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  • 1.
    Ahlstrand, Erik
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital. Department of Medicine, Division of Hematology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Svensson, Karolina
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden. Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Long-term molecular epidemiology of staphylococcus epidermidis blood culture isolates from patients with hematological malignancies2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, article id e99045Article in journal (Refereed)
    Abstract [en]

    Staphylococcus epidermidis is an important cause of bloodstream infections in patients with hematological malignancies. Knowledge of the long-term epidemiology of these infections is limited. We surveyed all S. epidermidis blood culture isolates from patients treated for hematological malignancies at the University Hospital of Orebro, Sweden from 1980 to 2009. A total of 373 S. epidermidis isolates were identified and multilocus sequence typing, staphylococcal chromosome cassette mec (SCCmec) typing and standard antibiotic susceptibility testing were employed to characterize these isolates. The majority of the isolates 361/373 (97%) belonged to clonal complex 2, and the 373 isolates were divided into 45 sequence types (STs); Simpson's Diversity Index was 0.56. The most prevalent STs were ST2 (243/373, 65%) and ST215 (28/373, 8%). Ninety three percent (226/243) of the ST2 isolates displayed either SCCmec type III or IV. ST2 and 215 were isolated during the entire study period, and together these STs caused temporal peaks in the number of positive blood cultures of S. epidermidis. Methicillin resistance was detected in 213/273 (78%) of all isolates. In the two predominating STs, ST2 and ST215, methicillin resistance was detected in 256/271 isolates (95%), compared with 34/100 (34%) in other STs (p<0.001). In conclusion, in this long-term study of patients with hematological malignancies, we demonstrate a predominance of methicillin-resistant ST2 among S. epidermidis blood culture isolates.

  • 2.
    Ehlersson, Gustaf
    et al.
    School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Svartström, Olov
    Department of Clinical Microbiology, Linköping University Hospital, Linköping, Sweden.
    Stenmark, Bianca
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Medical Sciences. Department of Laboratory Medicine, Clinical Microbiology, Faculty of Health and Medical Sciences, Örebro University, Örebro, Sweden.
    Phenotypic characterisation of coagulase-negative staphylococci isolated from blood cultures in newborn infants, with a special focus on Staphylococcus capitis2017In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227, Vol. 106, no 10, p. 1576-1582Article in journal (Refereed)
    Abstract [en]

    AIM: This Swedish study determined which species of coagulase-negative staphylococci (CoNS) were found in neonatal blood cultures and whether they included Staphylococcus capitis clones with decreased susceptibility to vancomycin.

    METHODS: CoNS isolates (n = 332) from neonatal blood cultures collected at Örebro University Hospital during 1987-2014 were identified to species level with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). The antibiotic susceptibility pattern of S. capitis isolates was determined by the disc diffusion test and Etest, and the presence of heterogeneous glycopeptide-intermediate S. capitis (hGISC) was evaluated.

    RESULTS: Staphylococcus epidermidis (67.4%), Staphylococcus haemolyticus (10.5%) and S. capitis (9.6%) were the most common CoNS species. Of the S. capitis isolates, 75% were methicillin-resistant and 44% were multidrug-resistant. No isolate showed decreased susceptibility to vancomycin, but at least 59% displayed the hGISC phenotype. Staphylococcus capitis isolates related to the strain CR01 displaying pulsotype NRCS-A were found.

    CONCLUSION: Staphylococcus epidermidis, S. haemolyticus and S. capitis were the predominant species detected in neonatal blood cultures by MALDI-TOF MS. The number of episodes caused by S. capitis increased during the study period, but no isolates with decreased susceptibility to vancomycin were identified. However, S. capitis isolates related to the strain CR01 displaying pulsotype NRCS-A were found.

  • 3.
    Golparian, Daniel
    et al.
    WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, Swedish Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, Swedish Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Unemo, Magnus
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. WHO Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, Swedish Reference Laboratory for Pathogenic Neisseria, Department of Laboratory Medicine, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Analytical specificity and sensitivity of the novel dual-target GeneProof Neisseria gonorrhoeae PCR kit for detection of N-gonorrhoeae2015In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 123, no 11, p. 955-958Article in journal (Refereed)
    Abstract [en]

    Detection of Neisseria gonorrhoeae relies increasingly on nucleic acid amplification tests (NAATs). The specificity of many gonococcal NAATs has been suboptimal and supplementary testing remains recommended in Europe and several additional countries. The novel dual-target GeneProofNeisseria gonorrhoeae PCR kit, targeting porA pseudogene and 16S rRNA gene, showed a high specificity and sensitivity when isolates of non-gonococcal Neisseria and related species (n=144), and gonococci (n=104) were tested. However, rare gonococcal porA mutants were only detected in the 16S rRNA gene target and two non-gonococcal isolates showed a low-level cross-reactivity in the 16S rRNA gene target. The detection limit for both targets was 1.5 copies per reaction.

  • 4.
    Hamad, Tarza
    et al.
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University, Örebro, Sweden; Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University, Örebro, Sweden.
    Nilsdotter-Augustinsson, Åsa
    Department of Infectious Diseases, and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University, Örebro, Sweden.
    Antibiotic susceptibility among Staphylococcus epidermidis isolated from prosthetic joint infections, with focus on doxycycline2015In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 123, no 12, p. 1055-1060Article in journal (Refereed)
    Abstract [en]

    In recent years, coagulase-negative staphylococci such as Staphylococcus epidermidis have gained importance as nosocomial pathogens, especially in immunocompromised patients and prosthetic joint infections (PJIs). These infections are often long lasting and difficult to treat due to the production of bacterial biofilm and the transformation of the bacteria into a stationary growth phase. Rifampicin is able to penetrate the biofilm, but to reduce the risk of development of rifampicin resistance it should be used in combination with an additional antibiotic. In this study we used Etest to investigate the antimicrobial susceptibility of 134 clinical isolates of S.epidermidis obtained from PJIs to six oral antibiotics: doxycycline, rifampicin, linezolid, fusidic acid, clindamycin, and ciprofloxacin. We also performed synergy testing on doxycycline in combination with each of the remaining antibiotics. Ninety-three (69%) of the 134 isolates were susceptible to doxycycline, 94/134 (70%) to rifampicin, 56/134 (42%) to clindamycin, 25/134 (19%) to ciprofloxacin, 81/134 (60%) to fusidic acid, and 100% to linezolid. Thirty-two (80%) of the 40 isolates not fully susceptible to rifampicin were susceptible to doxycycline. Doxycycline in combination with each of the other investigated antibiotics exerted an additive effect on nearly half of the isolates, with the exception of clindamycin, which displayed an even higher percentage of additive effect (69%). To conclude, as the majority of the S.epidermidis isolates were susceptible to doxycycline, this antimicrobial agent may provide a potential alternative for combination therapy together with rifampicin.

