title: Impact of traditional hospital strain of methicillin-resistant Staphylococcus aureus (MRSA) and community strain of MRSA on mortality in patients with community-onset S aureus bacteremia.
abstract: Community-associated methicillin-resistant Staphylococcus aureus (MRSA) has become an important pathogen in community and nosocomial infections. The impact of these emerging MRSA strains on mortality in adult patients with community-onset S aureus bacteremia remains uncertain. We defined community strain MRSA (CoSt-MRSA) and hospital strain MRSA (HoSt-MRSA) according to the results of staphylococcus cassette chromosome mec (SCCmec) molecular typing: CoSt-MRSA isolates had SCCmec type IV or V genes, and HoSt-MRSA isolates had SCCmec type I, II, or III genes. We quantitatively evaluated the impact of the MRSA strain on mortality in patients with CoSt-MRSA or HoSt-MRSA bacteremia by comparison with mortality in patients with methicillin-susceptible S aureus (MSSA) bacteremia.We studied an observational cohort of 500 patients with MSSA bacteremia, 111 patients with CoSt-MRSA, and 133 patients with HoSt-MRSA bacteremia from January 1, 2001, through December 31, 2007. The 90-day cumulative probability of survival in patients with MSSA, CoSt-MRSA, and HoSt-MRSA bacteremia was 71%, 70%, and 55%, respectively (p = 0.014, by Wilcoxon rank-sum test).Compared to patients with MSSA bacteremia, patients with HoSt-MRSA bacteremia were associated with an increased risk of mortality in the first multivariate analysis model adjusting for all potential confounders (hazard ratio [HR], 1.525; 95% confidence interval [CI], 1.091-2.131), in the second model adjusting for all confounders except acute severity of bacteremia (HR, 1.489; 95% CI, 1.071-2.070), and in stratified analysis in patients with low Charlson comorbidity scores (score 0-2) (HR, 3.093; 95% CI, 1.507-6.350).Compared to patients with MSSA bacteremia, patients with CoSt-MRSA bacteremia did not show significant differences in mortality rate in the 2 multivariate analysis models (first model: HR, 1.106; 95% CI, 0.748-1.637; second model: HR, 1.028; 95% CI, 0.697-1.516) or in stratified analysis (HR, 1.092; 95% CI, 0.539-2.214).In conclusion, using MSSA as reference, traditional hospital strain MRSA had a higher impact on bacteremia mortality than community strain MRSA.
authors.affiliation: From Department of Emergency Medicine (SYC); Division of Infectious Diseases (JTW, SCC), Department of Internal Medicine; and Department of Laboratory Medicine (PRH), National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei; Institute of Preventive Medicine (SYC, JTW, MSL, WCC, KLC); and Institute of Epidemiology (THHC), College of Public Health, National Taiwan University, Taipei; and Department of Internal Medicine (JLW), E-Da Hospital, I-Shou University, Kaohsiung, Taiwan.
authors.forename: Shey-Ying
authors.initials: SY
authors.lastname: Chen
authors.forename: Jann-Tay
authors.initials: JT
authors.lastname: Wang
authors.forename: Tony Hsiu-Hsi
authors.initials: TH
authors.lastname: Chen
authors.forename: Mei-Shu
authors.initials: MS
authors.lastname: Lai
authors.forename: Wei-Chu
authors.initials: WC
authors.lastname: Chie
authors.forename: Kuo-Liong
authors.initials: KL
authors.lastname: Chien
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
authors.forename: Jiun-Ling
authors.initials: JL
authors.lastname: Wang
authors.forename: Shan-Chwen
authors.initials: SC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000890:Anti-Infective Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000382:microbiology* / Q000401:mortality*; D017714:Community-Acquired Infections / Q000401:mortality*; D003428:Cross Infection / Q000382:microbiology* / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008875:Middle Aged; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000401:mortality*; D015996:Survival Rate; D055815:Young Adult
chemical_list: D000890:Anti-Infective Agents
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