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López-Luis BA, Sifuentes-Osornio J, Lambraño-Castillo D, Ortiz-Brizuela E, Ramírez-Fontes A, Tovar-Calderón YE, Leal-Vega FJ, Bobadilla-Del-Valle M, Ponce-de-León A. Risk factors and outcomes associated with vancomycin-resistant Enterococcus faecium and ampicillin-resistant Enterococcus faecalis bacteraemia: A 10-year study in a tertiary-care centre in Mexico City. J Glob Antimicrob Resist 2020; 24:198-204. [PMID: 33359937 DOI: 10.1016/j.jgar.2020.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/31/2020] [Accepted: 12/06/2020] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES We sought to identify risk factors associated with vancomycin-resistant Enterococcus faecium (VRE) and ampicillin-resistant Enterococcus faecalis (ARE) bacteraemia, predictors of 30-day mortality, and 90-day recurrence-free survival according to resistance. METHODS We evaluated clinical records of patients with E. faecalis and E. faecium bacteraemia (2007-2017). We performed bivariate and multivariate logistic regression analyses to identify factors associated with VRE and ARE bacteraemia and predictors of 30-day mortality. A Kaplan-Meier estimate of 90-day recurrence-free survival was done. RESULTS We identified 192 and 147 E. faecium and E. faecalis bacteraemia episodes, respectively, of which 55.7% of E. faecium were VRE (94% vanA) and 12.2% of E. faecalis were ARE. Factors related to VRE bacteraemia were previous hospitalisation (aOR, 80.18, 95% CI 1.81-634), history of central venous catheter (aOR, 11.15, 95% CI 2.48-50.2) and endotracheal cannula use (aOR, 17.91, 95% CI 1.22-262.82). There was higher attributable mortality to VRE (28%, 95% CI 14-68%; P < 0.001) and ARE (10%, 95% CI 0.1-36%; P = 0.58) compared with their susceptible counterparts. APACHE II (aOR, 1.45, 95% CI 1.26-1.66) and history of chemotherapy (aOR, 3.52, 95% CI 1.09-11.39) were predictors of E. faecium bacteraemia 30-day mortality. We could not recognise any factor related to ARE bacteraemia or E. faecalis 30-day mortality. CONCLUSION History of hospitalisation and invasive device use were related to VRE bacteraemia. APACHE II and history of chemotherapy were predictors of mortality. We could not identify factors related to ARE or predictors of mortality.
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Affiliation(s)
- Bruno Ali López-Luis
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - José Sifuentes-Osornio
- Department of Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Darwin Lambraño-Castillo
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Edgar Ortiz-Brizuela
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Andrea Ramírez-Fontes
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Yanet Estrella Tovar-Calderón
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Francisco Javier Leal-Vega
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Miriam Bobadilla-Del-Valle
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico
| | - Alfredo Ponce-de-León
- Laboratory of Clinical Microbiology, Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Avenida Vasco de Quiroga No. 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, 14080, Mexico City, Mexico.
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Rubin IMC, Pedersen MS, Mollerup S, Kaya H, Petersen AM, Westh H, Pinholt M. Association between vancomycin-resistant Enterococcus faecium colonization and subsequent infection: a retrospective WGS study. J Antimicrob Chemother 2020; 75:1712-1715. [PMID: 32125377 DOI: 10.1093/jac/dkaa074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Since 2012, the incidence of vancomycin-resistant Enterococcus faecium (VREfm) has increased dramatically in Copenhagen and vanA E. faecium has become endemic and polyclonal. OBJECTIVES To examine whether a patient with a positive VRE clinical sample had the same VREfm in a preceding screening sample (within 60 days). METHODS We performed a 30 month retrospective study. From our laboratory information system (LIS), we identified all patients with an invasive VREfm isolate and a VREfm rectal screening isolate within 60 days before infection. VREfm pairs (screening isolate and invasive isolate) were whole-genome sequenced. All isolates were analysed using SeqSphere and core-genome MLST (cgMLST) types were determined. We examined all isolates for the presence of the three most dominant vanA plasmids in the Capital Region of Denmark. Two novel vanA plasmids were closed by Nanopore/Illumina sequencing. RESULTS We found a total of 19 VREfm pairs. Of these, 13 patients had pairs with matching cgMLST types and vanA plasmids and a median number of 6 days from identification of carriage to clinical infection. One patient had a pair with non-matching cgMLST types but matching vanA plasmids and 24 days between identification of carriage to clinical infection. Five patients had pairs with non-matching cgMLST types and non-matching vanA plasmids and a median number of 18 days from identification of carriage to clinical infection. CONCLUSIONS Of our 19 pairs, 13 were a match regarding cgMLST types (68%) and 1 more (5%) had matching vanA plasmids. Infection was thus preceded by colonization with the same isolates in 13 out of 19 patients. The five mismatches (26%) could be explained by the longer interval between colonization and infection.
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Affiliation(s)
- Ingrid Maria Cecilia Rubin
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Department of Gastroenterology, Hvidovre Hospital, Hvidovre, Denmark
| | | | - Sarah Mollerup
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
| | - Hülya Kaya
- Statens Serum Institut, Copenhagen, Denmark
| | - Andreas Munk Petersen
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Department of Gastroenterology, Hvidovre Hospital, Hvidovre, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Westh
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark.,Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Mette Pinholt
- Department of Clinical Microbiology, Hvidovre Hospital, Hvidovre, Denmark
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Integration of genomic and clinical data augments surveillance of healthcare-acquired infections. Infect Control Hosp Epidemiol 2019; 40:649-655. [PMID: 31012399 DOI: 10.1017/ice.2019.75] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Determining infectious cross-transmission events in healthcare settings involves manual surveillance of case clusters by infection control personnel, followed by strain typing of clinical/environmental isolates suspected in said clusters. Recent advances in genomic sequencing and cloud computing now allow for the rapid molecular typing of infecting isolates. OBJECTIVE To facilitate rapid recognition of transmission clusters, we aimed to assess infection control surveillance using whole-genome sequencing (WGS) of microbial pathogens to identify cross-transmission events for epidemiologic review. METHODS Clinical isolates of Staphylococcus aureus, Enterococcus faecium, Pseudomonas aeruginosa, and Klebsiella pneumoniae were obtained prospectively at an academic medical center, from September 1, 2016, to September 30, 2017. Isolate genomes were sequenced, followed by single-nucleotide variant analysis; a cloud-computing platform was used for whole-genome sequence analysis and cluster identification. RESULTS Most strains of the 4 studied pathogens were unrelated, and 34 potential transmission clusters were present. The characteristics of the potential clusters were complex and likely not identifiable by traditional surveillance alone. Notably, only 1 cluster had been suspected by routine manual surveillance. CONCLUSIONS Our work supports the assertion that integration of genomic and clinical epidemiologic data can augment infection control surveillance for both the identification of cross-transmission events and the inclusion of missed and exclusion of misidentified outbreaks (ie, false alarms). The integration of clinical data is essential to prioritize suspect clusters for investigation, and for existing infections, a timely review of both the clinical and WGS results can hold promise to reduce HAIs. A richer understanding of cross-transmission events within healthcare settings will require the expansion of current surveillance approaches.
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Abstract
Healthcare-associated infections (HAIs) pose a significant burden to patient safety. Institutions can implement hospital infection control (HIC) measures to reduce the impact of HAIs. Since patients can carry pathogens between institutions, there is an economic incentive for hospitals to free ride on the HIC investments of other facilities. Subsidies for infection control by public health authorities could encourage regional spending on HIC. We develop coupled mathematical models of epidemiology and hospital behavior in a game-theoretic framework to investigate how hospitals may change spending behavior in response to subsidies. We demonstrate that under a limited budget, a dollar-for-dollar matching grant outperforms both a fixed-amount subsidy and a subsidy on uninfected patients in reducing the number of HAIs in a single institution. Additionally, when multiple hospitals serve a community, funding priority should go to the hospital with a lower transmission rate. Overall, subsidies incentivize HIC spending and reduce the overall prevalence of HAIs.
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Affiliation(s)
- Sarah E Drohan
- Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ 08544;
| | - Simon A Levin
- Program in Applied and Computational Mathematics, Princeton University, Princeton, NJ 08544;
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544
- Princeton Environmental Institute, Princeton University, Princeton, NJ 08544
| | - Bryan T Grenfell
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892
| | - Ramanan Laxminarayan
- Princeton Environmental Institute, Princeton University, Princeton, NJ 08544;
- Center for Disease Dynamics, Economics & Policy, Washington, DC 20036
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Genome-Based Analysis of Enterococcus faecium Bacteremia Associated with Recurrent and Mixed-Strain Infection. J Clin Microbiol 2018; 56:JCM.01520-17. [PMID: 29263205 PMCID: PMC5824064 DOI: 10.1128/jcm.01520-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/12/2017] [Indexed: 11/20/2022] Open
Abstract
Vancomycin-resistant Enterococcus faecium (VREfm) bloodstream infections are associated with high recurrence rates. This study used genome sequencing to accurately distinguish the frequency of relapse and reinfection in patients with recurrent E. faecium bacteremia and to investigate strain relatedness in patients with apparent VREfm and vancomycin-susceptible E. faecium (VSEfm) mixed infection. A retrospective study was performed at the Cambridge University Hospitals NHS Foundation Trust (CUH) between November 2006 and December 2012. We analyzed the genomes of 44 E. faecium isolates from 21 patients (26 VREfm isolates from 12 patients with recurrent bacteremia and 18 isolates from 9 patients with putative VREfm/VSEfm mixed infection). Phenotypic antibiotic susceptibility was determined using a Vitek2 instrument. Genomes were compared with those of a further 263 E. faecium isolates associated with bacteremia in patients at CUH over the same time period. Pairwise comparison of core genomes indicated that 10 (71%) episodes of recurrent VREfm bacteremia were due to reinfection with a new strain, with reinfection being more likely with increasing time between the two positive cultures. The majority (78%) of patients with a mixed VREfm and VSEfm infection had unrelated strains. More than half (59%) of study isolates were closely related to another isolate associated with bacteremia from CUH. This included 60% of isolates associated with reinfection, indicating acquisition in the hospital. This study provides the first high-resolution insights into recurrence and mixed infection by E. faecium and demonstrates that reinfection with a new strain, often acquired from the hospital, is a driver of recurrence.