  • 5.
    Hedlund, Linda
    et al.
    Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University Hospital.
    Söderquist, Bo
    Örebro University Hospital.
    Presence of arginine catabolic mobile element among community-acquired meticillin-resistant staphylococcus aureus is linked to a specific genetic background2013In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 121, no 3, p. 221-225Article in journal (Refereed)
    Abstract [en]

    The prevalence of arginine catabolic mobile element (ACME) among diverse and heterogeneous community-associated methicillin-resistant Staphylococcus aureus community-associated Methicillin-resistant S. aureus (CA-MRSA) (n = 114) in a low-endemic area, i.e. Sweden, was investigated. Among the CA-MRSA, represented by 47 different spa types, ACME was only found in 10 isolates with a common genetic background [t008, SCCmec type IV, Panton-Valentine leukocidin (PVL) positive, and indistinguishable or closely related pulsed-field gel electrophoresis (PFGE)-patterns] corresponding to USA300. This strain does not seem to be established in our area as most of the patients contracted the CA-MRSA abroad. Presence of ACME does not seem to be associated with colonization, long-term carriership, or intra-familiar transmission in a higher extent than CA-MRSA in general.

  • 6.
    Hellmark, Bengt
    Örebro University, School of Health and Medical Sciences.
    Genotypic and phenotypic characterisation of Staphylococcus epidermidis isolated from prosthetic joint infections2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Staphylococcus epidermidis has emerged in recent years as an important nosocomial pathogen, especially in infections associated with implanted foreign body materials (e.g., prosthetic joints and heart valves) and in individuals with a compromised immune system (e.g., cancer patients and neonates). Although rare, implant infections are long lasting and cause severe suffering for the patient that includes pain and disability and even increased mortality. One aim of the present thesis was to develop and evaluate a genetic method for species identification and simultaneous detection of rifampicin resistance in staphylococci. A second aim was to examine S. epidermidis isolated from prosthetic joint infections (PJIs) and from wrists and nares of healthy individuals regarding their antibiotic susceptibility, biofilm production, virulence factors, and epidemiology. Comparison with phenotypic diagnostics revealed that 8 (16%) of 49 isolates differed in their species identification in favour of the genetic method. In addition, mutations associated with rifampicin resistance, including two not previously reported, were possible to detect in all isolates resistant to rifampicin. Antibiotic susceptibility testing of 61 PJI isolates showed multi-drug resistance in 91%. Furthermore, the results of the synergy testing revealed that no antibiotic combination was significantly better than the others. Hence, the effects that were possible to detect were isolate dependent. To find a method for discriminating between invasive (n=61) and commensal (n=24) isolates of S. epidermidis genotypic and phenotypic characterisations of biofilm production (including the ica and aap genes), antibiotic susceptibility, virulence-related genes (such as agr and ACME) and epidemiology were performed (using multilocus sequence typing [MLST], typing of the staphylococcal chromosome cassette mec [SCCmec] and PhenePlate). Significant differences were found in antibiotic susceptibility, i.e. there was more resistance among invasive isolates. MLST sequence types (ST) ST2 and ST215 dominated the invasive isolates.

    List of papers
    1. Simultaneous species identification and detection of rifampicin resistance in staphylococci by sequencing of the rpoB gene
    Open this publication in new window or tab >>Simultaneous species identification and detection of rifampicin resistance in staphylococci by sequencing of the rpoB gene
    2008 (English)In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 28, no 2, p. 183-190Article in journal (Refereed) Published
    Abstract [en]

    In recent years, coagulase-negative staphylococci (CoNS) have been increasingly recognised as causative agents of various infections, especially in immunocompromised patients and related to implanted foreign body materials. In this study, rpoB sequencing was used for simultaneous species identification and detection of rifampicin resistance in clinical staphylococci isolates. Forty-nine (96%) out of 51 isolates, representing 17 different Staphylococcus species according to the initial phenotypic species identification, were identified to the species level using rpoB sequencing. Furthermore, the two remaining isolates were Kocuria sp. and Corynebacterium sp. respectively, according to 16S rRNA sequencing. Comparison with the phenotypic diagnostics also revealed that 8 (16%) of the 49 isolates differed regarding identified species. Discrepant analysis confirmed the result of the rpoB sequencing for all except 2 of these isolates, which could not be distinguished as single species using 16S rRNA sequencing. Regarding detection of rifampicin resistance, isolates obtained pre- and post-treatment with rifampicin were examined. These isolates comprised S. aureus (7 patients) and S. lugdunensis (1 patient). Rifampicin resistance was mainly detected following short-term treatment with rifampicin in combination with isoxazolyl-penicillin, or long-term treatment with rifampicin and ciprofloxacin. Each rifampicin-resistant isolate displayed an identical rpoB sequence as their corresponding rifampicin-susceptible isolates except for one (n = 6) or two (n = 1) nonsynonymous single nucleotide polymorphisms, or insertion of one codon (n = 1). In conclusion, rpoB sequencing is a rapid, objective and accurate method of species identification and simultaneous detection of rifampicin resistance in staphylococci.

    Place, publisher, year, edition, pages
    Berlin: Springer, 2008
    National Category
    Medical and Health Sciences Microbiology in the medical area
    Research subject
    Biomedicine
    Identifiers
    urn:nbn:se:oru:diva-3467 (URN)10.1007/s10096-008-0604-5 (DOI)18716806 (PubMedID)
    Available from: 2008-12-08 Created: 2008-12-08 Last updated: 2018-01-13Bibliographically approved
    2. Antibiotic susceptibility among Staphylococcus epidermidis isolated from prosthetic joint infections with special focus on rifampicin and variability of the rpoB gene
    Open this publication in new window or tab >>Antibiotic susceptibility among Staphylococcus epidermidis isolated from prosthetic joint infections with special focus on rifampicin and variability of the rpoB gene
    2009 (English)In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 15, no 3, p. 238-244Article in journal (Refereed) Published
    Abstract [en]

    Staphylococcus epidermidis is the most important pathogen in infections related to implanted foreign materials, especially prosthetic joint infections (PJIs). The aim of this study was to investigate the antimicrobial activities of 16 antibiotics against S. epidermidis isolated from PJIs, with special focus on rifampicin and rpoB variability. Ninety-one per cent of the isolates were multiresistant (i.e. resistant to members of more than three classes of antibiotics). Thirty-nine per cent were resistant to rifampicin, associated with one or two single-nucleotide polymorphisms (SNPs) in rpoB. Using IsoSensitest agar with supplements, 61% were resistant to oxacillin, and using Mueller-Hinton II agar with supplement, 84% were resistant. Using the Etest, 58% were resistant to cefoxitin, and using the disk diffusion test, 91% were resistant. The mecA gene was detected in 85% of the isolates. Regarding recently available antibiotics, all isolates were susceptible to tigecycline and linezolid, and 97% were susceptible to daptomycin. In addition, two novel antibiotics, dalbavancin and ceftobiprole, were tested, although not yet available for routine use. The MIC(50) and MIC(90) values of these novel antibiotics were 0.032 and 0.047 mg/L and 0.5 and 1.5 mg/L, respectively. Among the other antibiotics, the rates of resistance varied between 0% (vancomycin) and 82% (trimethoprim-sulphamethoxazole). S. epidermidis strains causing PJIs often show multiresistance, including resistance to rifampicin, which is mainly caused by one or two SNPs. Some of the newer antimicrobial agents may provide alternatives for monotherapy or combination therapy with rifampicin. Detection of mecA is necessary before initiating treatment of infections due to S. epidermidis when it displays intermediate susceptibility to cefoxitin.

