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  • 1.
    Hällgren, Anita
    et al.
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Burman, Lars G
    Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Isaksson, Barbro
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Olsson-Liljeqvist, Barbro
    Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Nilsson, Lennart
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Saeedi, Baharak
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Walther, Sten
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine. Linköping University, Faculty of Health Sciences.
    Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units2005In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 37, no 8, p. 561-571Article in journal (Refereed)
    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.

  • 2.
    Hällgren, Anita
    et al.
    Department ofMolecularandClinicalMedicine Linköping University.
    Claesson, Carina
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences.
    Saeedi, Baharak
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Microbiology.
    Monstein, Hans-Jurg
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine.
    Hanberger, Håkan
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Infectious Diseases in Östergötland.
    Nilsson, Lennart
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology . Linköping University, Faculty of Health Sciences.
    Molecular detection of aggregation substance, enterococcal surface protein, and cytolysin genes and in vitro adhesion to urinary catheters of Enterococcus faecalis and E. faecium of clinical origin2009In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 299, no 5, p. 323-332Article in journal (Refereed)
    Abstract [en]

    It has been hypothesized that nosocomial enterococci might have virulence factors that enhance their ability to colonise hospitalised patients. The objectives of this study were to investigate the prevalence of genes encoding 3 virulence factors: aggregation substance (asa1), enterococcal surface protein (esp), and 5 genes within the cytolysin operon (cylA, cylB, cylM, cylL(L), cylL(S)) and cytolysin production in 115 enterococcal clinical isolates (21 Enterococcus faecium and 94 E. faecalis). Adhesion to siliconized latex urinary catheters in relation to presence of esp was analysed in a subset of isolates. The isolates were previously characterised by pulsed-field gel electrophoresis (PFGE). esp was the only virulence gene found in E. faecium. It was found in 71% of the 21 E. faecium isolates. asa1, esp, and the cyl operon were found in 79%, 73% and 13% respectively, of the 94 E. faecalis isolates. There was a complete agreement between presence of the cyl operon and phenotypic cytolysin production. Isolates belonging to a cluster of genetically related isolates carried esp and asa1 more often when compared to unique isolates. No difference was found with respect to cyl genes. 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. In conclusion, E. faecalis isolates with high-level gentamicin resistance (HLGR) belonging to clusters of genetically related isolates widely distributed in Swedish hospitals, were likely to carry both esp and asa1. Adhesion was not affected by esp.   

  • 3.
    Hällgren, Anita
    et al.
    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.
    Claesson, Carina
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Saeedi, Baharak
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Monstein, Hans-Jürg
    Linköping University, Department of Biomedicine and Surgery. Linköping University, Faculty of Health Sciences.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart E.
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical originManuscript (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).

  • 4.
    Hällgren, Anita
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Saeedi, Baharak
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Nilsson, Maud
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Monstein, Hans-Jürg
    Linköping University, Department of Biomedicine and Surgery. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Genetic relatedness among Enterococcus faecalis with transposon-mediated high-level gentamicin resistance in Swedish intensive care units2003In: Journal of Antimicrobial Chemotherapy, ISSN 0305-7453, E-ISSN 1460-2091, Vol. 52, no 2, p. 162-167Article in journal (Refereed)
    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.

  • 5.
    Saeedi, Baharak
    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.
    Characterization of clinical enterococcal isolates in Swedish hospitals: studies on genetic relatedness and high-level gentamicin resistance2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During the last few decades, and in parallel with increasing resistance to multiple antibiotics, enterococci have become one of the leading pathogens that cause nosocomial infections. High-level gentamicin resistant (HLGR) enterococci have become frequent. Thus, there are compelling reasons to control the transmission of enterococci with HLGR. Many different typing methods have been used for epidemiological typing of enterococci. Pulsed-field gel electrophoresis (PFGE) has been shown to be the most discriminating typing method and is currently considered the "gold standard" for typing of enterococci. However, PFGE is an expensive method and remains time-consuming, which may be of critical importance when comparing data obtained from numerous isolates.

    The aim of this thesis was to characterize clinical enterococcal isolates from patients admitted to Swedish hospitals, with special focus on HLGR strains and their genetic relatedness. Our purpose was also to develop a faster PFGE protocol for typing of enterococci, as well as to investigate if the Phene Plate (PhP) system can be used as a rapid screening method for detection of genetically related isolates of enterococci. If this could be achieved, it would be possible to minimize the number of isolates subjected to PFGE typing, which would save time and money.