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Ye JJ, Shie SS, Cheng CW, Yang JH, Huang PY, Wu TS, Lee MH, Huang CT. Clinical characteristics and treatment outcomes of vancomycin-resistant Enterococcus faecium bacteremia. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2017; 51:705-716. [PMID: 29046248 DOI: 10.1016/j.jmii.2017.08.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/28/2017] [Accepted: 08/31/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Vancomycin-resistant Enterococcus faecium (VRE-fm) bacteremia causes significant mortality in hospitalized patients. We sought to investigate clinical characteristics, treatment outcomes, and microbiological eradication associated with VRE-fm bacteremia. METHODS A retrospective cohort study was conducted and included 210 adult patients admitted between January 1, 2011 and December 31, 2015. RESULTS The mean Pitt bacteremia score was 4.7. ICU stay (48.6%) and mechanical ventilation (46.2%) were common. Diabetes mellitus was the most common concomitant disease (43.3%), followed by malignancies, including hematologic malignancies (14.3%) and solid cancers (28.1%). The 14-day and 28-day mortality rates were 37.1% and 50.5%, respectively. Linezolid or daptomycin treatment for at least 10 days and higher Pitt bacteremia scores were independently associated with 14-day and 28-day mortality. Longer treatment duration of linezolid or daptomycin predicted microbiological eradication independently. Daptomycin-treated patients tended to have higher 14-day and 28-day mortality, and lower microbial eradication rates (20.8% versus 8.7%; 40.6% versus 26.1%; 14.1% versus 26.1%; respectively) than linezolid-treated patients, and cumulative survival rates at 14 and 28 days tended to be lower in patients who received low-dose daptomycin (<10 mg/kg/day) than that in those who received linezolid and high-dose daptomycin (≥10 mg/kg/day); however, the differences were not statistically significant. CONCLUSION Higher disease severity and inappropriate treatment were associated with increased mortality and longer treatment duration of linezolid or daptomycin was associated with microbial eradication for the patient with VRE-fm bacteremia.
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Affiliation(s)
- Jung-Jr Ye
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Kee-Lung, Kee-Lung, Taiwan.
| | - Shian-Sen Shie
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
| | - Chun-Wen Cheng
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
| | - Jeng-How Yang
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
| | - Po-Yen Huang
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan; Infection Control Committee, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
| | - Ting-Shu Wu
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan; Infection Control Committee, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
| | - Ming-Hsun Lee
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
| | - Ching-Tai Huang
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung University College of Medicine, Taoyuan, Taiwan.
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Resistance Mechanisms, Epidemiology, and Approaches to Screening for Vancomycin-Resistant Enterococcus in the Health Care Setting. J Clin Microbiol 2016; 54:2436-47. [PMID: 27147728 DOI: 10.1128/jcm.00211-16] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Infections attributable to vancomycin-resistant Enterococcus (VRE) strains have become increasingly prevalent over the past decade. Prompt identification of colonized patients combined with effective multifaceted infection control practices can reduce the transmission of VRE and aid in the prevention of hospital-acquired infections (HAIs). Increasingly, the clinical microbiology laboratory is being asked to support infection control efforts through the early identification of potential patient or environmental reservoirs. This review discusses the factors that contribute to the rise of VRE as an important health care-associated pathogen, the utility of laboratory screening and various infection control strategies, and the available laboratory methods to identify VRE in clinical specimens.
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O'Driscoll T, Crank CW. Vancomycin-resistant enterococcal infections: epidemiology, clinical manifestations, and optimal management. Infect Drug Resist 2015; 8:217-30. [PMID: 26244026 PMCID: PMC4521680 DOI: 10.2147/idr.s54125] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Since its discovery in England and France in 1986, vancomycin-resistant Enterococcus has increasingly become a major nosocomial pathogen worldwide. Enterococci are prolific colonizers, with tremendous genome plasticity and a propensity for persistence in hospital environments, allowing for increased transmission and the dissemination of resistance elements. Infections typically present in immunosuppressed patients who have received multiple courses of antibiotics in the past. Virulence is variable, and typical clinical manifestations include bacteremia, endocarditis, intra-abdominal and pelvic infections, urinary tract infections, skin and skin structure infections, and, rarely, central nervous system infections. As enterococci are common colonizers, careful consideration is needed before initiating targeted therapy, and source control is first priority. Current treatment options including linezolid, daptomycin, quinupristin/dalfopristin, and tigecycline have shown favorable activity against various vancomycin-resistant Enterococcus infections, but there is a lack of randomized controlled trials assessing their efficacy. Clearer distinctions in preferred therapies can be made based on adverse effects, drug interactions, and pharmacokinetic profiles. Although combination therapies and newer agents such as tedizolid, telavancin, dalbavancin, and oritavancin hold promise for the future treatment of vancomycin-resistant Enterococcus infections, further studies are needed to assess their possible clinical impact, especially in the treatment of serious infections.
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Affiliation(s)
- Tristan O'Driscoll
- Department of Pharmacy Practice, Chicago College of Pharmacy, Downers Grove, IL, USA
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Abel zur Wiesch P, Kouyos R, Abel S, Viechtbauer W, Bonhoeffer S. Cycling empirical antibiotic therapy in hospitals: meta-analysis and models. PLoS Pathog 2014; 10:e1004225. [PMID: 24968123 PMCID: PMC4072793 DOI: 10.1371/journal.ppat.1004225] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 05/13/2014] [Indexed: 01/12/2023] Open
Abstract
The rise of resistance together with the shortage of new broad-spectrum antibiotics underlines the urgency of optimizing the use of available drugs to minimize disease burden. Theoretical studies suggest that coordinating empirical usage of antibiotics in a hospital ward can contain the spread of resistance. However, theoretical and clinical studies came to different conclusions regarding the usefulness of rotating first-line therapy (cycling). Here, we performed a quantitative pathogen-specific meta-analysis of clinical studies comparing cycling to standard practice. We searched PubMed and Google Scholar and identified 46 clinical studies addressing the effect of cycling on nosocomial infections, of which 11 met our selection criteria. We employed a method for multivariate meta-analysis using incidence rates as endpoints and find that cycling reduced the incidence rate/1000 patient days of both total infections by 4.95 [9.43–0.48] and resistant infections by 7.2 [14.00–0.44]. This positive effect was observed in most pathogens despite a large variance between individual species. Our findings remain robust in uni- and multivariate metaregressions. We used theoretical models that reflect various infections and hospital settings to compare cycling to random assignment to different drugs (mixing). We make the realistic assumption that therapy is changed when first line treatment is ineffective, which we call “adjustable cycling/mixing”. In concordance with earlier theoretical studies, we find that in strict regimens, cycling is detrimental. However, in adjustable regimens single resistance is suppressed and cycling is successful in most settings. Both a meta-regression and our theoretical model indicate that “adjustable cycling” is especially useful to suppress emergence of multiple resistance. While our model predicts that cycling periods of one month perform well, we expect that too long cycling periods are detrimental. Our results suggest that “adjustable cycling” suppresses multiple resistance and warrants further investigations that allow comparing various diseases and hospital settings. The rise of antibiotic resistance is a major concern for public health. In hospitals, frequent usage of antibiotics leads to high resistance levels; at the same time the patients are especially vulnerable. We therefore urgently need treatment strategies that limit resistance without compromising patient care. Here, we investigate two strategies that coordinate the usage of different antibiotics in a hospital ward: “cycling”, i.e. scheduled changes in antibiotic treatment for all patients, and “mixing”, i.e. random assignment of patients to antibiotics. Previously, theoretical and clinical studies came to different conclusions regarding the usefulness of these strategies. We combine meta-analyses of clinical studies and epidemiological modeling to address this question. Our meta-analyses suggest that cycling is beneficial in reducing the total incidence rate of hospital-acquired infections as well as the incidence rate of resistant infections, and that this is most pronounced at low baseline levels of resistance. We corroborate our findings with theoretical epidemiological models. When incorporating treatment adjustment upon deterioration of a patient's condition (“adjustable cycling”), we find that our theoretical model is in excellent accordance with the clinical data. With this combined approach we present substantial evidence that adjustable cycling can be beneficial for suppressing the emergence of multiple resistance.
