Nasal carriage of inducible dormant and community-associated methicillin-resistant Staphylococcus aureus in an ambulatory population of predominantly university students.
BACKGROUND
We studied risk factors for nasal colonization with inducible dormant methicillin-resistant Staphylococcus aureus (ID-MRSA) and community-associated MRSA (CA-MRSA) in a cohort of predominantly university students.


METHODS
Nasal surveillance cultures were performed in student health and ambulatory clinics. Molecular features were identified and risk factors for CA-MRSA and ID-MRSA colonization were determined by logistic regression.


RESULTS
Of the 1000 participants, 89% (n = 890) were university students. Sixty-four percent were female, 59% Caucasian. The mean age was 23.5 years; 1.6% (n = 16) were CA-MRSA and 1.4% (n = 14) were ID-MRSA colonized. Fifteen (94%) of the CA-MRSA strains were PFGE type IV. pvl (Panton-Valentine leukocidin gene) positivity was 75% in CA-MRSA and 57% in ID-MRSA. ID-MRSA isolates were pulsed-field gel electrophoresis (PFGE) type I, 7%; type II, 14%; type V, 7%; and type IV, 71%. CA-MRSA SCCmec classification was 94% type IV and 6% type V. Risk factors for carriage of CA-MRSA were older age (OR 1.046, p=0.040) and dog ownership (OR 1.450, p=0.019). Single family home (OR 0.040, p=0.007) was a protective factor. There were no significant variables of association found for ID-MRSA colonization.


CONCLUSIONS
ID-MRSA/CA-MRSA colonization was low. Most isolates were PFGE types IV and II, pvl-positive and susceptible to several antibiotics. Older age and dog ownership were risk factors for CA-MRSA. Future studies are needed to assess the impact of ID-MRSA carriage.
Bearman
Gonzalo M L
GM
Department of Internal Medicine, Division of Infectious Diseases, Virginia Commonwealth University Medical Center, Richmond, VA 23298-0019, USA. gbearman@vcu.edu
Rosato
Adriana E
AE
Assanasen
Susan
S
Kleiner
Elizabeth A
EA
Elam
Kara
K
Haner
Cheryl
C
Wenzel
Richard P
RP
D000293:Adolescent; D000328:Adult; D000818:Animals; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology*; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D009296:Nasal Cavity / Q000382:microbiology*; D057805:Pets; D011159:Population Surveillance; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013334:Students; D014495:Universities; D014768:Virginia / Q000453:epidemiology; D055815:Young Adult