479. A Study of the Relationship Between MRSA Colonization and Acquisition of Infection with the Similar or Different Strains
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Objective: The aims of this study were to determine the MRSA colonization status of patients admitted to 9 separate intensive care units (ICUs) in 5 different hospitals in the same geographic area. We also determined a variety of fingerprints on all of the isolates.
Design: This prospective study was conducted at 5 hospitals and included 9 ICU’s (medical, surgical, cardiac, cardio-thoracic and neurosurgical). Over a 9 month time period, all patients admitted to the ICU had a MRSA surveillance nasal swab tested by PCR (BD GeneOhm Sciences, San Diego, CA) with repeat PCR testing every week during the course of their ICU stay and upon transfer or discharge out of the ICU. Patients that developed a culture proven MRSA infection were also evaluated. MRSA strains from both PCR positive nasal swabs and from infection cultures were characterized by determining the SCCmec and spa type and by DNA fingerprint analysis using Rep-PCR (bioMerieux, Durham, NC).
Results: Over the 9 month time period, a total of 7723 patients were cultured at 9 hospital ICU’s. Of the total, 887 (11%) were MRSA culture positive or PCR surveillance swab positive and 6836 (89%) were MRSA negative. Out of 407 separate patient isolates collected, 122 were nosocomial, 96 were health-care associated (HCA) and 120 were community-acquired(CA). They were characterized by determining the SCCmec and by clonal complex (CC). Of the 407 isolates, 331 were CC5, the remaining 76 isolates were divided among 10 other types ( between 1-42) in each category. The CC5 isolates were evenly distributed amongst all 5 facilities. The predominant SCCmec type was II. About 10% of colonized patients became infected during the study period and infection rates were evenly distributed.
Conclusions: Over a 9 month period in a narrow geographic distribution, surveillance for MRSA isolates revealed a fairly even distribution of nosocomial, HCA and CA. Initial fingerprinting and typing did not reveal any unique types or clusters among the facilities. The rise of CA isolates in ICU’s is alarming.
Donna Armellino, RN1, Dazhi Chen, MD2, Bruce Farber, MD2, Taynet Febles, MD2, Christine Ginocchio, PhD3, Diamanto Korologos, Masters Degree2, Barry Kreiswirth, PhD4, Jose Mediavilla, BS5, Nancy Musa, RN2, Mary Ellen Schilling, RN6, Frank Zhang, MD2 and  T. T. Febles, None..
B. Farber, None..
D. Armellino, None..
M. Schilling, None..
C. Ginocchio, None..
N. Musa, None..
F. Zhang, None..
D. Korologos, None..
D. Chen, None..
B. N. Kreiswirth, None..
J. Mediavilla, None., (1)Infectious Disease/Infection Control, North Shore University Hospital-Manhasset, Manhasset, NY, (2)North Shore University Hospital, Manhasset, NY, (3)North Shore Health System Core Laboratory, Lake Success, NY, (4)Public Health Research Institute, Newark, NJ, (5)University of Medicine and Dentistry of NJ, PHRI TB Center, Newark, NJ, (6)North Shore University Hospital