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Affiliation(s)
- Pia Abel zur Wiesch
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
- Division of Global Health Equity, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| | - Roger Kouyos
- Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
| | - Sören Abel
- Division of Infectious Diseases, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wolfgang Viechtbauer
- Department of Psychiatry and Psychology, School for Mental Health and Neuroscience, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
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Cheng AC, Murdoch DR, Harrell LJ, Barth Reller L. Clinical profile and strain relatedness of recurrent enterococcal bacteremia. ACTA ACUST UNITED AC 2009; 37:642-6. [PMID: 16126563 DOI: 10.1080/00365540510043257] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We defined the molecular epidemiology of recurrent enterococcal bacteremia using pulsed field gel electrophoresis. We identified 27 patients, comprising 60 episodes; strain relatedness was demonstrated in 8 patients with isolates separated by up to 6 y. Carriage of pathogenic enterococci may be prolonged, although re-infection with novel strains is more commonly seen.
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Affiliation(s)
- Allen C Cheng
- Department of Medicine, Duke University School of Medicine, Durham, NC, USA.
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Vancomycin-resistant enterococci in fecal samples from hospitalized patients and non-hospitalized individuals in Gaza City. J Public Health (Oxf) 2009. [DOI: 10.1007/s10389-008-0242-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Top J, Willems R, Bonten M. Emergence of CC17 Enterococcus faecium: from commensal to hospital-adapted pathogen. ACTA ACUST UNITED AC 2008; 52:297-308. [PMID: 18279340 DOI: 10.1111/j.1574-695x.2008.00383.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
For many years, Enterococcus faecium was considered to be a commensal of the digestive tract, which only sporadically caused opportunistic infections in severely ill patients. Over the last two decades, vancomycin-resistant E. faecium (VREF) has emerged worldwide as an important cause of nosocomial infections, especially in immunocompromised patients. The global Vancomycin-resistant enterococci (VRE) epidemic was preceded by the emergence of ampicillin-resistant E. faecium (AREfm) in the United States in the early 1980s, followed by the rapid emergence of VRE in the 1990s. A similar increase of VRE may occur in countries with still low levels of VRE in hospitals (such as The Netherlands), but increasing incidence of AREfm infections. Molecular epidemiological studies of both human- and animal-derived E. faecium isolates using multilocus sequence typing revealed the existence of host-specific genogroups, including a specific genetic lineage designated CC17, associated with hospital-related isolates. These strains were characterized by ampicillin and quinolone resistance. In addition, the majority of these CC17 isolates contain over hundred hospital-clade-specific genes, including mobile elements, phage genes and plasmid sequences, hypothetical and membrane proteins and antibiotic and regulatory genes and a putative pathogenicity island including the esp gene.
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Affiliation(s)
- Janetta Top
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
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Top J, Banga NMI, Hayes R, Willems RJ, Bonten MJM, Hayden MK. Comparison of multiple-locus variable-number tandem repeat analysis and pulsed-field gel electrophoresis in a setting of polyclonal endemicity of vancomycin-resistant Enterococcus faecium. Clin Microbiol Infect 2008; 14:363-9. [PMID: 18261124 DOI: 10.1111/j.1469-0691.2007.01945.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In order to assess whether multiple-locus-variable number tandem repeat analysis (MLVA) could replace pulsed-field gel electrophoresis (PFGE) for genotyping vancomycin-resistant isolates of Enterococcus faecium (VREF), this study compared the typeability, discriminatory power, concordance and costs of these methods for VREF isolates obtained from patients, environmental samples and the hands of healthcare workers (HCWs) in a medical intensive care unit (ICU) where VREF was endemic. Over a 58-day period, 393 VREF isolates (373 vanA, one vanA/B, 19 vanB) were cultured from patient rectal swabs (n = 76), the environment (n = 270) and the hands of HCWs (n = 47). PFGE was able to divide 358 (91.1%) isolates into 19 PFGE types (>six bands different) and 24 subtypes (one to three bands different). MLVA was able to type 391 (99.5%) isolates into 11 genotypes. The discriminatory power of PFGE subtypes was 83%, as compared to 68% for MLVA. Concordance between the two methods, based on matched or mismatched MLVA types and PFGE types or subtypes, was 67.5% and 82.8%, respectively. Using PFGE, 13 isolates could be genotyped in 3 days; MLVA genotyped 94 isolates in 2 days. For both methods, the estimated costs were Euro 7 ($10)/isolate. PFGE and MLVA produced highly concordant results when assigning genotypes to nosocomial VREF isolates. MLVA was faster, but PFGE subtyping was more discriminatory.
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Affiliation(s)
- J Top
- Department of Medical Microbiology, Division of Acute Internal Medicine and Infectious Diseases, University Medical Centre Utrecht, Utrecht, The Netherlands.
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Hendrickx APA, van Wamel WJB, Posthuma G, Bonten MJM, Willems RJL. Five genes encoding surface-exposed LPXTG proteins are enriched in hospital-adapted Enterococcus faecium clonal complex 17 isolates. J Bacteriol 2007; 189:8321-32. [PMID: 17873043 PMCID: PMC2168695 DOI: 10.1128/jb.00664-07] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Most Enterococcus faecium isolates associated with hospital outbreaks and invasive infections belong to a distinct genetic subpopulation called clonal complex 17 (CC17). It has been postulated that the genetic evolution of CC17 involves the acquisition of various genes involved in antibiotic resistance, metabolic pathways, and virulence. To gain insight into additional genes that may have favored the rapid emergence of this nosocomial pathogen, we aimed to identify surface-exposed LPXTG cell wall-anchored proteins (CWAPs) specifically enriched in CC17 E. faecium. Using PCR and Southern and dot blot hybridizations, 131 E. faecium isolates (40 CC17 and 91 non-CC17) were screened for the presence of 22 putative CWAP genes identified from the E. faecium TX0016 genome. Five genes encoding LPXTG surface proteins were specifically enriched in E. faecium CC17 isolates. These five LPXTG surface protein genes were found in 28 to 40 (70 to 100%) of CC17 and in only 7 to 24 (8 to 26%) of non-CC17 isolates (P < 0.05). Three of these CWAP genes clustered together on the E. faecium TX0016 genome, which may comprise a novel enterococcal pathogenicity island covering E. faecium contig 609. Expression at the mRNA level was demonstrated, and immunotransmission electron microscopy revealed an association of the five LPXTG surface proteins with the cell wall. Minimal spanning tree analysis based on the presence and absence of 22 CWAP genes revealed grouping of all 40 CC17 strains together with 18 hospital-derived but evolutionary unrelated non-CC17 isolates in a distinct CWAP-enriched cluster, suggesting horizontal transfer of CWAP genes and a role of these CWAPs in hospital adaptation.
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Affiliation(s)
- Antoni P A Hendrickx
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX Utrecht, The Netherlands.
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15
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Insertion sequence-driven diversification creates a globally dispersed emerging multiresistant subspecies of E. faecium. PLoS Pathog 2007; 3:e7. [PMID: 17257059 PMCID: PMC1781477 DOI: 10.1371/journal.ppat.0030007] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 11/30/2006] [Indexed: 01/12/2023] Open
Abstract
Enterococcus faecium, an ubiquous colonizer of humans and animals, has evolved in the last 15 years from an avirulent commensal to the third most frequently isolated nosocomial pathogen among intensive care unit patients in the United States. E. faecium combines multidrug resistance with the potential of horizontal resistance gene transfer to even more pathogenic bacteria. Little is known about the evolution and virulence of E. faecium, and genomic studies are hampered by the absence of a completely annotated genome sequence. To further unravel its evolution, we used a mixed whole-genome microarray and hybridized 97 E. faecium isolates from different backgrounds (hospital outbreaks (n = 18), documented infections (n = 34) and asymptomatic carriage of hospitalized patients (n = 15), and healthy persons (n = 15) and animals (n = 21)). Supported by Bayesian posterior probabilities (PP = 1.0), a specific clade containing all outbreak-associated strains and 63% of clinical isolates was identified. Sequencing of 146 of 437 clade-specific inserts revealed mobile elements (n = 74), including insertion sequence (IS) elements (n = 42), phage genes (n = 6) and plasmid sequences (n = 26), hypothetical (n = 58) and membrane proteins (n = 10), and antibiotic resistance (n = 9) and regulatory genes (n = 11), mainly located on two contigs of the unfinished E. faecium DO genome. Split decomposition analysis, varying guanine cytosine content, and aberrant codon adaptation indices all supported acquisition of these genes through horizontal gene transfer with IS16 as the predicted most prominent insert (98% sensitive, 100% specific). These findings suggest that acquisition of IS elements has facilitated niche adaptation of a distinct E. faecium subpopulation by increasing its genome plasticity. Increased genome plasticity was supported by higher diversity indices (ratio of average genetic similarities of pulsed-field gel electrophoresis and multi locus sequence typing) for clade-specific isolates. Interestingly, the previously described multi locus sequence typing-based clonal complex 17 largely overlapped with this clade. The present data imply that the global emergence of E. faecium, as observed since 1990, represents the evolution of a subspecies with a presumably better adaptation than other E. faecium isolates to the constraints of a hospital environment.
