Graduation Year

2004

Document Type

Thesis

Degree

M.S.P.H.

Degree Granting Department

Public Health

Major Professor

Heather Stockwell, Sc.D.

Co-Major Professor

Roger Sanderson, M.A.

Committee Member

Yougui Wu, Ph.D.

Keywords

antibiotic resistance, mrsa, bacterial infections, infection control, hospital epidemiology

Abstract

Methicillin-Resistant Staphylococcus aureus (MRSA) began as a nosocomial infection due to overuse of antibiotics. Several previous studies have reported an increase in this infection in adult patients who have not been hospitalized. It has also been reported that there is an increase in MRSA in children. Some of these children became infected even though they were not at high risk for the infection. After approval from the All Children's Hospital Institutional Review Board (IRB), a cross sectional study was conducted with pediatric admissions and pediatric emergency room visits to determine the characteristics of Methicillin-Sensitive Staphylococcus aureus and MRSA. During this study, a review of 672 medical charts was conducted. The study participants ranged in age from newborns to 18 years of age. In order to be enrolled in the study, the subjects' cultures were collected either as outpatients or within 72 hours of admission. The data that was collected from each chart included age, race/ethnicity, gender, type of infection, preexisting medical conditions, and risk factors for infection. The potential risk factors include antibiotic use, previous surgery or outpatient procedure, previous MRSA infection, immunotherapy, community worn device, and residence in a facility. Statistical analysis was conducted using Epi Info and SAS software packages. In regards to demographic characteristics, black children are 2.98 times more likely to have an MRSA infection than white children. Gender and age were not risk factors for the development of the infection. The risk factors that were significant in whites were home health care (OR= 6.12, CI= 5.16, 7.08), community worn device (OR= 2.28, CI= 1.67, 2.89), previous hospitalization (OR= 2.43, CI= 1.95, 2.91), previous MRSA infection (OR= 3.69, CI= 2.90, 4.48), and previous surgery (OR= 2.02, CI= 1.51, 2.53). In blacks, females were more likely to have MRSA (OR= 2.57, CI= 1.73, 3.41). This finding may be due to the small sample size of black children in the study. Of the analyzed risk factors, home health care (OR= 2.95, CI= 1.11, 4.79), community worn device (OR= 2.85, CI= 1.71, 4.01), previous hospitalization (OR= 1.98, CI= 1.13, 2.83), previous surgery (OR= 2.79, CI= 1.79, 3.79), and previous antibiotic (OR= 5.60, CI= 4.66, 6.54) use were all significant risk factors in blacks. Effect modification was tested between race and all risk factors. Race was an effect modifier only for the risk factor of previous antibiotic use (pvalue =.02). Adjustment of confounding was performed for each race due to the presence of effect modification. After the adjustment for confounding in whites, only home health care (OR=4.37 CI= 1.55, 12.32), previous MRSA infection (OR= 2.86 CI= 1.16, 7.05), and previous hospitalization (OR= 2.00 CI= 1.14, 3.50) remained statistically significant. In blacks, after adjustment of confounding, only previous antibiotic use (OR= 5.13 CI= 1.75, 15.08) remained significant. Adjustment for confounding was also preformed on the total risk factors model. A dose response relationship was present with increasing risk factors present.

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