinical Centre of Serbia, the hospital stays at Zemun and Zvezdara University Medical Centres were identified as a protector factors. The obtained results could be valuable in predicting the fecal VRE colonization status at patient admission and consequent implementation of infection control measures targeting at-risk inpatients where VRE screening is not routinely performed.

The use of core genome multilocus sequence typing to determine the duration of vancomycin-resistant Enterococcus faecium outbreaks

The prevalence of vancomycin-resistant Enterococcus faecium has increased rapidly, and in Denmark, we are facing an endemic outbreak situation in hospitals. The aim of this study was to use whole-genome sequencing (WGS) and core genome multilocus sequencing typing (cgMLST) to determine the duration of VREfm outbreaks and thereby evaluate the effect of our infection control strategies. We included all VREfm isolates from six hospitals in the Capital Region of Denmark that were sequenced between 2012 and 2020. Ward data were collected from our laboratory information system. A ward outbreak was defined as two patient samples from the same ward within a period of 30 days belonging to the same cgMLST cluster. cgMLST complex types were determined using Ridom SeqSphere v7.2.3, where a maximum of 20 allelic differences between isolates defines a cluster. We included 1690 patient isolates between 2012 and 2020. Our collection consisted of 45 unique clusters and 227 ward outbreaks. The median duration of outbreaks was 20 days. We reported a median outbreak duration of VREfm outbreaks based on WGS data to be 20 days, and thus concluded that our infection control precautions are adequate.

Resistance in Vancomycin-Resistant Enterococci

Serious infections owing to vancomycin-resistant enterococci have historically proven to be difficult clinical cases, requiring combination therapy and management of treatment-related toxicity. Despite the introduction of new antibiotics with activity against vancomycin-resistant enterococci to the therapeutic armamentarium, significant challenges remain. An understanding of the factors driving the emergence of resistance in vancomycin-resistant enterococci, the dynamics of gastrointestinal colonization and microbiota-mediated colonization resistance, and the mechanisms of resistance to the currently available therapeutics will permit clinicians to be better prepared to tackle these challenging hospital-associated pathogens.

Risk factors for development of vancomycin-resistant enterococcal bacteremia among VRE colonizers : A retrospective case control study

AIMS

We aimed to determine the proportion of vancomycin-resistant enterococci (VRE) colonized patients among all inpatients who later developed VRE bacteremia during hospital stay and to identify the risk factors for VRE bacteremia at a tertiary hospital.

MATERIAL AND METHODS

Patients with positive rectal screening or any clinically significant positive culture results for VRE were included in 1‑year follow-up. Colonization with VRE was defined as a positive culture (rectal, stool, urinary) for VRE without infection and VRE bacteremia was defined as positive blood culture if the signs and symptoms were compatible with infection. To determine the risk factors for VRE bacteremia among VRE colonized patients, a retrospective case control study was performed. The two groups were compared in terms of variables previously defined as risk factors in the literature.

RESULTS

Of 947 positive samples, 17 VRE bacteremia were included in the analysis. Cephalosporin use for more than 3 days within 3 months was a significant risk factor for bacteremia (p = 0.008). Prior use of carbapenems was found to be statistically significant for bacteremia (p = 0.007). In multivariate analyses the use of carbapenems and cephalosporins was an independent risk factor for developing bacteremia among VRE colonizers (odds ratio, OR, 6.67; 95% confidence interval, CI, 1.30-34; p = 0.022 and OR 4.32, 95% CI 1.23-15; p = 0.022, respectively).

CONCLUSION

A VRE colonization in patients receiving broad-spectrum beta-lactam antibiotics including carbapenems and cephalosporins may result in bacteremia. It is possible to keep mortality at very low levels in VRE bacteremia with effective infection control measures, rapid infectious diseases consultation and rational antimicrobial treatment based on current epidemiological data.