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16
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Van Wamel WJB, Hendrickx APA, Bonten MJM, Top J, Posthuma G, Willems RJL. Growth condition-dependent Esp expression by Enterococcus faecium affects initial adherence and biofilm formation. Infect Immun 2006; 75:924-31. [PMID: 17118984 PMCID: PMC1828491 DOI: 10.1128/iai.00941-06] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A genetic subpopulation of Enterococcus faecium, called clonal complex 17 (CC-17), is strongly associated with hospital outbreaks and invasive infections. Most CC-17 strains contain a putative pathogenicity island encoding the E. faecium variant of enterococcal surface protein (Esp). Western blotting, flow cytometric analyses, and electron microscopy showed that Esp is expressed and exposed on the surface of E. faecium, though Esp expression and surface exposure are highly varied among different strains. Furthermore, Esp expression depends on growth conditions like temperature and anaerobioses. When grown at 37 degrees C, five of six esp-positive E. faecium strains showed significantly increased levels of surface-exposed Esp compared to bacteria grown at 21 degrees C, which was confirmed at the transcriptional level by real-time PCR. In addition, a significant increase in surface-exposed Esp was found in half of these strains when grown at 37 degrees C under anaerobic conditions compared to the level in bacteria grown under aerobic conditions. Finally, amounts of surface-exposed Esp correlated with initial adherence to polystyrene (R(2) = 0.7146) and biofilm formation (R(2) = 0.7535). Polystyrene adherence was competitively inhibited by soluble recombinant N-terminal Esp. This study demonstrates that Esp expression on the surface of E. faecium (i) varies consistently between strains, (ii) is growth condition dependent, and (iii) is quantitatively correlated with initial adherence and biofilm formation. These data indicate that E. faecium senses and responds to changing environmental conditions, which might play a role in the early stages of infection when bacteria transit from oxygen-rich conditions at room temperature to anaerobic conditions at body temperature. In addition, variation of surface exposure may explain the contrasting findings reported on the role of Esp in biofilm formation.
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Affiliation(s)
- Willem J B Van Wamel
- Eijkman-Winkler Institute, Room G04-614, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
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17
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Leavis HL, Willems RJL, Top J, Bonten MJM. High-level ciprofloxacin resistance from point mutations in gyrA and parC confined to global hospital-adapted clonal lineage CC17 of Enterococcus faecium. J Clin Microbiol 2006; 44:1059-64. [PMID: 16517894 PMCID: PMC1393140 DOI: 10.1128/jcm.44.3.1059-1064.2006] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
To substantiate a common genetic background of ciprofloxacin-resistant Enterococcus faecium, 32 ciprofloxacin-resistant (Cip(r)) and 31 ciprofloxacin-susceptible (Cip(s)) isolates from outbreaks, clinical infections, surveillances, and animals from 10 different countries were genotyped by multilocus sequence typing. Additionally, susceptibilities to ampicillin and vancomycin and the presence of esp were determined and the quinolone resistance-determining regions of parC, gyrA, parB, and gyrE were sequenced. High-level Cip(r) (MIC > or = 64 microg/ml) due to point mutations in the quinolone resistance-determining region was unique to a distinct hospital-adapted genetic complex in E. faecium, previously designated CC17. Low-level Cip(r) (MIC = 4 microg/ml) in non-CC17 strains is not attributable to point mutations in any subunit of the topoisomerase genes, and the mechanism of resistance remains unclear. Acquisition of mutations in parC and gyrA, leading to high-level Cip(r), is, in addition to ampicillin resistance and the presence of a putative pathogenicity island, another cumulative step in hospital adaptation of CC17.
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Affiliation(s)
- Helen L Leavis
- Department of Internal Medicine, Division of Infectious Diseases and Internal Medicine, Eijkman-Winkler Institute, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584CX Utrecht, The Netherlands.
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18
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19
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Mascini EM, Bonten MJM. Vancomycin-resistant enterococci: consequences for therapy and infection control. Clin Microbiol Infect 2005; 11 Suppl 4:43-56. [PMID: 15953021 DOI: 10.1111/j.1469-0691.2005.01164.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens, initially in the USA, but now also in Europe, where hospital outbreaks are being reported with increasing frequency, although the incidence of VRE infections remains extremely low in most European countries. The recently demonstrated in-human transmission of vancomycin resistance from VRE to methicillin-resistant Staphylococcus aureus (MRSA) in two American patients underscores the potential danger of a coexisting reservoir of both pathogens. As MRSA is already endemic in many European hospital settings, prevention of endemicity with VRE seems relevant, but should be balanced against the costs associated with the implementation of effective strategies. The presence of a large community reservoir of VRE in Europe could hamper the feasibility of infection control strategies. Although the prevalence of colonisation amongst healthy subjects has apparently decreased after the ban on avoparcin use in the agricultural industry, a large proportion of admitted patients are still potential sources of VRE transmission. With no risk profile available to identify these carriers, effective screening, followed by barrier precautions for carriers, seems to be impossible. Recent studies, however, have suggested that hospital outbreaks are almost exclusively caused by specific genogroups of VRE that can be characterised phenotypically and genotypically (e.g., co-resistance to ampicillin and the presence of the variant esp gene). Based on our own experience, we propose that VRE infection control programmes should be restricted to patients colonised with these VRE strains. If such a strain is cultured from a clinical sample, surveillance amongst contact patients is recommended and barrier precautions should be implemented in the case of documented spread.
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Affiliation(s)
- E M Mascini
- Eijkman-Winkler Institute for Medical Microbiology, Infectious Diseases and Inflammation, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
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20
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Coque TM, Willems RJL, Fortún J, Top J, Diz S, Loza E, Cantón R, Baquero F. Population structure of Enterococcus faecium causing bacteremia in a Spanish university hospital: setting the scene for a future increase in vancomycin resistance? Antimicrob Agents Chemother 2005; 49:2693-700. [PMID: 15980338 PMCID: PMC1168696 DOI: 10.1128/aac.49.7.2693-2700.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Over an 8-year period (1995 to 2002), 86 Enterococcus faecium blood isolates from 84 patients, of which 54 were ampicillin resistant (AREF) and 32 were ampicillin susceptible (ASEF), were studied in a university hospital (1,200 beds; serving a population of 600,000) in Spain, a country characterized by a near-absence of resistance to vancomycin and very high rates of ampicillin resistance among enterococci. Clonal relatedness by pulsed-field gel electrophoresis (PFGE), antibiotic susceptibility, presence of the virulence/epidemicity genes esp(Efm) and hyl(Efm), and identification of purK alleles were studied. A group of isolates was also analyzed by amplified fragment length polymorphism (AFLP) and multilocus sequence typing. Medical charts (30 variables collected) were reviewed for 60/84 patients. ASEF showed high clonal diversity (32 PFGE types, 11 purK alleles, 4 AFLP genogroups), did not harbor putative virulence genes, and had no specific association with hospital acquisition. AREF isolates belonged to a clonal complex (CC) of genetically related strains (purK-1, AFLP genogroup C), occasionally harboring putative virulence traits, and were from patients with particular risk factors. Within this CC, previously associated with vancomycin-resistant E. faecium isolates causing outbreaks worldwide (W. L. Homan et al., J. Clin. Microbiol. 40:1963-1971, 2002), a great genetic diversity of antibiotic resistance and virulence/epidemicity profiles was found. Associations between esp and a >7-day hospital stay and between purK-1, hospital location, and nosocomial acquisition were noted (P < 0.001). These findings reflect the importance of local environmental differences in the evolution of this CC, suggesting that the emergence of vancomycin resistance among AREF strains in Spain may be a question of time.
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Affiliation(s)
- Teresa M Coque
- Departamento de Microbiologíca, Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Carretera de Colmenar, km. 9.1, Madrid 28034, Spain.
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21
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Abstract
Smith and colleagues discuss evidence suggesting that antibiotic use in agriculture has contributed to antibiotic resistance in the pathogenic bacteria of humans.
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Affiliation(s)
- David L Smith
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, USA.
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22
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Kelly L, Smith DL, Snary EL, Johnson JA, Harris AD, Wooldridge M, Morris JG. Animal growth promoters: to ban or not to ban? A risk assessment approach. Int J Antimicrob Agents 2005; 24:205-12. [PMID: 15325422 DOI: 10.1016/j.ijantimicag.2004.04.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Accepted: 04/01/2004] [Indexed: 11/24/2022]
Abstract
The use of antibiotics for animal growth promotion has been controversial because of the potential transfer of antibiotic resistance from animals to humans. Such transfer could have severe public health implications in that treatment failures could result. We have followed a risk assessment approach to evaluate policy options for the streptogramin-class of antibiotics: virginiamycin, an animal growth promoter, and quinupristin/dalfopristin, a antibiotic used in humans. Under the assumption that resistance transfer is possible, models project a wide range of outcomes depending mainly on the basic reproductive number (R(0)) that determines the potential for person-to-person transmission. Counter-intuitively, the benefits of a ban on virginiamycin were highest for intermediate values of R(0), and lower for extremely high or low values of R(0).
