1248. Comparison of community-onset and healthcare-associated methicillin-resistant Staphylococcus aureus blood stream infection at an academic center for 3 years
Session: Poster Abstract Session: Staphylococcal Resistance and Epidemiology
Saturday, October 22, 2011
Room: Poster Hall B1
Background:  Methicillin-resistant Staphylococcus aureus (MRSA) blood stream infections (BSI) are associated with longer hospital stays, higher mortality, and increased costs.  MRSA BSI can be classified epidemiologically as Healthcare-associated (HA), culture obtained >48 hours after admission; Healthcare-associated Community Onset (HACO), culture obtained ≤48 hours after admission with identified healthcare-associated risk factors; or Community-associated (CA), culture obtained ≤48 hours. Genotyping can identify new strains of MRSA and potential outbreak clusters associated with CA-MRSA or HA-MRSA BSI, and helps to define MRSA epidemiology for infection control.

Methods:  Molecular genotyping and medical chart review were conducted on 288 MRSA BSI isolates from 1/07 to 12/09. Genotyping was performed by repetitive element polymerase chain reaction (rep-PCR, DiversiLABTM, Biomeriux, NC), spa typing, staphylococcal chromosome cassette (SCC) mec typing, and pulsed-field gel electrophoresis (PFGE). Multi-locus sequence typing clonal complexes were inferred from known spa types and SCCmec typing.  Clinical risk factors and antibiotic susceptibility data were also collected.

Results:  Among 288 MRSA BSI isolates, 60% male, 72% white, mean age 57 years (range 19 to 99 years). Clinical and molecular genotyping results are shown below.

 

HA-MRSA

HACO-MRSA

CA-MRSA

# of cases

121

138

29

Primary bacteremia (%)

89(74%)

103(75%)

16(55%)

Mortality(%)

33(27%)

23(17%)

2(7%)

# repPCR types

32

40

14

# spa types

18

24

6

PFGE types

100, 200, 300, 500, 1000, ST239

100, 200, 300, 500, 800, 1000, ST239

100, 300, 500, 800

Clonal Complex (MLST)

5, 8, 30, 59, 8/239

5, 8, 30, 45, 59, 8/72, 8/239 

5, 8

SCCmec types

II, III, IV

II, III, IV

II, IV

Conclusion: Distinct molecular and epidemiological characteristics exist between HA-, HACO-, and CA-MRSA BSI strains. Rep-PCR genotyping method offers higher discriminatory capability than spa or PFGE. Traditional CA-MRSA strains (PFGE 300, SCC mec IV) are causing nosocomial infections and HA-MRSA strains (PFGE 100, SCC mec II) are causing community infections.  Rapid molecular genotyping can identify potential spread of MRSA in the hospital and improve MRSA surveillance and infection control to reduce hospital transmission of MRSA.


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, Jose Mediavilla, BS3, Lisa Hines, RN, CIC1, Barry Kreiswirth, PhD4, Preeti Pancholi, PhD5 and Kurt Stevenson, MD, MPH6, (1)Internal Medicine, Ohio State University Medical Center, Columbus, OH, (2)Ohio State University Medical Center and College of Medicine, Columbus, OH, (3)Public Health Research Institute Tuberculosis Center, International Center for Public Health, Newark, NJ, (4)University of Medicine and Dentistry of NJ, PHRI TB Center, Newark, NJ, (5)Clinical Microbiology, The Ohio State Univ Med Ctr, Columbus, OH, (6)The Ohio State University Medical Center, Columbus, OH

Disclosures:

S. H. Wang, None

Y. Khan, None

J. Mediavilla, None

L. Hines, None

B. Kreiswirth, None

P. Pancholi, None

K. Stevenson, None

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