    Place, publisher, year, edition, pages
    Oxford: Blackwell, 2009
    National Category
    Medical and Health Sciences Infectious Medicine
    Research subject
    Biomedicine
    Identifiers
    urn:nbn:se:oru:diva-11784 (URN)10.1111/j.1469-0691.2008.02663.x (DOI)19196261 (PubMedID)
    Available from: 2010-09-08 Created: 2010-09-08 Last updated: 2017-12-12Bibliographically approved
    3. In vitro antimicrobial synergy testing of coagulase-negative staphylococci isolated from prosthetic joint infections using Etest and with a focus on rifampicin and linezolid
    Open this publication in new window or tab >>In vitro antimicrobial synergy testing of coagulase-negative staphylococci isolated from prosthetic joint infections using Etest and with a focus on rifampicin and linezolid
    2010 (English)In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 29, no 5, p. 591-595Article in journal (Refereed) Published
    Abstract [en]

    In recent years, coagulase-negative staphylococci (CoNS) have been increasingly recognised as causative agents of various infections, especially in immunocompromised patients and related to implanted foreign body materials. CoNS, and especially Staphylococcus epidermidis, transform into a stationary growth phase and produce biofilm when involved in a foreign body infection, making them difficult to eradicate with antimicrobials. Rifampicin has the ability to penetrate biofilm, but resistance may develop rapidly. To reduce the emergence of resistance, rifampicin should be combined with additional antimicrobials, of which several different ones have been proposed, including the relatively new class of antimicrobials, oxazolidinones, represented by linezolid. Thirty-seven CoNS isolates from patients with prosthetic joint infection were investigated by synergy testing using Etest. Nine antimicrobial combinations, based on either rifampicin or linezolid, were tested. For 16 (43%) of the isolates, a synergistic (n = 5), additive (n = 14) and/or antagonistic (n = 11) effect were identified. In conclusion, Etest is an objective and easily performed in vitro method for antimicrobial synergy testing. However, each isolate requires testing for the specific combination considered for treatment.

    Place, publisher, year, edition, pages
    Berlin: Springer, 2010
    National Category
    Medical and Health Sciences Infectious Medicine
    Research subject
    Infectious Diseases; Biomedicine
    Identifiers
    urn:nbn:se:oru:diva-15250 (URN)10.1007/s10096-010-0902-6 (DOI)000276659200014 ()20221891 (PubMedID)
    Available from: 2011-04-13 Created: 2011-04-13 Last updated: 2018-03-02Bibliographically approved
    4. Comparison of Staphylococcus epidermidis isolated from prosthetic joint infections commensal isolates in regards to antibiotic susceptibility, agr type, biofilm production, and epidemiology
    Open this publication in new window or tab >>Comparison of Staphylococcus epidermidis isolated from prosthetic joint infections commensal isolates in regards to antibiotic susceptibility, agr type, biofilm production, and epidemiology
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences Infectious Medicine
    Research subject
    Infectious Diseases
    Identifiers
    urn:nbn:se:oru:diva-15251 (URN)
    Available from: 2011-04-13 Created: 2011-04-13 Last updated: 2017-10-17Bibliographically approved
    5. SCCmec and ACME in Staphylococcus epidermidis isolated from prosthetic joint infections
    Open this publication in new window or tab >>SCCmec and ACME in Staphylococcus epidermidis isolated from prosthetic joint infections
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences Infectious Medicine
    Research subject
    Biomedicine
    Identifiers
    urn:nbn:se:oru:diva-15252 (URN)
    Available from: 2011-04-13 Created: 2011-04-13 Last updated: 2017-10-17Bibliographically approved
  • 7.
    Hellmark, Bengt
    et al.
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology.
    Berglund, C.
    Department of Clinical Microbiology and Chemistry, Aleris MEDILAB, Täby, Sweden.
    Nilsdotter-Augustinsson, Å.
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, University of Linköping, Linköping, Sweden.
    Unemo, Magnus
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Region Örebro County, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Region Örebro County, Örebro, Sweden.
    Staphylococcal cassette chromosome mec (SCCmec) and arginine catabolic mobile element (ACME) in Staphylococcus epidermidis isolated from prosthetic joint infections2013In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 32, no 5, p. 691-697Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to characterise the staphylococcal cassette chromosome mec (SCCmec) in Staphylococcus epidermidis isolated from prosthetic joint infections (PJIs) and, if possible, assign them to any of the presently known SCCmec types. In addition, the isolates were examined for the presence of the arginine catabolic mobile element (ACME). Sixty-one S. epidermidis isolates obtained from PJIs and 24 commensal S. epidermidis isolates were analysed. The mecA gene was detected in 49 of the 61 (80 %) PJI isolates and in four of the 24 (17 %) commensal isolates, and the composition of the SCCmec was further analysed. SCCmec types I and IV were the most common types among the PJI isolates. However, for over half (57 %) of the isolates, it was not possible to assign an SCCmec type. ACME was detected in eight (13 %) of the PJI isolates and in 14 (58 %) of the commensal isolates. The characterisation of the SCCmec elements revealed a large heterogeneity, with a high frequency of isolates carrying more than one type of the ccr gene complex. ACME was more common among the commensal isolates and may represent a survival benefit for S. epidermidis colonising healthy individuals in the community.

  • 8.
    Hellmark, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Berglund, Carolina
    Nilsdotter-Augustinsson, Åsa
    Unemo, Magnus
    Söderquist, Bo
    SCCmec and ACME in Staphylococcus epidermidis isolated from prosthetic joint infectionsManuscript (preprint) (Other academic)
  • 9.
    Hellmark, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Söderquist, Bo
    Örebro University, School of Health and Medical Sciences.
    Unemo, Magnus
    Örebro University, School of Health and Medical Sciences.
    Simultaneous species identification and detection of rifampicin resistance in staphylococci by sequencing of the rpoB gene2008In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 28, no 2, p. 183-190Article in journal (Refereed)
    Abstract [en]

    In recent years, coagulase-negative staphylococci (CoNS) have been increasingly recognised as causative agents of various infections, especially in immunocompromised patients and related to implanted foreign body materials. In this study, rpoB sequencing was used for simultaneous species identification and detection of rifampicin resistance in clinical staphylococci isolates. Forty-nine (96%) out of 51 isolates, representing 17 different Staphylococcus species according to the initial phenotypic species identification, were identified to the species level using rpoB sequencing. Furthermore, the two remaining isolates were Kocuria sp. and Corynebacterium sp. respectively, according to 16S rRNA sequencing. Comparison with the phenotypic diagnostics also revealed that 8 (16%) of the 49 isolates differed regarding identified species. Discrepant analysis confirmed the result of the rpoB sequencing for all except 2 of these isolates, which could not be distinguished as single species using 16S rRNA sequencing. Regarding detection of rifampicin resistance, isolates obtained pre- and post-treatment with rifampicin were examined. These isolates comprised S. aureus (7 patients) and S. lugdunensis (1 patient). Rifampicin resistance was mainly detected following short-term treatment with rifampicin in combination with isoxazolyl-penicillin, or long-term treatment with rifampicin and ciprofloxacin. Each rifampicin-resistant isolate displayed an identical rpoB sequence as their corresponding rifampicin-susceptible isolates except for one (n = 6) or two (n = 1) nonsynonymous single nucleotide polymorphisms, or insertion of one codon (n = 1). In conclusion, rpoB sequencing is a rapid, objective and accurate method of species identification and simultaneous detection of rifampicin resistance in staphylococci.