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Affiliation(s)
- L Kelly
- Veterinary Laboratories Agency, Centre for Epidemiology and Risk Analysis, New Haw, Addlestone, Surrey KT15 3NB, UK
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23
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Smith DL, Levin SA, Laxminarayan R. Strategic interactions in multi-institutional epidemics of antibiotic resistance. Proc Natl Acad Sci U S A 2005; 102:3153-8. [PMID: 15677330 PMCID: PMC549473 DOI: 10.1073/pnas.0409523102] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The increasing frequency of antibiotic resistance in hospital-acquired infections is a major public health concern that has both biological and economic causes. Here we develop conceptual mathematical models that couple the economic incentives and population biology of hospital infection control (HIC). We show that the optimal investment by a hospital for HIC changes with the proportion of patients already colonized with antibiotic-resistant bacteria (ARB) at the time of admission. As that proportion increases, the optimal behavior of a hospital is to increase spending to control ARB with low transmissibility and decrease spending on those with high transmissibility. In some cases, the global optimum investment in HIC can shift discontinuously from one that contains transmission to a do-nothing policy once the proportion already colonized at the time of admission becomes too great. We also show that investments in HIC are determined by a strategic game when several hospitals share patients. Hospitals acting selfishly and rationally will free-ride on the investments of other hospitals, and the level of free-riding should increase with the number of other hospitals in the area. Thus, in areas with many hospitals, the rational strategy for each hospital is to spend less than in areas with few hospitals. Thus, we predict that transmission rates and the prevalence of ARB should be higher in urban hospitals, for instance, compared with rural hospitals. We conclude that regional coordination and planning for HIC is an essential element of public health planning for hospital-acquired infections.
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Affiliation(s)
- David L Smith
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892-2220, USA.
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24
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Top J, Schouls LM, Bonten MJM, Willems RJL. Multiple-locus variable-number tandem repeat analysis, a novel typing scheme to study the genetic relatedness and epidemiology of Enterococcus faecium isolates. J Clin Microbiol 2004; 42:4503-11. [PMID: 15472301 PMCID: PMC522339 DOI: 10.1128/jcm.42.10.4503-4511.2004] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiresistant Enterococcus faecium is a major cause of hospital acquired infections and outbreaks. Here, we describe the development of multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) as a novel typing method to assess the genetic relatedness of E. faecium isolates. Six VNTR loci were used to genotype 392 isolates recovered from different animals and human community, hospital survey, and clinical isolates. From 3 to 13 alleles were found per locus, resulting in 127 different MLVA profiles. Clustering of MLVA profiles confirmed the host-specific genogroups found by multilocus sequence typing (MLST) and showed the grouping of clinical and epidemic isolates that belonged to the MLST-C1 cluster in a distinct MLVA-C1 cluster (sensitivity of 97% and specificity of 90%). Furthermore, the discriminatory power of MLVA is comparable to MLST. MLVA profiles appeared to be relatively stable, since isolates from a single outbreak shared the same MLVA profile, which is a prerequisite when MLVA is used to study hospital outbreaks. Our data show that MLVA is a highly reproducible and portable typing method; in contrast to MLST, it is fast, relatively cheap, and easy to perform. Furthermore, it has the abilities of MLST to recognize genetically related and potential epidemic isolates. Submission of MLVA profiles is possible via a Web-based database for international comparison.
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Affiliation(s)
- Janetta Top
- Eijkman-Winkler Institute for Microbiology, Infectious Diseases and Inflammation, University Medical Center Utrecht, Utrecht, The Netherlands.
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25
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Smith DL, Dushoff J, Perencevich EN, Harris AD, Levin SA. Persistent colonization and the spread of antibiotic resistance in nosocomial pathogens: resistance is a regional problem. Proc Natl Acad Sci U S A 2004; 101:3709-14. [PMID: 14985511 PMCID: PMC373527 DOI: 10.1073/pnas.0400456101] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infections with antibiotic-resistant bacteria (ARB) in hospitalized patients are becoming increasingly frequent despite extensive infection-control efforts. Infections with ARB are most common in the intensive care units of tertiary-care hospitals, but the underlying cause of the increases may be a steady increase in the number of asymptomatic carriers entering hospitals. Carriers may shed ARB for years but remain undetected, transmitting ARB to others as they move among hospitals, long-term care facilities, and the community. We apply structured population models to explore the dynamics of ARB, addressing the following questions: (i) What is the relationship between the proportion of carriers admitted to a hospital, transmission, and the risk of infection with ARB? (ii) How do frequently hospitalized patients contribute to epidemics of ARB? (iii) How do transmission in the community, long-term care facilities, and hospitals interact to determine the proportion of the population that is carrying ARB? We offer an explanation for why ARB epidemics have fast and slow phases and why resistance may continue to increase despite infection-control efforts. To successfully manage ARB at tertiary-care hospitals, regional coordination of infection control may be necessary, including tracking asymptomatic carriers through health-care systems.
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Affiliation(s)
- David L Smith
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892-2220, USA.
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26
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Willems RJ, Top J, Smith DJ, Roper DI, North SE, Woodford N. Mutations in the DNA mismatch repair proteins MutS and MutL of oxazolidinone-resistant or -susceptible Enterococcus faecium. Antimicrob Agents Chemother 2004; 47:3061-6. [PMID: 14506009 PMCID: PMC201155 DOI: 10.1128/aac.47.10.3061-3066.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in mutS and mutL, which encode DNA mismatch repair (MMR) proteins, can confer hypermutator phenotypes and may facilitate the emergence of mutational antibiotic resistance in bacteria. Linezolid-resistant enterococci (LRE) rarely emerge during therapy and contain mutations in 23S rRNA genes. As enterococci with defective MMR could be prone to the development of oxazolidinone resistance mutations, we investigated 13 clinical isolates of Enterococcus faecium, including 2 LRE, for mutations in mutSL. A 4,944-bp fragment spanning mutSL was sequenced from two pairs of linezolid-resistant (MICs, 64 micro g/ml) and linezolid-susceptible (MICs, 2 micro g/ml) E. faecium isolates (one pair from Austria and one pair from the United Kingdom) identical by pulsed-field gel electrophoresis. The pairs represented distinct strains in which linezolid resistance had emerged during therapy. The MutSL peptides of all four isolates had amino acid substitutions compared with the sequence of E. faecium strain DO (used for genome sequencing). These were Val352Ile (one pair of isolates only) and Met628Leu in MutS and Leu387Pro, Tyr406Phe, Thr415Ser, Phe427Leu, and Phe565Ile in MutL. The significance of these changes remains unknown; these isolates did not show a demonstrable hypermutator phenotype. The same substitutions were found in two of nine geographically diverse linezolid-susceptible enterococcal isolates; the other seven isolates had MutSL sequences identical to that of strain DO. Multilocus sequence typing revealed that all isolates with alternate MutSL peptides belonged to a distinct lineage of a prevalent E. faecium clonal complex, designated CC17. Further studies are needed to investigate the prevalence of these MutSL mutations and their possible roles in the emergence of E. faecium strains resistant to oxazolidinones and other antibiotic classes.
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Affiliation(s)
- Rob J Willems
- Diagnostic Laboratory for Infectious Diseases and Perinatal Screening, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
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27
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Mascini EM, Jalink KP, Kamp-Hopmans TEM, Blok HEM, Verhoef J, Bonten MJM, Troelstra A. Acquisition and duration of vancomycin-resistant enterococcal carriage in relation to strain type. J Clin Microbiol 2004; 41:5377-83. [PMID: 14662914 PMCID: PMC308960 DOI: 10.1128/jcm.41.12.5377-5383.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In May 2000, the first outbreak of vancomycin-resistant Enterococcus faecium (VREF) was detected in the University Medical Center Utrecht in the nephrology ward. The question arose why some VREF strains spread among hospitalized patients, whereas other strains do not. Thirty patients who were found to be colonized with VREF between May and November 2000 were included in the study. Molecular typing confirmed that 19 of them carried an identical epidemic strain which harbored the esp gene while 11 were colonized by nonepidemic strains that were all esp negative. Acquisition of the outbreak strain was significantly associated with diabetes mellitus, renal transplantation, and extensive use of antibiotics, especially cephalosporins, in the 2-month period before the first isolation of VREF. To establish the duration of colonization, prospective surveillance of VREF carriage for a 6-month period starting from the first isolation of VREF was realized for 20 patients. After 6 months, VREF was still recovered from 60% of carriers of the outbreak strain versus 20% of carriers of nonepidemic strains (P < 0.01). However, antibiotic use during the follow-up period was significantly higher by carriers of the outbreak strain than by carriers of nonepidemic strains. The fact that the outbreak strain was recovered for a longer period of time than nonepidemic strains may facilitate dissemination of the strain. The results support a careful restrictive antibiotic policy for wards at risk for spread of VREF and implementation of isolation precautions for patients who are colonized with esp-positive outbreak strains.
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Affiliation(s)
- E M Mascini
- Department of Hospital Hygiene and Infection Prevention, Eijkman-Winkler Centre for Microbiology, Infectious Diseases, and Inflammation, University Medical Center Utrecht, Utrecht, The Netherlands.