    In paper I, we performed a thorough investigation of eight different parameters of importance for the separation of DNA fragments by PFGE. This resulted in a modified PFGE protocol for typing of enterococci with much enhanced resolution. HLGR E. faecalis isolates obtained from patients admitted to eight Swedish ICUs during 1996 and 1998 (paper II), and isolates obtained from patients with bacteremia in the County of Östergötland during the period 1994-2001 (paper III) were characterized by our modified PFGE method. We found that the majority (69%) of isolates from ICUs in the eastern and central parts of southern Sweden, belonged to one dominating cluster, and the same cluster was also found in blood isolates from Östergötland. In nearly all cases, HLGR was due to the presence of the aac(6 ')Ie-aph(2 '')la gene situated on a Tn5281-like transposon (paper II). In the County of Östergötland, HLGR E. faecalis was first isolated from blood cultures in 1996, and the first blood isolates of HLGR E. faecium were found in 1999. During the study period, only 4 HLGR E. faecium isolates were observed, and all of them showed unique PFGE patterns.

    To evaluate the efficiency of the gentamicin disk diffusion method for detection of HLGR in clinical isolates of enterococci, all enterococcal blood isolates from paper III were studied with a 30-µg gentamicin disk as recommended by SRGA, and the method was found to have 100% sensitivity and specificity when compared with PCR.

    A "biochemical fingerprinting" method (PhP) was compared with PFGE for epidemiological characterization of enterococci. In earlier studies of the PhP method, enterococci were collected mainly from the environment or from normal human flora. Our study indicates that PhP may be a useful screening method for clinical E. faecalis isolates, with a relatively high concordance with PFGE, but that it is less useful for E. faecium since the concordance for E. faecium was low. To fully evaluate PhP as a tool for epidemiological characterization of enterococci from clinical settings, and to address questions regarding the validity of PFGE, further studies using additional genotyping methods, preferably newer typing systems based on DNA sequencing such as MLST, are warranted.

    List of papers
    1. Modified pulsed-field gel electrophoresis protocol for typing of enterococci
    Open this publication in new window or tab >>Modified pulsed-field gel electrophoresis protocol for typing of enterococci
    Show others...
    2002 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 110, no 12, p. 869-874Article in journal (Refereed) Published
    Abstract [en]

    Controlling the spread of vancomycin-resistant enterococci (VRE) is an important task in hospital epidemiology. Pulsed-field gel electrophoresis (PFGE) has become the golden standard for molecular epidemiological characterisation of enterococcal isolates. For separation of DNA fragments by PFGE, different electrophoresis conditions have been recommended, but none of these protocols allows a satisfactory separation of both small and large DNA fragments of enterococci simultaneously. In this study we have speeded up the preparation of chromosomal DNA and defined new electrophoresis conditions that enhance separation of small and large DNA fragments for subtyping of enterococci with a 24 h PFGE.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-26482 (URN)10.1034/j.1600-0463.2002.1101205.x (DOI)11034 (Local ID)11034 (Archive number)11034 (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, p. 162-167Article 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, p. 405-409Article 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. Phene Plate (PhP) biochemical fingerprinting: a screening method for epidemiological typing of enterococcal isolates?
    Open this publication in new window or tab >>Phene Plate (PhP) biochemical fingerprinting: a screening method for epidemiological typing of enterococcal isolates?
    Show others...
    2005 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 113, no 9, p. 603-612Article in journal (Refereed) Published
    Abstract [en]

    Pulsed-field gel electrophoresis (PFGE) is currently considered the gold standard for genotyping of enterococci. However, PFGE is both expensive and time-consuming. The purpose of this study was to investigate whether the PhP system can be used as a reliable clinical screening method for detection of genetically related isolates of enterococci. If so, it should be possible to minimize the number of isolates subjected to PFGE typing, which would save time and money. Ninety-nine clinical enterococcal isolates were analysed by PhP (similarity levels 0.90–0.975) and PFGE (similarity levels ≤3 and ≤6 bands) and all possible pairs of isolates were cross-classified as matched or mismatched. We found that the probability that a pair of isolates (A and B) belonging to the same type according to PhP also belong to the same cluster according to PFGE, i.e. p(APFGE=BPFGE • APhP=BPhP), and the probability that a pair of isolates of different types according to PhP also belong to different clusters according to PFGE, i.e. p(APFGE≠BPFGE • APhP≠BPhP), was relatively high for E. faecalis (0.86 and 0.96, respectively), but was lower for E. faecium (0.51 and 0.77, respectively). The concordance which shows the probability that PhP and PFGE agree on match or mismatch was 86%–93% for E. faecalis and 54%–66% for E. faecium, which indicates that the PhP method may be useful for epidemiological typing of E. faecalis in the current settings but not for E. faecium.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-33468 (URN)10.1111/j.1600-0463.2005.apm_217.x (DOI)19490 (Local ID)19490 (Archive number)19490 (OAI)
    Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13Bibliographically approved
  • 6.
    Saeedi, Baharak
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Hällgren, Anita
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Jonasson, Jon
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Genetic relatedness of Enterococcus faecalis isolates with high-level gentamicin resistance from patients with bacteraemia in the south east of Sweden 1994-20012004In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 36, no 6-7, p. 405-409Article in journal (Refereed)
    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.

