Staphylococcus aureus nasal carriage in a student community: prevalence, clonal relationships, and risk factors.
OBJECTIVE
To evaluate the prevalence and risk factors of nasal Staphylococcus aureus (SA) in the community.


METHODS
Cross-sectional study.


METHODS
Wake Forest University, Winston-Salem, North Carolina.


METHODS
Four hundred fifty students were screened for nasal SA carriage during the fall of 2000, 2001, and 2002.


METHODS
Students were screened by nose swabs. A self-administered questionnaire collected information on demographics and medical history. Antibiotic testing and PFGE were performed on isolates. Risk factors were determined by logistic regression analysis.


RESULTS
Of 450 volunteers, 131 (29%) were SA carriers. Antibiotic resistance was high for azithromycin (26%) and low for ciprofloxacin (1%), tetracycline (5%), mupirocin (1%), and methicillin (2%). PFGE patterns were not associated with carriage. Age, male gender, white race, medical student, allergen injection therapy, chronic sinusitis, rheumatoid arthritis, hospitalization for 6 months or less, and use of antibiotics were associated with carrier status by univariate analysis. Stepwise multivariate logistic regression led to a best fitting model with older age (OR, 1.04; CI95, 1.005-1.079), male gender (OR, 1.50; CI95, 0.982-2.296), and chronic sinusitis (OR, 2.71; CI95, 0.897-8.195) as risk factors. Antibiotic use (< 4 weeks) (OR, 0.41; CI95, 0.152-1.095) and allergen injection therapy (OR, 0.41; CI95, 0.133-1.238) were protective. Analyses of carriers revealed candidate factors for persistent carriage to be nasal SA colonization rate and male gender. Factors for azithromycin resistance were non-medical students and antibiotic use in the past 6 months.


CONCLUSIONS
Older male volunteers suffering from chronic sinusitis and not taking antibiotics were at higher risk for carrying SA.
Bischoff
Werner E
WE
Department of Internal Medicine, Section on Infectious Diseases, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1042, USA.
Wallis
Michelle L
ML
Tucker
Keith B
KB
Reboussin
Beth A
BA
Sherertz
Robert J
RJ
D000328:Adult; D000367:Age Factors; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D003430:Cross-Sectional Studies; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D016106:Methicillin Resistance; D009297:Nasal Mucosa / Q000382:microbiology*; D009657:North Carolina / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D013203:Staphylococcal Infections / Q000453:epidemiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D013334:Students; D011795:Surveys and Questionnaires; D014495:Universities