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28
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Torell E, Kühn I, Olsson-Liljequist B, Haeggman S, Hoffman BM, Lindahl C, Burman LG. Clonality among ampicillin-resistant Enterococcus faecium isolates in Sweden and relationship with ciprofloxacin resistance. Clin Microbiol Infect 2004; 9:1011-9. [PMID: 14616743 DOI: 10.1046/j.1469-0691.2003.00701.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate clonal relationships in a nationwide sample of human Enterococcus faecium isolates. METHODS Biochemical fingerprinting (PhP (PhenePlate) typing) was used to compare 180 fecal ampicillin-resistant E. faecium (ARE) isolates with 169 matched fecal ampicillin-susceptible E. faecium (ASE) isolates from patients in 23 hospitals, collected in 1998, and to study 39 fecal ARE isolates from non-hospitalized individuals collected in 1998, and five ARE and 29 ASE isolates from the early 1990s. Representative ARE and ASE isolates were subjected to pulsed-field gel electrophoresis (PFGE) analysis of genomic DNA and sequencing of the regions encoding the fluoroquinolone targets of the enzymes GyrA and ParC. RESULTS Both PhP and PFGE results showed a higher homogeneity among ARE than among ASE isolates (P < 0.001). One PhP type (FMSE1) comprised 73% of the hospital ARE isolates (53% of ARE isolates from non-hospitalized individuals, and four of five ARE isolates from the early 1990s), but only 1% of the ASE isolates. PFGE of the hospital E. faecium isolates revealed that 23 of the 25 ARE isolates and one of the 22 ASE isolates were of one dominating type. High-level resistance to ciprofloxacin (MIC > 16 mg/L) was present in 91% of ARE isolates, whereas only low-level resistance (MIC 4-16 mg/L; 35% of isolates) was found among ASE isolates. One mutation in parC (codon 80) and one of two mutations in gyrA (codons 83 or 87) were detected in all ARE isolates tested with high-level ciprofloxacin resistance, but were lacking in ARE and ASE isolates with low-level ciprofloxacin resistance. CONCLUSION Most ARE isolates in Sweden were clonally related. High-level ciprofloxacin resistance was found in ARE isolates of PhP type FMSE1 as well as in other PhP types, but never in ASE isolates.
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Affiliation(s)
- E Torell
- Department of Medical Sciences, Section for Infectious Diseases, Uppsala University Hospital, Uppsala, Sweden.
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29
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Leavis H, Top J, Shankar N, Borgen K, Bonten M, van Embden J, Willems RJL. A novel putative enterococcal pathogenicity island linked to the esp virulence gene of Enterococcus faecium and associated with epidemicity. J Bacteriol 2004; 186:672-82. [PMID: 14729692 PMCID: PMC321477 DOI: 10.1128/jb.186.3.672-682.2004] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Enterococcus faecalis harbors a virulence-associated surface protein encoded by the esp gene. This gene has been shown to be part of a 150-kb putative pathogenicity island. A gene similar to esp has recently been found in Enterococcus faecium isolates recovered from hospitalized patients. In the present study we analyzed the polymorphism in the esp gene of E. faecium, and we investigated the association of esp with neighboring chromosomal genes. The esp gene showed considerable sequence heterogeneity in the regions encoding the nonrepeat N- and C-terminal domains of the Esp protein as well as differences in the number of repeats. DNA sequencing of chromosomal regions flanking the esp gene of E. faecium revealed seven open reading frames, representing putative genes implicated in virulence, regulation of transcription, and antibiotic resistance. These flanking regions were invariably associated with the presence or absence of the esp gene in E. faecium, indicating that esp in E. faecium is part of a distinct genetic element. Because of the presence of virulence genes in this gene cluster, the lower G+C content relative to that of the genome, and the presence of esp in E. faecium isolates associated with nosocomial outbreaks and clinically documented infections, we conclude that this genetic element constitutes a putative pathogenicity island, the first one described in E. faecium. Except for the presence of esp and araC, this pathogenicity island is completely different from the esp-containing pathogenicity island previously disclosed in E. faecalis.
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Affiliation(s)
- Helen Leavis
- Diagnostic Laboratory for Infectious Diseases, National Institute for Public Health and the Environment, Bilthoven, The Netherlands
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Leavis HL, Willems RJL, Top J, Spalburg E, Mascini EM, Fluit AC, Hoepelman A, de Neeling AJ, Bonten MJM. Epidemic and nonepidemic multidrug-resistant Enterococcus faecium. Emerg Infect Dis 2003; 9:1108-15. [PMID: 14519248 PMCID: PMC3016763 DOI: 10.3201/eid0909.020383] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The epidemiology of vancomycin-resistant Entero- coccus faecium (VREF) in Europe is characterized by a large community reservoir. In contrast, nosocomial outbreaks and infections (without a community reservoir) characterize VREF in the United States. Previous studies demonstrated host-specific genogroups and a distinct genetic lineage of VREF associated with hospital outbreaks, characterized by the variant esp-gene and a specific allele-type of the purK housekeeping gene (purK1). We investigated the genetic relatedness of vanA VREF (n=108) and vancomycin-susceptible E. faecium (VSEF) (n=92) from different epidemiologic sources by genotyping, susceptibility testing for ampicillin, sequencing of purK1, and testing for presence of esp. Clusters of VSEF fit well into previously described VREF genogroups, and strong associations were found between VSEF and VREF isolates with resistance to ampicillin, presence of esp, and purK1. Genotypes characterized by presence of esp, purK1, and ampicillin resistance were most frequent among outbreak-associated isolates and almost absent among community surveillance isolates. Vancomycin-resistance was not specifically linked to genogroups. VREF and VSEF from different epidemiologic sources are genetically related; evidence exists for nosocomial selection of a subtype of E. faecium, which has acquired vancomycin-resistance through horizontal transfer.
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Affiliation(s)
- Helen L Leavis
- University Medical Center Utrecht, Utrecht, the Netherlands
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31
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DeLisle S, Perl TM. Vancomycin-resistant enterococci: a road map on how to prevent the emergence and transmission of antimicrobial resistance. Chest 2003; 123:504S-18S. [PMID: 12740236 DOI: 10.1378/chest.123.5_suppl.504s] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Nosocomial acquisition of microorganisms resistant to multiple antibiotics represents a threat to patient safety. Here we review the mechanisms that have allowed highly resistant strains belonging to the Enterococcus genus to proliferate within our health-care institutions. These mechanisms indicate that decreasing the prevalence of resistant organisms requires active surveillance, adherence to vigorous isolation, hand hygiene and environmental decontamination measures, and effective antibiotic stewardship. We suggest how to tailor such a complex, multidisciplinary program to the needs of a particular health-care setting so as to maximize cost-effectiveness.
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Affiliation(s)
- Sylvain DeLisle
- US Veterans Administration Medical Center, Department of Internal Medicine, Division of Pulmonary and Critical Care, University of Maryland, Baltimore 21201, USA.
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Baran J, Paruchuri R, Ramanathan J, Riederer KM, Khatib R. Unrecognized cross-infection with vancomycin-resistant Enterococcus faccium and faecalis detected by molecular typing of blood isolates. Infect Control Hosp Epidemiol 2002; 23:172-3. [PMID: 12002229 DOI: 10.1086/503458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Baran J, Ramanathan J, Riederer KM, Khatib R. Stool colonization with vancomycin-resistant enterococci in healthcare workers and their households. Infect Control Hosp Epidemiol 2002; 23:23-6. [PMID: 11868888 DOI: 10.1086/501963] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To determine the prevalence of stool colonization with vancomycin-resistant enterococci (VRE) among healthcare workers (HCWs) and their families. DESIGN Prospective assessment of fecal colonization with VRE. SETTING A 603-bed, tertiary-care teaching hospital. PARTICIPANTS Healthy volunteers recruited from hospital employees and their households were screened to exclude pregnancy, diabetes mellitus, immunosuppressive disorders, and recent use of antimicrobials. INTERVENTION Self-obtained stool swabs were used to obtain cultures. Isolated enterococci were screened for vancomycin resistance and species were identified. Intra-household isolates were genotyped using pulsed-field gel electrophoresis (PFGE). RESULTS The participants (n = 228; age range, 28 days to 80 years) were from 137 households with and 91 without employees who had contact with patients. Enterococcus species were isolated from 127 stool specimens (55.7%). VRE were detected in 12 individuals, representing 6 E. casseliflavus, 5 E. faecium, and 1 E. gallinarum. VRE were more commonly isolated in employees who had contact with patients (5 of 52 vs 0 of 40; relative risk [RR], 1.9; 95% confidence interval [CI95], 1.5 to 2.2; P = .07) and their household members (10 of 137 vs 2 of 91; RR, 3.3; CI95, 0.7 to 14.8; P = .13). In 2 households (2 adults in a physician's household and an adult plus a child in a nurse's household) PFGE analysis demonstrated identical intra-household strains of vancomycin-resistant E. faecium. CONCLUSIONS VRE colonization was found in 5.3% of screened stools and was more prevalent in HCWs who had contact with patients and their households. Identical PFGE patterns between 2 employees who had contact with patients and their household members demonstrated probable intra-household spread. Although the mode of acquisition was uncertain, the association with employees who had contact with patients suggests possible occupational sources. These findings demonstrate the spread of VRE within the household and implicate occupational risk for its acquisition.