State-Wide Genomic and Epidemiological Analyses of Vancomycin-Resistant Enterococcus faecium in Tasmania's Public Hospitals

From 2015 onwards, the number of vancomycin-resistant Enterococcus faecium (VREfm) isolates increased in Tasmania. Previously, we examined the transmission of VREfm at the Royal Hobart Hospital (RHH). In this study, we performed a state-wide analysis of VREfm from Tasmania's four public acute hospitals. Whole-genome analysis was performed on 331 isolates collected from screening and clinical specimens of VREfm. In silico multi-locus sequence typing (MLST) was used to determine the relative abundance of broad sequence types (ST) across the state. Core genome MLST (cgMLST) was then applied to identify potential clades within the ST groupings followed by single-nucleotide polymorphic (SNP) analysis. This work revealed that differences in VREfm profiles are evident between the state's two largest hospitals with the dominant vanA types being ST80 at the RHH and ST1421 at Launceston General Hospital (LGH). A higher number of VREfm cases were recorded at LGH (n = 54 clinical, n = 122 colonization) compared to the RHH (n = 14 clinical, n = 67 colonization) during the same time period, 2014-2016. Eleven of the clinical isolates from LGH were vanA and belonged to ST1421 (n = 8), ST1489 (n = 1), ST233 (n = 1), and ST80 (n = 1) whereas none of the clinical isolates from the RHH were vanA. For the recently described ST1421, cgMLST established the presence of individual clusters within this sequence type that were common to more than one hospital and that included isolates with a low amount of SNP variance (≤16 SNPs). A spatio-temporal analysis revealed that VREfm vanA ST1421 was first detected at the RHH in 2014 and an isolate belonging to the same cgMLST cluster was later collected at LGH in 2016. Inclusion of isolates from two smaller hospitals, the North West Regional Hospital (NRH) and the Mersey Community Hospital (MCH) found that ST1421 was present in both of these institutions in 2017. These findings illustrate the spread of a recently described sequence type of VREfm, ST1421, to multiple hospitals in an Australian state within a relatively short time span.

Predictors for vancomycin resistant Enterococcus faecium transforming from colonization to infection: a case control study

Background

Little is known about risk factors for subsequent infections among vancomycin resistant Enterococcus faecium (VREfm) colonizers, especially characterized by concordant pulsotypes (CP) of paired colonization and infection-related isolates.

Methods

This case-control study was conducted at a teaching hospital between 2011 and 2014. Targeted patients received active surveillance culture for VREfm by anal swabs at admission. Cases were those who developed VREfm infection within 180 days after colonization of VREfm. Controls were those colonized with VREfm without subsequent VREfm infection. CP were defined by similarities ≥86.7% using pulsed-field gel electrophoresis between paired colonization and infection-related isolates.

Results

Ninety-seven cases and 194 controls were enrolled. By conditional multivariable logistic regression analysis, the risk factors for subsequent infection among VREfm colonizers were intensive care unit (ICU) admission (adjusted odds ratio [aOR], 9.32; 95% CI, 3.61–24.02), receipt of central venous catheters (CVC) (aOR, 3.38; 95% CI, 1.30–8.82), and utilization of third- and fourth-generation cephalosporins (aOR, 4.06; 95% CI, 1.79–9.20, and aOR, 5.32; 95% CI, 1.85– 10.29, respectively) (all P ≤ 0.01). Fifty-six (57.7%) of case patients belonged to the CP group, which were associated with ICU admission (aOR, 3.74; 95% CI, 1.38–10.13), and infection developing within 30 days after colonization (aOR, 3.34; 95% CI, 1.25–8.91).

Conclusions

Among VREfm colonizers, being admitted to ICU and receiving CVC or broad spectrum cephalosporins, were the risk factors for subsequent infections. These findings highlight the importance of conducting more strict infection control measures on specific groups of VREfm colonizers.

Nosocomial Outbreak Caused by NDM-5 and OXA-181 Carbapenemase Co-producing Escherichia coli

Carbapenemase-producing Enterobacteriaceae (CPE) is an important and increasing threat to global health. From July to September 2017, 20 inpatients at a tertiary care hospital in Korea were either colonized or infected with carbapenem-resistant Escherichia coli strains. All of E. coli isolates co-produced bla_NDM-5 and bla_OXA-181 carbapenemase genes and shared ≥88% clonal relatedness on the basis of a cladistic calculation of the distribution of pulsed-field gel electrophoresis patterns. Rapid detection of CPE is one of the most important factors to prevent CPE dissemination because it takes long time for CPE to become negative.

