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Ampicillin-resistant enterococci in a Swedish University Hospital: nosocomial spread and risk-factors for infection
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
2001 (English)In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, Vol. 33, no 3, 182-187 p.Article in journal (Refereed) Published
Abstract [en]

Ampicillin-resistant enterococci (ARE) have recently emerged as clinical pathogens in Sweden. Between 1991 and 1995 the incidence of ARE among enterococcal isolates at Uppsala University Hospital increased from 0.5% to 8.1%. Shedding of ARE from infected cases and risk factors for infection with ARE were studied during a period of 7 months for 38 ARE cases and 38 controls with ampicillin-susceptible enterococci. ARE cases had longer mean duration of hospitalization than controls (29 d vs. 15 d; p = 0.002). In univariate analysis other risk factors for infection with ARE were found to be prior therapy with > 2 antimicrobials (odds ratio [OR] 3.3; 95% confidence interval [CI] 1.2-9.5), > 4 weeks of antimicrobial therapy (OR 6.9; CI 1.8-28.3) and cephalosporin therapy (OR 9.1; CI 2.6-33.7). Fourteen of 26 skin carriers of ARE were found to be shedding ARE to the environment, compared to 2 of 12 non-skin carriers (p = 0.03). Pulsed-field gel electrophoresis suggested multifocal origin of the majority of the infecting ARE strains. Non-recognized fecal colonization and silent spread of ARE among many patients and over a prolonged time period is suggested to be the main explanation for the increase of ARE infections in our hospital. Infection control measures focusing on protecting patients at high risk for ARE infections and further efforts to optimize antimicrobial use are proposed.

Place, publisher, year, edition, pages
2001. Vol. 33, no 3, 182-187 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-90181DOI: 10.1080/00365540151060789PubMedID: 11303807OAI: oai:DiVA.org:uu-90181DiVA: diva2:162445
Available from: 2003-03-28 Created: 2003-03-28 Last updated: 2009-09-25Bibliographically approved
In thesis
1. Epidemiology of Enterococci with Acquired Resistance to Antibiotics in Sweden: Special emphasis on Ampicillin and Vancomycin
Open this publication in new window or tab >>Epidemiology of Enterococci with Acquired Resistance to Antibiotics in Sweden: Special emphasis on Ampicillin and Vancomycin
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Enterokocker med förvärvad resistens mot ampicillin och vancomycin i Sverige
Abstract [en]

The first hospital outbreak of vancomycin-resistant enterococci (VRE) and carriage rates of VRE and ampicillin-resistant enterococci (ARE) in Sweden were investigated. Clonal relationships and mutations in fluoroquinolone resistance determining regions among ARE collected nation-wide were studied. Risk factors for ARE infection, shedding of ARE and the presence of the virulence gene esp in ARE isolates and patients on a hematology unit and other units at Uppsala University Hospital were further investigated.

The first Swedish hospital VRE outbreak was due to clonal spread of E. faecium, vanA. The nation wide carriage rates of ARE and VRE were 21.5% / 1% and 6% / 0%, among hospitalized patients and non-hospitalized individuals respectively. All ARE and VRE were E. faecium and >90% resistant to ciprofloxacin. All VRE carried vanB. Carriage of ARE was independently associated with >5 days of antibiotic treatment. Phenotypic and genetic typing showed a significantly higher homogeneity among ARE compared to matched ASE E. faecium isolates. Mutations conferring high-level ciprofloxacin resistance were found only in ARE. Risk factors for ARE infection included long duration of hospital stay and exposure to antibiotics. Skin carriage was associated with ARE shedding. ARE bacteremia was independently associated with prior ARE colonization and hematopoietic stem cell transplantation. Death was more common in ARE septicemia cases compared to controls. Esp was significantly more common in ARE surveillance compared to ARE blood isolates from patients on the hematology ward.

In conclusion, VRE were rare but clonally related multi-resistant ARE E. faecium were highly prevalent in Swedish hospitals. Spread of ARE in hospitals during the 1990s is suggested to be the main explanation for the emergence of ARE in Sweden. Spread was facilitated by use of antibiotics and probably by the presence of virulence genes in E. faecium isolates.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 80 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1237
Communicable diseases, Antimicrobial resistance, enterococci, epidemiology in Sweden, intra-hospital spread, shedding, risk-factors, infection, colonization, virulence factors, ARE, VRE, Php, PFGE, esp, gyrA, parC, Infektionssjukdomar
National Category
Infectious Medicine
Research subject
Infectious Diseases
urn:nbn:se:uu:diva-3344 (URN)91-554-5574-3 (ISBN)
Public defence
2003-04-24, Avdelningen för Klinisk Mikrobiologi, Hörsalen, Dag hammarskölds väg 17, Uppsala, 09:15
Available from: 2003-03-28 Created: 2003-03-28Bibliographically approved

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