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Affiliation(s)
- Joseph Baran
- Medical Education Department, St John Hospital & Medical Center, Detroit, MI 48236, USA
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Wong MT, Kauffman CA, Standiford HC, Linden P, Fort G, Fuchs HJ, Porter SB, Wenzel RP. Effective suppression of vancomycin-resistant Enterococcus species in asymptomatic gastrointestinal carriers by a novel glycolipodepsipeptide, ramoplanin. Clin Infect Dis 2001; 33:1476-82. [PMID: 11588692 DOI: 10.1086/322687] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2001] [Revised: 04/06/2001] [Indexed: 01/16/2023] Open
Abstract
Nosocomial bloodstream infections due to vancomycin-resistant enterococci (VRE) are associated with increased morbidity rates, mortality rates, and hospitalization costs. Gastrointestinal carriage of VRE is an important risk factor for subsequent infections. This 3-arm, phase II, double-blinded, randomized, multicenter, placebo-controlled study evaluated the safety and efficacy of oral ramoplanin (a novel, nonabsorbed glycolipodepsipeptide) versus placebo for suppression of gastrointestinal VRE colonization. Sixty-eight patients who were colonized with VRE were enrolled and received 2 daily doses of ramoplanin (100 mg or 400 mg) or placebo orally for 7 days. The primary end point was the proportion of persons per group from whom VRE were not recovered (VRE-free) on days 7, 14, and 21 after screening. After treatment, VRE-free status was as follows: day 7, none of the 20 patients in the placebo group, and 17 of 21 (P<.001) and 18 of 20 (P<.001) in the 100-mg and 400-mg ramoplanin groups, respectively; on day 14, 2 of 20 patients in the placebo group, and 6 of 21 (P=.134) and 7 of 17 (P=.028), in the 100-mg and 400-mg ramoplanin groups, respectively. By day 21, there were no differences between treatment groups. Adverse events were similar for all treatment groups. Ramoplanin was safe and effective in temporarily suppressing gastrointestinal VRE carriage.
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Affiliation(s)
- M T Wong
- Department of Internal Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, USA.
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Abstract
Biotherapeutic agents offer unique advantages over traditional treatments for infectious diarrhea, and several have been shown to be effective (Table 4). These therapeutic microbial agents are most effective in types of infectious diseases that are associated with a disruption of the normal intestinal microecology (e.g., AAD, C. difficile disease). The impact of biotherapeutic agents on rotaviral diarrhea is of special clinical importance because this is the most common cause of pediatric diarrhea, and there is no defined treatment. Strong efforts need to be made to limit antibiotic exposure in children. Biotherapeutic agents offer a safe and effective nonantibiotic method of treating this important pathogen, especially after the withdrawal of a rotaviral vaccine from the market by the FDA. However, for many biotherapeutic agents, well-done, placebo-controlled trials still are lacking, and not all types of infectious diarrhea respond to these agents. Continued research in this innovative therapeutic area is warranted.
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Affiliation(s)
- G W Elmer
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle, Washington, USA.
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36
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Abstract
Important characteristics of hospital infection control are specific to pediatric facilities. For example, colonization and infection with vancomycin-resistant enterococci, which are widely spread in many units housing adult patients, are uncommon in children, especially in the neonatal intensive care unit where vancomycin use is heavy. Characteristics of the neonatal intensive care unit, such as the insulated environment and infrequent treatment with antibiotics with broad anaerobic activity, likely account for this finding. Artificial fingernails have been discovered to promote colonization with potential pathogens; their implication in recent nursery epidemics emphasizes the need to prohibit their use in this environment in particular. Finally, nosocomial viral infections occur with regularity in pediatric hospitals. Programs that successfully and cost-effectively control hospital spread of respiratory syncytial virus, however, demonstrate that rational, multifaceted interventions can nearly eliminate transmission of certain viral pathogens on the pediatric wards.
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Affiliation(s)
- M Neely
- Department of Pediatrics, Case Western Reserve University School of Medicine, Rainbow Babies and Children's Hospital, University Hospitals of Cleveland, Cleveland, Ohio 44106, USA
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37
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Baran J, Riederer KM, Ramanathan J, Khatib R. Recurrent vancomycin-resistant Enterococcus bacteremia: prevalence, predisposing factors, and strain relatedness. Clin Infect Dis 2001; 32:1381-3. [PMID: 11303278 DOI: 10.1086/319996] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2000] [Revised: 10/05/2000] [Indexed: 11/03/2022] Open
Abstract
We studied the prevalence of recurrent vancomycin-resistant Enterococcus (VRE) bacteremia, predisposing factors, and strain relatedness during a 3 year period at our institution. Of 36 inpatients who had episodes of bacteremia, 3 (8.3%) had recurrent episodes. Predisposing factors were mucositis and neutropenia (1 patient) and chronic renal failure requiring hemodialysis (2). Recurrent episodes separated by < or = 3 months were caused by identical or related strains, and those at greater intervals by distinct strains. Recurrent VRE bacteremia is uncommon.
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Affiliation(s)
- J Baran
- St. John Hospital and Medical Center, Detroit, MI 48236, USA.
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38
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de Lencastre H, Brown AE, Chung M, Armstrong D, Tomasz A. Role of transposon Tn5482 in the epidemiology of vancomycin-resistant Enterococcus faecium in the pediatric oncology unit of a New York City Hospital. Microb Drug Resist 2000; 5:113-29. [PMID: 10432272 DOI: 10.1089/mdr.1999.5.113] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
During a 36-month period between 1993 and 1995 in the Pediatric Oncology Unit of Memorial Sloan Kettering Cancer Center, 74 patients experienced episodes of infection or colonization caused by vancomycin-resistant enterococci (VRE). Characterization of the 74 bacterial isolates by microbiological and molecular techniques (pulsed-field gel electrophoresis and hybridization with DNA probes specific for the vanA and vanB genes and for IS1251) identified 73 Enterococcusfaecium and one Enterococcusfaecalis (vanB) among the primary VRE isolates. Most (69/73) of the E. faecium isolates carried vanA and four isolates, the vanB gene complex. The overwhelming majority (67/69) of the vanA -positive isolates also gave hybridization signal for IS1251, indicating the presence of the newly described conjugative transposon Tn5482. No hybridization with IS1251 was obtained with the four vanB-carrying isolates. About 30% of the vanA-positive strains (23/69) were represented by PFGE subtype variants of a single clone, most isolates of which were recovered during a 4-month period between April to June of 1994. The larger portion of the vanA-carrying VRE represented by close to 70% of the isolates (46/69) belonged to as many as 37 different clonal types, indicating tremendous genetic diversity. Among 67 of the 69 vanA-carrying isolates, the localization of the Tn5482-associated vanA gene complex could be unequivocally identified either on the chromosome (40/69) or in plasmids (27/69). Transconjugants recovered from filter mating experiments using either a chromosomally located or plasmid-borne vanA donor strain and a single vancomycin-susceptible strain of either E. faecium or E. faecalis were analyzed by molecular typing techniques. Seven out of 10 independent transconjugants recovered from the same cross showed extensive differences in PFGE pattern and also in the localization of the vanA hybridizing DNA fragment transferred from the common VRE donor with chromosomally located vanA. The observations suggest that the extensive genetic diversity observed among the clinical isolates of VRE may be generated during conjugation between vancomycin-resistant and -susceptible enterococcal isolates. The observations also suggest that the epidemic spread of VRE in the United States may be linked to the frequent presence of Tn5482 among the American isolates.
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Affiliation(s)
- H de Lencastre
- Laboratory of Microbiology, The Rockefeller University, New York, NY 10021, USA
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39
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Suppola JP, Kolho E, Salmenlinna S, Tarkka E, Vuopio-Varkila J, Vaara M. vanA and vanB incorporate into an endemic ampicillin-resistant vancomycin-sensitive Enterococcus faecium strain: effect on interpretation of clonality. J Clin Microbiol 1999; 37:3934-9. [PMID: 10565910 PMCID: PMC85849 DOI: 10.1128/jcm.37.12.3934-3939.1999] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clonal spread and horizontal transfer in the spread of vancomycin resistance genes were investigated. Multiplex PCR, pulsed-field gel electrophoresis (PFGE), hybridization of enterococcal plasmids with the vanA and vanB probes, and sequencing of a fragment of vanB were used in the analysis. Before May 1996, 12 vancomycin-resistant Enterococcus faecium (VRE) isolates were found in Finland. Between May 1996 and October 1997, 156 VRE isolates were found in the Helsinki area. Between December 1997 and April 1998, fecal samples from 359 patients were cultured for VRE. One new case of colonization with VRE was found. During the outbreak period, 88% (137 of 155) of the VRE isolates belonged to two strains (VRE types I and II), as determined by PFGE. Each VRE type I isolate possessed vanB, and five isolates also had vanA. Of the 34 VRE type II isolates, 27 possessed vanA and 7 possessed vanB. Fifteen of 21 (71%) ampicillin-resistant, vancomycin-sensitive E. faecium (VSE) isolates found during and after the outbreak period in one ward were also of type II. Two VSE type II isolates were found in the hospital before the outbreak in 1995. By PFGE, the three groups (vanA, vanB, or no van gene) of type II shared the same band differences with the main type of VRE type II with vanA. None of the differences was specific to or determinative for any of the groups. Our material suggests that vanA and vanB incorporate into an endemic ampicillin-resistant VSE strain.
