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Use of molecular typing methods in characterizing MRSA infections in Ohio

Sommerhalter, Kristin McCarthy
http://rave.ohiolink.edu/etdc/view?acc_num=osu1440090373

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Public Health.
Methicillin-resistant Staphylococcus aureus (MRSA) is a genetically heterogeneous bacterial organism responsible for causing significant human disease. Molecular strain typing of MRSA is regularly implemented to enhance surveillance procedures, supplement outbreak control programs, and to characterize evolutionary patterns of MRSA. Numerous molecular strain typing methods have been developed to characterize MRSA, but all have significant advantages and disadvantages. Four of the more commonly used typing methods include pulsed field gel electrophoresis (PFGE), Staphylococcal protein A (spa) typing, repetitive element PCR (rep-PCR) typing, and Staphylococcal chromosome cassette mec (SCCmec) typing. The objective of this dissertation was to investigate the use of molecular typing methods in characterizing MRSA using a set of isolates collected from eight hospitals in Ohio from 2007 through 2010. Our three specific aims were: 1.) To evaluate the discriminatory power and concordance of rep-PCR, spa, SCCmec and PFGE typing in the molecular characterization of MRSA 2.) To characterize the association between spa type assignment and MRSA infection presentation and 3.) To describe the distribution and diversity of MRSA isolate strain types across seven community hospitals in Ohio collected over a one year period. In our study we found that rep-PCR typing had the highest discriminatory power of the four typing methods, and that there was high directional concordance between rep-PCR typing and spa typing, PFGE typing, and SCCmec typing. spa typing also exhibited high directional concordance with PFGE and SCCmec typing. We also found a lack of independence between spa type assignment and MRSA specimen type. Specifically, isolates assigned to spa type 2 were more likely to come from a blood specimen than a skin / soft tissue specimen, and isolates assigned to spa type 1 were less likely to come from either a blood specimen or a sputum specimen than from a skin / soft tissue specimen. Finally, we found that two rep-PCR types persisted at different time intervals across all seven community hospitals, and that there was high rep-PCR type diversity among our isolates at each hospital. We also found evidence that rep-PCR typing might be useful in detecting outbreak strains. There were two spa types that persisted across also seven hospitals across the entire study period, and there was moderate diversity in spa type assignment among the isolates at each hospital. These differences give some support to using rep-PCR typing over spa typing for short term MRSA surveillance. Molecular strain typing is a ubiquitous tool for characterizing MRSA, but there are a number of different typing methods available to use. Our results suggest that rep-PCR typing is highly concordant with other popular typing methods and is a useful tool for short term surveillance. We also found that spa typing is associated with the manifestation of an MRSA infection. Future studies should focus on correlating these strain type patterns to virulence factors associated with persistence and pathogenesis.
Kurt Stevenson (Advisor)
Amy Ferketich (Committee Member)
Abigail Norris Turner (Committee Member)
Rebecca Andridge (Committee Member)
243 p.
Epidemiology; Public Health

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Citations

  • Sommerhalter, K. M. (2015). Use of molecular typing methods in characterizing MRSA infections in Ohio [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440090373

    APA Style (7th edition)

  • Sommerhalter, Kristin. Use of molecular typing methods in characterizing MRSA infections in Ohio. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1440090373.

    MLA Style (8th edition)

  • Sommerhalter, Kristin. "Use of molecular typing methods in characterizing MRSA infections in Ohio." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440090373

    Chicago Manual of Style (17th edition)

osu1440090373
951
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This open access ETD is published by The Ohio State University and OhioLINK.