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Molecular epidemiology of coagulase-negative staphylococci in hospitals and in the community
Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background

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.

Methods

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.

Results

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.

Conclusion

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.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1354
Keyword [en]
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 Category
Microbiology in the medical area Microbiology in the medical area Infectious Medicine
Research subject
Clinical Bacteriology; Microbiology; Infectious Diseases
Identifiers
URN: urn:nbn:se:umu:diva-34289ISBN: 978-91-7459-020-3 (print)OAI: oai:DiVA.org:umu-34289DiVA: diva2:320366
Public defence
2010-09-03, Byggnad 6L, Major Groove,, Mikrobiologi, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2010-05-28 Created: 2010-05-25 Last updated: 2012-07-09Bibliographically approved
List of papers
1. Molecular epidemiology of meticillin-resistant coagulase-negative staphylococci in a Swedish county hospital: evidence of intra- and interhospital clonal spread
Open this publication in new window or tab >>Molecular epidemiology of meticillin-resistant coagulase-negative staphylococci in a Swedish county hospital: evidence of intra- and interhospital clonal spread
2006 (English)In: Journal of Hospital Infection, ISSN 0195-6701, E-ISSN 1532-2939, Vol. 64, no 2, 177-183 p.Article in journal (Refereed) Published
Abstract [en]

During a 10-month period in 2003, consecutive routine clinical cultures from patients treated in 15 different ward units in a Swedish county hospital were screened for the presence of meticillin-resistant coagulase-negative staphylococci (CNS). Genetic similarity between isolates was analysed using pulsed-field gel electrophoresis (PFGE). The results were compared with multi-drug-resistant Staphylococcus epidermidis isolated previously at the tertiary referral hospital. In total, 428 isolates of CNS were identified, of which 188 (44%) were meticillin resistant. Three clusters (Groups A, B and C) of S. epidermidis, each consisting of more than 10 isolates, with a PFGE-DNA similarity of >90% were identified. The strains in Groups A and B (N=15 and N=13, respectively), which were generally resistant to gentamicin, co-trimoxazole and clindamycin, originated from 24 patients, of whom 21 had been treated in the intensive care unit (ICU) before sampling. The third cluster, Group C, involved 14 isolates from 14 patients. Only two of these patients had stayed at the ICU, and all for less than one day. Isolates in Group C were less resistant than those in Groups A and B. Isolates belonging to Group A showed an identical PFGE profile compared with multi-drug-resistant S. epidermidis isolated from patients at the referral hospital. This study demonstrated the persistence and spread of meticillin-resistant clones of CNS within the county hospital, especially in the ICU, and possible interhospital spread of a multi-drug-resistant clone between the county and referral hospitals.

Keyword
Coagulase-negative staphylococci; Meticillin resistant; PFGE; Clonal spread; Epidemiology; Intrahospital; Interhospital
National Category
Microbiology in the medical area
Research subject
Clinical Bacteriology
Identifiers
urn:nbn:se:umu:diva-22742 (URN)10.1016/j.jhin.2006.06.013 (DOI)16911846 (PubMedID)
Available from: 2009-05-18 Created: 2009-05-18 Last updated: 2017-12-13Bibliographically approved
2. Clonality among multidrug-resistant hospital-associated Staphylococcus epidermidis in northern Europe
Open this publication in new window or tab >>Clonality among multidrug-resistant hospital-associated Staphylococcus epidermidis in northern Europe
Show others...
2009 (English)In: Scandinavian Journal of Infectious Diseases, ISSN 0036-5548, E-ISSN 1651-1980, Vol. 41, no 9, 642-649 p.Article in journal (Refereed) Published
Abstract [en]

Using pulsed-field gel electrophoresis (PFGE) we have previously described the occurrence and possible dissemination of a clone of multidrug-resistant Staphylococcus epidermidis (MDRSE) in 2 hospitals in northern Sweden during 2001-2003. The aims of the present study were to investigate if this clone still persisted, 7 y later, in these 2 hospitals and whether this specific clone was detectable among clinical isolates from 9 other hospitals, 6 Swedish as well as a Norwegian, Danish and a German hospital. In total, 173 clinical isolates of MDRSE isolated during 2003 to 2008 were analysed using PFGE, of which 22 isolates were also characterized by multilocus sequence typing (MLST). Two dominating PFGE types (types A and B) were identified, consisting of 56 (32%) and 38 (22%) isolates, respectively. Type A, which was detected in the Norwegian and all Swedish hospitals, proved indistinguishable to the clone previously identified in 2001-2003 and corresponded with a novel sequence type (ST215). Type B was discovered in the German, Danish and in 7 Swedish hospitals and corresponded with ST2. In conclusion, we have demonstrated the occurrence, persistence and potential dissemination of 2 MDRSE genotypes, including a novel sequence type (ST215), within hospitals in northern Europe.

