liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • 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
Enterococci in Swedish intensive care units: studies on epidemiology, mechanisms of antibiotic resistance and virulence factors
Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of this thesis was to study enterococci in Sweden, their resistance to antibiotics in general and high-level gentamicin resistance (HLGR) in particular, with a special focus on the ICU setting. Dynamics of rectal colonisation during prolonged intensive care unit (ICU) stay was assessed. In addition, enterococcal virulence factors and the ability to adhere to abiotic surfaces such as urinary catheters were studied.

We found that among prolonged-stay patients admitted to ICUs, the rectal flora was altered, with a decrease in Gram-negative rods in favour of Gram-positive bacteria, mainly Coagulase negative staphylococci and enterococci.

Among clinical enterococcal isolates from patients admitted to Swedish ICUs, although vancomycin resistant enterococci (VRE) were only sporadically found, multidrug resistance was common. This was most apparent in Enterococcus faecium, where the majority of isolates were ampicillin- and quinolone resistant. Enterococcus faecalis was still the most frequently isolated enterococcal species in clinical specimens. Among patients admitted to Swedish ICUs 1996-1998, E. faecalis with HLGR was found in higher frequency (20%) than previously reported. The majority (89%) of these isolates belonged to two dominating clusters of genetically related E. faecalis. Cluster I (69%), which was predominantly found in the eastern and central parts of southern Sweden and Cluster II (20%) in south-western Sweden.

In the County of Östergötland, the first E. faecalis with HLGR isolated from blood cultures was found in 1996. The yearly incidence of isolates with HLGR in E. faecalis bacteraemia was studied from 1996-2001, and varied between 9-22%. The majority of these isolates were genetically related and belonged to Cluster I, also found in the previous study. The first blood isolate of E. faecium with HLGR in the County of Östergötland was found in 1999. A clone of E. faecium, with HLGR and ampicillin resistance, was found to colonise 6/10 and 2/11 prolonged-stay patients admitted from November 2001 through January 2002 to the general ICU and cardio-thoracic ICU, respectively, at the University Hospital of Linköping.

All studied isolates with HLGR carried the gene aac(6')-Ie-aph(2'')-Ia encoding the bifunctional aminoglycoside modifying enzyme Aac(6')Ie-Aph(2'')Ia, which conveys resistance to all commercially available amino-glycosides except streptomycin. The location of the gene, aac(6')Ie-aph(2'')-Ia, was studied in 45 E. faecalis isolates and the gene was carried on a Tn5281-like transposon in all isolates except one. The 30 µg disc diffusion test, as recommended by the SRGA, had 100% sensitivity and specificity when compared to PCR detection of aac(6')-Ie-aph(2'')-Ia.

E. faecalis isolates with HLGR belonging to widely disseminated clusters of genetically related isolates were more likely to carry both the gene encoding enterococcal surface protein (esp) and the gene encoding aggregation substance (asa1) compared to unique isolates. Esp was the only virulence factor found among E. faecium isolates, where it was common. E. faecalis isolates adhered with higher bacterial densities to urinary tract catheters compared to E. faecium isolates. In vitro adherence to urinary tract catheters was not affected by esp.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2005. , 99 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 880
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-28709Local ID: 13876ISBN: 91-737-3861-1 (print)OAI: oai:DiVA.org:liu-28709DiVA: diva2:249520
Public defence
2005-02-18, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings Universitet, Linköping, 13:00 (English)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-09-28Bibliographically approved
List of papers
1. Antimicrobial susceptibility patterns of enterococci in intensive care units in Sweden evaluated by different MIC breakpoint systems
Open this publication in new window or tab >>Antimicrobial susceptibility patterns of enterococci in intensive care units in Sweden evaluated by different MIC breakpoint systems
Show others...
2001 (English)In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 48, no 1, 53-62 p.Article in journal (Refereed) Published
Abstract [en]

