Methicillin resistant Staphylococcus aureus: carriage rates and characterization of students in a Texas university

To evaluate the carriage rates of Staphylococcus aureus and methicillin resistant Staphylococcus aureus (MRSA) in a university student population and describe risk factors associated with the carriage of each.

Cross-sectional study (N = 203). Institutional Review Board approval was obtained from Texas State University-San Marcos.

Texas State University-San Marcos, San Marcos, TX.

Two-hundred and three university student samples were collected from December 2007 to July 2008.

None indicated.

The sample set was screened for S. aureus and MRSA identification by standard microbiological techniques and confirmed by use of a Vitek 2 per manufacturer recommendation. Antibiotic susceptibility testing was conducted on each MRSA isolate by Vitek 2. A questionnaire was conducted with each student to acquire demographic and risk factor information. Demographic data is shown by raw numbers, percentages, mean, and median where applicable. The compiled data was screened and analyzed by chi square (p values) and odds ratio (OR) with confidence interval (CI) to determine significance.

Of the 203 participants who were screened, 60 (29.6%) carried S. aureus. Univariate analysis found that only hospitalization in the past 12 months was significantly associated with the risk of being a S. aureus carrier (OR=3.0, 95% CI 1.28-7.03). Of the 60 participants that carried S. aureus, 15 were identified as MRSA. This relates to a 7.4% MRSA carriage rate among generally healthy university students. Univariate analysis found that hospitalization in the past 12 months (OR = 4.2, 95% CI 1.29-13.36) and recent skin infection (OR = 4.4, 95% CI 1.07-18.24) were significantly associated with the risk of being a MRSA carrier. No unique antibiotic susceptibility patterns were identified with the MRSA isolates.

The carriage rate of S. aureus is consistent with similar studies. MRSA carriage in this university study appears high as compared to the general population. Although this study did not confirm a variety of risk factors for carriage of MRSA previously identified by others, university healthcare personnel should be aware of the changing epidemiology of MRSA and preventive measures needed to avoid outbreaks.