  • 10.
    Hellmark, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Söderquist, Bo
    Unemo, Magnus
    Nilsdotter- Augustinsson, Åsa
    Comparison of Staphylococcus epidermidis isolated from prosthetic joint infections commensal isolates in regards to antibiotic susceptibility, agr type, biofilm production, and epidemiologyManuscript (preprint) (Other academic)
  • 11.
    Hellmark, Bengt
    et al.
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Region Örebro County, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Region Örebro County, Örebro, Sweden.
    Unemo, Magnus
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Region Örebro County, Örebro, Sweden.
    Nilsdotter-Augustinsson, Åsa
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, University of Linköping, Linköping, Sweden.
    Comparison of Staphylococcus epidermidis isolated from prosthetic joint infections and commensal isolates in regard to antibiotic susceptibility, agr type, biofilm production, and epidemiology2013In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 303, no 1, p. 32-39Article in journal (Refereed)
    Abstract [en]

    Staphylococcus epidermidis is the predominant bacterial species in the normal flora of the human skin and superficial mucosal membranes. However, it has also emerged as the most important pathogen in infections related to foreign-body materials, such as prosthetic joints and heart valves. The aims of this study were to characterise S. epidermidis isolated from prosthetic joint infections (PJI; n = 61) and commensal isolates from healthy individuals (n = 24) in regard to antimicrobial sensitivity, agr type, hid gene presence, biofllm production including presence of ica and aap genes involved in the biofilm formation process and epidemiology using both phenotypic (the PhenePlate-system) and genotypic [multilocus sequence typing (MLST)] methods. Among the PJI isolates, the majority (67%) were multidrug-resistant. Two major clusters of PJI isolates could be identified; 44% belonged to MLST sequence type (ST) 2, all but one were of agr type 1, and 31% were assigned ST215 and were of agr type 3. Of the commensal isolates, only one isolate was multidrug-resistant, and they were more molecular epidemiologically diverse with mainly MLST singletons and a maximum of 3 isolates assigned to the identical ST. Biofilm production was detected in 41% of the PJI isolates and 58% of the commensal isolates, with the aap gene (95%) more frequently detected than the ica genes (62%) in the biofilm-positive isolates. In conclusion, S. epidermidis isolated from PJIs and commensal isolates differed regarding antimicrobial sensitivity and molecular epidemiological typing using MLST, but not substantially in the distribution of agr types, biofilm production, or the presence of ica and aap genes.

  • 12.
    Hellmark, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Unemo, Magnus
    Nilsdotter-Augustinsson, Å.
    Söderquist, Bo
    Örebro University, School of Health and Medical Sciences.
    Antibiotic susceptibility among Staphylococcus epidermidis isolated from prosthetic joint infections with special focus on rifampicin and variability of the rpoB gene2009In: Clinical Microbiology and Infection, ISSN 1198-743X, E-ISSN 1469-0691, Vol. 15, no 3, p. 238-244Article in journal (Refereed)
    Abstract [en]

    Staphylococcus epidermidis is the most important pathogen in infections related to implanted foreign materials, especially prosthetic joint infections (PJIs). The aim of this study was to investigate the antimicrobial activities of 16 antibiotics against S. epidermidis isolated from PJIs, with special focus on rifampicin and rpoB variability. Ninety-one per cent of the isolates were multiresistant (i.e. resistant to members of more than three classes of antibiotics). Thirty-nine per cent were resistant to rifampicin, associated with one or two single-nucleotide polymorphisms (SNPs) in rpoB. Using IsoSensitest agar with supplements, 61% were resistant to oxacillin, and using Mueller-Hinton II agar with supplement, 84% were resistant. Using the Etest, 58% were resistant to cefoxitin, and using the disk diffusion test, 91% were resistant. The mecA gene was detected in 85% of the isolates. Regarding recently available antibiotics, all isolates were susceptible to tigecycline and linezolid, and 97% were susceptible to daptomycin. In addition, two novel antibiotics, dalbavancin and ceftobiprole, were tested, although not yet available for routine use. The MIC(50) and MIC(90) values of these novel antibiotics were 0.032 and 0.047 mg/L and 0.5 and 1.5 mg/L, respectively. Among the other antibiotics, the rates of resistance varied between 0% (vancomycin) and 82% (trimethoprim-sulphamethoxazole). S. epidermidis strains causing PJIs often show multiresistance, including resistance to rifampicin, which is mainly caused by one or two SNPs. Some of the newer antimicrobial agents may provide alternatives for monotherapy or combination therapy with rifampicin. Detection of mecA is necessary before initiating treatment of infections due to S. epidermidis when it displays intermediate susceptibility to cefoxitin.

  • 13.
    Hellmark, Bengt
    et al.
    Örebro University, School of Health and Medical Sciences.
    Unemo, Magnus
    Nilsdotter-Augustinsson, Åsa
    Söderquist, Bo
    In vitro antimicrobial synergy testing of coagulase-negative staphylococci isolated from prosthetic joint infections using Etest and with a focus on rifampicin and linezolid2010In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 29, no 5, p. 591-595Article in journal (Refereed)
    Abstract [en]

    In recent years, coagulase-negative staphylococci (CoNS) have been increasingly recognised as causative agents of various infections, especially in immunocompromised patients and related to implanted foreign body materials. CoNS, and especially Staphylococcus epidermidis, transform into a stationary growth phase and produce biofilm when involved in a foreign body infection, making them difficult to eradicate with antimicrobials. Rifampicin has the ability to penetrate biofilm, but resistance may develop rapidly. To reduce the emergence of resistance, rifampicin should be combined with additional antimicrobials, of which several different ones have been proposed, including the relatively new class of antimicrobials, oxazolidinones, represented by linezolid. Thirty-seven CoNS isolates from patients with prosthetic joint infection were investigated by synergy testing using Etest. Nine antimicrobial combinations, based on either rifampicin or linezolid, were tested. For 16 (43%) of the isolates, a synergistic (n = 5), additive (n = 14) and/or antagonistic (n = 11) effect were identified. In conclusion, Etest is an objective and easily performed in vitro method for antimicrobial synergy testing. However, each isolate requires testing for the specific combination considered for treatment.