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Affiliation(s)
- J P Suppola
- Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, 00014 Helsinki, Finland.
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40
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Abstract
Glycopeptide resistance may be either constitutive or transferable (on plasmids or as a transposon), and four phenotypes (van A, B, C, D) have been described to date. Recent data suggest solid media screening protocols appear to be insensitive at detecting low levels of carriage, and up to 40% of colonized patients may be falsely glycopeptide-resistant enterococci (GRE) negative. Managing GRE-colonized or -infected patients using contact precautions appears to be useful in controlling clonal outbreaks, but may be of limited utility once GRE is endemic. Alternate strategies to manage GRE-colonized patients with prolonged carriage and in outpatient or home health settings include using risk-based transmission assessment to limit the logistic and psychosocial difficulties associated with the use of continuous contact precautions. The therapeutic options for treating GRE infection remain limited. Attempts to decolonize GRE-colonized patients with bacitracin appear to be of limited utility.
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41
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Noskin GA, Siddiqui F, Stosor V, Hacek D, Peterson LR. In vitro activities of linezolid against important gram-positive bacterial pathogens including vancomycin-resistant enterococci. Antimicrob Agents Chemother 1999; 43:2059-62. [PMID: 10428937 PMCID: PMC89415 DOI: 10.1128/aac.43.8.2059] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The emergence of resistance in gram-positive bacteria has necessitated a search for new antimicrobial agents. Linezolid is an oxazolidinone, a new class of antibacterial agents with enhanced activity against pathogens. We compared the activity of linezolid to those of other antimicrobial agents against 3,945 clinical isolates. Linezolid demonstrated potent activity against all isolates tested. For all vancomycin-susceptible enterococci, staphylococci, and streptococci, the activity of linezolid was comparable to that of vancomycin. Against oxacillin-resistant staphylococci and vancomycin-resistant enterococci, linezolid was the most active agent tested. In summary, linezolid appears to be a promising new antimicrobial agent for the treatment of gram-positive infections.
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Affiliation(s)
- G A Noskin
- Division of Infectious Diseases, Department of Medicine, Northwestern University Medical School, Northwestern Memorial Hospital, Chicago, Illinois 60611, USA.
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42
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Morrison D, Woodford N, Barrett SP, Sisson P, Cookson BD. DNA banding pattern polymorphism in vancomycin-resistant Enterococcus faecium and criteria for defining strains. J Clin Microbiol 1999; 37:1084-91. [PMID: 10074530 PMCID: PMC88653 DOI: 10.1128/jcm.37.4.1084-1091.1999] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1998] [Accepted: 12/26/1998] [Indexed: 12/23/2022] Open
Abstract
The degree of DNA banding pattern polymorphism exhibited by vancomycin-resistant Enterococcus faecium (VREM) strains isolated on a renal unit over an 11-month period was investigated. Thirty VREM strains from different patients were analyzed by pulsed-field gel electrophoresis (PFGE; with extended run and optimal pulse times), ribotyping, plasmid profile analysis, biotyping, pyrolysis mass spectrometry, and antibiogram analysis. PFGE resolved 17 banding patterns which formed four distinct clusters at the 82% similarity level. Intercluster band differences ranged from 14 to 31 bands. The strains in one cluster, which contained seven patterns that differed from each other by one to seven bands and from the common pattern by five bands, were confirmed to be a single strain by four of the five other typing methods. The strains in a second cluster with eight patterns, which differed from each other by 1 to 12 bands, contained two subclusters. This subdivision was supported by ribotyping and biotyping. However, it was unclear whether these subclusters represented distinct strains. In one strain, marked polymorphism (patterns that differed from each other by up to four bands) was observed in the ribotype pattern. This study demonstrates the high degree of DNA banding pattern polymorphism found for some strains of VREM and illustrates the complexity involved in defining such strains.
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Affiliation(s)
- D Morrison
- Laboratory of Hospital Infection, Central Public Health Laboratory, London, United Kingdom.
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43
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Willems RJ, Top J, van den Braak N, van Belkum A, Mevius DJ, Hendriks G, van Santen-Verheuvel M, van Embden JD. Molecular diversity and evolutionary relationships of Tn1546-like elements in enterococci from humans and animals. Antimicrob Agents Chemother 1999; 43:483-91. [PMID: 10049255 PMCID: PMC89148 DOI: 10.1128/aac.43.3.483] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report on a detailed study on the molecular diversity and evolutionary relationships of Tn1546-like elements in vancomycin-resistant enterococci (VRE) from humans and animals. Restriction fragment length polymorphism (RFLP) analysis of the VanA transposon of 97 VRE revealed seven different Tn1546 types. Subsequent sequencing of the complete VanA transposons of 13 VRE isolates representing the seven RFLP types followed by sequencing of the identified polymorphic regions in 84 other VanA transposons resulted in the identification of 22 different Tn1546 derivatives. Differences between the Tn1546 types included point mutations in orf1, vanS, vanA, vanX, and vanY. Moreover, insertions of an IS1216V-IS3-like element in orf1, of IS1251 in the vanS-vanH intergenic region, and of IS1216V in the vanX-vanY intergenic region were found. The presence of insertion sequence elements was often associated with deletions in Tn1546. Identical Tn1546 types were found among isolates from humans and farm animals in The Netherlands, suggesting the sharing of a common vancomycin resistance gene pool. Application of the genetic analysis of Tn1546 to VRE isolates causing infections in Hospitals in Oxford, United Kingdom, and Chicago, Ill., suggested the possibility of the horizontal transmission of the vancomycin resistance transposon. The genetic diversity in Tn1546 combined with epidemiological data suggest that the DNA polymorphism among Tn1546 variants can successfully be exploited for the tracing of the routes of transmission of vancomycin resistance genes.
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Affiliation(s)
- R J Willems
- Research Laboratory for Infectious Diseases, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
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44
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Tremlett CH, Brown DF, Woodford N. Variation in structure and location of VanA glycopeptide resistance elements among enterococci from a single patient. J Clin Microbiol 1999; 37:818-20. [PMID: 9986864 PMCID: PMC84569 DOI: 10.1128/jcm.37.3.818-820.1999] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Forty-six VanA glycopeptide-resistant enterococci (GRE) from a single patient were investigated for variation in structure and location of VanA resistance elements. Together with identification to species level and pulsed-field gel electrophoresis, these data divided the GRE into 10 groups and subgroups. Combining data in this manner appears helpful when investigating the epidemiology of GRE.
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Affiliation(s)
- C H Tremlett
- Clinical Microbiology and Public Health Laboratory, Addenbrooke's Hospital, Cambridge CB2 2QW, United Kingdom
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45
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Savor C, Pfaller MA, Kruszynski JA, Hollis RJ, Noskin GA, Peterson LR. Comparison of genomic methods for differentiating strains of Enterococcus faecium: assessment using clinical epidemiologic data. J Clin Microbiol 1998; 36:3327-31. [PMID: 9774587 PMCID: PMC105323 DOI: 10.1128/jcm.36.11.3327-3331.1998] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genomic DNA extracted from 45 vancomycin-resistant Enterococcus faecium (VRE) isolates was cleaved with HindIII and HaeIII and subjected to agarose gel electrophoresis. The ability of this method (restriction endonuclease analysis [REA]) to distinguish strains at the subspecies level was compared with results previously determined by pulsed-field gel electrophoresis (PFGE). Chart reviews were performed to provide a clinical correlation of possible epidemiologic relatedness. A likely clinical association was found for 29 patients as part of two outbreaks. REA found 21 of 21 isolates were the same type in the first outbreak, with PFGE calling 19 strains the same type. In the second outbreak with eight patient isolates, HindIII found six were the same type and two were unique types. HaeIII found three strains were the same type, two strains were a separate type, and three more strains were unique types, while PFGE found three were the same type and five were unique types. No single "ideal" method can be used without clinical epidemiologic investigation, but any of these techniques is helpful in providing focus to infection control practitioners assessing possible outbreaks of nosocomial infection.
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Affiliation(s)
- C Savor
- Department of Medicine, Northwestern University, Northwestern Memorial Hospital and Northwestern University, Chicago, Illinois, USA
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46
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Schoonmaker DJ, Bopp LH, Baltch AL, Smith RP, Rafferty ME, George M. Genetic analysis of multiple vancomycin-resistant Enterococcus isolates obtained serially from two long-term-care patients. J Clin Microbiol 1998; 36:2105-8. [PMID: 9650975 PMCID: PMC104991 DOI: 10.1128/jcm.36.7.2105-2108.1998] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Fifty-eight vancomycin-resistant enterococcal isolates were obtained from two patients over 9 weeks. Numerous pulsed-field gel electrophoresis fingerprinting types were isolated from each patient. By PCR, all isolates were vanA+. However, many isolates from patient B were found to lack vanA by hybridization. Our results demonstrate the importance of examining multiple isolates, especially from patients who are at high risk of infection.
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Affiliation(s)
- D J Schoonmaker
- Wadsworth Center, New York State Department of Health, Albany 12208, USA.
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47
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Bradford Hawley H, Laurel Elder B. Multiple-drug resistant enterococci: Laboratory identification, prevention, and treatment. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1069-417x(00)80030-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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