555. A dynamic transmission model for Staphylococcus aureus in the US population
Session: Poster Abstract Session: MRSA Surveillance and Infection Prevention
Friday, October 21, 2011
Room: Poster Hall B1
Background: To develop a mathematical model for Staphylococcus aureus (SA) transmission in the US population, based on past epidemiological trends and natural history.  Such models can help project future trends and assess impact of population-level interventions.

Methods: We employ a Susceptible-Colonized-Infected-Recovered-Susceptible compartmental modeling framework for methicillin-susceptible SA (MSSA) and methicillin-resistant SA (MRSA). Susceptible individuals can become either colonized or directly infected with MRSA or MSSA via adequate contact with Colonized/Infected individuals. The model is dynamic and accounts for the US population growth. For model calibration/validation, we use the published 1999-2005 SA infection data in conjunction with the 2001-2004 NHANES colonization data. We include a vaccination component in the model, to illustrate the potential population-level impact of a hypothetical vaccine.

Results: The model is able to capture both the colonization and infection data (p-value for model/data correlation <0.0001 for MRSA infection data and <0.05 for MSSA infection data) and successfully renders the 2004-2005 MRSA infection data left out at calibration. Baseline model projections illustrate how MRSA might expand and gradually replace MSSA over time, in the absence of intervention, if the 1999-2005 epidemiological trends continued.  Model-estimated basic reproduction numbers (R°) are greater than 1 for both MRSA and MSSA, with MRSA slightly higher than MSSA (1.5 vs. 1.4). We illustrate with a hypothetical case scenario how vaccination could reduce burden of disease within the US population.

Conclusion: Based on past (1999-2005) trends and natural history, projections from a basic dynamic transmission model at US population level show how MRSA might continue to expand and gradually replace MSSA over time. R° model estimates emphasize the need for efficient means of infection control. Prevention methods, including vaccination, can help reduce burden of disease within the US population.


Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

Cosmina Hogea, PhD, GlaxoSmithKline Biologicals, Philadelphia, PA, Robertino Mera, PhD, Research Statistics Unit, GlaxoSmithKline, Durham, NC, Heather Amrine-Madsen, PhD, GlaxoSmithKline, Durham, NC, Thierry van Effelterre, PhD, GlaxoSmithKline Biologicals, Wavre, Belgium, Karine Goraj, GlaxoSmithKline Biologicals, Rixensart, Belgium and Camilo Acosta, GlaxoSmithKline Global Health Outcomes, Philadelphia, PA

Disclosures:

C. Hogea, GlaxoSmithKline Biologicals: Employee, Salary

R. Mera, GlaxoSmithKline : Employee, Salary

H. Amrine-Madsen, GlaxoSmithKline : Employee, Salary

T. van Effelterre, GlaxoSmithKline Biologicals: Employee, Salary

K. Goraj, GlaxoSmithKline Biologicals: Employee, Salary

C. Acosta, GlaxoSmithKline : Employee, Salary

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.