Emergence of an Australian-like pstS-null vancomycin resistant Enterococcus faecium clone in Scotland

Multi-locus sequencing typing (MLST) is widely used to monitor the phylogeny of microbial outbreaks. However, several strains of vancomycin-resistant Enterococcus faecium (VREfm) with a missing MLST locus (pstS) have recently emerged in Australia, with a few cases also reported in England. Here, we identified similarly distinct strains circulating in two neighbouring hospitals in Scotland. Whole genome sequencing of five VREfm strains isolated from these hospitals identified four pstS-null strains in both hospitals, while the fifth was multi-locus sequence type (ST) 262, which is the first documented in the UK. All five Scottish isolates had an insertion in the tetM gene, which is associated with increased susceptibility to tetracyclines, providing no other tetracycline-resistant gene is present. Such an insertion, which encompasses a dfrG gene and two currently uncharacterised genes, was additionally identified in all tested vanA-type pstS-null VREfm strains (5 English and 68 Australian). Phylogenetic comparison with other VREfm genomes indicates that the four pstS-null Scottish isolates sequenced in this study are more closely related to pstS-null strains from Australia rather than the English pstS-null isolates. Given how rapidly such pstS-null strains have expanded in Australia, the emergence of this clone in Scotland raises concerns for a potential outbreak.

Vancomycin-resistant Enterococcus in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation address vancomycin-resistant enterococci (VRE) infections in SOT candidates and recipients. VRE are an important cause of infection and have been named by the CDC as a serious public threat. Typically, a commensal of the gastrointestinal tract, VRE may become pathogenic after abdominal organ manipulation like transplantation. This guideline reviews the microbiology, antimicrobial resistance mechanisms, epidemiology, and clinical manifestations of VRE infection in the context of solid organ transplantation. Treatment regimens including combination therapies and novel investigational agents are also reviewed. Finally, an updated appraisal of infection control measures relevant to VRE infection and colonization is presented.

Vancomycin use in surrounding patients during critical illness and risk for persistent colonization with vancomycin-resistant Enterococcus

The optimal duration of contact precautions for vancomycin-resistant enterococcus (VRE)-colonized patients is uncertain and individual patient characteristics alone may not predict risk of prolonged colonization. Using a cohort of adult patients who underwent testing for VRE at intensive care unit (ICU) admission, we tested the association between local (unit-level) vancomycin use and persistent colonization with VRE. Higher unit-level vancomycin use significantly prolonged VRE colonization (P=0.03) independent of patient-level vancomycin use and unit VRE density.

Mathematical modelling of vancomycin-resistant enterococci transmission during passive surveillance and active surveillance with contact isolation highlights the need to identify and address the source of acquisition

Background

Clinical studies and mathematical simulation suggest that active surveillance with contact isolation is associated with reduced vancomycin-resistant enterococci (VRE) prevalence compared to passive surveillance. Models using pre- and post-intervention data that account for the imperfect observation and serial dependence of VRE transmission events can better estimate the effectiveness of active surveillance and subsequent contact isolation; however, such analyses have not been performed.

Methods

A mathematical model was fitted to surveillance data collected pre- and post-implementation of active surveillance with contact isolation in the haematology-oncology ward. We developed a Hidden Markov Model to describe undetected and observed VRE colonisation/infection status based on the detection activities in the ward. Bayesian inference was used to estimate transmission rates. The effectiveness of active surveillance was assumed to be via increased detection and subsequent contact isolation of VRE positive patients.

Results

We estimated that 31% (95% credible interval: 0.33–85%) of the VRE transmissions were due to cross-transmission between patients. The ratio of transmission rates from patients with contact isolation versus those without contact isolation was 0.33 (95% credible interval: 0.050–1.22).

Conclusions

The majority of the VRE acquisitions in the haematology-oncology ward was estimated to be due to background rates of VRE, rather than within ward patient to patient acquisition. The credible interval for cross-transmission was wide which results in a large degree of uncertainty in the estimates. Factors that could account for background VRE acquisition include endogenous acquisition from antibiotic selection pressure and VRE in the environment. Contact isolation was not significantly associated with reduced VRE transmission in settings where the majority of VRE acquisition was due to background acquisition, emphasising the need to identify and address the source of acquisition. As the credible interval for the ratio of VRE transmission in contact isolated versus non-contact isolated patients crossed 1, there is a probability that the transmission rate in contact isolation was not lower. Our finding highlights the need to optimise infection control measures other than active surveillance for VRE and subsequent contact isolation to reduce VRE transmission. Such measures could include antimicrobial stewardship, environmental cleaning, and hand hygiene.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3388-y) contains supplementary material, which is available to authorized users.