  • 14.
    Khan, Faisal Ahmad
    et al.
    Örebro University, School of Science and Technology.
    Hellmark, Bengt
    Örebro University, School of Health Sciences. Örebro University Hospital.
    Ehricht, Ralf
    Abbott (Alere Technologies GmbH), Jena, Germany; InfectoGnostics Research Campus, Jena, Germany; Research Alliance - Leibniz Health Technologies, Leibniz Institute of Photonic Technology, Jena, Germany.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Jass, Jana
    Örebro University, School of Science and Technology.
    Related carbapenemase-producing Klebsiella isolates detected in both a hospital and associated aquatic environment in Sweden2018In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 37, no 12, p. 2241-2251Article in journal (Refereed)
    Abstract [en]

    Carbapenem antibiotics are one of the last-resort agents against multidrug-resistant (MDR) bacteria. The occurrence of carbapenemase-producing Enterobacteriaceae (CPE) in wastewater and aquatic environments is an indication of MDR bacteria in the community. This study evaluated CPE in aquatic environments and compared them to the local hospital isolates in Sweden. Phenotypic and genotypic analyses of antibiotic resistance of environmental and clinical CPE were performed. The relatedness of the isolates and possible clonal dissemination was evaluated using phylogenetic and phyloproteomic analysis. Klebsiella oxytoca carrying carbapenemase genes (blaVIM-1, blaIMP-29) were isolated from wastewater and the recipient river, while K. oxytoca (blaVIM-1) and Klebsiella pneumoniae (blaVIM-1, blaOXA-48, blaNDM-1, blaKPC-3) were isolated from patients at the local clinics or hospital. The K. oxytoca classified as sequence type 172 (ST172) isolated from the river was genotypically related to two clinical isolates recovered from patients. The similarity between environmental and clinical isolates suggests the dispersion of blaVIM-1 producing K. oxytoca ST172 from hospital to aquatic environment and the likelihood of its presence in the community. This is the first report of CPE in aquatic environments in Sweden; therefore, surveillance of aquatic and hospital environments for CPE in other urban areas is important to determine the major transfer routes in order to formulate strategies to prevent the spread of MDR bacteria.

  • 15.
    Khassebaf, Jasmine
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Davidsson, Sabina
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital. Department of Urology, Örebro University Hospital, Örebro, Sweden.
    Unemo, Magnus
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Nilsdotter-Augustinsson, Åsa
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Infectious Diseases, County Council of Östergötland, Linköping, Sweden.
    Söderquist, Bo
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Örebro University Hospital.
    Antibiotic susceptibility of Propionibacterium acnes isolated from orthopaedic implant-associated infections2015In: Anaerobe, ISSN 1075-9964, E-ISSN 1095-8274, Vol. 32, p. 57-62Article in journal (Refereed)
    Abstract [en]

    Introduction: Prosthetic joint infections (PJIs) caused by Propionibacterium acnes account for a larger proportion of the total number of PJIs than previously assumed and thus knowledge of the antimicrobial susceptibility patterns of P. acnes is of great value in everyday clinical practice.

    Materials and methods: Using Etest, the present study investigated the susceptibility of 55 clinical isolates of P. acnes, obtained from orthopaedic implant-associated infections of the knee joint (n = 5), hip joint (n = 17), and shoulder joint (n = 33), to eight antimicrobial agents: benzylpenicillin, clindamycin, metronidazole, fusidic acid, doxycycline, moxifloxacin, linezolid and rifampicin. Synergy testing was also conducted, in which rifampicin was combined with each of the remaining seven antibiotics.

    Results: All isolates (n = 55) were susceptible to most of the antibiotics tested, with the exception of 100% resistance to metronidazole, five (9.1%) isolates displaying decreased susceptibility to clindamycin, and one (1.8%) to moxifloxacin. None of the antimicrobial agents investigated were synergistic with each other when combined and nine isolates were antagonistic for various antimicrobial combinations. The majority of the antimicrobial combinations had an indifferent effect on the isolates of P. acnes. However, the combination of rifampicin and benzylpenicillin showed an additive effect on nearly half of the isolates.

    Conclusion: Almost all P. acnes, isolated from orthopaedic implant-associated infections, predominantly PJIs, were susceptible to the antibiotics tested, with the exception of complete resistance to metronidazole. Synergy test could not demonstrate any synergistic effect but additive effects were found when combining various antibiotics. Antagonistic effects were rare.

  • 16.
    Littorin, C.
    et al.
    School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden .
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Nilsdotter-Augustinsson, Åsa
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Infectious Diseases, County Council of Östergötland, Linköping, Sweden .
    Söderquist, Bo
    Örebro University, School of Medical Sciences. Departments of Infectious Diseases and Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    In vitro activity of tedizolid and linezolid against Staphylococcus epidermidis isolated from prosthetic joint infections2017In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 36, no 9, p. 1549-1552Article in journal (Refereed)
    Abstract [en]

    Prosthetic joint infections (PJIs) are rare but long-lasting and are serious complications without any spontaneous resolution, requiring additional surgery and long-term treatment with antibiotics. Staphylococci are the most important aetiological agents of PJIs, and among the coagulase-negative staphylococci Staphylococcus epidermidis is the most common. However, S. epidermidis often displays multidrug resistance (MDR), demanding additional treatment options. The objective was to examine the effectiveness of tedizolid and linezolid against S. epidermidis isolated from PJIs. The standard antibiotic susceptibility pattern of S. epidermidis (n = 183) obtained from PJIs was determined by disc diffusion test, and MIC was determined by Etest for tedizolid, linezolid, and vancomycin. Tedizolid displayed MIC values ranging from 0.094 to 0.5 mg/L (MIC50: 0.19 mg/L, MIC90: 0.38 mg/L), linezolid MIC values ranging from 0.25 to 2 mg/L (MIC50: 0.75 mg/L, MIC90: 1 mg/L), and vancomycin MIC values ranging from 0.5 to 3 mg/L (MIC50 and MIC90 both 2 mg/L). According to the disc diffusion test, 153/183 (84%) isolates were resistant to ≥3 antibiotic groups, indicating MDR. In conclusion, S. epidermidis isolates from PJIs were fully susceptible, and the MIC50 and MIC90 values for tedizolid were two- to four-fold dilution steps lower compared with linezolid. Tedizolid is not approved, and there are no reports of long-term treatment, but it may display better tolerability and fewer adverse effects than linezolid; it thus could be a possible treatment option for PJIs, alone or in combination with rifampicin.

  • 17.
    Magnusson, Charlotta
    et al.
    School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Stegger, Marc
    Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark.
    Hellmark, Bengt
    Örebro University, School of Health Sciences.
    Stenmark, Bianca
    Örebro University, School of Medical Sciences. Örebro University Hospital.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Staphylococcus aureus isolates from nares of orthopaedic patients in Sweden are mupirocin susceptible2019In: Infectious Diseases, ISSN 2374-4235, E-ISSN 2374-4243, Vol. 51, no 6, p. 475-478Article in journal (Refereed)
  • 18.
    Månsson, Emeli
    et al.
    Örebro University, School of Medical Sciences. Centre for Clinical Research, Hospital of Västmanland Västerås, Västerås, Sweden.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine.
    Stegger, Marc
    Statens Serum Institut, Copenhagen, Denmark.
    Andersen, Paal Skytt
    Statens Serum Institut, Copenhagen, Denmark.
    Sundqvist, Martin
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Genomic relatedness of Staphylococcus pettenkoferi isolates of different origins2017In: Journal of Medical Microbiology, ISSN 0022-2615, E-ISSN 1473-5644, Vol. 66, no 5, p. 601-608Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of the study was to characterize clinical and environmental Staphylococcus pettenkoferi isolates with regard to genomic diversity and antibiotic susceptibility pattern. Repetitive-sequence-based PCR and core genome phylogenetic analysis of whole-genome sequencing (WGS) data verified the presence of distinct clades comprising closely related S. pettenkoferi isolates from different geographical locations and origins.