Three hundred and twenty-two (322) clinical isolates were collected from patients admitted to intensive care units (ICUs) at eight Swedish hospitals between December 1996 and December 1998. Of the isolates, 244 (76%) were Enterococcus faecalis, 74 (23%) were Enterococcus faecium and four (1%) were other Enterococcus spp. MICs of ampicillin, imipenem, meropenem, piperacillin/tazobactam, ciprofloxacin, trovafloxacin, clinafloxacin, gentamicin, streptomycin, vancomycin, teicoplanin, quinupristin/dalfopristin, linezolid and evernimicin were determined by Etest. Susceptible and resistant isolates were defined according to the species-related MIC breakpoints of the British Society for Antimicrobial Chemotherapy (BSAC), the National Committee for Clinical Laboratory Standards (NCCLS) and the Swedish Reference Group for Antibiotics (SRGA). Tentative breakpoints were applied for new/experimental antibiotics. Multidrug resistance among enterococci in ICUs is not uncommon in Sweden, particularly among E. faecium, and includes ampicillin resistance and concomitant resistance to fluoroquinolones. Almost 20% of E. faecalis isolates showed high-level resistance to gentamicin and concomitant resistance to fluoroquinolones. Vancomycin-resistant enterococci were only found sporadically. Among the new antimicrobial agents, linezolid and evernimicin showed the best activity against all enterococcal isolates. There was good concordance between the BSAC, NCCLS and SRGA breakpoints in detecting resistance. When applying the SRGA breakpoints for susceptibility, isolates were more frequently interpreted as intermediate. This might indicate earlier detection of emerging resistance using the SRGA breakpoint when the native population is considered susceptible, but with the risk that isolates belonging to the native susceptible population will be incorrectly interpreted as intermediate.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-25743 (URN)10.1093/jac/48.1.53 (DOI)10175 (Local ID)10175 (Archive number)10175 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
2. Genetic relatedness among Enterococcus faecalis with transposon-mediated high-level gentamicin resistance in Swedish intensive care units
Open this publication in new window or tab >>Genetic relatedness among Enterococcus faecalis with transposon-mediated high-level gentamicin resistance in Swedish intensive care units
Show others...
2003 (English)In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 52, no 2, 162-167 p.Article in journal (Refereed) Published
Abstract [en]

We studied 45 isolates of Enterococcus faecalis with high-level gentamicin resistance (HLGR), all but one concomitantly resistant to ciprofloxacin, and 25 ciprofloxacin-resistant isolates without HLGR for genetic relatedness using pulsed-field gel electrophoresis (PFGE). E. faecalis were isolated from patients admitted to intensive care units at eight hospitals in southern Sweden from December 1996 through December 1998. Genomic analysis by PFGE resulted in three clusters of genetically related isolates (designated clusters I, II and III) and 23 unique clones. Cluster I was found predominantly in the eastern and central parts of southern Sweden and clusters II and III in south-western Sweden. Among the 45 isolates with HLGR, 69% belonged to cluster I, 20% to cluster II, and 11% had unique PFGE patterns, which suggests that the majority of isolates with HLGR are closely related. Among the 25 ciprofloxacin-resistant isolates without HLGR, 68% had unique PFGE patterns, 12% belonged to cluster I and 20% to cluster III, which suggests the ciprofloxacin-resistant isolates are not related. All isolates with HLGR contained the aac(6)Ie-aph(2)Ia gene, which was carried on a Tn5281-like transposon in all isolates except one. We conclude that HLGR in E. faecalis was mainly due to dissemination of genetically related clones during the time studied, and that HLGR in these isolates was due to the presence of the aac(6)Ie-aph(2)Ia gene.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26483 (URN)10.1093/jac/dkg315 (DOI)11035 (Local ID)11035 (Archive number)11035 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
3. Genetic relatedness of Enterococcus faecalis isolates with high-level gentamicin resistance from patients with bacteraemia in the south east of Sweden 1994-2001
Open this publication in new window or tab >>Genetic relatedness of Enterococcus faecalis isolates with high-level gentamicin resistance from patients with bacteraemia in the south east of Sweden 1994-2001
Show others...
2004 (English)In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 36, no 6-7, 405-409 p.Article in journal (Refereed) Published
Abstract [en]

High-level gentamicin resistant (HLGR) enterococci (Enterococcus faecalis and Enterococcus faecium) have become a substantial nosocomial problem in many countries. In this study, we investigated the prevalence of HLGR enterococci and their genetic relatedness in blood culture isolates from patients with bacteraemia admitted to the 3 hospitals in Östergötland, a county in the south east of Sweden, during 1994–2001. 36 of 250 E. faecalis (14%) and 4 of 106 E. faecium isolates (4%) were shown by PCR to carry the aac(6′)-Ie-aph(2″)-Ia aminoglycoside modifying gene and these isolates were also classified as HLGR enterococci by the gentamicin antibiotic disk diffusion method. A majority of HLGR E. faecalis isolates (83%) belonged to the same cluster of genetically related isolates, according to the pulsed-field gel electrophoresis (PFGE) patterns, whereas all 4 HLGR E. faecium isolates had unique PFGE patterns. In conclusion, our study showed that in contrast to studies from many other countries, the presence of HLGR enterococci was more common in E. faecalis than in E. faecium and appeared the first time in 1996 and 1999, respectively. Bacteraemia with HLGR enterococci in Östergötland was mainly due to the spread of a cluster related of E. faecalis strains.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24621 (URN)10.1080/00365540410020622 (DOI)6802 (Local ID)6802 (Archive number)6802 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
4. Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units
Open this publication in new window or tab >>Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units
Show others...
2005 (English)In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 37, no 8, 561-571 p.Article in journal (Refereed) Published
Abstract [en]

The aims of this study were to gain insight into the dynamics of the rectal flora during prolonged ICU stay, with a particular focus on colonization and cross-transmission with resistant pathogens, and to evaluate methods for the rapid isolation of relevant bacteria from rectal swabs. Patients admitted to a general intensive care unit (GICU) or a cardiothoracic ICU (TICU) at the University Hospital of Linköping, Sweden, between 1 November 2001 and January 2002 with a length of stay > 5 d were included (n = 20). Chromogenic UTI agar medium was used for discrimination of different species, and appropriate antibiotics were added to detect resistance. Direct plating was compared to enrichment broth for a subset of specimens. The study showed an early alteration in rectal flora, with a dramatic decrease in Gram-negative rods in favour of Gram-positive bacteria. An ampicillin- and high-level gentamicin resistant clone of Enterococcus faecium was found in 6 of 10 patients in the GICU and 2 of 11 patients in the TICU. Enrichment broth did not enhance the detection of Gram-negative bacteria compared to direct plating on Chromogenic UTI medium, but enrichment broths were needed for optimal detection of resistant Gram-positive bacteria.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30071 (URN)10.1080/00365540510038947 (DOI)15533 (Local ID)15533 (Archive number)15533 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
5. Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical origin
Open this publication in new window or tab >>Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical origin
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [sv]

Enterococcal isolates, 21 E. faecium and 94 E. faecalis, isolated from blood cultures, rectal specimens and various other clinical samples were examined for the presence of the virulence factors hemolysin/cytolysin, aggregation substance (asa1) and enterococcal surface protein (esp). The isolates were previously characterized by pulsed-field gel electrophoresis (PFGE). Adhesion to siliconized latex urinary catheters was analysed in 14 clinical isolates and 3 control strains. Densities of adhering bacteria were determined by a bioluminescence assay of bacterial ATP. The only virulence factor found in E. faecium, esp, was found in 71% of the 21 E. faceium isolates. Cytolysin production, asa1 and esp were found in 13%, 79% and 73%, respectively, of the 94 E. faecalis isolates. Isolates belonging to a cluster of genetically related isolates differed significantly with respect to carriage of esp and asa1 compared to unique isolates, with the virulence factors more commonly found among clustered isolates (p<0.01). No difference was found with respect to cytolysio production (p = 0.76). E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared (p = 0.38 and 0.64).

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-82081 (URN)
Available from: 2012-09-28 Created: 2012-09-28 Last updated: 2012-09-28Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Hällgren, Anita

Search in DiVA

By author/editor
Hällgren, Anita
By organisation
Clinical MicrobiologyInfectious DiseasesFaculty of Health Sciences
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 348 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • 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