Hospital acquired vancomycin resistant enterococci in surgical intensive care patients - a prospective longitudinal study

Background

Vancomycin resistant enterococci (VRE) occur with enhanced frequency in hospitalised patients. This study elucidates the prevalence of VRE on admission among surgical intensive care unit (SICU) patients, whether these patients are at special risk for VRE acquisition and which risk factors support this process.

Methods

Patients admitted to SICUs of the University Hospital Münster were examined during August-October 2017. VRE screening was performed within 48 h after admission and directly prior to discharge of patients. In parallel risk factors were recorded to estimate their effect on VRE acquisition during SICU stay.

Results

In total, 374 patients (68% male) with a median age of 66 years were admitted to one of the SICUs during the investigation period. Of all, 336 patients (89.8%) were screened on admission and 268 (71.7%) on discharge. Nine patients were admitted with previously known VRE colonisation. Twelve (3.6%) further patients were VRE positive on admission. During ICU stay, eight (3.0%) additional patients turned out to be VRE colonised. Risk factors found to be significantly associated with VRE acquisition were median length of stay on the ICU (14 vs. 3 days; p = 0.01), long-term dialysis (12.5% vs. 2.0% of patients; p = 0.05), and antibiotic treatment with flucloxacillin (28.6% vs. 7.2% of patients; p = 0.01) or piperacillin/tazobactam (57.1% vs. 26.6% of patients; p = 0.01).

Conclusions

SICU patients are not at special risk for VRE acquisition. Previous stay on a SICU should therefore not be considered as specific risk factor for VRE colonisation.

Vancomycin-resistant Enterococcus faecium sequence type 796 - rapid international dissemination of a new epidemic clone

Background

Vancomycin-resistant Enterococcus faecium (VRE) is a leading cause of hospital-acquired infections. New, presumably better-adapted strains of VRE appear unpredictably; it is uncertain how they spread despite improved infection control. We aimed to investigate the relatedness of a novel sequence type (ST) of vanB E. faecium - ST796 - very near its time of origin from hospitals in three Australian states and New Zealand.

Methods

Following near-simultaneous outbreaks of ST796 in multiple institutions, we gathered then tested colonization and bloodstream infection isolates’ antimicrobial resistance (AMR) phenotypes, and phylogenomic relationships using whole genome sequencing (WGS). Patient meta-data was explored to trace the spread of ST796.

Results

A novel clone of vanB E. faecium (ST796) was first detected at one Australian hospital in late 2011, then in two New Zealand hospitals linked by inter-hospital transfers from separate Melbourne hospitals. ST796 also appeared in hospitals in South Australia and New South Wales and was responsible for at least one major colonization outbreak in a Neonatal Intensive Care Unit without identifiable links between centers. No exceptional AMR was detected in the isolates. While WGS analysis showed very limited diversity at the core genome, consistent with recent emergence of the clone, clustering by institution was observed.

Conclusions

Evolution of new E. faecium clones, followed by recognized or unrecognized movement of colonized individuals then rapid intra-institutional cross-transmission best explain the multi-center, multistate and international outbreak we observed.

Electronic supplementary material

The online version of this article (10.1186/s13756-018-0335-z) contains supplementary material, which is available to authorized users.

Advances in prevention and treatment of vancomycin-resistant Enterococcus infection

PURPOSE OF REVIEW

This article reviews data, particularly from the last 2 years, addressing the prevention and treatment of vancomycin-resistant Enterococcus (VRE). We focus on infection control, particularly active screening, use of contact precautions as well as pharmacologic options for therapy. This is timely given the evolving priorities in efforts towards the prevention and treatment of multidrug-resistant organisms globally.

RECENT FINDINGS

Key findings include new data regarding the impact of contact precautions on the incidence of VRE colonization and bloodstream infection, new laboratory screening methods, and novel decolonization strategies and treatments.

SUMMARY

Additional and specific measures beyond standard precautions for infection prevention of VRE remain controversial. Horizontal measures such as chlorhexidine bathing appear beneficial, as are nontouch environmental cleaning methods. Treatment options for invasive disease have improved considerably in the last decade. Decolonization strategies require further research. Overall, the threat of VRE seems exaggerated.

