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An individual-based network model to evaluate interventions for controlling pneumococcal transmission
University of Skövde, School of Life Sciences.
University of Skövde, School of Life Sciences.
Karolinska Inst, Swedish Inst Infect Dis Control, Dept Bacteriol, SE-17182 Solna, Sweden / Karolinska Inst, Dept Microbiol Tumor Biol & Cell Biol, SE-17177 Stockholm, Sweden.
University of Skövde, School of Life Sciences.
2008 (English)In: BMC Infectious Diseases, ISSN 1471-2334, Vol. 8, 83- p.Article in journal (Refereed) Published
Abstract [en]

Background: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, but also a common colonizer of the upper respiratory tract. The emergence and spread of antibiotic resistant pneumococcal strains has threatened effective therapy. The long-term effects of measures aiming to limit pneumococcal spread are poorly understood. Computational modeling makes it possible to conduct virtual experiments that are impractical to perform in real life and thereby allows a more full understanding of pneumococcal epidemiology and control efforts. Methods: We have developed a contact network model to evaluate the efficacy of interventions aiming to control pneumococcal transmission. Demographic data from Sweden during the mid-2000s were employed. Analyses of the model's parameters were conducted to elucidate key determinants of pneumococcal spread. Also, scenario simulations were performed to assess candidate control measures. Results: The model made good predictions of previous findings where a correlation has been found between age and pneumococcal carriage. Of the parameters tested, group size in day-care centers was shown to be one of the most important factors for pneumococcal transmission. Consistent results were generated from the scenario simulations. Conclusion: We recommend, based on the model predictions, that strategies to control pneumococcal disease and organism transmission should include reducing the group size in day-care centers.

Place, publisher, year, edition, pages
2008. Vol. 8, 83- p.
Identifiers
URN: urn:nbn:se:his:diva-6868DOI: 10.1186/1471-2334-8-83ISI: 000257399500002PubMedID: 18559109Scopus ID: 2-s2.0-47349104286OAI: oai:DiVA.org:his-6868DiVA: diva2:573088
Available from: 2012-11-29 Created: 2012-11-29 Last updated: 2014-10-27Bibliographically approved
In thesis
1. Studies on emergence and spread of antibiotic resistant Streptococcus pneumoniae
Open this publication in new window or tab >>Studies on emergence and spread of antibiotic resistant Streptococcus pneumoniae
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Streptococcus pneumoniae is one of the major contributors to mortality and morbidity around  the  world.  It  causes  a  wide  variety  of  diseases  ranging  from  uncomplicated respiratory  infections  to  life-threatening  invasive  infections  such  as  meningitis  and septicemia. In recent years, the effectiveness of antibiotic therapy has been hampered by  the  increasing  rates  of  resistant  pneumococci.  As  antibiotic  resistance  increases, there is a growing need for interventions that minimize opportunities for development and spread  of resistant  pneumococci.  The aim  of this  thesis  was  to learn  more  about emergence  and  spread  of  antibiotic  resistant  pneumococci  using  both  theoretical  and empirical methods.  Since the increasing prevalence of resistant pneumococci is mainly due to the spread of strains belonging to few clones, interventions for controlling pneumococcal transmission  in  the  community  were  studied.  Model  predictions  suggested  that interventions for efficiently control organism transmission should include reduction of group sizes in the day-care centers. Simulations also indicated that it appears extremely difficult  to  reduce  the  rates  of  penicillin  non-susceptible  pneumococci  by  simply decreasing  the  penicillin  consumption  assumed  that  reduced  penicillin  susceptibility does not imply a fitness cost for the organism. Managing the penicillin resistance rates in pneumococci then probably requires a more restrictive use of penicillin together with other  control  measures  such  as  vaccine  programs.  Although  clonal  spread  is  the primary  mechanism  for  the  rapid  emergence  of  resistance  in  pneumococci,  natural competence  for  genetic  transformation  also  seems  to  be  involved.  Further  molecular understanding  of competence regulation  is  important  to be  able  to prevent  horizontal spread  of  resistance  genes.  Studying  the  competence  regulation  by  theoretical  means led  to  the  conclusion  that  down-regulation  of  competence  is  probably  caused  by  a repressor acting on the comCDE operon at the level of transcription.  Despite the globally emerging frequency of resistant pneumococci, we conclude in a prospective study that antimicrobial resistance in invasive pneumococci in south-west Sweden remains limited. Any correlations between resistance pattern and clinical parameters could not be revealed. However, the serotype distribution was observed to differ  between  strains  with  reduced  susceptibility  and  fully  susceptible  strains  as isolates  with  decreased  susceptibility  more  frequently  belonged  to  the  serotypes included in the 7-valent vaccine.

Place, publisher, year, edition, pages
Stockholm: Karolinska Institutet, 2010. 82 p.
National Category
Natural Sciences
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-4699 (URN)978-91-7457-027-4 (ISBN)
Funder
Knowledge Foundation
Available from: 2011-04-27 Created: 2011-02-01 Last updated: 2014-10-24Bibliographically approved

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