Molecular epidemiology of coagulase-negative staphylococci in hospitals and in the community
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Coagulase-negative staphylococci (CoNS) and in particular Staphylococcus epidermidis have emerged as major pathogens primarily causing nosocomial infections in patients with indwelling medical devices. These infections are often caused by multidrug-resistant strains of S. epidermidis (MDRSE). Other clinical entities due to CoNS are lower urinary tract infections (UTI) in women and native valve endocarditis. The purpose of this work was to investigate the frequency of antibiotic resistance and the molecular epidemiology of both hospital and community-associated isolates of S. epidermidis in order to examine if certain clones are related to MDRSE infections. Furthermore, we aimed to explore if specific clones of S. saprophyticus are associated with UTI in women.
A total of 359 hospital-associated methicillin-resistant isolates of CoNS obtained from 11 hospitals in northern Europe and 223 community-associated staphylococcal isolates were examined. Furthermore, 126 isolates of S. saprophyticus isolated from women with uncomplicated UTI from five different locations in northern Europe were analyzed. Pulsed-field gel electrophoresis (PFGE) was used for genotyping. Additionally, some of the S. epidermidis isolates were analyzed with multilocus sequence typing (MLST). Antibiotic susceptibility was determined for all isolates by the disc diffusion test.
293 of the 359 (82%) hospital-associated and 124 of the 223 (56%) community-associated isolates belonged to the species S. epidermidis. Among the hospital-associated S. epidermidis isolates, two dominating PFGE types (type A and B) were distinguished, comprising 78 (27%) and 51 (17%) isolates, respectively. Type A, which was detected in a Norwegian and eight Swedish hospitals, corresponded with a novel sequence type (ST215). Type B was discovered in a German, a Danish and seven Swedish hospitals and corresponded with ST2. In contrast, community-associated isolates of S. epidermidis were genetically extremely diverse with no predominating genotype, and showed a low rate of antibiotic resistance; only two (1.6%) methicillin-resistant strains were detected.
Among 126 analyzed isolates of S. saprophyticus, 47 different PFGE profiles were identified. Several clusters of genetically highly related isolates were detected among isolates obtained from different locations and periods of time.
We have demonstrated the occurrence, persistence and potential dissemination of two multidrug-resistant S. epidermidis (MDRSE) genotypes, including a novel sequence type (ST215), within hospitals in northern Europe. Community-associated isolates of S. epidermidis showed a low rate of methicillin-resistance and were genetically heterogeneous. These results indicate that MDRSE by large are confined to the hospital setting in our region. Moreover, although the S. saprophyticus population was quite heterogeneous, indistinguishable isolates of S. saprophyticus causing lower UTI in women were identified in different countries 11 years apart, indicating the persistence and geographical spread of some clones of S. saprophyticus.
Place, publisher, year, edition, pages
Umeå: Umeå university , 2010. , 74 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1354
staphylococcus epidermidis, staphylococcus saprophyticus, electrophoresis, gel, pulsed-field, genetic diversity, methicillin-resistance, UTI, drug resistance, multiple, bacterial, epidemiology, molecular, cross infection, molecular sequence data
National CategoryMicrobiology in the medical area Microbiology in the medical area Infectious Medicine
Research subject Clinical Bacteriology; Microbiology; Infectious Diseases
IdentifiersURN: urn:nbn:se:umu:diva-34289ISBN: 978-91-7459-020-3OAI: oai:DiVA.org:umu-34289DiVA: diva2:320366
2010-09-03, Byggnad 6L, Major Groove,, Mikrobiologi, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Söderquist, Bo, Docent/Lektor
Wiström, Johan, DocentMonsen, Tor, DocentSjöstedt, Anders, Professor
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