Predictive utility of swab screening for vancomycin-resistant Enterococcus in selection of empiric antibiotics for Enterococcus sterile-site infections: a retrospective cohort study

BACKGROUND

Swab screening for vancomycin-resistant Enterococcus (VRE) is used to identify VRE carriers and thus prevent transmission of this organism. We tested whether screening results could have unintended benefits in predicting the vancomycin susceptibility of subsequent Enterococcus infections experienced by these patients.

METHODS

We conducted a retrospective cohort study of all patients admitted to a large tertiary care hospital between 2010 and 2015 who underwent swab screening for VRE before experiencing an Enterococcus sterile-site infection. We derived test characteristics using the screening result as the test variable predicting the presence or absence of vancomycin resistance in the sterile-site Enterococcus species.

RESULTS

Culture results for sterile-site samples were positive for Enterococcus for 619 patients during the study period. Of these, 488 (79%) had previously undergone VRE screening. A total of 19 (4%) of the 488 screening results were positive for VRE, and 10 (2%) of the sterile-site Enterococcus isolates were resistant to vancomycin. The overall specificity of VRE swabs was 97% (95% confidence interval [CI] 96%-99%), sensitivity was 70% (95% CI 35%-93%), the positive likelihood ratio was 28 (95% CI 14-56), and the negative likelihood ratio was 0.31 (95% CI 0.12-0.79). The post-test probability of vancomycin resistance in a sterile-site culture, given a positive result with VRE screening swab, was 37% using study data and 83% using published aggregate prevalence data for VRE in the United States.

INTERPRETATION

Prior VRE screening swab results represent a useful tool for predicting vancomycin resistance in sterile-site Enterococcus infections. Patients with a positive result for VRE screening swab and Enterococcus identified by culture of sterile-site samples should receive empiric treatment with linezolid or daptomycin until sensitivity results are available.

Clearance of infant vancomycin-resistant Enterococcus faecium carriage after a neonatal inpatient outbreak

A follow-up cohort study was undertaken to document clearance of fecal vancomycin-resistant Enterococcus faecium carriage in 19 infants colonized during a hospital outbreak. By the conclusion of the 14-month study period, all participants had returned terminal negative fecal specimens, supporting the hypothesis that carriage is transient in this population.

A decade of genomic history for healthcare-associated Enterococcus faecium in the United Kingdom and Ireland

Vancomycin-resistant Enterococcus faecium (VREfm) is an important cause of healthcare-associated infections worldwide. We undertook whole-genome sequencing (WGS) of 495 E. faecium bloodstream isolates from 2001-2011 in the United Kingdom and Ireland (UK&I) and 11 E. faecium isolates from a reference collection. Comparison between WGS and multilocus sequence typing (MLST) identified major discrepancies for 17% of isolates, with multiple instances of the same sequence type (ST) being located in genetically distant positions in the WGS tree. This confirms that WGS is superior to MLST for evolutionary analyses and is more accurate than current typing methods used during outbreak investigations. E. faecium has been categorized as belonging to three clades (Clades A1, hospital-associated; A2, animal-associated; and B, community-associated). Phylogenetic analysis of our isolates replicated the distinction between Clade A (97% of isolates) and Clade B but did not support the subdivision of Clade A into Clade A1 and A2. Phylogeographic analyses revealed that Clade A had been introduced multiple times into each hospital referral network or country, indicating frequent movement of E. faecium between regions that rarely share hospital patients. Numerous genetic clusters contained highly related vanA-positive and -negative E. faecium, which implies that control of vancomycin-resistant enterococci (VRE) in hospitals also requires consideration of vancomycin-susceptible E. faecium Our findings reveal the evolution and dissemination of hospital-associated E. faecium in the UK&I and provide evidence for WGS as an instrument for infection control.

Causative Organisms and Associated Antimicrobial Resistance in Healthcare-Associated, Central Line-Associated Bloodstream Infections From Oncology Settings, 2009-2012

BACKGROUND

Recent antimicrobial resistance data are lacking from inpatient oncology settings to guide infection prophylaxis and treatment recommendations. We describe central line-associated bloodstream infection (CLABSI) pathogens and antimicrobial resistance patterns reported from oncology locations to the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN).