    Methodology: Phylogenetic relationships between 25 S. pettenkoferi isolates collected from blood cultures and intra-operative air sampling were determined by repetitive-sequence-based PCR typing and analysis of similar to 157 000 SNPs identified in the core genome after WGS. Antibiotic susceptibility testing and tests for biofilm production (microtitre plate assay) were performed.

    Results: Repetitive-sequence-based PCR as well as WGS data demonstrated the close relatedness of clinically significant blood culture isolates to probable contaminants, as well as to environmental isolates. Antibiotic-susceptibility testing demonstrated a low level of antimicrobial resistance. The mecA gene was present in two cefoxitin-resistant isolates. No isolates were found to produce biofilm.

    Conclusion: Close genomic relatedness of S. pettenkoferi isolates from different geographical locations and origins were found within clades, but with substantial genomic difference between the two major clades. The ecological niche of S. pettenkoferi remains unconfirmed, but the presence of S. pettenkoferi in the air of the operating field favours the suggestion of a role in skin flora. Identification of S. pettenkoferi in clinical samples should, in a majority of cases, most likely be regarded as a probable contamination, and its role as a possible pathogen in immunocompromised hosts remains to be clarified.

  • 19.
    Månsson, Emeli
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Centre for Clinical Research, Uppsala University, Uppsala, Sweden; County Hospital, Västerås, Sweden.
    Hellmark, Bengt
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Sundqvist, Martin
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden.
    Sequence types of Staphylococcus epidermidis associated with prosthetic joint infections are not present in the laminar airflow during prosthetic joint surgery2015In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 123, no 7, p. 589-595Article in journal (Refereed)
    Abstract [en]

    Molecular characterization of Staphylococcus epidermidis isolates from prosthetic joint infections (PJIs) has demonstrated a predominance of healthcare-associated multi-drug resistant sequence types (ST2 and ST215). How, and when, patients acquire these nosocomial STs is not known. The aim was to investigate if sequence types of S. epidermidis associated with PJIs are found in the air during prosthetic joint surgery. Air sampling was undertaken during 17 hip/knee arthroplasties performed in operating theaters equipped with mobile laminar airflow units in a 500-bed hospital in central Sweden. Species identification was performed using MALDI-TOF MS and 16S rRNA gene analysis. Isolates identified as S. epidermidis were further characterized by MLST and antibiotic susceptibility testing. Seven hundred and thirty-five isolates were available for species identification. Micrococcus spp. (n = 303) and coagulase-negative staphylococci (n = 217) constituted the majority of the isolates. Thirty-two isolates of S. epidermidis were found. S. epidermidis isolates demonstrated a high level of allelic diversity with 18 different sequence types, but neither ST2 nor ST215 was found. Commensals with low pathogenic potential dominated among the airborne microorganisms in the operating field during prosthetic joint surgery. Nosocomial sequence types of S. epidermidis associated with PJIs were not found, and other routes of inoculation are therefore of interest in future studies.

  • 20.
    Prag, Gustaf
    et al.
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Falk-Brynhildsen, Karin
    Department of Cardiothoracic and Vascular Surgery, Örebro University Hospital, Örebro, Sweden.
    Jacobsson, Susanne
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Unemo, Magnus
    Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden. Örebro University Hospital. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden; Department of Infectious Diseases, Örebro University Hospital, Örebro, Sweden.
    Decreased susceptibility to chlorhexidine and prevalence of disinfectant resistance genes among clinical isolates of Staphylococcus epidermidis2014In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 122, no 10, p. 961-967Article in journal (Refereed)
    Abstract [en]

    Staphylococcus epidermidis, despite regarded as a commensal, is recognized as a nosocomial pathogen usually by acting as an opportunist, especially in infections associated with implanted foreign body materials. Pre-operative antiseptic preparation is an important strategy for reducing the risk of complications such as surgical site infection (SSI). The currently most widely used antiseptic compounds are alcohols and quaternary ammonium compounds (QACs), predominantly chlorhexidine.

    The aim of this study was to investigate if decreased susceptibility to chlorhexidine among S. epidermidis was present in our setting. S. epidermidis (n=143) were obtained from prosthetic joint infections (PJI) (n=61), commensals (n=24), post-operative infections after cardiothoracic surgery (n=31), and the skin of the chest after routine disinfection prior cardiothoracic surgery (n=27). Determination of MIC of chlorhexidine was performed on Müeller Hinton agar plates supplemented with serial dilutions of chlorhexidine. Five QAC resistance genes; qacA/B, smr, qacH, qacJ, and qacG, were detected using PCR.

    Decreased susceptibility to chlorhexidine was found in 54% of PJI isolates, 68% of cardiothoracic isolates, 21% of commensals, and 7% of isolates obtained from the skin of cardiothoracic patients, respectively.

    The qacA/B gene was present in 62/143 isolates (43%), smr in 8/143 (6%) and qacH in one isolate (0.7%). The qacA/B gene was found in 52% of PJI isolates, 61% of cardiothoracic isolates, 25% of commensals, and 19% of isolates obtained from the skin of cardiothoracic patients. In conclusion, decreased susceptibility to chlorhexidine as well as QAC resistance genes was highly prevalent among S. epidermidis causing deep SSIs.

  • 21.
    Salih, Lavin
    et al.
    School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Tevell, Staffan
    Örebro University, School of Medical Sciences. Department of Infectious Diseases, Karlstad Hospital, Karlstad, Sweden.
    Månsson, Emeli
    Örebro University, School of Medical Sciences. Centre for Clinical Research, Hospital of Västmanland, Region Västmanland, Västerås, Sweden; Centre for Clinical Research, Hospital of Västmanland, Uppsala University, Västerås, Sweden.
    Nilsdotter-Augustinsson, Åsa
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Infectious Diseases, County Council of Östergötland, Linköping, Sweden.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Staphylococcus epidermidis isolates from nares and prosthetic joint infections are mupirocin susceptible2018In: Journal of bone and joint infection, ISSN 2206-3552, Vol. 3, no 1, p. 1-4Article in journal (Refereed)
    Abstract [en]

    The objective of the present study was to investigate the antibiotic susceptibility including mupirocin among Staphylococcus. epidermidis isolated from prosthetic joint infections (PJIs) (n=183) and nasal isolates (n=75) from patients intended to undergo prosthetic joint replacements. Susceptibility to mupirocin (used for eradication of nasal carriership of Staphylococcus aureus) was investigated by gradient test, and susceptibility to various other antimicrobial agents was investigated by disc diffusion test. All isolates, except three from PJIs and one from the nares, were fully susceptible to mupirocin. Multi-drug resistance (≥3 antibiotic classes) was found in 154/183 (84.2%) of the PJI isolates but only in 2/75 (2.7%) of the nares isolates, indicating that S. epidermidis causing PJIs do not originate from the nares.

