475. The Prevalence of Methicillin-Resistant Staphylococcus aureus (MRSA) Nasal Colonization Among Health Care Workers (HCW) at an Urban Hospital
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Community-associated MRSA (CA-MRSA) is endemic in our community. Since 2004, CA-MRSA has increased from 28% to 46% of all new MRSA infections. We hypothesized that HCW colonization with MRSA may also have increased in this period. We compared the prevalence, clinical, and molecular epidemiological features of MRSA nasal colonization among HCW at a single urban hospital between 2004-5 and 2008-9.
Methods: We studied 254 HCW in 2004-5 and 256 HCW in 2008-9. Laboratory methods and subject selection were identical in both studies. Swabs were obtained from the anterior nares of consented HCW, inoculated onto S110 agar plates and incubated at 37° for 24-72 hours. S. aureus (SA) was identified by yellow-orange color. We confirmed methicillin resistance by PCR for the mecA gene and by growth on oxacillin screen agar. Presumptive identification of CA-MRSA or hospital-associated MRSA (HA-MRSA) was performed by PCR for the mecIVa and the Panton-Valentine Leukocidin (pvl) genes. Epidemiological data was collected from confidential surveys.
Results: The sample size and demographic distribution of HCW type and departments were similar for both study periods. Of 254 HCW in 2004-5, 84 (33%) carried SA including 11 (4.2%) with MRSA. Of 256 HCW in 2008-9, 69 (26.9%) carried SA; only 5 (2%) had MRSA. Only 2 of 11 MRSA in 2004-5, and 0 of 5 MRSA in 2008-9 were CAMRSA. . No major trends were noted in the type of HCW or hospital unit for HCW colonized with MRSA. All but one person reported recent care of patients with MRSA.
Conclusion: The prevalence of MRSA nasal carriage among HCW was low in both survey periods and there was no increase in CA-MRSA carriage in 2008-9 despite overall increases in both HA-MRSA and CA-MRSA at our institution. Persistent low rates of HCW MRSA nasal colonization may reflect an aggressive hand hygiene campaign and enforced contact precautions for patients admitted with MRSA. The nares may also not be the major reservoir for CA-MRSA colonization.
Henry Fraimow, MD, Christopher Knob, BS2, Florence Momplaisir, MD3, Annette Reboli, MD2 and  F. M. Momplaisir, None..
H. Fraimow, None..
C. Knob, None. 
A. C. Reboli,
Pfizer Role(s): Investigator, Scientific Advisor (Review Panel or Advisory Committee), Speaker's Bureau, Received: Research Support, Speaker Honorarium.
Merck Role(s): Investigator, Scientific Advisor (Review Panel or Advisory Committee), Received: Research Grant, Consulting Fee., (1)Cooper University Hospital, Camden, NJ, (2)Cooper University Hospital, Villanova, PA