395. Longitudinal study of Iowa families to determine prevalence of Staphylococcus aureus and observe colonization incidence and familial transmission
Session: Poster Abstract Session: MRSA, MSSA, Enterococci
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Methicillin-resistant Staphylococcus aureus (MRSA) has been characterized in swine workers, healthcare workers, and other high-risk groups in the United States, but little is known about non-high risk groups. We intend to determine the prevalence of Staphylococcus aureus (S. aureus) and MRSA colonization in Iowans at baseline, observe incident colonization events during follow-up, and determine the frequency of transmission within family units. Additionally, many hospital programs, outpatient and surgical centers, and long-term care facilities utilize prophylactic decolonization, but the role of pharyngeal swabs in S. aureus colonization of healthy adults is unknown. We plan to assess the importance of this colonization site within our participants.

Methods: Families from Johnson and Keokuk Co., Iowa were enrolled. Participants self-collected pharyngeal and nasal swabs, or nasal swabs weekly for 52 weeks from adult and minor participants respectively. Swabs were inoculated into Baird-Parker Broth and incubated for 24 hours, then streaked onto Baird-Parker Agar and ChromAgar media and incubated for 48 hours. Presumptive positive colonies were streaked onto Columbia CNA with 5% sheep blood and incubated for 24 hours. S. aureus isolates were confirmed with catalase and coagulase tests, and StaphLatex agglutination assays. Molecular characteristics were determined through mecA and PVL polymerase chain reaction, and spa typing.

Results: A total of 263 individuals were enrolled. Sixty-six adults (4 with MRSA) and 32 minors (1 with MRSA) were positive for S. aureus at baseline. This gives overall S. aureus prevalences of 37.3% and 37.2% for adults and children respectively, with 2.3% and 1.2% of these isolates being MRSA respectively.


Conclusion: Our observed S. aureus prevalences of 37.3% for adults is higher than observed in Gorwitz et al. 2008, however, we collected pharyngeal swabs in addition to nasal swabs, increasing our sensitivity. Pearson’s correlation to assess the association of nasal and pharyngeal swabs was statistically significant at p < 2.2e-16, indicating an individual who is colonized in one site is likely to be colonized in both the nares and the pharynx.

Blake Hanson, MS1, Ashley Kates, MS1, Sean O'malley1, Sarah Farina1, Cassandra Klostermann1, James Wu1, Thomas Meirick1, Megan Quick1, Brett Forshey, PhD1 and Tara Smith, PhD2, (1)Epidemiology, College of Public Health, University of Iowa, Iowa City, IA, (2)College of Public Health, University of Iowa, Iowa City, IA


B. Hanson, None

A. Kates, None

S. O'malley, None

S. Farina, None

C. Klostermann, None

J. Wu, None

T. Meirick, None

M. Quick, None

B. Forshey, None

T. Smith, None

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