  • 7.
    Saeedi, Baharak
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Hällgren, Anita
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Jonasson, Jon
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Modified pulsed-field gel electrophoresis protocol for typing of enterococci2002In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 110, no 12, p. 869-874Article in journal (Refereed)
    Abstract [en]

    Controlling the spread of vancomycin-resistant enterococci (VRE) is an important task in hospital epidemiology. Pulsed-field gel electrophoresis (PFGE) has become the golden standard for molecular epidemiological characterisation of enterococcal isolates. For separation of DNA fragments by PFGE, different electrophoresis conditions have been recommended, but none of these protocols allows a satisfactory separation of both small and large DNA fragments of enterococci simultaneously. In this study we have speeded up the preparation of chromosomal DNA and defined new electrophoresis conditions that enhance separation of small and large DNA fragments for subtyping of enterococci with a 24 h PFGE.

  • 8.
    Saeedi, Baharak
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Tärnberg, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Gill, Hans
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Hällgren, Anita
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Jonasson, Jon
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Nilsson, Lennart
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Kühn, I.
    Department of Microbiology and Tumour Biology Centre, Karolinska Institute, Stockholm, Sweden.
    Hanberger, Håkan
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Phene Plate (PhP) biochemical fingerprinting: a screening method for epidemiological typing of enterococcal isolates?2005In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 113, no 9, p. 603-612Article in journal (Refereed)
    Abstract [en]

    Pulsed-field gel electrophoresis (PFGE) is currently considered the gold standard for genotyping of enterococci. However, PFGE is both expensive and time-consuming. The purpose of this study was to investigate whether the PhP system can be used as a reliable clinical screening method for detection of genetically related isolates of enterococci. If so, it should be possible to minimize the number of isolates subjected to PFGE typing, which would save time and money. Ninety-nine clinical enterococcal isolates were analysed by PhP (similarity levels 0.90–0.975) and PFGE (similarity levels ≤3 and ≤6 bands) and all possible pairs of isolates were cross-classified as matched or mismatched. We found that the probability that a pair of isolates (A and B) belonging to the same type according to PhP also belong to the same cluster according to PFGE, i.e. p(APFGE=BPFGE • APhP=BPhP), and the probability that a pair of isolates of different types according to PhP also belong to different clusters according to PFGE, i.e. p(APFGE≠BPFGE • APhP≠BPhP), was relatively high for E. faecalis (0.86 and 0.96, respectively), but was lower for E. faecium (0.51 and 0.77, respectively). The concordance which shows the probability that PhP and PFGE agree on match or mismatch was 86%–93% for E. faecalis and 54%–66% for E. faecium, which indicates that the PhP method may be useful for epidemiological typing of E. faecalis in the current settings but not for E. faecium.

  • 9.
    Tegnell, Anders
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Saeedi, Baharak
    Linköping University, Department of Molecular and Clinical Medicine, Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Isaksson, Barbro
    Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Microbiology. Linköping University, Faculty of Health Sciences.
    Granfeldt, Hans
    Linköping University, Department of Medicine and Care, Thoracic Surgery. Linköping University, Faculty of Health Sciences.
    Öhman, Lena
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    A clone of coagulase-negative staphylococci among patients with post-cardiac surgery infections2002In: Journal of Hospital Infection, ISSN 0195-6701, E-ISSN 1532-2939, Vol. 52, no 1, p. 37-42Article in journal (Refereed)
    Abstract [en]

    Coagulase-negative staphylococci (CoNS) are important causes of hospital-acquired infections such as infections after cardiac surgery. Efforts to reduce these infections are hampered by the lack of knowledge concerning the epidemiology of CoNS in this setting. Forty strains of CoNS collected during the surgical revision of 27 patients operated on between 1997 and 2000 were analysed. Strains were also collected from the ambient air in the operating suite. Their pulsed-field gel electrophoresis (PFGE) characteristics and antibiotic resistance were analysed. Using PFGE 19 of 40 strains from 15 of 27 patients were shown to belong to one clone, and strains from this clone were also isolated from the ambient air. This clone had caused infections throughout the period. Antibiotic resistance did not correlate with PFGE patterns. Using PFGE one clone could be identified that caused 56% of the CoNS infections during this period. A strain from this clone was also found in the air of the operating suite suggesting the origin of the CoNS causing infections was the hospital environment.

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