Keyword
clonal spread of multidrug-resistant staphylococci
National Category
Microbiology in the medical area Infectious Medicine
Research subject
Clinical Bacteriology; Infectious Diseases
Identifiers
urn:nbn:se:umu:diva-34175 (URN)10.1080/00365540903146987 (DOI)19634070 (PubMedID)
Available from: 2010-05-20 Created: 2010-05-18 Last updated: 2017-12-12Bibliographically approved
3. Near absence of methicillin-resistance and pronounced genetic diversity among Staphylococcus epidermidis isolated from healthy persons in northern Sweden
Open this publication in new window or tab >>Near absence of methicillin-resistance and pronounced genetic diversity among Staphylococcus epidermidis isolated from healthy persons in northern Sweden
Show others...
2011 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 119, no 8, 505-512 p.Article in journal (Refereed) Published
Abstract [en]

The main aim of the study was to examine if hospital-associated clones of multidrug-resistant Staphylococcus epidermidis (MDRSE), commonly identified in hospitals in our region, also are spread among healthy persons in the community. A total of 124 isolates of S. epidermidis sampled from subjects attending a Travel health clinic, Umeå, Sweden during 2008 were examined with antibiotic susceptibility testing and pulsed field gel electrophoresis (PFGE) analysis.

Resistance to methicillin or any antibiotic was detected in two and 26 of the isolates, respectively. PFGE analysis showed an extensive genetic diversity with 86 different PFGE types, of whom 62 were singletons. No isolates belonged to the previously described hospital-associated MDRSE genotypes, indicating that MDRSE by large are confined to the hospital setting in our region. In conclusion, community-associated isolates of S. epidermidis showed a low level of methicillin-resistance and were genetically extremely diverse with no predominating genotype.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2011
Keyword
Staphylococcus epidermidis, Community-Acquired Infections, Electrophoresis, Gel, Pulsed-Field, genetic diversity, Epidemiology, Methicillin Resistance, Multilocus sequence typing
National Category
Microbiology in the medical area Infectious Medicine
Research subject
Infectious Diseases; Clinical Bacteriology
Identifiers
urn:nbn:se:umu:diva-34288 (URN)10.1111/j.1600-0463.2011.02757.x (DOI)000292648700003 ()
Available from: 2010-05-25 Created: 2010-05-25 Last updated: 2017-12-12Bibliographically approved
4. Molecular epidemiology of Staphylococcus saprophyticus isolated from women with uncomplicated community-acquired urinary tract infection
Open this publication in new window or tab >>Molecular epidemiology of Staphylococcus saprophyticus isolated from women with uncomplicated community-acquired urinary tract infection
Show others...
2007 (English)In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 45, no 5, 1561-1564 p.Article in journal (Refereed) Published
Abstract [en]

Staphylococcus saprophyticus is a common cause of urinary tract infections (UTIs) in women. Little is known about the molecular epidemiology of S. saprophyticus UTIs. In the current study, we compared 76 isolates of S. saprophyticus prospectively isolated from women with uncomplicated UTI participating in a randomized placebo-controlled treatment trial performed in northern Sweden from 1995 to 1997 with 50 strains obtained in 2006 from five different locations in northern Europe with pulsed-field gel electrophoresis (PFGE). The aim was to elucidate the molecular epidemiology of this uropathogenic species and to investigate whether specific clones are associated with UTI in women. A total of 47 different PFGE profiles were detected among the 126 analyzed isolates. Ten clusters consisting of 5 to 12 isolates each showing PFGE DNA similarity of >85% were identified. Several clusters of genetically highly related isolates were detected in the original trial as well as among isolates obtained during 2006 from different locations. In the original trial, clonal persistence was found among 16 of 21 (76%) patients examined in the placebo group at follow-up 8 to 10 days after inclusion, indicating a low spontaneous short-time bacteriological cure rate. We conclude that multiple clones of S. saprophyticus were causing lower UTIs in women. The result suggests that some human-pathogenic clones of S. saprophyticus are spread over large geographical distances and that such clones may persist over long periods of time.

National Category
Microbiology in the medical area
Research subject
Clinical Bacteriology
Identifiers
urn:nbn:se:umu:diva-20978 (URN)10.1128/JCM.02071-06 (DOI)17344356 (PubMedID)
Available from: 2009-03-31 Created: 2009-03-31 Last updated: 2017-12-13Bibliographically approved

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