1256. Molecular genotyping of methicillin resistant Staphylococcus aureus (MRSA) from tertiary medical center and 7 referring community hospitals  
Session: Poster Abstract Session: Staphylococcal Resistance and Epidemiology
Saturday, October 22, 2011
Room: Poster Hall B1
Background: MRSA is an increasing cause of healthcare-associated (HA) and community -associated (CA) infections. Historically, HA-MRSA and CA-MRSA differed in specific MRSA strains types, patient populations, and clinical presentations.  To determine if transmission of CA- and HA-MRSA is occurring between a tertiary medical center (MC) and 7 referring rural community hospitals (CH), a comparison of clinical characteristics and molecular genotypes of MRSA isolates was conducted.

Methods: Molecular genotyping and medical chart reviews were conducted on 1317 patients with MRSA clinical infections between January, 2007 to March, 2010.  Molecular genotyping was performed by repetitive element polymerase chain reaction (Rep-PCR DiversiLABTM , Biomerieux, NC). Pulsed Field Gel Electrophoresis (PFGE) and Staphylococcal chromosome cassette (SCC) mecA typing were derived from DiversiLABTM  MRSA library.  PFGE and SCC confirmations were performed on selected isolates.   

Results: Clinical and molecular characteristics of MC and CH isolates are listed in the table below.   

 Hospitals

Medical Center

Community Hospitals

Total number (n)

904

413

Gender male (%)

512(57%)

195(47%)

Median Age (years)

53

48

White Race (%)

622(69%)

391 (95%)

Blood

304 (34%)

8 (2%)

SSTI

230(25%)

310 (75%)

Respiratory

189(21%)

35(8.5%)

HA-MRSA

305(34%)

21 (5%)

HACO-MRSA

383(42%)

34 (8%)

CA-MRSA

209(23%)

340 (82%)

Mortality

123 (14%)

8 (2%)

# repPCR types

77

47

PFGE USA types

100, 200, 300, 400, 500, 600, 700, 800, 1000, 1100, Iberian, ST239, Novel type

100, 300, 400, 500, 600, 700, 800, 1000, ST239

SCC mecA types

II, III, IV

II, III, IV

# census tracts

484

87

# zip codes

242

77

Conclusion: Distinct molecular and epidemiological characteristics exist between MRSA isolates within this referral network of hospitals.  The percentage of CA- and HA-MRSA classifications and relative proportions of molecular genotypes of rep-PCR varied between MC and CH.  However, specific MRSA PFGE strains were commonly shared between the hospitals.   We predict social network and temporospatial analysis will allow more complete understanding of MRSA transmission between facilities.  


Subject Category: C. Clinical studies of bacterial infections and antibacterials including sexually transmitted diseases and mycobacterial infections (surveys, epidemiology, and clinical trials)

Shu-Hua Wang, MD, MPH&TM1, Yosef Khan, MBBS, MPH2, Lisa Hines, RN, CIC1, Preeti Pancholi, PhD3 and Kurt Stevenson, MD, MPH4, (1)Internal Medicine, Ohio State University Medical Center, Columbus, OH, (2)Ohio State University Medical Center and College of Medicine, Columbus, OH, (3)Clinical Microbiology, The Ohio State Univ Med Ctr, Columbus, OH, (4)The Ohio State University Medical Center, Columbus, OH

Disclosures:

S. H. Wang, None

Y. Khan, None

L. Hines, None

P. Pancholi, None

K. Stevenson, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.