  • 22.
    Stenmark, Bianca
    et al.
    Department of Laboratory Medicine, Faculty of Medicine and Health, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Health Sciences.
    Söderquist, Bo
    Örebro University, School of Medical Sciences. Department of Laboratory Medicine, Faculty of Medicine and Health, Örebro University Hospital, Örebro, Sweden.
    Genomic analysis of Staphylococcus capitis isolated from blood cultures in neonates at a neonatal intensive care unit in Sweden2019In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 38, no 11, p. 2069-2075Article in journal (Refereed)
    Abstract [en]

    Emergence of a genetically distinct, multidrug-resistant Staphylococcus capitis clone (NRCS-A) present in neonatal intensive care units has recently been extensively reported. The aims of the present study were to investigate which clones of S. capitis isolated from blood in a Swedish neonatal intensive care unit (NICU) have been present since 1987 and to investigate whether the NRCS-A clone has disseminated in Sweden. All S. capitis isolates from blood cultures of neonates (≤ 28 days of age) between 1987 and 2017 (n = 46) were whole-genome sequenced, and core genome multilocus sequence typing (cgMLST) was performed. Single-nucleotide polymorphism (SNP)-based phylogenetic relationships between the S. capitis isolates and in silico predictions of presence of genetic traits specific to the NRCS-A clone were identified. Furthermore, antibiotic susceptibility testing, including screening for heterogeneous glycopeptide-intermediate resistance, was performed. Thirty-five isolates clustered closely to the isolates previously determined as belonging to the NRCS-A clone and had fewer than 81 core genome loci differences out of 1063. Twenty-one of these isolates were multidrug resistant. The NRCS-A clone was found in 2001. Six pairs of isolates had differences of fewer than two SNPs. Genetic traits associated with the NRCS-A clone such as nsr, ebh, tarJ, and CRISPR were found in all 35 isolates. The increasing incidence of S. capitis blood cultures of neonates is predominantly represented by the NRSC-A clone at our NICU in Sweden. Furthermore, there were indications of transmission between cases; adherence to basic hygiene procedures and surveillance measures are thus warranted.

  • 23.
    Stenmark, Bianca
    et al.
    Örebro University, School of Medical Sciences. Örebro University Hospital.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Increase of S. capitis in neonates with bacteremia in Sweden due to the emergence of a multidrug-resistant clone2018Conference paper (Refereed)
    Abstract [en]

    Background: Staphylococcus capitis has traditionally been considered a commensal due to its low pathogenicity in healthy adults; however, it has been shown to cause 20% of all cases of neonatal sepsis in neonatal intensive care units (NICUs). In addition, S. capitis strains with reduced susceptibility to last line anti-staphylococcal agents such as vancomycin and linezolid are emerging in NICUs. The aim of this study was to characterize S. capitis isolated from blood in a Swedish NICU and to investigate if the multidrug-resistant clone NRCS-A has disseminated in Sweden.

    Materials/methods: All S. capitis isolates from neonatal blood cultures collected at Örebro University Hospital during 1987 to the 1st of March 2017 (n=42), were included. Several more episodes of neonatal sepsis with growth of coagulase-negative staphylococci were registered during this time period but probably considered as contaminants and therefore not preserved. Antibiotic susceptibility testing was performed using standardized disc diffusion method on cefoxitin, fusidic acid, clindamycin, erythromycin, gentamicin, rifampicin, trimethroprim/sulfamethoxazole and norfloxacin. Isolates resistant to ≥3 antibiotics were defined as multidrug-resistant. The isolates were whole genome sequenced using the Nextera XT kit (Illumina) on a MiSeq (Illumina). Single nucleotide polymorphisms found with the online tool REALPHY 1.12 in the alignments of shared homologous sites with the reference (the S. capitis NRCS-A strain CR01) were used to create phylogenetic trees.

    Results: Seventeen isolates out of the 42 isolates (40%) were multidrug-resistant (resistant to fusidic acid, cefoxitin and gentamicin) and 33 out of the 42 isolates (79%) clustered with the multi-resistant NRCS-A clone (Figure 1). The earliest isolate within the NRCS-A cluster was from 2001.

    Conclusions: Although prevalent since 2001, the increase of S. capitis in neonates with bacteremia since 2010 in Örebro county is mainly due to the dissemination of the multidrug-resistant NRCS-A clone and therefore warrants increased surveillance of the epidemiology and etiology of neonatal sepsis to prevent the spread of this clone.

  • 24.
    Svensson, Karolina
    et al.
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences.
    Söderquist, Bo
    Örebro University, School of Health and Medical Sciences. Department of Infectious Diseases, Örebro University Hospital, Örebro, Sweden.
    Characterization of SCCmec elements in methicillin-resistant Staphylococcus epidermidis isolated from blood cultures from neonates during three decades2011In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 119, no 12, p. 885-893Article in journal (Refereed)
    Abstract [en]

    Staphylococcus epidermidis is a major cause of nosocomial infections in immunocompromised patients and the predominant pathogen in catheter-related infections and bloodstream infections. Approximately 70-80% of S. epidermidis carry the mecA gene encoding methicillin resistance. The mecA gene is located on a mobile genetic element, the staphylococcal cassette chromosome mec (SCCmec). The aim of this study was to characterize the SCCmec elements as well as the adjacent arginine catabolic mobile element (ACME) in 30 clinical blood isolates of mecA positive S. epidermidis obtained from neonates and collected over a period of three decades. The ccr and mec gene complexes were identified using PCR. The SCCmec elements were found among 29/30 isolates and 13 different combinations of ccr gene complexes and mec gene complexes were identified. Staphylococcus epidermidis regularly carried multiple copies of ccr gene complexes, but only one class of mec gene complex. Three isolates could be assigned the SCCmec type III (3A). The combinations of ccr gene complexes and the mec gene complexes differed among the three decades. The most frequent combination was class B mec in combination with ccr1 and ccr2. Staphylococcus epidermidis may constitute a large reservoir for SCCmec elements, and frequent exchange of mobile genetic elements between staphylococcal species may explain the emergence of new MRSA strains.

  • 25.
    Söderquist, Bo
    et al.
    Örebro University, School of Medical Sciences.
    Björklund, Sanna
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Hellmark, Bengt
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Laboratory Medicine, Örebro University Hospital, Örebro, Sweden.
    Jensen, Anders
    Department of Biomedicine, Aarhus University, Aarhus, Denmark.
    Brüggemann, Holger
    Department of Biomedicine, Aarhus University, Aarhus, Denmark.
    Finegoldia magna Isolated from Orthopedic Joint Implant-Associated Infections2017In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 55, no 11, p. 3283-3291Article in journal (Refereed)
    Abstract [en]

    The anaerobic Gram-positive coccus Finegoldia magna is a rare cause of infections of bone and joints. The aim of this study was to describe the microbiological and clinical characteristics of orthopedic implant-associated infections caused by F. magna We retrospectively analyzed samples consisting of anaerobic Gram-positive cocci and samples already identified as F. magna from patients with orthopedic infections. The isolates found were determined to the species level using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The antibiotic susceptibility pattern was determined by Etest. Whole-genome sequencing (WGS) was performed. Clinical data were extracted from each patient's journal. In nine patients, orthopedic joint implant-associated infections were identified as being caused by F. magna The isolates were susceptible to most of the antibiotics tested, with the exception of rifampin and moxifloxacin in a few cases. Five of the nine infections were monomicrobial. The most common antibiotic used to treat the infection was penicillin V, but five of the nine patients received a combination of antibiotics. Eight patients underwent surgical treatment, with extraction of the implant performed in seven cases and reimplantation in only two cases. The WGS showed a relatively small core genome, with 126,647 single nucleotide polymorphisms identified within the core genome. A phylogenomic analysis revealed that the isolates clustered into two distinct clades. Orthopedic implant-associated infections caused by F. magna are rare, but the bacteria are generally susceptible to antibiotics. Despite this, surgical treatment combined with long-term antibiotics is often necessary. The WGS analysis revealed a high heterogeneity and suggested the existence of at least two different Finegoldia species.

