Emergence of community-associated methicillin-resistant Staphylococcus aureus strains as a cause of healthcare-associated bloodstream infections in Korea.
BACKGROUND
The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains causing bloodstream infection (BSI) has not been studied in Korea.


OBJECTIVE
We sought to determine the prevalence of CA-MRSA strains among isolates recovered from patients with MRSA BSIs and to explore epidemiological changes in Korea. We also sought to evaluate clinical characteristics relevant to the development of healthcare-associated BSIs.


METHODS
We prospectively collected consecutive MRSA isolates from patients with BSI at 4 hospitals from July 1 through November 30, 2007, and we also included MRSA isolates recovered from culture of blood samples collected during a previous year (October 1, 2004 through September 30, 2005) at a different hospital. Molecular typing studies were performed, including pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, Staphylococcus protein A (spa) typing, and staphylococcal cassette chromosome mec (SCCmec) typing. We compared the clinical characteristics and outcomes of patients with healthcare-associated BSI due to CA-MRSA strains with those of patients with healthcare-associated BSI due to healthcare-associated MRSA (HA-MRSA) strains.


RESULTS
There were 76 cases of MRSA BSI, of which 4 (5.3%) were community-associated and 72 (94.7%) were healthcare-associated. Among the 72 HA-MRSA BSIs, 18 (25%) were community onset, and 54 (75%) were hospital onset. PFGE type D-ST72-spa B-SCCmec type IVA MRSA, the predominant genotype of CA-MRSA in Korea, accounted for 19 (25%) of all 76 MRSA BSIs, including 17 (23.6%) of 72 HA-MRSA BSIs and 11 (20.8%) of 53 hospital-onset HA-MRSA BSIs. Patients with healthcare-associated BSIs due to CA-MRSA strains carrying SCCmec type IVA tended to have fewer healthcare-associated risk factors, compared with patients with healthcare-associated BSIs due to HA-MRSA strains carrying other SCCmec types. The presence of a central venous catheter or other invasive device was the only independent factor differentiating patients infected with hospital-associated genotype strains from patients infected with other strains. Clinical outcomes were similar between both groups.


CONCLUSIONS
CA-MRSA strains are emerging as a major cause of BSI in healthcare settings in Korea. This changing epidemiology of MRSA poses a challenge to public health and infection control in hospital settings.
Park
Sun Hee
SH
Department of Internal Medicine, Catholic University of Korea, Seoul, Korea.
Park
Chulmin
C
Yoo
Jin-Hong
JH
Choi
Su-Mi
SM
Choi
Jung-Hyun
JH
Shin
Hyun-Ho
HH
Lee
Dong-Gun
DG
Lee
Seungok
S
Kim
JaYoung
J
Choi
So Eun
SE
Kwon
Young-Mi
YM
Shin
Wan-Shik
WS
D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology* / Q000503:physiopathology; D015373:Bacterial Typing Techniques; D016022:Case-Control Studies; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology* / Q000503:physiopathology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology* / Q000503:physiopathology; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008297:Male; D016106:Methicillin Resistance / Q000235:genetics; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology* / Q000503:physiopathology