METHODS

CLABSI data reported to NHSN from 2009 to 2012 from adult inpatient oncology locations were compared to data from nononcology adult locations within the same hospitals. Pathogen profile, antimicrobial resistance rates, and CLABSI incidence rates per 1000 central line-days were calculated. CLABSI incidence rates were compared using Poisson regression.

RESULTS

During 2009-2012, 4654 CLABSIs were reported to NHSN from 299 adult oncology units. The most common organisms causing CLABSI in oncology locations were coagulase-negative staphylococci (16.9%), Escherichia coli (11.8%), and Enterococcus faecium (11.4%). Fluoroquinolone resistance was more common among E. coli CLABSI in oncology than nononcology locations (56.5% vs 41.5% of isolates tested; P < .0001) and increased significantly from 2009-2010 to 2011-2012 (49.5% vs 60.4%; P = .01). Furthermore, rates of CLABSI were significantly higher in oncology compared to nononcology locations for fluoroquinolone-resistant E. coli (rate ratio, 7.37; 95% confidence interval [CI], 6.20-8.76) and vancomycin-resistant E. faecium (rate ratio, 2.27, 95% CI, 2.03-2.53). However, resistance rates for some organisms, such as Klebsiella species and Pseudomonas aeruginosa, were lower in oncology than in nononcology locations.

CONCLUSIONS

Antimicrobial-resistant E. coli and E. faecium have become significant pathogens in oncology. Practices for antimicrobial prophylaxis and empiric antimicrobial therapy should be regularly assessed in conjunction with contemporary antimicrobial resistance data.

A multicentre hospital outbreak in Sweden caused by introduction of a vanB2 transposon into a stably maintained pRUM-plasmid in an Enterococcus faecium ST192 clone

The clonal dissemination of VanB-type vancomycin-resistant Enterococcus faecium (VREfm) strains in three Swedish hospitals between 2007 and 2011 prompted further analysis to reveal the possible origin and molecular characteristics of the outbreak strain. A representative subset of VREfm isolates (n = 18) and vancomycin-susceptible E. faecium (VSEfm, n = 2) reflecting the spread in time and location was approached by an array of methods including: selective whole genome sequencing (WGS; n = 3), multi locus sequence typing (MLST), antimicrobial susceptibility testing, virulence gene profiling, identification of mobile genetic elements conferring glycopeptide resistance and their ability to support glycopeptide resistance transfer. In addition, a single VREfm strain with an unrelated PFGE pattern collected prior to the outbreak was examined by WGS. MLST revealed a predominance of ST192, belonging to a hospital adapted high-risk lineage harbouring several known virulence determinants (n≥10). The VREfm outbreak strain was resistant to ampicillin, gentamicin, ciprofloxacin and vancomycin, and susceptible to teicoplanin. Consistently, a vanB2-subtype as part of Tn1549/Tn5382 with a unique genetic signature was identified in the VREfm outbreak strains. Moreover, Southern blot hybridisation analyses of PFGE separated S1 nuclease-restricted total DNAs and filter mating experiments showed that vanB2-Tn1549/Tn5382 was located in a 70-kb sized rep17/pRUM plasmid readily transferable between E. faecium. This plasmid contained an axe-txe toxin-antitoxin module associated with stable maintenance. The two clonally related VSEfm harboured a 40 kb rep17/pRUM plasmid absent of the 30 kb vanB2-Tn1549/Tn5382 gene complex. Otherwise, these two isolates were similar to the VREfm outbreak strain in virulence- and resistance profile. In conclusion, our observations support that the origin of the multicentre outbreak was caused by an introduction of vanB2-Tn1549/Tn5382 into a rep17/pRUM plasmid harboured in a pre-existing high-risk E. faecium ST192 clone. The subsequent dissemination of VREfm to other centres was primarily caused by clonal spread rather than plasmid transfer to pre-existing high-risk clones.

Management of urinary tract infections from multidrug-resistant organisms

Antibiotic resistance worsens clinical outcomes and, in some cases, significantly impacts the clinical management of urinary tract infections in the outpatient setting. This article presents the prevalence and mechanism of relevant antimicrobial resistance patterns encountered among uropathogens, and discusses the efficacy of antibiotic regimens and novel therapies in treating commonly encountered multidrug-resistant organisms.