Nasal carriage of inducible dormant and community-associated methicillin-resistant Staphylococcus aureus in an ambulatory population of predominantly university students

• Published in: International journal of infectious diseases 2010-09, Vol.14, p.e18-e24
• Main Authors: Bearman, Gonzalo M.L, Rosato, Adriana E, Assanasen, Susan, Kleiner, Elizabeth A, Elam, Kara, Haner, Cheryl, Wenzel, Richard P
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Animals; CA-MRSA; Carrier State - epidemiology; Carrier State - microbiology; Cohort Studies; Community-Acquired Infections - epidemiology; Community-Acquired Infections - microbiology; Dogs; Epidemiology; Female; Humans; ID-MRSA; Infectious Disease; Male; Methicillin-Resistant Staphylococcus aureus - classification; Methicillin-Resistant Staphylococcus aureus - drug effects; Methicillin-Resistant Staphylococcus aureus - genetics; Methicillin-Resistant Staphylococcus aureus - isolation & purification; Nasal Cavity - microbiology; Pathogenesis; Pets; Population Surveillance; Pulmonary/Respiratory; Risk Factors; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Students; Universities; Virginia - epidemiology; Young Adult
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2009.09.005

Abstract 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 SCC mec 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.