  • 26.
    Tevell, Staffan
    et al.
    Örebro University, School of Medical Sciences. Department of Infectious Diseases, Karlstad Hospital and Centre for Clinical Research, Värmland County Council, Karlstad, Sweden.
    Baig, Sharmin
    Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark.
    Hellmark, Bengt
    Örebro University, School of Health Sciences. Department of Laboratory Medicine.
    Martins-Simoes, Patricia
    Institute for Infectious Agents, Department of Bacteriology, National Reference Center for Staphylococci, Hospices Civils de Lyon, Lyon, France; Centre International de Référence en Infectiologie INSERM U1111 CNRS UMR 5308 ENS University of Lyon, Lyon, France.
    Wirth, Thierry
    Institut de Systématique, Evolution, Biodiversité (ISYEB), UNR-CNRS 7205, Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Paris, France; cole Pratique des Hautes Études, PSL Université, Paris, France.
    Butin, Marine
    Centre International de Référence en Infectiologie INSERM U1111 CNRS UMR 5308 ENS University of Lyon, Lyon, France; Neonatal Intensive Care Unit, Hôpital Femme Mère Enfant, Hospices Civils de Lyon, Lyon, France.
    Nilsdotter-Augustinsson, Åsa
    Department of Infectious Diseases and Department of Clinical and Experimental Medicine, Linköping University, Norrköping, Sweden.
    Söderquist, Bo
    Örebro University, School of Medical Sciences. Department of Laboratory Medicine.
    Stegger, Marc
    Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark.
    Presence of the neonatal Staphylococcus capitis outbreak clone (NRCS-A) in prosthetic joint infectionsManuscript (preprint) (Other academic)
  • 27.
    Tevell, Staffan
    et al.
    Örebro University, School of Health and Medical Sciences, Örebro University, Sweden. Department of Infectious Diseases, Karlstad Hospital, Karlstad, Sweden.
    Claesson, C.
    Division of Clinical Microbiology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Clinical Microbiology, County Council of Östergötland, Linköping, Sweden.
    Hellmark, Bengt
    Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden.
    Söderquist, Bo
    Örebro University, School of Medicine, Örebro University, Sweden. Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, Sweden; Department of Infectious Diseases, Örebro University Hospital, Örebro, Sweden.
    Nilsdotter-Augustinsson, Å.
    Division of Infectious Diseases, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden; Department of Infectious Diseases, County Council of Östergötland, Linköping, Sweden.
    Heterogeneous glycopeptide intermediate Staphylococcus epidermidis isolated from prosthetic joint infections2014In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 33, no 6, p. 911-917Article in journal (Refereed)
    Abstract [en]

    Methicillin-resistant Staphylococcus epidermidis (MRSE) poses a major problem in prosthetic joint infections (PJIs). Vancomycin is often considered the drug of choice in the empirical treatment of staphylococcal PJIs. As recent decades have seen reports of heterogeneous glycopeptide intermediate S. aureus (hGISA), our aim was to examine the prevalence of heterogeneous glycopeptide intermediate S. epidermidis (hGISE) in PJIs. S. epidermidis isolates (n = 122) from 119 patients in three Swedish counties between 1993 and 2012 were included. All were isolated from perioperative tissue samples from revision surgery in clinically verified PJIs. Antimicrobial susceptibility testing against staphylococcal antibiotics was performed. The macromethod Etest (MME) and glycopeptide resistance detection (GRD) Etest were used to detect hGISE. Standard minimal inhibitory concentration (MIC) determination revealed no vancomycin-resistant isolates, while teicoplanin resistance was detected in 14 out of 122 isolates (11.5 %). hGISE was found in 95 out of 122 isolates (77.9 %), 64 out of 67 of isolates with teicoplanin MIC > 2 mg/L (95.5 %) and 31 out of 55 of isolates with teicoplanin MIC a parts per thousand currency sign2 mg/L (56.4 %). Thus, the presence of hGISE cannot be ruled out by teicoplanin MIC a parts per thousand currency sign2 mg/L alone. Multidrug resistance was detected in 86 out of 95 hGISE isolates (90.5 %) and in 16 out of 27 isolates (59.3 %), where hGISE could not be detected. In conclusion, hGISE detected by MME or GRD was common in this material. However, hGISE is difficult to detect with standard laboratory diagnostic routines. Glycopeptide treatment may not be sufficient in many of these PJIs, even if standard MIC classifies the isolated S. epidermidis as susceptible.

  • 28.
    Tevell, Staffan
    et al.
    Örebro University, School of Medical Sciences. Department of Infectious Diseases, Karlstad Hospital, Karlstad, Sweden.
    Hellmark, Bengt
    Örebro University, School of Health Sciences. Department of Laboratory Medicine.
    Nilsdotter-Augustinsson, Å.
    Department of Infectious Diseases, Linköping University, Linköping, Sweden; Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
    Söderquist, Bo
    Örebro University, School of Medical Sciences.
    Staphylococcus capitis isolated from prosthetic joint infections2017In: European Journal of Clinical Microbiology and Infectious Diseases, ISSN 0934-9723, E-ISSN 1435-4373, Vol. 36, no 1, p. 115-122Article in journal (Refereed)
    Abstract [en]

    Further knowledge about the clinical and microbiological characteristics of prosthetic joint infections (PJIs) caused by different coagulase-negative staphylococci (CoNS) may facilitate interpretation of microbiological findings and improve treatment algorithms. Staphylococcus capitis is a CoNS with documented potential for both human disease and nosocomial spread. As data on orthopaedic infections are scarce, our aim was to describe the clinical and microbiological characteristics of PJIs caused by S. capitis. This retrospective cohort study included three centres and 21 patients with significant growth of S. capitis during revision surgery for PJI between 2005 and 2014. Clinical data were extracted and further microbiological characterisation of the S. capitis isolates was performed. Multidrug-resistant (≥3 antibiotic groups) S. capitis was detected in 28.6 % of isolates, methicillin resistance in 38.1 % and fluoroquinolone resistance in 14.3 %; no isolates were rifampin-resistant. Heterogeneous glycopeptide-intermediate resistance was detected in 38.1 %. Biofilm-forming ability was common. All episodes were either early post-interventional or chronic, and there were no haematogenous infections. Ten patients experienced monomicrobial infections. Among patients available for evaluation, 86 % of chronic infections and 70 % of early post-interventional infections achieved clinical cure; 90 % of monomicrobial infections remained infection-free. Genetic fingerprinting with repetitive sequence-based polymerase chain reaction (rep-PCR; DiversiLab®) displayed clustering of isolates, suggesting that nosocomial spread might be present. Staphylococcus capitis has the potential to cause PJIs, with infection most likely being contracted during surgery or in the early postoperative period. As S. capitis might be an emerging nosocomial pathogen, surveillance of the prevalence of PJIs caused by S. capitis could be recommended.

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