uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Effect of excluding duplicate isolates of Escherichia coli and Staphylococcus aureus in a 14 year consecutive database
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Bacteriology.
2007 (English)In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 59, no 5, 913-918 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: It is recommended that duplicate isolates are excluded when reporting resistance rates. The rationale for this is that failing to do so will yield falsely high resistance rates. We analysed a 14 year consecutive database of Escherichia coli (n=62,380) and Staphylococcus aureus (n=28,178) using various cut-off algorithms to determine the importance of excluding duplicates and principal differences between the bacteria. METHODS: Susceptibility testing was performed according to the Swedish Reference Group for Antibiotics guidelines. Duplicates were excluded on the basis of species, individual and time (exclusion cut-offs of 7, 14, 30, 45, 90, 180, 270 and 365 days) from the first isolate. RESULTS: Although 30% of the isolates were excluded using a 365 day exclusion algorithm, the effects on resistance rates of excluding duplicates were small. Irrespective of cut-off, resistance in S. aureus decreased when duplicates were excluded. Using 7-30 days cut-offs, resistance in E. coli decreased or was not affected, whereas higher resistance rates were obtained when exclusion was based on a 365 day cut-off. Fluoroquinolone resistance was a clear exception to this rule. CONCLUSIONS: Although the effect of exclusion of duplicates was minor, we suggest that exclusion cut-offs should match the study timeline. The data presented on E. coli, from urinary tract infections, and S. aureus, from skin and soft tissue infections, suggest that E. coli infection, >90 days after the first culture, is mainly caused by new less-resistant strains. Patients with S. aureus continue to be colonized with the same strain.

Place, publisher, year, edition, pages
2007. Vol. 59, no 5, 913-918 p.
Keyword [en]
antimicrobial resistance, surveillance, urinary tract infections, skin and soft tissue infections
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-112600DOI: 10.1093/jac/dkm040ISI: 000247006200015PubMedID: 17332004OAI: oai:DiVA.org:uu-112600DiVA: diva2:286930
Available from: 2010-01-15 Created: 2010-01-15 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Antibiotic Resistance and Population Dynamics of Escherichia coli in Relation to a Large Scale Antibiotic Consumption Intervention
Open this publication in new window or tab >>Antibiotic Resistance and Population Dynamics of Escherichia coli in Relation to a Large Scale Antibiotic Consumption Intervention
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Antibiotic resistance challenges the practice and development of modern medicine. The aim of this thesis was to test the hypothesis that antibiotic resistance is reversible once the selection pressure of an antibiotic is removed. A decisive reduction (85%) in trimethoprim and trimethoprim-sulfamethoxazole over 24 months in Kronoberg County, Sweden, is described. The resistance baseline prior to the intervention and the effects of the intervention on resistance levels, trimethoprim resistance genes (dfr-genes) and population structure in Escherichia coli were studied.

The effects of different algorithms for excluding patient duplicate isolates were small but systematic. An identical algorithm was used throughout.

The drastic decrease in the use of trimethoprim containing drugs did not result in a corresponding decrease in trimethoprim resistance. This was true both for total trimethoprim resistance and for trimethoprim mono-resistance. The distributions of E. coli phenotypes, dfr-genes and E. coli sequence types were stable. The marginal effect on resistance rates was explained by a low fitness cost of trimethoprim resistance observed in vitro and the high levels of associated resistance in trimethoprim resistant isolates.

Trimethoprim resistance was, although widespread in the E. coli population, more common in certain E. coli sequence types. The distributions of dfr-genes were different in E. coli and K. pneumoniae and between different E. coli sequence types. These results indicate mechanisms related to the genetic back-bone of E coli to be important for the acquisition and persistence of antibiotic resistance.

The findings of this thesis indicates that, at least for some classes of antibiotics, we may have overestimated the usefulness of a strategy for reversing antimicrobial resistance based on the fitness cost of resistance. We have equally underestimated the conserving effects of associated resistance. The stability of the dfr-genes and E. coli sequence types underlines the importance of associated resistance and successful lineages in the spread and maintenance of antibiotic resistance in E. coli.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 81 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 512
Keyword
reversibility, trimethoprim, dfr, associated resistance, MLST
National Category
Infectious Medicine Microbiology in the medical area Microbiology in the medical area
Research subject
Infectious Diseases
Identifiers
urn:nbn:se:uu:diva-112190 (URN)978-91-554-7700-4 (ISBN)
Public defence
2010-02-26, Universitetshuset, sal IV, Övre Slottsgatan, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2010-02-02 Created: 2010-01-11 Last updated: 2010-02-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed
By organisation
Infectious DiseasesClinical Bacteriology
In the same journal
Journal of Antimicrobial Chemotherapy
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 715 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf