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Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical origin
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.
Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Biomedicine and Surgery. Linköping University, Faculty of Health Sciences.
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(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: urn:nbn:se:liu:diva-82081OAI: oai:DiVA.org:liu-82081DiVA: diva2:557711
Available from: 2012-09-28 Created: 2012-09-28 Last updated: 2012-09-28Bibliographically approved
In thesis
1. Enterococci in Swedish intensive care units: studies on epidemiology, mechanisms of antibiotic resistance and virulence factors
Open this publication in new window or tab >>Enterococci in Swedish intensive care units: studies on epidemiology, mechanisms of antibiotic resistance and virulence factors
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:nbn:se:liu:diva-28709 (URN)13876 (Local ID)91-737-3861-1 (ISBN)13876 (Archive number)13876 (OAI)
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

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Hällgren, AnitaClaesson, CarinaSaeedi, BaharakMonstein, Hans-JürgHanberger, HåkanNilsson, Lennart E.

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Clinical MicrobiologyInfectious DiseasesFaculty of Health SciencesDepartment of Biomedicine and Surgery
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